QB64-PE/internal/help/_WIDTH_(function).txt

{{DISPLAYTITLE:_WIDTH (function)}}
The [[_WIDTH (function)|_WIDTH]] function returns the width of an image handle or of the current write page.


{{PageSyntax}}
: {{Parameter|columns&}} = [[_WIDTH (function)|_WIDTH]][({{Parameter|imageHandle&}})]


{{PageDescription}}
* If {{Parameter|imageHandle&}} 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|screen]] window use zero for the handle value or nothing: {{Parameter|columns&}} = [[_WIDTH (function)|_WIDTH]](0) ''or'' {{Parameter|columns&}} = [[_WIDTH (function)|_WIDTH]]
* If the image specified by {{Parameter|imageHandle&}} is in text only([[SCREEN]] 0) mode, the number of characters per row is returned.
* If the image specified by {{Parameter|imageHandle&}} is in graphics mode, the number of pixels per row is returned. 
* If {{Parameter|imageHandle&}} is an invalid handle, then an [[ERROR Codes|invalid handle error]] is returned.
* The last visible pixel coordinate of a program [[SCREEN|screen]] is '''[[_WIDTH (function)|_WIDTH]] - 1'''.


{{PageExamples}}
''Example:'' A SUB program that centers text in any graphic screen mode except text mode [[SCREEN (statement)|SCREEN]] 0.

{{CodeStart}}

 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

{{CodeEnd}}

: ''Explanation:'' [[_NEWIMAGE]] enlarges a screen to 800 pixels wide which is what [[_WIDTH (function)|_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'''



{{PageSeeAlso}}
* [[_HEIGHT]], [[_LOADIMAGE]], [[_NEWIMAGE]]
* [[WIDTH]]
* [[Bitmaps]]


{{PageNavigation}}
<