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Published by CFS Documentation cell Division of Centre for Electronics Design and Technology of India A Scientific Society of Department of Electronics, Govt. of India, New Delhi.

First Edition: 1999

TRADE MARKS: All brand name and product names mentioned in this book are trade marks or registered trade mark of their respective companies. Every effort has been made to supply complete and accurate information. However, CEDTI assumes no responsibility for its use, nor for any infringement of the intellectual property rights of third parties which would result from such use. No part of this publication may be stored in a retrieval system, transmitted or reproduced in any forms or by any means, electronic, photocopy, photograph, magnetic or otherwise, without written permission of CEDTI.

CEDTI/CFS/99/4/5.3/R1

FOREWORD The Information Technology and Telecom sectors have suddenly opened up avenues, which require a very large specially trained manpower. These sectors are highly dynamic and need training and re-training of manpower at a rapid rate. The growing gap of requirement of the industry and its fulfilment has created a challenging situation before manpower training institutes of the country. To meet this challenge most effectively, Centre for Electronics Design and Technology of India (CEDTI) has launched its nation-wide franchising scheme. Centre for Electronics Design and Technology of India (CEDTI) is an Autonomous Scientific Society under the Govt. of India, Department of Electronics with its Headquarters at New Delhi. It operates seven centres located at Aurangabad, Calicut, Gorakhpur, Imphal, Mohali, Jammu and Tezpur. The scheme will be implemented and coordinated by these centres. The scheme endeavours to promote high quality computer and information technology education in the country at an affordable cost while ensuring uniform standards in order to build a national resource of trained manpower. Low course fees will make this education available to people in relatively small, semi urban and rural areas. State-of-the-art training will be provided keeping in view the existing and emerging needs of the industrial and Govt. sectors. The examinations will be conducted by CEDTI and certificates will also be awarded by CEDTI. The scheme will be operated through all the seven centres of CEDTI. The CEDTI functions under the overall control and guidance of the Governing Council with Secretary, Department of Electronics as its Chairman. The members of the council are drawn from scientific, government and industrial sectors. The Centres have separate executive committees headed by Director General, CEDTI. The members of these committees are from academic/professional institutes, state governments, industry and department of electronics. CEDTI is a quality conscious organisation and has taken steps to formally get recognition of the quality and standards in various activities. CEDTI, Mohali was granted the prestigious ISO 9002 certificate in 1997. The other centres have taken steps to obtain the certification as early as possible. This quality consciousness will assist CEDTI in globalizing some of its activities. In keeping with its philosophy of ‘Quality in every Activity’, CEDTI will endeavour to impart state of the art – computer and IT training through its franchising scheme. The thrust of the Software Courses is to train the students at various levels to carry out the Management Information System functions of a medium sized esTablishment, manufacture Software for domestic and export use, make multimedia presentations for management and effectively produce various manufacturing and architectural designs. The thrust of the Hardware Courses at Technician and Telecommunication Equipment Maintenance Course levels is to train the students to diagnose the faults and carry out repairs at card level in computers, instruments, EPABX, Fax etc. and other office equipment. At Engineer and Network Engineer levels the thrust is to train them as System Engineers to instal and supervise the Window NT, Netware and Unix Networking Systems and repair Microcontrollers / Microprocessor based electronic applications.

An Advisory Committee comprising eminent and expert personalities from the Information Technology field have been constituted to advise CEDTI on introduction of new courses and revising the syllabus of existing courses to meet the changing IT needs of the trade, industry and service sectors. The ultimate objective is to provide industry-specific quality education in modular form to supplement the formal education. The study material has been prepared by the CEDTI, document centre. It is based on the vast and rich instructional experience of all the CEDTI centres. Any suggestions on the improvement of the study material will be most welcome.

(R. S. Khandpur) Director General (CEDTI)

1. INTRODUCTION TO DATA TYPES AND CONVENTIONS OF AutoLISP

1.1 INTEGER An Integer is a whole number that does not contain a decimal point. AutoLISP integers are 32 bit signed numbers with values ranging from + 2,147,483 to - 2,147. AutoLISP uses 32 bit internally; those transferred between AutoLISP and AutoCAD are restricted to 16 bit values and hence the user can pass integer values ranging from - 32,768 to + 32,767 only. e.g.: 23, 45, -32768

1.2 REAL A real number is a number containing a decimal point (i.e., floating point numbers) and can be either positive or negative. Real numbers are stored in double precision floating point format, providing at least 14 significant digits of precision, even through the AutoCAD command line areas shows only 6 significant digits. e.g.: 34, 56, 123, -29.9,-3.0

1.3 STRING A string is a group of characters enclosed within quoted strings. The backslash allows control characters or escape code to be included within the string. Individual strings are limited to 132 characters. e.g. :“cadd”, “CADD”, “123”, “A123”, A123” “\nEnter first point”

1.4 LIST A list is a group of related values separated by spaces and enclosed within parenthesis. List provides an efficient method of storing numerous related values. e.g.: (3 2 4) (a b c d), (1 “ONE”)

1.5 SYMBOL A symbol is a character or a collection of alphanumeric and notation characters except the following: (), ., `,” and;. A symbol name cannot consists of only numeric characters.



e.g.: a, xyz, a1, p1

1.6 FILE DESCRIPTOR File descriptors are alphanumeric labels assigned to files opened by AutoLISP. When an AutoLISP function needs to write or read from a file the label of the must be referenced. The following example opens the file text.dat for reading. Command: (open “text.dat” “r”)

1.7 ENTITY NAMES An entity name is a number assigned to objects in a drawing. It is actually a pointer to a file maintained by AutoCAD from which AutoLISP can find the object’s database record and its vectors. This label can be referenced by AutoLISP functions to allow a selection of objects for processing in various ways. The following example uses the “entlast”, function to get the name of the last object entered into the drawing. Command: (entlast)

1.8 SELECTION SETS Selection sets are groups of one or more objects. You can interactively add objects to or more objects from selection sets, with AutoLISP routines.

1.9 SURBS AND EXTERNAL SUBRS Most of the AutoLISP functions are built-in subroutines called SUBRS. The functions defined by external ADS and ARX applications are called EXTERNAL SUBRS. The names of Subrs and External subrs are not case sensitive. For example the “princ” function is a Subrs. The “acad_strlsort” function is External subrs.

1.10 CONSTANTS When you explicitly use a data type in an AutoLISP expression that value is known in a constant. There is a predefined constant pi evaluating to 3.14159 and a symbol T evaluating to “TRUE”. Constants should not be used as symbols. For example in the following expression the symbol “a” is set to a constant value “CADD”.



Command: (setq a “CADD”)

1.11 CONVENTIONS OF AUTOLISP AutoLISP code is usually stored in ASCII text files with a “.LSP” or “.MNL’ extension. Although AutoLISP code can be entered at the command line, testing and debugging are considerably easier when you load the AutoLISP code from a file rather than re-enter it each time when you make a refinement. •

AutoLISP follows the prefix notation . i.e., the function name should precede the arguments. e.g. (+ 4 5)

•

Symbol names can consist of any sequence of printable characters except the following:- (), `, “, ; and \

•

Expressions can span multiple lines. Each expression beings with a left parenthesis and consist of a function name and an optional list of arguments, each of which can itself be an expression. The expression ends with a right parenthesis. e.g. (+ 2 3). The arguments in form of expression lead to nesting of functions. e.g. ( + 2 3 ), ( + A B), (+ 2 3) 4)

•

The following characters terminate a symbol name or a numeric constant (), `, “, ; , (space) and end of line)

•

More than one blank space in an expression is considered as a single space. e.g. ( + 2 3 ), ( + 2 3) 7)

•

An AutoLISP expression or a function should start with a open or left parternership i.e., “(“and end with a close or right parenthesis”)”.

•

Symbol and function names are not case sensitive, i.e., you may use upper or lower case characters.

•

Numerals can be preceded by an optional “+” or “-” sign.

•

Real numbers consist of one or more numeric digits, followed by a decimal point i.e., .4 is not recognized as a real; it should be entered as 0.4. Similarly 5. is not recognized as real; it should be entered as 5.0. Integer values range between 32,768 and +32,767.

•

There should be a blank space between a function name and its arguments.



•

Expressions nested within other expressions return their result to the surrounding expressions. AutoLISP evaluates from the innermost expression and returns the value to the surrounding expressions. e.g. (+ (*3 2) (/ (+1.5 2.5))) returns 8.0

•

Comments can be included in a program and they should begin with a semicolon “ ; ” e.g. (+ 5 3 )

•

; This is an Addition

Variables can be evaluated at the “Command prompt” in autoCAD with a preceding “!” symbol. e.g. (seta 1 3) Command: !a returns 3

2. ARITHMETIC AND TRIGONOMETRIC FUNCTIONS

2.1 ARITHMETIC FUNCTIONS Thee are four functions under this group. The arguments for these function can be numbers, variables, symbols and constants. If any one argument is real then the result will be a real value. If all the arguments are integers then the result will be an integer. Syntax : (+ ...)

This function returns the sum of all numbers, which are real or integer. If all numbers are integers then the result is an integer value. If any one number is a real number then the result will be a real value. e.g. Command: (+ 5 3)

returns 8

(+ 6.2 3)

returns 9.2

(+ 8.75 -4)

returns 4.75

(+ 5. 7 9)

returns 21.0

Syntax: (- ...)



This function returns the result after subtracting from . If more than two numbers are given as arguments then the result will be the sum of second and the remaining arguments subtracted from . If only one argument is present then the result will be the value of subtraced from 0. e.g. Command: (- 5 4)

Syntax: (

returns 1

(- 5.5 2)

returns 5.5

(- 8 6 4)

returns -2

(- 10 -5)

returns 15

(- 3)

returns -3

...)

This function returns the product of all operands. If only one is given then this function returns the result of multiplying it by one and supplying no arguments returns the result zero.

e.g. Command: (* 5 4)

returns 20

(* 5.5 2)

returns 11.0

(* 1 2 3)

returns 6

Syntax: (/

...)

This function returns the quotient by dividing by . If more than two operands are given then will be divided by the product of others. If only one is given the function returns the result dividing it by one and supplying no arguments returns zero. e.g. Command: (/ 5 4)

returns 1

(/ 5 4.0)

returns 1.25

(/ 12 2 3)

returns 2

2.2 TRIGONOMETRIC FUNCTIONS



There are three functions under this group. Using these basic. Trigonometric functions you can evaluate any expressions involving Trigonometric calculations. Sin Syntax: (cos) This function returns the sine value of the as a real value. The = Syntax: (>= [...]) This checks and returns T if is greater than or equal to and nil otherwise. If more than two s are given then T is returned, if each is GREATER THAN or EQUAL TO the to its right. e.g.

(> = 50 40)

returns T

(> = 5 4 3 2)

returns T

(> = 45 3 2)

returns nil

(> = “b” “c”)

returns nil

eq Syntax: (eg )



This function returns, T if the two expressions given are identical. Otherwise it returns NIL. This function determines whether and are bound to the same object. e.g. Command:

(setq a `(1 2 3) b `(1 2 3) c b) (eq a c) returns nil

This returns nil because a and c are not the same lists. (eq b c)

returns nil

This returns T if a and b are exactly the same. equal Syntax: (equal []) This function returns T, if the two expressions evaluate to the same value. This is not the same as eq function. the optional parameter denotes the maximum amount by which the and can differ and still be considered equal. e.g. Command:

(setq a(*3 2) b (*6 1) ) (equal a b)

returns T

(equal `a `b)

returns nil

e.g. Command:

(setq a 5.34679105) (setq b 5.34678106) (equal a b 0.00000001)

return T

minusp Syntax: (minusp ) This function returns, T if the specified is negative and otherwise it returns NIL. e.g. Command:

(minusp -1)

returns T



(minusp -3,4)

returns T

(minusp 4)

returns nil

boundp Syntax: (boundp ) This function returns T, if the specified is bound to a symbol and returns NIL if no value is bound to the . If the is an undefined symbol then it is automatically created and is bound to NIL.

e.g. Command:

(setq a 1 b bil) (boundp `a)

returns T

(boundp `b)

returns nil

zerop Syntax: (zerop ) This function returns T, if the specified is real or integer and evaluated to zero. Otherwise it returns NIL. e.g. Command:

(setq a 0 b 1) (zerop a)

returns T

(zerop b)

returns nil

(zero 0.1)

returns nil

listp Syntax: (listp ) This function returns T, if the specified is a list. Otherwise it returns NIL. e.g. Command:

(setq a `( (2 3) 4 5) )



(listp a)

returns T

(listp (cadr a) )

returns T

(listp `a)

retuns nil

type Syntax: (type ) This function checks the data type of the specified . The allowed data types are: TYPE

DESCRIPTION

REAL

Floating-point numbers

FILE

File descriptors

STR

Strings

INT

Integers

SYM

Symbols

LIST

Lists

SUBR

Internal functions

PICKSET

Selection sets

ENAME

Entity names

PAGETB e.g.

Function paging table

Command:

(setq a 1 b 4.5 d `(1 2 3) ) (type a)

returns INT

(type b)

returns REAL

(type d)

returns LIST

(type - )

returns SUBR

(type c)

returns nil

6.1 LOGICAL OPERATORS Syntax: (and ....)



This function returns T if all the s evaluate to a non nil value. It returns NIL, if any one of the given s evaluate to NIL and ceases further evaluation. You can also supply variable names as s. e.g. Command: (setq a 5 b 10 c nil) (and (> a 2) (< b 25 ) 0

returns T

(and (= a 5) (= c 05) )

returns nil

(and a b)

returns T

(and a b c)

returns nil

or Syntax: (for ...) The function returns the value T, if any one or all the s in the argument list evaluate to a non nil value. If all the s evaluate to nil then the function returns NIL. Variable names can also be supplied as arguments. e.g. Command: (setq x 10 y 20 z 30 a nil b nl) (or (= x 10) (= y 2) )

returns T

(or (= x 10) (= y 20) )

returns T

(or (= x 11) (= y 21) )

returns nil

(or x ( (= y 20) )

returns T

(or x y)

returns T

(or a b)

returns nil



7. STRING HANDLING FUNCTIONS

String is a group of characters enclosed within quotation marks. A single string value is limited to 132 characters. Strings of unlimited length can be created by joining the strings together and control characters can also be included within quoted strings. Applications can also compare a string to a wild-card pattern and this facility is widely used when you are building a selection set and retrieving the entirely data by application name. strcase Syntax: (strcase []) This function converts the alphabetic characters of the to upper or lower case, depending on the optional argument . When is not specified or evaluated to NIL, the is converted to upper case. Otherwise it is converted to lower case characters. e.g. Command: (strcase “Hello”)

returns “HELLO”

(strcase “HELLo” 1)

returns “hello”

strcat Syntax: (strcat string2>...) This function combines multiple strings into a single string vlaue Blank and null strings can also be combined. e.g. Command: (strcat “cadd” “centre”)

returns “cadcentre”

(strcat “cadd” “ “ “centre” returns “cadd centre” strlen Syntax: (strlen ) This function returns the number of characters in the specified . Blank spaces are also considered as valid characters. e.g. Command: (strlen “AutoCAD Mechanical Desktop”)



returns 26

(strlen “cadd”)

returns 5

(strlen “ “)

returns 1

substr Syntax: (substr []) This function returns the substring of a . The argument specifies the first character of the string to be included the substring. The number of characters to be included in the substring is specified by . If is not specified then the function returns all characters including the following the specified character. e.g. Command: (substr “strength” 3 4)

returns “reng”

(substr “strength” 3)

returns “rength”

(substr “cadd centre” 3)

returns “dd centre”

(substr “cadd centre” 3 4)

returns “dd c”

(substr “cadd centre” 1)

returns “cadd centre”

(substr “cadd centre” 10)

returns “re”

wcmatch Syntax: (wcmatch ) This function enables the application to compare a to a wild-card pattern. If the string matches with the pattern then this function returns T else NIL. The wild-card patterns are similar to the regular expressions used by many application programs. The and the can be either a quoted string or a variable. This function compares the first 500 characters of the and specified. The can contain the wild-card matching characters shown in the following table: CHAR

DEFINITION

#

Matches any single numeric digit.

@

Matches any alphabetic character.



.

Matches any single non alphanumeric character

* Matches any character sequence including an empty string and can be used anywhere in the search pattern. ?

Matches any single character.

~

Matches any thing other than the next character.

[..]

Matches any one of the characters inside.

[~..]

Matches any one character except those enclosed.

-

Used in [ ] to specify a range of characters.

,

Separates any two patterns.

`

Escapes special characters.

The following example tests the string with the patterns. e.g. Command: (wcmatch “Name” “N*”)

returnsT

(wcmatch “Name” ???,~*m*,N*”)

returns T

(wcmatch “Name” “*”, *”)

returns NIL

read Syntax: (read< string>) This function returns the first atom or list in the specified . The cannot contain blank spaces except within list or string. e.g. Command: (read “end”)

returns end

(read “end of”)

returns end

In the above case from the string “end of” only end is returned as, a blank space is encountered after the first word.



8. CONVERSION FUNCTIONS The functions convert data types and units. AutoLISP also provides functions to handle decimal ASCII codes. atof Syntax: (atof ) This function returns the conversion of a string to a real value. e.g. Command: (atof “3.4”) (atof “5’

returns 3.4 returns 5.0

atoi Syntax: (atoi ) This function returns the conversion of a string to an integer. e.g. Command: (atoi “34”) (atoi “5.0”)

returns 34 returns 5

itoa Syntax: (itoa ) This function returns the integer given as arguemnt into a string. e.g. Command: (itoa 34)

returns “34”

rtos Syntax: (rtos [mode>] [precision>]) This function converts the specified to a string according to the settings of and . The and arguments must be integers. The following are the argument values:



MODE

EDITING FORMAT

1. 2. 3. 4. 5.

Scientific Decimal Engineering (feet and decimal inches) Architectural (feet and fractional inches) Fractional

The denotes the number of decimal places. When and are not specified, the current strings of the AutoCAD system variables LUNITS and LUPRECA are used. e.g. Command: (rtos 3.4)

returns “3.4000”

(rtos 5 2 2)

returns “5.00”

(rtos 3.5 4)

returns “3 1/2”

(rtos 2.5 1 2)

returns “2.50 E+00”

ascii Syntax: (ascii ) This function returns the ascii code of the first character of the . e.g. Command: (ascii “A”)

returns 65

(ascii “CADD”

returns 67 (ASCII coee of “C”

angtos Syntax: (angtos [[ ]]) This function is used to convert the specified to a string depending on the settings of and . The arguments and must be integer values. The following are the argument values: MODE

EDITING FORMAT

0 1 2

Degrees Degrees/minutes/seconds Grads



3 4

Radians Surveyor’s units

The denotes the number of decimal places. When and are not specified, the current settings of the AutoCAD system variables AUNITS and AUPREC are used.

e.g. Command: (setq a (angle (` 2 4 ) ` (2 2) ) ) (angtos a 0 0)

returns “270”

(angtos a 1 0)

returns “270d”

(angtos a 0 4)

returns “270.0000”

(angtos a 3 3)

returns “4.712r”

chr Syntax: (chr ) This function returns the ASCII characters corresponding to the integer given as argument. The value returned is a string. e.g. Command: (chr 65) (chr 97)

returns “A” returns “a”

rem Syntax: (ren ...) The list function combines a number of expressions into a list. This returns the ‘s as independent elements within parentheses. The elements can be of any type, the number of elements are not limited and this function is frequently used to define a 2D or 3D point variable (a list of two or three real). e.g. Command:

(list 5 10.0)

returns (5 10.0)

(list “A” “B”)

returns (“A” “B”)

(list 5 “A”)

returns ( 5 “A”)

(list `A `B)

returns (A B)

(list (list 5 10) )

returns ((5 10))

(setq A 2 B 5) (list A B)

returns (2 5)

(list (+ A 4) B)

returns (6 5)

The list function may be a nested list, which contains lists as members. e.g. Command:

(setq K (list 1 2 3) )

returns (1 2 3)



(setq L (list“C” “A” “D” “D”)

returns (“C” “A” “D” “D”)

(setq K L

returns ((1 2 3) (“C” “A” “D” “D”))

Polar Syntax: (polar ) This function locates a 3D point with respect to the given at a given and . The must be specified in RADIANS. Though the can be a 3D point, is always with respect to the current construction plane. The point is a list of two real. e.g. Command: (polar `(2 2) 0 3)

returns (5.0 2.0)

The new point is fixed at an angle 0, at a distance of 3 units from the point 2,2. Command: (polar (`2 2) 0.785398 1.414)

returns (3.0 3.0)

The new point is located at an angle of 45 degrees (denoted as 0.785398 in radian measure) at a distance of 1.414 from 2,2. angle Syntax: (angle ) This function returns the angle between the two given points in RADIANS. The angle is measured from X axis of current construction plane and if a 3D point is supplied then they are project onto the current construction plane. e.g. Command:

(angle `(2 2) `(3 3))

returns 0.785398

(corresponds to 45 degrees) (angle `(2 2) `(3 4))

returns 1.5707

(corresponds to 90 degrees) (angle `(2 2) `(4 2))

returns 0.0

(corresponds of 0 degrees) distance Syntax: (distance ) This function returns the numeric distance between the two given points and . The points can be list of a 2 or 3 real numbers or integers.



e.g. Command:

(setq P1 `(2 2) P2 `(2 4)) (distance P1 P2)

returns 2.0

(setq P1 `(2 0 0) P2 `(0 0 2 )) (distance P1 P2)

returns 2.82843

FILE HANDLING Every engineering design process, irrespective of the trade, whether Mechanical, Civil or Architectural, needs data. These data are standards and thumb rules for an optimum design solution. In conventional design process, an engineer has to repeatedly refer volumes of catalogs, tables and charts which is a tedious process. In the modern world, where computers are used to aid in the design process, one need not look the design data table. All the necessary data can be stored as data files and the design program can be made to open and read the files to locate the data. Data files in the present scenario are simple ASCII files generated either manually or through some other means AutoLISP provides powerful yet simple functions to search and access the data files, read and write/append information on to the data file. A file can be opened and read/modified anywhere in a program. When you open a file, AutoLISP provides a pointer which has to be assigned to a variable for further reference. The functions included in this chapter are as listed below. The functions included in this chapter are,

findfile

open

close

read-line

write-line

read-char

write-char

getfiled

findfile

Searches the AutoCAD library path for the specified file findfile ) Returns:



If the file is found

Path of file as a STRING

If the file is not found

nil

The FINDFILE function searches for the given file whose name is given as the string argument in the AutoCAD library path. The file name should also include the extension of the file. If the drive or directory prefix is given then the file is searched only in the specified drive or directory. Example: If there is a file named “shaft.lsp” in the path c:\acadr14,then, Command: (findfile “shaft.lsp”) “C:\\ACADR14\\shaft.lsp” otherwise, Command: (findfile “shaft.lsp”) Nil Open Opens a file for access by the AutoLISP I/O functions (open Returns: If the file is found

File Pointer (descriptor)

If the file is not found

nil

The filename argument is a string that specifies the name and extension of the file to be opened. The mode argument is the read/write flag. It must be a string containing a single lower case letter. The following table describes the valid mode letters.

Open mode

Description

“r”

Open for reading. If filename does not exit, open returns nil.

“w”

Open for writing. If filename does not exit, a new files is created and opened. If filename already exists, Its existing data is overwritten.

