WIDTH (function): Difference between revisions
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* 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]] | * 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 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 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. | * 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'''. | * The last visible pixel coordinate of a program [[SCREEN|screen]] is '''[[_WIDTH (function)|_WIDTH]] - 1'''. | ||
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{{PageExamples}} | {{PageExamples}} | ||
''Example:'' A SUB program that centers text in any graphic screen mode except text mode [[ | ''Example:'' A SUB program that centers text in any graphic screen mode except text mode [[SCREEN]] 0. | ||
{{CodeStart}} | {{CodeStart}} | ||
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Align 15, 5, s&, "This text is centered on the screen!" | Align 15, 5, s&, "This text is centered on the screen!" | ||
SUB Align (Tcolor, Trow, mode&, txt$) | SUB Align (Tcolor, Trow, mode&, txt$) | ||
center& = {{Cl|_WIDTH (function)|_WIDTH}} (mode&) \ 2 'returns pixels in graphic modes | center& = {{Cl|_WIDTH (function)|_WIDTH}} (mode&) \ 2 'returns pixels in graphic modes | ||
MaxCol = (center& \ 8) + 1 'screen text width = 8 pixels | MaxCol = (center& \ 8) + 1 'screen text width = 8 pixels | ||
Tcol = MaxCol - ({{Cl|LEN}}(txt$) \ 2) | Tcol = MaxCol - ({{Cl|LEN}}(txt$) \ 2) | ||
{{Cl|COLOR}} Tcolor: {{Cl|LOCATE}} Trow, Tcol: {{Cl|PRINT}} txt$; | {{Cl|COLOR}} Tcolor: {{Cl|LOCATE}} Trow, Tcol: {{Cl|PRINT}} txt$; | ||
END SUB | END SUB | ||
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: ''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$) \ 2''' | : ''Note:'' The screen handle parameter is required because using no handle could assume other page handles created by functions like [[_NEWIMAGE]] or [[_PUTIMAGE]]. Use the correct handle in the SUB call! When using SCREEN 0, the MaxCol variable is not needed because _WIDTH returns the number of text columns, not pixels. Use the center value and add 1. '''Tcol = (center& + 1) - LEN(txt$) \ 2''' | ||
Latest revision as of 01:21, 29 January 2023
The _WIDTH function returns the width of an image handle or of the current write page.
Syntax
- columns& = _WIDTH[(imageHandle&)]
Description
- If 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 window use zero for the handle value or nothing: columns& = _WIDTH(0) or columns& = _WIDTH
- If the image specified by imageHandle& is in text only(SCREEN 0) mode, the number of characters per row is returned.
- If the image specified by imageHandle& is in graphics mode, the number of pixels per row is returned.
- If imageHandle& is an invalid handle, then an invalid handle error is returned.
- The last visible pixel coordinate of a program screen is _WIDTH - 1.
Examples
Example: A SUB program that centers text in any graphic screen mode except text mode SCREEN 0.
s& = _NEWIMAGE(800, 600, 256) SCREEN s& Align 15, 5, s&, "This text is centered on the screen!" SUB Align (Tcolor, Trow, mode&, txt$) center& = _WIDTH (mode&) \ 2 'returns pixels in graphic modes MaxCol = (center& \ 8) + 1 'screen text width = 8 pixels Tcol = MaxCol - (LEN(txt$) \ 2) COLOR Tcolor: LOCATE Trow, Tcol: 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
See also