mirror of
https://github.com/QB64Official/qb64.git
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88 lines
3.9 KiB
Text
88 lines
3.9 KiB
Text
{{DISPLAYTITLE:_LOADIMAGE}}
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The [[_LOADIMAGE]] function loads an image into memory and returns valid [[LONG]] image handle values that are less than -1.
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{{PageSyntax}}
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:{{Parameter|handle&}} = [[_LOADIMAGE]]({{Parameter|filename$}}[, {{Parameter|mode%}}])
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{{PageParameters}}
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*{{Parameter|filename$}} is literal or variable [[STRING]] file name value.
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*Optional {{Parameter|mode%}} [[INTEGER]] values can be:
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**32 = 32-bit
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**33 = hardware image
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{{PageDescription}}
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*Various common image file formats supported, like BMP, JPG, PNG, etc. A path can also be given.
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*The {{Parameter|mode%}} can designate 32-bit color or 33 ('''version 1.000 and up'''). Omit to use the current graphic screen settings.
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*Mode 33 images are '''hardware''' accelerated and are created using [[_LOADIMAGE]] or [[_COPYIMAGE]] ('''version 1.000 and up''').
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*Loaded images can be read invisibly using [[POINT]]. Image coordinates start at 0 up to the [[_WIDTH (function)|_WIDTH]] - 1 and [[_HEIGHT]] - 1.
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*Images can be made into a program [[SCREEN (statement)|SCREEN]] or page adopting the size and palette settings or placed using [[_PUTIMAGE]].
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*Returns -1 as an invalid handle if it can't load the image. Valid [[LONG]] handle returns are less than -1 ({{Parameter|handle&}} < -1).
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*Valid images only need to be loaded once. The handle can be used repeatedly until freed.
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*'''Images are not deallocated when the [[SUB]] or [[FUNCTION]] they are created in ends. Free them with [[_FREEIMAGE]].'''
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{{PageErrors}}
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*Some picture file images may not load when a {{Parameter|mode%}} value is designated. Try loading it without a {{Parameter|mode%}} designation.
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*'''It is important to free unused or discarded images with [[_FREEIMAGE]] to prevent CPU memory overflow errors.'''
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*'''In text-only [[SCREEN]] 0, {{Parameter|mode%}} 32 must be specified.''' When loading an [[_ICON]] image use 32 for the {{Parameter|mode%}} too.
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{{PageExamples}}
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''Example 1:'' To display an image in 32-bit color using its resolution as a program screen:
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{{CodeStart}} '' ''
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i& = {{Cl|_LOADIMAGE}}("mypic.jpg", 32)
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{{Cl|SCREEN (statement)|SCREEN}} i& '' ''
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{{CodeEnd}}
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''Example 2:'' [[DRAW]]ing and rotating an image 360 degrees using Turn Angle. [[POINT]] is used to read the invisible image source.
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{{CodeStart}}
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{{Cl|SCREEN (statement)|SCREEN}} {{Cl|_NEWIMAGE}}(800, 600, 32)
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img& = {{Cl|_LOADIMAGE}}("QB64.PNG") 'load the image file to be drawn
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wide% = {{Cl|_WIDTH (function)|_WIDTH}}(img&): deep% = {{Cl|_HEIGHT}}(img&)
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TLC$ = "BL" + {{Cl|STR$}}(wide% \ 2) + "BU" + {{Cl|STR$}}(deep% \ 2) 'start draw at top left corner
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RET$ = "BD BL" + {{Cl|STR$}}(wide%) 'return to left side of image
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{{Cl|_SOURCE}} img&
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{{Cl|_DEST}} 0
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DO
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{{Cl|FOR...NEXT|FOR}} angle% = 0 {{Cl|TO}} 360 {{Cl|STEP}} 15
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{{Cl|CLS}}
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{{Cl|DRAW}} "BM400, 300" + "TA=" + {{Cl|VARPTR$}}(angle%) + TLC$
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{{Cl|FOR...NEXT|FOR}} y = 0 {{Cl|TO}} deep% - 1
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{{Cl|FOR...NEXT|FOR}} x = 0 {{Cl|TO}} wide% - 1
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{{Cl|DRAW}} "C" + {{Cl|STR$}}({{Cl|POINT}}(x, y)) + "R1" 'color and DRAW each pixel
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{{Cl|NEXT}}
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{{Cl|DRAW}} RET$
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{{Cl|NEXT}}
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{{Cl|_DISPLAY}} 'NOTE: CPU usage will be HIGH!
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{{Cl|NEXT}}
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{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} > "" '' ''
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{{CodeEnd}}
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{{small|Code by Ted Weissgerber}}
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:''NOTE:'' Speed varies with image size.
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===More examples===
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*[[SAVEIMAGE]] (QB64 Image to Bitmap SUB by Galleon)
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*[[Program ScreenShots]] (Member-contributed program for legacy screen modes)
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*[[ThirtyTwoBit SUB]] (QB64 Image area to bitmap)
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{{PageSeeAlso}}
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*[[_FREEIMAGE]], [[_ICON]]
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*[[_PUTIMAGE]], [[_MAPTRIANGLE]]
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*[[_NEWIMAGE]], [[_COPYIMAGE]]
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*[[_PRINTIMAGE]] (printer)
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*[[_PALETTECOLOR (function)]], [[_COPYPALETTE]], [[_ICON]]
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*[[SCREEN (statement)]]
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*[[Hardware images]]
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*[[Bitmaps]], [[Icons and Cursors]], [[GIF Images]]
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{{PageNavigation}}
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