“a”

Open for appending. If filename does not exit, a new file is created a new file is created and opened. If filename already exists, it is opened and the



pointer is positioned at the end of the existing data, so new data you write to the file is appended to the existing data. Open function returns a file description to be used by the other I/O functions. The file descriptor must be assigned to a symbol that uses the seta function as shown below. All further reference to the file should be through the file descriptor. Example Assuming that the files named in the following examples do not exit, Command: (setq f (open “new.txt” “w”)

Command: (setq f(open “nosuch.fil” “r”)) nil Command: (setq f (open “lofgile” “a”))

When a file “data.txt” exists, Command: (setq f (open “data.txt” “r”))

Close Closes an open file (close ) Returns on success

nil

on failure

error message

The argument is a file descriptor obtained from the open function. After a close, the file descriptor is unchanged but is no longer valid. All files opened in a program have to be closed before the program is terminated. Example The following code counts the number of lines in the file check.txt and sets the variable no_lines equal to that number: (setq fil_id(open “check.txt” “r”) no_lines 0) (while (read-linefil_id) (setq no_lines ( 1 + no_lines))) (close fil_id)



read – char Returns the ASCII code of the character read from an open file or from keyboard. (read-char []) Returns on success

nil

on failure

error message

This function returns the decimal ASCII code representing the character read from the keyboard input buffer or from an open file described by the . If there are no s and characters in the keyboard input buffer, the function waits for a keyboard input. Example Command: (setq f (open “data.txt” “r”))

Command: (read-char f) 106

write – char Writes a character to the screen or to an open file (write – char []) Returns on success

write the character

on failure

error message

This function writes a character to the screen or to an open file. The argument is a decimal ASCII code for the character specified by the . If no is given then the character is written on the screen else the character will be written to the specified file. Example Command: (write – char 65) A Command: setq fp O(open “data.txt” “a” ))

Command: (write – char 65 fp)



The last example writes character A onto the open file whose is fp. In either case, WRITE – CHAR will echo the argument (65 in this case) at the Command: prompt read – line

Reads a string from the keyboard or from an open file. (read – line []) Returns on success

line read as string

on failure

nil

This function returns the line read from the keyboard or from an open file. When this function is repeated with the file descriptor then the function returns the next line of the file. Example Assuming that fp is a valid open file pointer, (read-line fp) returns the next input line from the file, or returns nil if the end-of-file has been reached. write – line Writes a string to the screen or to an open file (write – line []) Returns: on success

string omitting the quotes

on failure error message This function write the to the screen or to an open file. The function returns a quoted string to the file if is specified. Otherwise the is written on the screen Example Assuming that fp is a valid open file descriptor. (write – line “Welcome” fp) writes Welcome in the file.



getfiled Display the standard AutoCAD file dialog box, and returns that the name

(getfiled ) Returns If file is selected

the file selected as string

If file not selected

nil

The argument specifies the dialog box label. The arguments specifies a default file name to use for the dialog box. It can be empty string also. The argument specifies the default file name extension, used as a mask for the files presented to the user in a scrolling list box. This function returns the name of the selected by the user, or nil if no file was selected. The argument is an integer value ( a bit-coded field), the meaning of the various bit values are:

Bit Value

Meaning

1. 2. 4. 8.

Display “alert” message if the user selects an existing file. Disables the “Type It” button in the dialog box. Allows the user to change the file extension or no extension at all. Performs an AutoCAD library search for the filename entered.

Example: Command: (getfiled “Select a Lisp File” “c:\acadr14” “lsp” 8) “C:\\ACADR14\\Surf.lsp”

If you choose a file from the dialog box and click on OK then AutoCAD returns the selected lisp file name.

ENTITY HANDLING entlast Returns the name of the last non-deleted main object (entity) in the drawing.

(entlast) The entity name of the last drawn entity.



The entlast function is frequently used to obtain the name of a new entity that has just been added with the command function. The entity need not be on the screen or on a thawed layer to be selected. Example: (setq e1 (entlast)) Sets e1 to the name of the last drawn entity in the drawing.

entnext Returns the name of the next object (entityO in the drawing.

(entnext []) Returns: if next entity is found

The Entity name of the entity

if not found

nil

This function retrieves entity names sequentially. When the optional parameter is not specified, the function returns the entity name of the first entity in database, else it returns the name of the seceding entity specified by . Example (setq e1 (entnext)) returns the entity name of the first entity in the drawing. (setq e2 (entnext e1)) returns the entity name of the entity following e1.

entsel Prompts the user to select a single object (entity) by specifying a point (entsel []) Returns entity found at point picked

The Entity name and the point picked as a

Entity not found

nil

list.



This function is used to select an entity by specifying a point. The function returns a list containing entity name and the point selected. When the optional argument is specified, AutoCAD prints the string in the command prompt area and waits for user input. When it is not specified, AutoCAD displays a default prompt Select Object: in the command prompt are: Example: Assuming if there is an object passing through point 3,3 Command: (entsel “Pick entity:”) Pick entity: 3,3 ( (3.000000 3.000000 0.0))

nentsel Prompts the user to select an object (entity) by specifying a point, and provides access to the definition data contained within a complex object. (nentsel []) Returns Entity found at point picked Entity not found

The Entity name and the point picked as a list nil

This function provides access to the entities contained inside a nested entity. (such as POLYLINES and INSERTS) If the optional argument is passed then this function waits for user selection by issuing or else a standard prompt Select Object: will be issued. If the selected objet is not a nested entity (i.e. neither a POLYLINE nor a BLOCK INSERT) then this function returns same information as ENTSELF function. When a sub entity of a nested entity is selected, this function returns a list containing 4 elements. The first element of that list will be entity name of the selected subentity. The second element will be the point of selection, third one will be a matrix called `Model to World Transformation Matrix’ which specifies the location of the sub entity with respect to the insertion point of the block. The fourth member of the above list will be entity name of the block that contains the selected sub entity. If the selected entity is an ATTRIBUTE of an INSERT then this function returns only the entity name of the attribute and the pick point. The nentsel function will be a list as follows: ( (Px Py Pz) ((X0 Y0 Z0) (X1 Y1 Z1) (X2 Y2 Z2) (X3 Y3 Z)

Name of entity Pick point Model to World transformation matrix



) ( selected entity ) selected entity. )

Name of most deeply nested block containing

Name

of

outermost

block

containing

entupd Updates the screen image of an object (entity) (entupd ) Returns on success

The Entity name

When a polyline vertex or block attribute is modified with entmod, the entire complex entity is not updated on the screen. The entupd function can be used to cause a modified polyline or block to be updated on the screen. This function can be called with the entity name of any part of the polyline or block; it need not be the head entity. While entupd is intended for polylines and blocks with attributes, it can be called for any entity. It always regenerates the entity on the screen, including all subentities. Example Assuming that the first entity in the drawing is a polyline with spline fit data and with several vertices, then (setq e1 (entnext)) (setq e2 (entnext)) (setq en (entget)) (setq ed (subt (`10 1.0.2.0)

;Sets e1 to the polyline’s entity name ;Sets e2 to its first vertex ;Sets en to the vertex data ;Changes the vertex’s location in en to point ;(1,2)

assoc 10 en) en) ) (entmod en) (entupd e1)

;Moves the vertex in the drawing ;Regenerates the polyline entity e1

entmod Modifies the definition data of an object (entity) Entmod )



Returns on success

The Entity list

on failure

error message (mostly Bad entmod list).

This function modifies the database of the entity specified by . The is the associative list of the entity obtained by entget function. Example (command “line “ “2,3” “4,5” “ “) (setq en (entnext) e1 (entget en) ; gets the entity list of the line. e1(subst (cons 10 (list 4 4))(assoc 10 e1)e1) ) ;changes the starting point of the line to 4,4 (entmod e1) ;updates the database

entdel Deletes objects (entities) or undeletes previously deleted objects. (entdel ) Returns on success

The Entity name

on failure

error message (bad argument type)

This function is used to delete an entity in the current drawing editor. When used again, it undeletes the entity specified by in the current drawing editor. All deleted entities are purged when the current drawing is exited. Example If `a’ is a valid entity name, deletes the entity and returns entity name Command: (entdel a)

If `b’ is not a valid entity name Command: (entdel b) Error: bad argument type (ENTDEL B) *Cancel*



entmake Creates a new entity (graphical object) in the drawing (entmake ) Returns on success

The Entity

on failure

error message (bad entmake list value)

This function creates a new entity in the current drawing making use of the entity list specified by as the definition data. If successful then this returns the definition data and nil otherwise. The minimum data for making an entity are as follows: 1.

Entity type

2.

Basic geometric data

3.

Optional arguments

a. b. c. d. e. f.

Color Layer Linetype Extrusion direction Elevation Thickness

1.

Valid entity types are “LINE”, CIRCLE”, “ARC”, etc.,

2.

Geometric data for: LINE: Start point & End point CIRCLE: Center point & Radius



SELECTION SET SSGET FILTERS (ssget “X” This function selects all the entities conforming to a specified filter list. The is an association list that is used as a check to select objects. Each sub-list in the contains the group code and the value to matched. The group codes that can be used in a ssget “X” function are,

Code

Meaning

0 2 6 7 8 38 39 62

Entity type Block name of block references Line type name Text style name for text and attribute definitions Layer name Elevation (real) Thickness (real) color number (0 => “BYBLOCK” 256 = > “BYLAYER”) Attributes – follow flag for block references 3D extrusion direction vector (list of three reals).

66 210 Example:

(ssget “X” (list (cons 0 “line”))) (ssget “X” (list cons 0 “line”) (cons 8 “C”)))

;selects all lines ;selects all lines in the layer named C

sslength Returns an integer containing the number of objects (entities) in selection set (sslength)

)

Returns on success

no of entity names present in the set

on failure

error message

The number is returned as a real if it is greater than 32, 767. Selection sets never contain duplicate selections of the same entity.



Example (setq sset (ssget “L”)) sset

;Places the last object in selection set

(sslength sset)

ssdel Deletes an object (entity) from a selection set (ssdel < ename > selection set name on failure error message This is used to delete the entity specified by < ename > from the selection set . It returns the new selection set. If the entity is not found in the , the function returns nil. Example

(setq sd (ssget “X” (list (cons 0 :line”))); place all lines in the selection ; set sd. (set1 e1 (ssname sd0))

;selects the first entity in the ;selection set sd.

(ssdel e1 sd)

;deletes the lines e1 from the set sd.

sssetfirst Sets which objects are selected and gripped (sssetfirst [pickset>]) Returns on success

list of the variables passed

on failure

error message

Example The expressions below grips all the entities in the drawing Command: (setq a (ssget “x”))

Command: (sssetfirst a) (A)

ssgetfirst



Determines which objects are selected and gripped (ssgetfirst Returns on success

list of the selection sets (gripped / selected)

on failure

error message

Example Command: (ssgetfirst) [ nil)

APPLICATION HANDLING Almost all environments and software provide the user the tools to develop applications for his/her need through customization. It is appropriate because it is very difficult or rather impractical to group all the needs of the user by software developer himself. In this context, understanding the importance and the advantages of customization, Autodesk has developed AutoCAD with an open architecture, which encourages customizing to a large extent. Autodesk has considered both the noise and experienced user has given tools for various levels of customization. It depends on the knowledge and experience of the user, in AutoCAD as well as other programming language such as AutoLISP and C. It is also based on the nature and complexity of the application to the developed. AutoCAD can be customized through,

¾ ¾ ¾

AutoLISP, a programming language framed by the Autodesk for developing small applications involving either designing or drafting in AutoCAD. ADS – AutoCAD Development System, a programming language using the structure of `C’ language. ARX – AutoCAD Runtime Extension brings in the phenomena of OOPS in to AutoCAD environment. This is possible because of the C++ interface with AutoCAD. This increases the power of AutoCAD many times. Using ARX you can develop your own application which can have its own objects. (AutoCAD itself is a C++ application)



In order to utilize the function defined in these customized applications inside AutoCAD, AutoLISP provides functions to load them. And the objective of this chapter is to enable you to use those functions to load, unload and execute them. The functions dealt in this chapter are as listed below, xload

xunload

ads

arx

arxload

autoarxload

Autoload

autoxload

autozrxload

xload Loads an ADS application (xload []) This function load an . If the application is successfully loaded then this returns the application name or returns a standard error message otherwise. However, if the argument is supplied then the function returns the value of this argument upon failure instead of an error message. This function fails to load if the application is already loaded. Example (xload “/myappx/xapp”) if successful, returns “/myappx/xapp”

xunload Unloads an ADS application (xunload []) This function unloads an specified. If the application is successfully unloaded then it returns the application name else returns an error message. The should be entered as it was entered during xload. The directory name can be omitted for this function. If the xunload application fails it causes an AutoLISP error. However if the argument is supplied the functions the value of this argument argument is supplied then the function returns the value of this argument instead of issuing an error message. Example: (xunload “ame”) if successful, returns “ame”

ads Returns a list of the currently loaded ADS applications (ads) Each ADS application loaded and its path is a quoted string in the list. arx Returns a list of the currently loaded ARX applications



(arx) Each ARX application loaded and its path is a quoted string in the list.

Example Command: (arx) (“acadapp.arx” “ geomal.arx” “oleaprof.arx”)

arxload Loads an ARX application (arxload []) The argument is entered as a quoted string or as a variable that contains the name of an executable file. At the time the file is loaded, it is verified to be a valid ARX application. If the arxload operation fails then it normally causes an AutoLISP error. However, if the argument is supplied then arxload returns the value of this argument upon failure instead of an error message. If the application is successfully loaded then the application name is returned.

arxunload Unloads an ARX []) If the is successfully unloaded then the name is returned, otherwise, an error message is issued. Enter as a quoted string or as a variable containing the name of an application that was loaded with the arxload function. The name must be entered exactly as it was entered for the arxload function. If a path (directory name) or extension was entered for the application in arxload, it can be omitted in the arxunload function.

autoload Predefines command names to load an associated AutoLISP file (autoload ) The argument is a string that specifies the “.lsp” file that is loaded when one of the command defined by the argument is entered at the command prompt. The argument must be a list of strings. The autoload function returns nil. The following code defines the C:APP1, C:APP2 and C:APP3 functions to load the “bounsapp.lsp” file. The fist time one of the command APP1, APP2 or APP3 are entered at the command prompt the ARX application loads and the command continues. Example: (autoload “BOUNSAPP” (“APP1” “APP2” “APP3”))



autoxload Predefines command names to load an associated ADS application. (autoxload ) The argument is a string that specifies the ADS file that is loaded when one of the commands defined by the argument is entered at the command prompt. The argument must be a list of strings. The autoxload function returns nil. The following code defines the C:APP1, C:APP3 and C:APP3 functions to load the “bounsapp.lsp” file. The first time one of the command APP1, APP2 or APP3 are entered at the command prompt the ARX application loads and the command continues.Example: (autoxload “BOUNSAPP” (“APP1” “APP2” “APP3”))

DIALOG CONTROL LANGUAGE [DCL]

AutoCAD gives you a language called as Dialog Control Language (DCL) which has got its own syntax and functions, using which you could design your dialog box. Autodesk has provided two file ACAD.DCL and BASE.DCL in which many of the commonly used dialog box components, their structure and layout are predefined. The definition a dialog box is written using Dialog Control Language in separate ASCII files that contain the descriptions of the various elements of the dialog box. The above file should have a file name extension .dcl. A .dcl file can contain the description of a single or multiple dialogue boxes. The arrangement of elements (tiles) in a dialog box, such as buttons and edit_boxes, is determined by their order in the .dcl file.

Dialog Box Components The following figure shows the various components of a Dialog box, In dialog box creation these components are called as tiles.The two major components of a dialog box are tiles and the box itself. The tiles can be arranged in any desired format (lime rows or columns). The basic tiles, such as buttons, lists, edit boxes, images, toggle, radio button, etc., are predefined by the programmable dialog box facility of AutoCAD and are defined in BASE.DCL. By grouping the tiles into rows and columns, it is possible to create complex tiles, called subassembly. The layout of the tile and their functionality are controlled by the attributes associated with the tiles.



alignment alignment = position; Applied to:

all tiles

Specifies the justification of a tile within its cluster. The possible values of a tile inside a column are left, right or centered (default : left), the possible values of a tile inside a row are top, bottom, or centered (default : centered).

aspects_ratio aspect_ratio = real; Applied to:

image, image_button

Specifies the ratio of the width of the image to its height (width divided by height). Possible values are floating-point values (default : none).

Color Color = colorname; Applied to:

image, image,button

Specifies the background (fill) color of the image. Possible values are an integer or reserved word (default : 7) specified as an AutoCAD color number or as one of the symbolic names show in the following table.

Symbolic Name

Meaning

Dialog_line

Current dialog box line color

Dialog_foreground

Current dialog box foreground color (for text)

Dialog_foreground

Current dialog box background color



graphics_background

Current background of the AutoCAD graphics screen

black

AutoCAD color = 0 (black)

red

AutoCAD color = 1 (red)

yellow

AutoCAD color = 2 (yellow)

green

AutoCAD color = 3 (green)

cyan

AutoCAD color = 4 (cyan)

blue

AutoCAD color = 5 (blue)

magenta

AutoCAD color = 6 (magenta)

white graphica_foreground background)

AutoCAD color = 7 (white)(appears black on a light

edit_limit edit_limit = integer; Applied to:

edit_box

Specifies the maximum no of characters a user is allowed to enter in the edit_box. Possible values in an integer (default : 132). The maximum edit_limit allowed is 256 characters.

is_default is_default = true – false; Applied to:

button



Specifies whether the button is the default selected (“pushed”) when the user presses the accept (enter) key. Only one button in a dialog box can have the is_default attribute set to true.

is_enabled is_enabled = true – false; Applied to:

all active tiles

Specifies whether the tile is initially grayed out (unavailable). Possible values are true of false (default: true). If false, the tile is initially grayed out.

is_tab_stop is_tab_stop = true – false ; Applied to:

all active tiles

Specifies whether the tile receives keyboard focus when the user moves between tiles by pressing the TAB key. If the tile is disabled, it isn’t tab stop even if this attribute is true. If false, the tile is not a tab stop.

key key = “string” ; Applied to:

all active tiles

Specifies an ASCII name that the program uses to refer to this specific tile. Possible value is a quoted string (no default). Within a particular dialog box, each key value must be unique. This string is case sensitive: if you specify the key as Check_no BigTile, you cannot reference it as check_no. Because the value of a key isn’t visible to the user, its name can be whatever you choose (as long as it is unique to the dialog box).



label label = “string”; Applied to:

boxed_row, boxed_column, boxed_ratio_row, Bosed_radio_column, button, dialog, edit_box, list_box, Popup_list, radio_button, text, and toggle.

Specifies the text displayed within the tile. Possible value is a quoted string (default: a blank string, “ “ . The placement of label text is tile specific. If a character in the label string is preceded by an ampersand (&), that character becomes the mnemonic.

list list = “string”; Applied to:

list_box, popup_list

Specifies the initial set of lines (choices) to be placed in the popup_list or list_box. Possible value is a quoted string (no default). Lines are separated by a new line symbol (\n). Tab character (\t) can occur within each line.

mnemonic mnemonic = “char”; Applied to: all active tiles Specifies a keyboard mnemonic character for the tile. The mnemonic is underlined in the tile’s label. Possible value is quoted string of a single character (no default). The character must be one of the letters in the tile’s label. The character doesn’t have to be unique to the dialog box: if more than one tile has the same mnemonic, the user presses that key to cycle through the tiles sequentially.

value



value = “string“ ; Applied to:

text, active tiles (except buttons and image buttons)

Specifies the initial value of a tile. Possible value is a quoted string. The meaning of a tile’s value varies depending on the kind of tile. The value of a tile can change at run time, with user input or set_tile calls. The value attribute of a tile is not considered when the dialog box is laid out. After the layout is finished and the dialog box has been displayed, new_dialog uses the value attributes to initialize each tile in the dialog box. At tile’s value attribute has no effect on the size or spacing of tiles in the dialog box.

width width = number; Applied to:

all tiles

Specifies the width of a tile. Possible values are an integer or a real number representing the distance in character-width units. Do not specify this value unless the assigned defaults don’t provide acceptable appearance. You must specify, however, the width of image tiles and image buttons.

big_increment big_increment = integer; Applied to:

slider

Specifies the value used by the slider’s incremental controls. The default value of big_increment is one-tenth of the total range. The value must be within the range specified by min_value and max_value.



small_increment small_increment = integer; Applied to:

slider

Specifies the value by the slider’s incremental controls. Default value of small_increment is one one-hundredth the total range. The value must be within the range specified by min_value and max_value. This attribute is optional.

layout layout = position; Applied to:

slider

Specifies the orientation of a slider. Possible values are horizontal or vertical (default: horizontal). For horizontal sliders, the value increases from left to right. For vertical sliders, it increases from button to top.

Password_char Password_char = “cahr”; Applied to:

edit_box

Specifies the character to be used as the password character. If password_char is specified and is not null, that character is displayed in the edit box instead of the characters entered by the user. The use of this attribute has no effect on the retrieval of the value entered by the user. It alters only the display of the characters in the edit box.

DCL Tile Catalog Having seen the attributes which control the properties of the tiles, let us now have a detailed look at the various Tiles available and how to use them,

dialog : dialog {



initial_focus label value } A dialog is the tile that defines the dialog box. You should not specify both a label and value attribute: the value attributes that of the label. label

:Specifies the optional tile displayed in the tile bar.

initial_focus

:Specifies the key of the tile that receives the initial keyboard

initial_focus

:Specifies the key of the tile that receives the initial keyboard

focus.

focus. Example: To create a dialog shown, : dialog { label = “You did it . . . “; ok_only; }

button :button { alignment fixed_height fixed_width height is_cancel is_default is_enabled is_tab_stop key label mnemonic width } A button tile resembles a push button. The button’s label specifies text that appears inside the button. Dialog boxes must include an OK button (or its equivalent) for the user to press after using (or reading) the box. Many dialog boxes also include a Cancel button that enables the user to leave the dialog box without making any changes. Example



:button { label = “Execute”; fixed_height = true; fixed_width = true;

edit box :edit_box{ alignment edit_limit edit_width fixed_height fixed_width height is_enabled is_tab_stop key label mnemonic value width password_char. } An edit box is a field that enables the user to enter or edit a single line of text. An optional label can appear to the left of the box. If the entered text is longer than the length of the edit box, its scrolls horizontally.

Image :image { alignment aspect_ratio color fixed_height fixed_width height is_enabled is_tab_stop key label mnemonic value width } An image is a rectangle in which a vector graphic picture is displayed. You can use an image to display a vector, to fill an area with a color patch, or to display a slide image. Example: : image { width = 5; height = 5; key = “til”; }



list_box :list_box{ alignment fixed_height fixed_width height is_enabled is_tab_stop key label list mnemonic value width } Example: : list_box height = 10; width = 10; key = “lis”; }

popup_list :popup_list { alignment edit_width fixed_height fixed_width height is_enabled is_tap_stop key label list mnemonic value width }

radio_button : radio_button { alignment fixed_height fixed_width height is_enabled is_tab_stop key label mnemonic value width } Value:

A quoted string (no default). If the value is “1”, the radio_button is on; if it is “0”, the radio_buttons is off.



Example: :radio_button { label = “Left”; mnemonic = “L”; key = “left”; }

text text { alignment fixed-height fixed_width height key label value width } A text tile display a text string for titling or informational purposes.

toggle : toggle { alignment fixed_height fixed_width height key label value width }

Value : If the string is “0”, the toggle box is blank (without a check mark). If it is “1”, the box contains a check mark (or an X).

slider :slider { action alignment big_increment fixed_height fixed_width height key label layout max_value min_value mnemonic small_increment value width

ok_only ok_only;



The ok_only tile is solitary OK button, such as the kind that alert boxes use. The key of the OK button is “accept”. The ok_only tile is defined in the base.dcl file.

ok_cancel ok_cancel; The ok_cancel tile is a combination of the OK and Cancel buttons, and is the standard combination for dialog boxes that can originate changes to data. The key of the Cancel button is “cancel”. The of_cancel tile is defined in the base.dcl file.

errtile errtile; An error tile is a text tile that appears at the bottom of a dialog box. By default it’s blank, put programs can display messages in it by setting the value of the tile whose key is “error”. The errtile tile is defined in the base.dcl file.

column :column { alignment fixed_height fixed_width height label width } Tiles in a column are laid out vertically in the order in which they appear in the DCL file. A column can contain any kind of tile (except for solitary radio buttons), including rows and other columns. A column without a box has no additional attributes beyond the standard layout attributes.



boxed_column :boxed_column { alignment fixed_height fixed_width height label width } A boxed column is box like rectangular area with a border around it. All the tiles that is laid inside will be in a column fashion. If a boxed_column has a label, the label (title) is embedden in it on the top left corner of the box.

boxed_radio_column :bosed_radio_column { alignment fixed_height fixed_width height label width } A boxed_radio_column is very similar to the boxed_column in all means except one function. It encloses the radio_buttons in a column, at a point of time only one radio button can be selected. You treat the label the same way that you would treat the label of a boxed column.

radio_column :radio_column { alignment fixed_height fixed_width height width } A set of radio buttons arranged in a column.

row : row { alignment fixed_height fixed_width height label width } A row is like a column, but its tiles are laid out horizontally instead of vertically, in the order in which appear in the DCL file. A row without a box has no additional attributes beyond the standard layout attributes.



boxed_row :boxed_radio_row { alignment fixed_height fixed_width height label width } A boxed row has a border around it. If a boxed row has a label, the label appears embedded in it.

boxed_radio_row :boxed_radio_rwo { alignment fixed_height fixed_width height label width } A boxed radio row has a border around it. You treat the label the same way that you would treat the label of a boxed row. At any point of time only one radio_button can be selected indicating the option needed.

radio_row :boxed_radio_row{ alignment fixed_height fixed_width height label width } A set of radio button arranged in a row.

SAMPLE PROGRAMS This section gives you some sample DCL files. Try these first before creating any Dialogs of your own on the exercises, and clearly understand each and every line in these programs. Follow the instructions given. Example: 01

/* this is a comment. . . . A sample dialog which appears as shown in the figure. . .



The dialog name is mydial, and the coding is written in great.dcl. . . */ mydial:dialog { label = “This is my first dialog box”; //heading of dialog :text { label = “Great ! You’ve done it. . . “;//text tile } ok_only; } / / dialog ends here

load_dialog (load_dialog The dcl_file argument is a string that specifies the .dcl file to load. Returns a positive integer value (dcl_id) if successful, and returns a negative integer if it can’t open the file. The dcl_id is used as a handle in subsequent new_dialog and unload_dialog calls. This function is the complement of unload_dialog.

Example: (setq dcl_id (load_dialog “great.dcl”) ) returns 1 new_dialog (new_dialog The glgname argument is a string that specifies the dialog box, and dcl_id identifies the .dcl file (you must have obtained its value from the load_dialog call). Example: (new_dialog “mydial” dcl_id)

displays the dialog on screen





FILE HANDLING Every engineering design process, irrespective of the trade, whether Mechanical, Civil or Architectural, needs data. These data are standards and thumb rules for an optimum design solution. In conventional design process, an engineer has to repeatedly refer volumes of catalogs, tables and charts which is a tedious process. In the modern world, where computers are used to aid in the design process, one need not look the design data table. All the necessary data can be stored as data files and the design program can be made to open and read the files to locate the data. Data files in the present scenario are simple ASCII files generated either manually or through some other means AutoLISP provides powerful yet simple functions to search and access the data files, read and write/append information on to the data file. A file can be opened and read/modified anywhere in a program. When you open a file, AutoLISP provides a pointer which has to be assigned to a variable for further reference. The functions included in this chapter are as listed below. The functions included in this chapter are,

findfile

open

close

read-line

write-line

read-char

write-char

getfiled

findfile

Searches the AutoCAD library path for the specified file findfile ) Returns: If the file is found

Path of file as a STRING

If the file is not found

nil

The FINDFILE function searches for the given file whose name is given as the string argument in the AutoCAD library path. The file name should also include the extension of the file. If the drive or directory prefix is given then the file is searched only in the specified drive or directory.



Example: If there is a file named “shaft.lsp” in the path c:\acadr14,then, Command: (findfile “shaft.lsp”) “C:\\ACADR14\\shaft.lsp” otherwise, Command: (findfile “shaft.lsp”) Nil Open Opens a file for access by the AutoLISP I/O functions

(open Returns: If the file is found

File Pointer (descriptor)

If the file is not found

nil

The filename argument is a string that specifies the name and extension of the file to be opened. The mode argument is the read/write flag. It must be a string containing a single lower case letter. The following table describes the valid mode letters.

Open mode

Description

“r”

Open for reading. If filename does not exit, open returns nil.

“w”

Open for writing. If filename does not exit, a new files is created and opened. If filename already exists, Its existing data is overwritten.

“a”

Open for appending. If filename does not exit, a new file is created a new file is created and opened. If filename already exists, it is opened and the pointer is positioned at the end of the existing data, so new data you write to the file is appended to the existing data.

Open function returns a file description to be used by the other I/O functions. The file descriptor must be assigned to a symbol that uses the seta function as shown below. All further reference to the file should be through the file descriptor.



Example Assuming that the files named in the following examples do not exit, Command: (setq f (open “new.txt” “w”)

Command: (setq f(open “nosuch.fil” “r”)) nil Command: (setq f (open “lofgile” “a”))

When a file “data.txt” exists, Command: (setq f (open “data.txt” “r”))

Close Closes an open file (close ) Returns on success

nil

on failure

error message

The argument is a file descriptor obtained from the open function. After a close, the file descriptor is unchanged but is no longer valid. All files opened in a program have to be closed before the program is terminated. Example The following code counts the number of lines in the file check.txt and sets the variable no_lines equal to that number: (setq fil_id(open “check.txt” “r”) no_lines 0) (while (read-linefil_id) (setq no_lines ( 1 + no_lines))) (close fil_id) read – char Returns the ASCII code of the character read from an open file or from keyboard. (read-char []) Returns on success

nil



on failure

error message

This function returns the decimal ASCII code representing the character read from the keyboard input buffer or from an open file described by the . If there are no s and characters in the keyboard input buffer, the function waits for a keyboard input. Example Command: (setq f (open “data.txt” “r”))

Command: (read-char f) 106 write – char Writes a character to the screen or to an open file (write – char []) Returns on success

write the character

on failure

error message

This function writes a character to the screen or to an open file. The argument is a decimal ASCII code for the character specified by the . If no is given then the character is written on the screen else the character will be written to the specified file. Example Command: (write – char 65) A Command: setq fp O(open “data.txt” “a” ))

Command: (write – char 65 fp) The last example writes character A onto the open file whose is fp. In either case, WRITE – CHAR will echo the argument (65 in this case) at the Command: prompt read – line

Reads a string from the keyboard or from an open file. (read – line []) Returns



on success

line read as string

on failure

nil

This function returns the line read from the keyboard or from an open file. When this function is repeated with the file descriptor then the function returns the next line of the file. Example Assuming that fp is a valid open file pointer, (read-line fp) returns the next input line from the file, or returns nil if the end-of-file has been reached. write – line Writes a string to the screen or to an open file (write – line []) Returns: on success

string omitting the quotes

on failure error message This function write the to the screen or to an open file. The function returns a quoted string to the file if is specified. Otherwise the is written on the screen Example Assuming that fp is a valid open file descriptor. (write – line “Welcome” fp) writes Welcome in the file. getfiled Display the standard AutoCAD file dialog box, and returns that the name

(getfiled ) Returns If file is selected

the file selected as string

If file not selected

nil



The argument specifies the dialog box label. The arguments specifies a default file name to use for the dialog box. It can be empty string also. The argument specifies the default file name extension, used as a mask for the files presented to the user in a scrolling list box. This function returns the name of the selected by the user, or nil if no file was selected. The argument is an integer value ( a bit-coded field), the meaning of the various bit values are:

Bit Value

Meaning

1. 2. 4. 8.

Display “alert” message if the user selects an existing file. Disables the “Type It” button in the dialog box. Allows the user to change the file extension or no extension at all. Performs an AutoCAD library search for the filename entered.

Example: Command: (getfiled “Select a Lisp File” “c:\acadr14” “lsp” 8) “C:\\ACADR14\\Surf.lsp”

If you choose a file from the dialog box and click on OK then AutoCAD returns the selected lisp file name. entlast Returns the name of the last non-deleted main object (entity) in the drawing. (entlast) The entity name of the last drawn entity. The entlast function is frequently used to obtain the name of a new entity that has just been added with the command function. The entity need not be on the screen or on a thawed layer to be selected. Example: (setq e1 (entlast)) Sets e1 to the name of the last drawn entity in the drawing. entnext

Returns the name of the next object (entityO in the drawing. (entnext []) Returns: if next entity is found

The Entity name of the entity



if not found

nil

This function retrieves entity names sequentially. When the optional parameter is not specified, the function returns the entity name of the first entity in database, else it returns the name of the seceding entity specified by . Example (setq e1 (entnext)) returns the entity name of the first entity in the drawing. (setq e2 (entnext e1)) returns the entity name of the entity following e1. entsel Prompts the user to select a single object (entity) by specifying a point (entsel []) Returns entity found at point picked

The Entity name and the point picked as a list.

Entity not found

nil

This function is used to select an entity by specifying a point. The function returns a list containing entity name and the point selected. When the optional argument is specified, AutoCAD prints the string in the command prompt area and waits for user input. When it is not specified, AutoCAD displays a default prompt Select Object: in the command prompt are: Example: Assuming if there is an object passing through point 3,3 Command: (entsel “Pick entity:”) Pick entity: 3,3 ( (3.000000 3.000000 0.0)) nentsel Prompts the user to select an object (entity) by specifying a point, and provides access to the definition data contained within a complex object. (nentsel []) Returns



Entity found at point picked

The Entity name and the point picked as a list

Entity not found

nil

This function provides access to the entities contained inside a nested entity. (such as POLYLINES and INSERTS) If the optional argument is passed then this function waits for user selection by issuing or else a standard prompt Select Object: will be issued. If the selected objet is not a nested entity (i.e. neither a POLYLINE nor a BLOCK INSERT) then this function returns same information as ENTSELF function. When a sub entity of a nested entity is selected, this function returns a list containing 4 elements. The first element of that list will be entity name of the selected subentity. The second element will be the point of selection, third one will be a matrix called `Model to World Transformation Matrix’ which specifies the location of the sub entity with respect to the insertion point of the block. The fourth member of the above list will be entity name of the block that contains the selected sub entity. If the selected entity is an ATTRIBUTE of an INSERT then this function returns only the entity name of the attribute and the pick point. The nentsel function will be a list as follows: ( (Px Py Pz) ((X0 Y0 Z0) (X1 Y1 Z1) (X2 Y2 Z2) (X3 Y3 Z) ) ( entity ) )

Name of entity Pick point Model to World transformation matrix

Name of most deeply nested block containing selected

Name of outermost block containing selected entity.

entupd Updates the screen image of an object (entity) (entupd ) Returns on success

The Entity name

When a polyline vertex or block attribute is modified with entmod, the entire complex entity is not updated on the screen. The entupd function can be used to cause a modified polyline or block to be updated on the screen. This function can be called with the entity name of any part of the polyline or block; it need not be the head entity. While entupd is intended for polylines and blocks with attributes, it can be called for any entity. It always regenerates the entity on the screen, including all subentities.



Example Assuming that the first entity in the drawing is a polyline with spline fit data and with several vertices, then (setq e1 (entnext)) (setq e2 (entnext)) (setq en (entget)) (setq ed (subt (`10 1.0.2.0)

;Sets e1 to the polyline’s entity name ;Sets e2 to its first vertex ;Sets en to the vertex data ;Changes the vertex’s location in en to point ;(1,2)

assoc 10 en) en) ) (entmod en) (entupd e1)

;Moves the vertex in the drawing ;Regenerates the polyline entity e1

entmod Modifies the definition data of an object (entity) Entmod ) Returns on success

The Entity list

on failure

error message (mostly Bad entmod list).

