COMMAND$

The _WIDTH function returns the width of an image handle or of the current write page.

= _WIDTH[()]

• If is omitted, it's assumed to be the handle of the current SCREEN or write page.
• To get the width of the current program screen window use zero for the handle value or nothing: = _WIDTH(0) or = _WIDTH
• If the image specified by is in text only(SCREEN 0) mode, the number of characters per row is returned.
• If the image specified by is in graphics mode, the number of pixels per row is returned.
• If is an invalid handle, then an invalid handle error is returned.
• The last visible pixel coordinate of a program screen is _WIDTH - 1.

Example: A SUB program that centers text in any graphic screen mode except text mode SCREEN 0.

 s& = {{Cl|_NEWIMAGE}}(800, 600, 256)
 SCREEN s&
 Align 15, 5, s&, "This text is centered on the screen!"

 SUB Align (Tcolor, Trow, mode&, txt$)    
   center& = {{Cl|_WIDTH (function)|_WIDTH}} (mode&) \ 2     'returns pixels in graphic modes 
   MaxCol = (center& \ 8) + 1              'screen text width = 8 pixels
   Tcol = MaxCol - ({{Cl|LEN}}(txt$) \ 2)
   {{Cl|COLOR}} Tcolor: {{Cl|LOCATE}} Trow, Tcol: {{Cl|PRINT}} txt$;  
 END SUB

Explanation: _NEWIMAGE enlarges a screen to 800 pixels wide which is what _WIDTH function will return. The center is 800 \ 2 or 400. Since the text width is 8 pixels, that is divided by 8 to get 50 as the center text column. Then half of the text length is subtracted to find the starting text print LOCATE column.

Note: The screen handle parameter is required because using no handle could assume other page handles created by functions like _NEWIMAGE or _PUTIMAGE. Use the correct handle in the SUB call! When using SCREEN 0, the MaxCol variable is not needed because _WIDTH returns the number of text columns, not pixels. Use the center value and add 1. Tcol = (center& + 1) - LEN(txt$) \ 2

• _HEIGHT, _LOADIMAGE, _NEWIMAGE
• WIDTH
• Bitmaps