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https://github.com/QB64-Phoenix-Edition/QB64pe.git
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92 lines
4.2 KiB
Plaintext
92 lines
4.2 KiB
Plaintext
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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: handle& = _LOADIMAGE& (''filename$''[, ''mode&''])
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{{PageDescription}}
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* File types supported: BMP, JPG, PNG, GIF, PNM, XPM, XCF, PCX, TIF, LBM, and TGA. A path can also be given.
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* The ''Mode&'' can designate 256(8 bit) or 32 bit color. Omit to use the current graphic screen settings.
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* Some images may not load when a ''mode'' value is designated. Try loading it without a ''mode'' designation.
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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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* '''In text [[SCREEN]] 0 ''mode&'' 32 must be designated!''' When loading an [[_ICON]] image use 32 for the mode also.
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* Returns -1 as an invalid handle if it could not load the image. Valid {{KW|LONG}} handle returns are less than -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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* '''It is IMPORTANT to free unused or discarded images with [[_FREEIMAGE]] to prevent CPU memory overflow errors!'''
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* '''QB64 currently does not support icon files! A bad handle value will occur using _LOADIMAGE! See [[_ICON]] example 2.'''
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{{PageExamples}}
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''Example 1:'' Already in SCREEN 13 and want computer to match the 32-bit jpg/etc.
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colors to the current palette:
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{{CodeStart}} '' ''
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{{Cl|SCREEN (statement)|SCREEN}} 13
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i& = {{Cl|_LOADIMAGE}}("mypic.jpg")
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{{Cl|_PUTIMAGE}}, i& '' ''
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{{CodeEnd}}
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''Example 2:'' Already in SCREEN 13 but want to load an 8-bit image and adopt its
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palette as the current palette:
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{{CodeStart}} '' ''
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{{Cl|SCREEN (statement)|SCREEN}} 13
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i& = {{Cl|_LOADIMAGE}}("mypic256col.bmp", 256)
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{{Cl|_COPYPALETTE}} i&, 0
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{{Cl|_PUTIMAGE}}, i& '' ''
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{{CodeEnd}}
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''Example 3:'' Want 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 4:'' [[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:'' The ''QB64.PNG'' file picturing the QB64 bee can saved from the top of the [http://www.qb64.net/forum/index.php QB64 forum]. Speed varies with image size.
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''See Examples:''
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*{{KW|SAVEIMAGE}} (QB64 Image to Bitmap SUB by Galleon)
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*{{KW|Program ScreenShots}} (Member program for legacy screen modes)
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* {{KW|ThirtyTwoBit SUB}} (QB64 Image area to bitmap)
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{{PageSeeAlso}}
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*[[_FREEIMAGE]], [[_PUTIMAGE]], [[_NEWIMAGE]], [[_COPYIMAGE]], [[_PRINTIMAGE]] (printer)
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*[[_PALETTECOLOR (function)]], [[_COPYPALETTE]], [[_ICON]]
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*[[SCREEN (statement)]]
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*[[Bitmaps]], [[Icons and Cursors]], [[GIF Images]]
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{{PageNavigation}} |