This function modifies the database of the entity specified by . The is the associative list of the entity obtained by entget function. Example (command “line “ “2,3” “4,5” “ “) (setq en (entnext) e1 (entget en) ; gets the entity list of the line. e1(subst (cons 10 (list 4 4))(assoc 10 e1)e1) ) ;changes the starting point of the line to 4,4 (entmod e1) ;updates the database



entdel Deletes objects (entities) or undeletes previously deleted objects. (entdel ) Returns on success

The Entity name

on failure

error message (bad argument type)

This function is used to delete an entity in the current drawing editor. When used again, it undeletes the entity specified by in the current drawing editor. All deleted entities are purged when the current drawing is exited. Example If `a’ is a valid entity name, deletes the entity and returns entity name Command: (entdel a)

If `b’ is not a valid entity name Command: (entdel b) Error: bad argument type (ENTDEL B) *Cancel* entmake Creates a new entity (graphical object) in the drawing (entmake ) Returns on success

The Entity

on failure

error message (bad entmake list value)

This function creates a new entity in the current drawing making use of the entity list specified by as the definition data. If successful then this returns the definition data and nil otherwise.



The minimum data for making an entity are as follows: 1.

Entity type

2.

Basic geometric data

3.

Optional arguments

a. b. c. d. e. f.

Color Layer Linetype Extrusion direction Elevation Thickness

1.

Valid entity types are “LINE”, CIRCLE”, “ARC”, etc.,

2.

Geometric data for: LINE: Start point & End point CIRCLE: Center point & Radius

SSGET FILTERS (ssget “X” This function selects all the entities conforming to a specified filter list. The is an association list that is used as a check to select objects. Each sub-list in the contains the group code and the value to matched. The group codes that can be used in a ssget “X” function are,

Code

Meaning

0 2 6 7 8 38 39 62

Entity type Block name of block references Line type name Text style name for text and attribute definitions Layer name Elevation (real) Thickness (real) color number (0 => “BYBLOCK” 256 = > “BYLAYER”) Attributes – follow flag for block references 3D extrusion direction vector (list of three reals).

66 210 Example:

(ssget “X” (list (cons 0 “line”))) (ssget “X” (list cons 0 “line”)

;selects all lines



(cons 8 “C”)))

;selects all lines in the layer named C

sslength Returns an integer containing the number of objects (entities) in selection set (sslength)

)

Returns on success

no of entity names present in the set

on failure

error message

The number is returned as a real if it is greater than 32, 767. Selection sets never contain duplicate selections of the same entity. Example (setq sset (ssget “L”))

;Places the last object in selection set sset

(sslength sset) ssdel Deletes an object (entity) from a selection set (ssdel < ename > on failure

selection set name error message

This is used to delete the entity specified by < ename > from the selection set . It returns the new selection set. If the entity is not found in the , the function returns nil. Example

(setq sd (ssget “X” (list (cons 0 :line”))); place all lines in the selection ; set sd. (set1 e1 (ssname sd0))

;selects the first entity in the ;selection set sd.

(ssdel e1 sd)

;deletes the lines e1 from the set sd.

sssetfirst Sets which objects are selected and gripped (sssetfirst [pickset>])



Returns on success

list of the variables passed

on failure

error message

Example The expressions below grips all the entities in the drawing Command: (setq a (ssget “x”))

Command: (sssetfirst a) (A) ssgetfirst Determines which objects are selected and gripped (ssgetfirst Returns on success

list of the selection sets (gripped / selected)

on failure

error message

Example Command: (ssgetfirst) [ nil)

APPLICATION HANDLING Almost all environments and software provide the user the tools to develop applications for his/her need through customization. It is appropriate because it is very difficult or rather impractical to group all the needs of the user by software developer himself. In this context, understanding the importance and the advantages of customization, Autodesk has developed AutoCAD with an open architecture, which encourages customizing to a large extent. Autodesk has considered both the noise and experienced user has given tools for various levels of customization. It depends on the knowledge and experience of the user, in AutoCAD as well as other programming language such as AutoLISP and C. It is also based on the nature and complexity of the application to the developed.



AutoCAD can be customized through,

¾ ¾ ¾

AutoLISP, a programming language framed by the Autodesk for developing small applications involving either designing or drafting in AutoCAD. ADS – AutoCAD Development System, a programming language using the structure of `C’ language. ARX – AutoCAD Runtime Extension brings in the phenomena of OOPS in to AutoCAD environment. This is possible because of the C++ interface with AutoCAD. This increases the power of AutoCAD many times. Using ARX you can develop your own application which can have its own objects. (AutoCAD itself is a C++ application)

In order to utilize the function defined in these customized applications inside AutoCAD, AutoLISP provides functions to load them. And the objective of this chapter is to enable you to use those functions to load, unload and execute them.

The functions dealt in this chapter are as listed below, xload

xunload

ads

arx

arxload

autoarxload

Autoload

autoxload

autozrxload

xload Loads an ADS application (xload []) This function load an . If the application is successfully loaded then this returns the application name or returns a standard error message otherwise. However, if the argument is supplied then the function returns the value of this argument upon failure instead of an error message.



This function fails to load if the application is already loaded.

Example (xload “/myappx/xapp”) if successful, returns “/myappx/xapp”

xunload

Unloads an ADS application

(xunload []) This function unloads an specified. If the application is successfully unloaded then it returns the application name else returns an error message. The should be entered as it was entered during xload. The directory name can be omitted for this function. If the xunload application fails it causes an AutoLISP error. However if the argument is supplied the functions the value of this argument argument is supplied then the function returns the value of this argument instead of issuing an error message. Example: (xunload “ame”) if successful, returns “ame”

ads Returns a list of the currently loaded ADS applications

(ads) Each ADS application loaded and its path is a quoted string in the list.

arx Returns a list of the currently loaded ARX applications



(arx) Each ARX application loaded and its path is a quoted string in the list. Example Command: (arx) (“acadapp.arx” “ geomal.arx” “oleaprof.arx”)

arxload Loads an ARX application (arxload []) The argument is entered as a quoted string or as a variable that contains the name of an executable file. At the time the file is loaded, it is verified to be a valid ARX application. If the arxload operation fails then it normally causes an AutoLISP error. However, if the argument is supplied then arxload returns the value of this argument upon failure instead of an error message. If the application is successfully loaded then the application name is returned.

arxunload

Unloads an ARX []) If the is successfully unloaded then the name is returned, otherwise, an error message is issued. Enter as a quoted string or as a variable containing the name of an application that was loaded with the arxload function. The name must be entered exactly as it was entered for the arxload function. If a path (directory name) or extension was entered for the application in arxload, it can be omitted in the arxunload function.



autoload Predefines command names to load an associated AutoLISP file (autoload ) The argument is a string that specifies the “.lsp” file that is loaded when one of the command defined by the argument is entered at the command prompt. The argument must be a list of strings. The autoload function returns nil. The following code defines the C:APP1, C:APP2 and C:APP3 functions to load the “bounsapp.lsp” file. The fist time one of the command APP1, APP2 or APP3 are entered at the command prompt the ARX application loads and the command continues. Example:

(autoload “BOUNSAPP” (“APP1” “APP2” “APP3”)) autoxload Predefines command names to load an associated ADS application.

(autoxload ) The argument is a string that specifies the ADS file that is loaded when one of the commands defined by the argument is entered at the command prompt. The argument must be a list of strings. The autoxload function returns nil. The following code defines the C:APP1, C:APP3 and C:APP3 functions to load the “bounsapp.lsp” file. The first time one of the command APP1, APP2 or APP3 are entered at the command prompt the ARX application loads and the command continues. Example:

(autoxload “BOUNSAPP” (“APP1” “APP2” “APP3”))



DIALOG CONTROL LANGUAGE [DCL] AutoCAD gives you a language called as Dialog Control Language (DCL) which has got its own syntax and functions, using which you could design your dialog box. Autodesk has provided two file ACAD.DCL and BASE.DCL in which many of the commonly used dialog box components, their structure and layout are predefined. The definition a dialog box is written using Dialog Control Language in separate ASCII files that contain the descriptions of the various elements of the dialog box. The above file should have a file name extension .dcl. A .dcl file can contain the description of a single or multiple dialogue boxes. The arrangement of elements (tiles) in a dialog box, such as buttons and edit_boxes, is determined by their order in the .dcl file.

Dialog Box Components

The following figure shows the various components of a Dialog box, In dialog box creation these components are called as tiles.



The two major components of a dialog box are tiles and the box itself. The tiles can be arranged in any desired format (lime rows or columns). The basic tiles, such as buttons, lists, edit boxes, images, toggle, radio button, etc., are predefined by the programmable dialog box facility of AutoCAD and are defined in BASE.DCL. By grouping the tiles into rows and columns, it is possible to create complex tiles, called subassembly. The layout of the tile and their functionality are controlled by the attributes associated with the tiles.

alignment alignment = positive; Applied to:

all tiles

Specifies the justification of a tile within its cluster. The possible values of a tile inside a column are left, right or centered (default : left), the possible values of a tile inside a row are top, bottom, or centered (default : centered).

aspects_ratio aspect_ratio = real; Applied to:

image, image_button

Specifies the ratio of the width of the image to its height (width divided by height). Possible values are floating-point values (default : none).

Color Color = colorname; Applied to:

image, image,button

Specifies the background (fill) color of the image. Possible values are an integer or reserved word (default : 7) specified as an AutoCAD color number or as one of the symbolic names show in the following table. Symbolic Name

Meaning

Dialog_line

Current dialog box line color



Dialog_foreground

Current dialog box foreground color (for text)

Dialog_foreground

Current dialog box background color

graphics_background

Current background of the AutoCAD graphics screen

black

AutoCAD color = 0 (black)

red

AutoCAD color = 1 (red)

yellow

AutoCAD color = 2 (yellow)

green

AutoCAD color = 3 (green)

cyan

AutoCAD color = 4 (cyan)

blue

AutoCAD color = 5 (blue)

magenta

AutoCAD color = 6 (magenta)

white graphica_foreground

AutoCAD color = 7 (white)(appears black on a light background)

edit_limit edit_limit = integer; Applied to:

edit_box

Specifies the maximum no of characters a user is allowed to enter in the edit_box. Possible values in an integer (default : 132). The maximum edit_limit allowed is 256 characters.

is_default



is_default = true – false; Applied to:

button

Specifies whether the button is the default selected (“pushed”) when the user presses the accept (enter) key. Only one button in a dialog box can have the is_default attribute set to true.

is_enabled is_enabled = true – false; Applied to:

all active tiles

Specifies whether the tile is initially grayed out (unavailable). Possible values are true of false (default: true). If false, the tile is initially grayed out.

is_tab_stop

is_tab_stop = true – false ; Applied to:

all active tiles

Specifies whether the tile receives keyboard focus when the user moves between tiles by pressing the TAB key. If the tile is disabled, it isn’t tab stop even if this attribute is true. If false, the tile is not a tab stop. key key = “string” ; Applied to:

all active tiles

Specifies an ASCII name that the program uses to refer to this specific tile. Possible value is a quoted string (no default). Within a particular dialog box, each key value must be unique. This string is case sensitive: if you specify the key as Check_no BigTile, you cannot reference it as check_no. Because



the value of a key isn’t visible to the user, its name can be whatever you choose (as long as it is unique to the dialog box).

label label = “string”; Applied to:

boxed_row, boxed_column, boxed_ratio_row, Bosed_radio_column, button, dialog, edit_box, list_box, Popup_list, radio_button, text, and toggle.

Specifies the text displayed within the tile. Possible value is a quoted string (default: a blank string, “ “ . The placement of label text is tile specific. If a character in the label string is preceded by an ampersand (&), that character becomes the mnemonic. list list = “string”; Applied to:

list_box, popup_list

Specifies the initial set of lines (choices) to be placed in the popup_list or list_box. Possible value is a quoted string (no default). Lines are separated by a new line symbol (\n). Tab character (\t) can occur within each line. mnemonic mnemonic = “char”; Applied to: all active tiles Specifies a keyboard mnemonic character for the tile. The mnemonic is underlined in the tile’s label. Possible value is quoted string of a single character (no default). The character must be one of the letters in the tile’s label. The character doesn’t have to be unique to the dialog box: if more than one tile has the same mnemonic, the user presses that key to cycle through the tiles sequentially.



value value = “string“ ; Applied to:

text, active tiles (except buttons and image buttons)

Specifies the initial value of a tile. Possible value is a quoted string. The meaning of a tile’s value varies depending on the kind of tile. The value of a tile can change at run time, with user input or set_tile calls. The value attribute of a tile is not considered when the dialog box is laid out. After the layout is finished and the dialog box has been displayed, new_dialog uses the value attributes to initialize each tile in the dialog box. At tile’s value attribute has no effect on the size or spacing of tiles in the dialog box.

width width = number; Applied to:

all tiles

Specifies the width of a tile. Possible values are an integer or a real number representing the distance in character-width units. Do not specify this value unless the assigned defaults don’t provide acceptable appearance. You must specify, however, the width of image tiles and image buttons.

big_increment big_increment = integer; Applied to:

slider

Specifies the value used by the slider’s incremental controls. The default value of big_increment is one-tenth of the total range. The value must be within the range specified by min_value and max_value.

small_increment small_increment = integer;



Applied to:

slider

Specifies the value by the slider’s incremental controls. Default value of small_increment is one one-hundredth the total range. The value must be within the range specified by min_value and max_value. This attribute is optional.

layout layout = position; Applied to:

slider

Specifies the orientation of a slider. Possible values are horizontal or vertical (default: horizontal). For horizontal sliders, the value increases from left to right. For vertical sliders, it increases from button to top. Password_char Password_char = “cahr”; Applied to:

edit_box

Specifies the character to be used as the password character. If password_char is specified and is not null, that character is displayed in the edit box instead of the characters entered by the user. The use of this attribute has no effect on the retrieval of the value entered by the user. It alters only the display of the characters in the edit box Having seen the attributes which control the properties of the tiles, let us now have a detailed look at the various Tiles available and how to use them,

dialog



: dialog { initial_focus label value } A dialog is the tile that defines the dialog box. You should not specify both a label and value attribute: the value attributes that of the label. label

:Specifies the optional tile displayed in the tile bar.

initial_focus

:Specifies the key of the tile that receives the initial keyboard focus.

initial_focus

:Specifies the key of the tile that receives the initial keyboard focus.

Example: To create a dialog shown, : dialog { label = “You did it . . . “; ok_only; } button

:button { alignment fixed_height fixed_width height is_cancel is_default is_enabled is_tab_stop key label mnemonic width } A button tile resembles a push button. The button’s label specifies text that appears inside the button. Dialog boxes must include an OK button (or its equivalent) for the user to press after using (or reading) the box. Many dialog boxes also include a Cancel button that enables the user to leave the dialog box without making any changes.



Example :button { label = “Execute”; fixed_height = true; fixed_width = true; edit box

:edit_box{ alignment edit_limit edit_width fixed_height fixed_width height is_enabled is_tab_stop key label mnemonic value width password_char. } An edit box is a field that enables the user to enter or edit a single line of text. An optional label can appear to the left of the box. If the entered text is longer than the length of the edit box, its scrolls horizontally.

Image

:image { alignment aspect_ratio color fixed_height fixed_width height is_enabled is_tab_stop key label mnemonic value width }



An image is a rectangle in which a vector graphic picture is displayed. You can use an image to display a vector, to fill an area with a color patch, or to display a slide image. Example: : image { width = 5; height = 5; key = “til”; }

list_box

:list_box{ alignment fixed_height fixed_width height is_enabled is_tab_stop key label list mnemonic value width } Example: : list_box height = 10; width = 10; key = “lis”; }



popup_list :popup_list { alignment edit_width fixed_height fixed_width height is_enabled is_tap_stop key label list mnemonic value width }

radio_button : radio_button { alignment fixed_height fixed_width height is_enabled is_tab_stop key label mnemonic value width } Value:

A quoted string (no default). If the value is “1”, the radio_button is on; if it is “0”, the radio_buttons is off.

Example: :radio_button { label = “Left”; mnemonic = “L”; key = “left”; }

text text { alignment fixed-height fixed_width height key label value width }



A text tile display a text string for titling or informational purposes.

toggle

: toggle { alignment fixed_height fixed_width height key label value width }

Value : If the string is “0”, the toggle box is blank (without a check mark). If it is “1”, the box contains a check mark (or an X). slider

:slider { action alignment big_increment fixed_height fixed_width height key label layout max_value min_value mnemonic small_increment value width

ok_only ok_only;



The ok_only tile is solitary OK button, such as the kind that alert boxes use. The key of the OK button is “accept”. The ok_only tile is defined in the base.dcl file. ok_cancel ok_cancel;

The ok_cancel tile is a combination of the OK and Cancel buttons, and is the standard combination for dialog boxes that can originate changes to data. The key of the Cancel button is “cancel”. The of_cancel tile is defined in the base.dcl file.

errtile

errtile; An error tile is a text tile that appears at the bottom of a dialog box. By default it’s blank, put programs can display messages in it by setting the value of the tile whose key is “error”. The errtile tile is defined in the base.dcl file.



column :column { alignment fixed_height fixed_width height label width } Tiles in a column are laid out vertically in the order in which they appear in the DCL file. A column can contain any kind of tile (except for solitary radio buttons), including rows and other columns. A column without a box has no additional attributes beyond the standard layout attributes.

boxed_column

:boxed_column { alignment fixed_height fixed_width height label width

} A boxed column is box like rectangular area with a border around it. All the tiles that is laid inside will be in a column fashion. If a boxed_column has a label, the label (title) is embedden in it on the top left corner of the box.

boxed_radio_column :bosed_radio_column { alignment fixed_height fixed_width height label width



} A boxed_radio_column is very similar to the boxed_column in all means except one function. It encloses the radio_buttons in a column, at a point of time only one radio button can be selected. You treat the label the same way that you would treat the label of a boxed column.

radio_column :radio_column { alignment fixed_height fixed_width height width } A set of radio buttons arranged in a column.

row : row { alignment fixed_height fixed_width height label width } A row is like a column, but its tiles are laid out horizontally instead of vertically, in the order in which appear in the DCL file. A row without a box has no additional attributes beyond the standard layout attributes.

boxed_row



:boxed_radio_row {

alignment fixed_height fixed_width height label width } A boxed row has a border around it. If a boxed row has a label, the label appears embedded in it.

boxed_radio_row

:boxed_radio_rwo {

alignment fixed_height fixed_width height label width } A boxed radio row has a border around it. You treat the label the same way that you would treat the label of a boxed row. At any point of time only one radio_button can be selected indicating the option needed.



radio_row :boxed_radio_row{ alignment fixed_height fixed_width height label width } A set of radio button arranged in a row.

SAMPLE PROGRAMS This section gives you some sample DCL files. Try these first before creating any Dialogs of your own on the exercises, and clearly understand each and every line in these programs. Follow the instructions given. Example: 01

/* this is a comment. . . . A sample dialog which appears as shown in the figure. . . The dialog name is mydial, and the coding is written in great.dcl. . . */ mydial:dialog { label = “This is my first dialog box”; //heading of dialog :text { label = “Great ! You’ve done it. . . “;//text tile } ok_only; } / / dialog ends here



load_dialog (load_dialog The dcl_file argument is a string that specifies the .dcl file to load. Returns a positive integer value (dcl_id) if successful, and returns a negative integer if it can’t open the file. The dcl_id is used as a handle in subsequent new_dialog and unload_dialog calls. This function is the complement of unload_dialog.

Example: (setq dcl_id (load_dialog “great.dcl”) ) returns 1

new_dialog (new_dialog The glgname argument is a string that specifies the dialog box, and dcl_id identifies the .dcl file (you must have obtained its value from the load_dialog call). Example: (new_dialog “mydial” dcl_id)

displays the dialog on screen



Render Application Programming Interface The application-programming interface (API) to AutoCAD Render is provided by an ADS application. You can run AutoCAD Render commands from AutoLisp using (c: command) convention or through ADS using ADS_invoke ().

Return values for the API The AutoCAD Render API commands have three different return values that calling application can use to determine if the command is successful 1. IF the command fails, the function returns nil in AutoLisp or a NULL result buffer pointer in ADS 2. If the command is successful, and the command returns explicit values, it returns a value like .03 3. If the command is successful, and the command returns nonexplicit values, the function returns! (in ADS , this is a single result buffer with a restyle of RTSHORT and resval.rint=1) The setting of RMan Prompting does not affect the Render API FINISH Command The finish command lets you add a new surface finish, and modify, delete, import-export, or attach an existing finish. (c: finish mode [options])

The FINISH command has EIGHT modes 1 “N” Create New Finish SYNTAX: (c: finish “N” name [ka [kd [ks [roughness [color]]]]]) 2 “M” SYNTAX: -

Modify existing finish (c: finish “M” name [ka [kd [ks [roughness [color]]]]])

3 “D” SYNTAX: -

Delete existing finish (c: finish “D” name)

4 “R” SYNTAX: -

Rename existing finish (c: finish “R” old_name new_name)

5 “I” SYNTAX: -

Import existing finish (c: finish “I” name [overwrite])

6 “E” SYNTAX: 7 “A” SYNTAX: -

Export existing finish (c: finish “E” name [overwrite]) Attach existing finish to finish to entity or ACI (c: finish “A” name [ACI]| [SELECTION_SET])

8 “L” SYNTAX: -

List all finishes in the drawing or return a definition of the specified finish (c: finish “L” name)



The FINISH command has following options OPTION

DESCRIPTION

DEFAULT

NAME

Unique finish name

None

Ka

Ambient factor

.30

Kd

Diffuse factor

.70

Ks

Specular factor

.00

Roughness

Roughness factor

.10

Color

Any RGB triplet

Entity ACI

Overwrite

Replace definition

None

ACI

AutoCAD color Index

None

Selection Set

Entities attached

None

LIGHT Command The LIGHT command lets you add a new light, and modify or delete an existing light. (c: light mode [option]) This command is not allowed in paper space The LIGHT command has NINE modes 1 “ND” New distant light SYNTEX: (c: light “ND” name [intensity]) 2 “NP” SYNTEX: -

New point light (c: light “NP” name [intensity])

3 “NS” SYNTEX: -

New spotlight (c: light “NS” name [intensity])

4 “A” SYNTEX: -

Set ambient light intensity (c: light “A” [intensity])

5 “F” SYNTEX: -

Set point light falloff (c: light “F” [Falloff])

6 “M” SYNTEX: -

Modify existing light (c: light “M” name)



7 “D” SYNTEX: -

Delete existing light (c: light “D” name )

8 “R” SYNTEX: -

Rename an existing light (c: light “R” name)

9 “L” SYNTEX: -

List all lights in the drawing or return a definition of the specified light (c: light “L” name)

OPTION

DESCRIPTION

Name

Unique finish name

Intensity

DEFAULT none

Any positive real number or nil 1.00

Fall-off

Point light fall-off .

1

From

Light location

Current look-from point

To

Light target

Current look-from point

Color

Any RGB triplet

Depthmap

Valid values are 0 to 6

Conea

cone angle in degree (spot light) 10

Coned

cone delta in degrees (spot light)0

Beamed

1.0,1.0,1.0 0

Beam distribution (spot light)

0

RCONFIG Command The RCONFIG command reconfigures your current rendering setup. Use following syntax: (c: rconfig ) RENDER Command The RENDER command renders the current scene. (c: render) RENDSCR Command The RENDSCR command redisplays your last rendering (c: rendscr )



REPLAY Command The REPLAY command lets you display RND, TGA, TIFF, or GIF files on the AutoCAD rendering display (c: replay filename type [xoff yoff xsize ysize ])

The following table shows the REPLAY argument list.

