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.


Syntax:

handle& = _LOADIMAGE& (filename$[, mode&])


Description:

  • File types supported: BMP, JPG, PNG, GIF, PNM, XPM, XCF, PCX, TIF, LBM, and TGA. A path can also be given.
  • The Mode& can designate 256(8 bit) or 32 bit color. Omit to use the current screen settings.
  • Some images may not load when a mode value is designated. Try loading it without a mode designation.
  • