"Illegal Function Call" Using VIEW, WINDOW, GET, or PUT (42553)

SUMMARY

When using the QuickBasic graphics functions GET, PUT, VIEW, and WINDOW, it is very easy to encounter the error "Illegal Function Call." The error can be generated for many reasons.

This information applies to Microsoft QuickBasic Versions 4.00, 4.00b, and 4.50 for MS-DOS, to Microsoft Basic Compiler Versions 6.00 and 6.00b for MS-DOS and MS OS/2, and to Microsoft Basic PDS Version 7.00 for MS-DOS and MS OS/2.

MORE INFORMATION

If you encounter the above error, the following are some suggestions for determining where the error occurs:

If "Illegal Function Call" occurs on a GET statement, do the following:
1. Make sure you are actually GETting part of the screen or VIEW.
2. Make sure your array is large enough to hold the image. There is a formula in the "Microsoft QuickBasic: Programming in Basic" manual for Version 4.50 on Page 194 that calculates the size of the array:
  
  sizeinbytes=4+height*planes*INT((width*bitsperpixel/planes+7)/8)
If "Illegal Function Call" occurs on the PUT statement, do the following:
1. Make sure you are PUTting the image within the boundary of your WINDOW or VIEW statement.
2. Certain problems that occur with the WINDOW statement may not occur with the WINDOW SCREEN statement. The use of this statement is discussed in the "Microsoft QuickBasic 4.0: Basic Language Reference" manual for Versions 4.00 and 4.00b.
If you use the following code example, when run under QuickBasic Version 4.50, you will get an "Illegal Function Call" when trying to execute the PUT statement:
```
   DEFINT A-Z
   DIM image(40) AS LONG
   SCREEN 9
   VIEW (0,0)-(300,95)     ' Sets the view for the screen
   WINDOW (0,0)-(300,190)  ' Sets screen coordinates
   LINE (0,0)-(300,190),,B ' Draws a box around the vie
   GET (0,1)-(0,189),Image ' Gets vertical image
   SLEEP       10                ' Pause
   PUT (0,1),Image,PSET    ' Put image back to screen
   SLEEP 10                ' Pause
						
```
This error can be corrected in one of two ways:
1. The VIEW statement can be enlarged, from 95 to 96 or more. The WINDOW statement can be changed to a WINDOW SCREEN.
  
  The current program will not accept values of 95 or less with the current WINDOW statement, but it will if a WINDOW SCREEN is used. This WINDOW SCREEN statement alters the coordinates of the screen to create a right-hand coordinate system.