OPTION

DESCRIPTION

DEFAULT

File-name

Unique image filename

None

Type

Valid values are: GIF, TGA, TIFF, or RND

None

Xoff

Image X offset in pixels

0

Yoff

Image Y offset in pixels

0

Xsize

Image X size pixels

Image X size

Ysize

Image y size pixels

Image Y size

RPREF Command When you use Render, the type of rendering AutoCAD produces depends on yours specified preferences. The RPREF command lets you set these preferences (c: rpref keyword [options ]) SAVEIMG Command The SAVEIMG command lets you save any image in the framebuffer to a GIF, RND, TGA, or a TIFF file

(c: saveimg filename type [portion] [ xoff yoff xsize ysize ] [ compression ] ) when configured to render to a separate display,use the following syntax

(c: saveimg filename type [xoff yoff xsize ysize] [ compression ] )



OPTION

DESCRIPTION

DEFAULT

File-name

Unique image filename

None

Type

Valid values are : GIF,TGA, TIFF, or RND

None

Portion

Portion of the screen to save. Valid values are: “A” (Active viewport) “D” (Drawing viewport) “F” (Full screen)

“A”

Xoff

Image X offset in pixels

0

Yoff

Image Y offset in pixels

0

Xsize

Image X size pixels

Image X size

Ysize

Image y size pixels

Image Y size

Compression

Valid values are NONE, PACK, LZW& RLE

RLE

SCENE Command A scene represents a particular view of any portion of the drawing including the whole drawing, together with one or more lights . The SCENE command lets you create a new scene , or delete and modify an existing scene . (c: scene mode [options ] ) THE SCENE COMMAND has following modes 1 “N” Creates new scene SYNTAX: - (c: scene “N” name [view [lights ] ] ) 2 “M” Modifies existing scene SYNTAX: - (c: scene “M” name [view [lights ] ] ) 3 “D” Deletes existing scene SYNTAX: - (c: scene “D” name ) 4 “R” Rename existing scene SYNTAX: - (c: scene “R” old_name new_name) 5 “S” Sets current scene SYNTAX: - (c: scene “S” [ name ] ) 6

“L”

Lists all scenes in the drawing or return a definition of the specified scene



SYNTAX: - (c: scene “L” name )

STSTS Command The STATS command provides information about your last rendering ( c: stats [filename ] )

AutoCAD SQL interface The AutoCAD SQL Interface (ASI ) is programming library for accessing external databases from AutoCAD . The AutoCAD SQL Extension user command set is an ADS application build with ASI. ASI lets you access external database directly from AutoCAD using library unction supplied with AutoCAD. ASI can provide simultaneous access to different database management systems from the same program. The ASI interface consists of two levels. The first level is driver that communicates with the DBMS or with the database directly. The second level is a driver-independent library of functions that can communicate with any driver. The main purpose of library is to handle communications between the application program and multiple drivers. The driver performs syntax checking and execution of all the SQL statements passed to it from the library. Drivers include with the ASI are Dbase IV, DBASE III PLUS, INFORMIX, ORCALE, and PARADOX

ASI Files and Their Contents ASI includes these files 1. ASI Object Library ASI has three-object library 1. asiph.lib for the MetaWare compiler 2. asipw.lib for the WATCOM compiler 3. asi.a for the SPARC compiler 2. ASI Header Files ASI has two header files 1. asi.h containing general-purpose definitions for ASI 2. asierr.h containing definitions of code values returned in asi_err()

ASI Functions The ASI library contains functions that access the database by converting SQL expression to standard data structures that are transferred to the driver ASI Functions ASI Deals with three types of data



Internal Data ASI_SINT

Internal integer

ASI_SREAL

Internal real

ASI_SCHAR

Internal array

ASI_SNULL

Null value

Host variables ASI_HINT

int

ASI_HREAL

double

ASI_HCHAR

null terminated character string

ASI_HSHORT

short

ASI_HLONG

long

ASI_HFLONT

float

SQL data types ASI_CHAR

CHARACTER

ASI_NUMERIC

NUMERIC

ASI_DECIMAL

DECIMAL

ASI_INTEGER

INTEGER

ASI_SMALLINT

SMALLINT

ASI_FLOAT

FLOAT

ASI_REAL

REAL

ASI_DOUBLE

DOUBLE PRECISION



Database Processing Interaction with any database is divided into seven steps 1. 2. 3. 4. 5. 6. 7.

Connecting to database Opening a communication handle Compiling the original SQL statement Executing the SQL statement Fetching. This step follows the query execution Closing a communication handle Disconnecting from database

HANDLES All ASI function passes information to each other by using handle. A handle is an ASI defined data structure used for passing data back and forth between the application and the driver. There are three types of handle 1. Driver Handle Use of Driver handle is points to the active DBMS 2. Database Handle Use of Database handle is points to the active database 3. Communication Handle Use of Communication handle is points to the active row

Function Synopsis This section consists of a synopsis of library functions, grouped by topic. Each function is followed by a brief description Driver-based Functions ASI_CFGDRV Configures a driver ASI_INITDRV

Initializes a driver

ASI_INITSQL

Sets up the environment

ASI_TERMALLDRV Terminates all drivers ASI_TERMDRV

Terminates a driver



ASI_TERMSQL

Terminates the ASI interface

Processing Functions ASI_BND

Defines input buffers

ASI_CDS

Gets description of a column

ASI_CEX

Compiles and executes in one step

ASI_CHDL

Closes a handle to a database

ASI_COLSDSC

Gets full description of all columns in a query

ASI_COM

Compiles a SQL statement

ASI_CMT

Commits a transaction

ASI_CURROW

Gets the current row number

ASI_CVL

Gets a column value from current row

ASI_DEL

Deletes the current row while fetching

ASI_DUPL_COLSDSCDuplicates the column descriptor list ASI_EXE

Executes a SQL statement

ASI_FBK

Fetches in backward direction

ASI_FBR

Fetches the bottom row

ASI_FET

Fetches in the forward direction

ASI_FTR

Fetches the top row

ASI_GETTABLE ASI_LON

Get the results of query as a linked list Logs on to a database

ASI_LOF

Log off from a database

ASI_OHDL

Opens a handle to a database

ASI_OPR

Gets the stage of SQL statement processing

ASI_RBK

Rolls back a transaction

ASI_RLS_COL_DSC Releases memory allocated by as_dupl_colsdsc ASI_RLSTABLE

Rrlrases memory allocated by asi_gettable



ASI_ROWQTY

Gets number of rows in the selection set

ASI_SOB

Sets output buffers

ASI_STM

Gets the type of SQL statement

ASI_UPD

Updates current row while fetching

Error Code Handling ASI_ERR

Gets an error code value

ASI_ERRMSG

Gets an error message

ASI_SYNERRPOS

Gets an SQL statement syntax error position

ASI_XERR

Gets an error code value from the driver

SQL Statement Syntax ASI and ASELQED support SQL syntax compatible with the ANSI X3.135-1989 SQL Standard. ASI is also fully compatible with the ISO SQL Standard. A summary of SQL syntax and ASE SQL standards follows. The SQL standard listed is not a complete listed is of the ANSI standard. Some commands are a superset of the ANSI standard. SYNTACTIC NOTATION 1. Elements enclosed in square brackets ([ ]) are optional 2. Elements with ellipses (...) following may be repeated one or more times 3. Elements enclosed in braces ({ } ) are listed in sequence

ADS-Defined AutoLISP functions These functions are defined by the ADS program acadapp and only available if that program is loaded. Before calling these functions, use the xload function to verify that acadapp is available. 1.

(acad_colordlg colornum [flag])

Display the standard AutoCAD color selection dialogue box The colornum argument is an integer in range 0-256 The acad_colordlg function returns the color number that the user selects via the OK button. If the user cancels the dialogue box, acad_colordlg returns nil. 2.

(acad_helpdlg helpfile topic)



Display the standard AutoCAD Help dialogues box using a specified file. You can call this function from your AutoLISP routine to provide help on a standard AutoCAD command or own application specific help. 3.

(acad_strlsort list)

Sort a list of strings by alphabetical order. The list argument is the list of string to be sorted. The acad_strlsort function returns a list of the same string in alphabetical order.

AutoLISP Access to ADS-defined Commands These functions let you access ADS-defined AutoCAD commands from AutoLISP. They are available only when the associated ADS program is loaded. There are following functions in this sections (align ss s1 d1 s2 d2 s3 d3 ) Uses the ALIGN command to perform a 3D move. If successful align returns T, otherwise it returns nil.

(bherrs) Gets an error message generated by failed call to c: bhatch or c: bpoly. If successful, it sets the results to contain the message string; otherwise, the result is nil. The bherrs function is defined in acaddapp.exp. (c:bhatch pt [ss] [vector]) calls the BHATCH command and performs a boundary hatch on the specified area. The c: bhatch function is defined in acadapp.exp. (c; ppoly pt [ss] [vector]) Calls the BPOLY command and creates a boundary Polyline. The c: bpoly function is defined in acadapp.exp (c: psdrag mode) Calls the PSDRAG command and sets the integer value mode. The mode argument is an integer that equals either 0 or 1. The c: psdrag function is defined in acadapp.exp. (c: psfill ent pattern arg1 [arg2] ... ) Fill a polyline with a postscript file. The ent argument is the name of polyline. The pattern argument is a string containing the name of the fill pattern. The pattren string must be identical to the name of fill pattern defined in current acad.psf file. (c: psin filename position scale) Invokes the PSIN command to import an encapsulated PostScript (. eps) file. The position argument is a point specifying the insertion point of the PostScript block.



(mirror3d ss str pt xy ) Uses the MIRROR3D command to mirror 3D object about an arbitrary 3D plane.

(rotate3d ss str pt xy) Uses the ROTATE3D command to rotate 3D object an arbitrary 3D axis

(solxxx arg1 arg2 . . . ) Calls most REGION MODELER COMMANDS. Solxxx is name of a command; arg1 and arg2 are ordinary AutoLISP expressions. The REGION MODELER supports the following commands in AutoLISP.

Command

Returned value

SOLAREA

A real number

SOLFEAT

A selection set

SOLIDIFY

A selection set

SOLINT

A selection set

SOLMASSP

A list of mass properties

SOLMESH

The number 1

SOLPURGE

The number 1

SOLSEP

The number 1

SOLSUB

A selection set

SOLUNION

A selection set

SOLVAR

The value of the system variable

SOLWIRE

The number 1



ADS LIBRARY EXTENSIONS Externally Defined AutoCAD Functions These functions are standard AutoCAD facilities externally defined by the ADS program acadapp. They are available only if acadapp is loaded, which it is by default. You can invoke them via ads_invoke (), as described here. 1.

(acad_colordlg colornum [flag])

Display the standard AutoCAD color selection dialogue box The colornum argument is an integer in range 0-256 The acad_colordlg function returns the color number that the user selects via the OK button. If the user cancels the dialogue box, acad_colordlg returns nil. 2.

(acad_helpdlg helpfile topic)

Display the standard AutoCAD Help dialogues box using a specified file. You can call this function from your AutoLISP routine to provide help on a standard AutoCAD command or own application specific help. 3.

(acad_strlsort list)

Sort a list of strings by alphabetical order. The list argument is the list of string to be sorted. The acad_strlsort function returns a list of the same string in alphabetical order

Error Handling Use the error( ) function (in file calerr.c) to indicate error conditions, as shown in the previous code samples. An error () call has this format: Error (n, “error message”) This function sets the global integer variable cal_err to the value of n, and display an error message. If cal_err is already nonzero , the error () call has no effect. This avoids printing several error messages caused by single error. The “ERROR MESSAGE” string is used three ways, depending on the value of n: 1. If n is zero, error () prints the message string. 2. If n is the number of an error used by the standard calculator functions, error () prints the standard error message, with the string inserted into the variable portion of the standard message, if any.



3. If n is less than zero, error() prints the negative number and ignores the message string. This is useful for debugging and for reporting internal errors

The SAGET Library The SAGET library enhances the functionality of the standard ADS library. It provides a set of input functions equivalent to the standard ADS input functions ads_getxxx() plus some related utility functions. The extended user-input functions take exactly the same parameters and work exactly the same as their ADS counterparts. However , they provide addional functionality, as follows: 1.

Keyboard/AutoLISP input redirection

2.

Geometry calculator support

3.

Construction plane support

If you want to use the SAGET library in your ADS application, you must include the header file saget.c in your source files and compile your ADS application along with the source files saget.c and util.c. you can look at these source files to see how this library is implemented.

NOTE: ALL FIG. S COURTESY FROM AUTODESK MANUAL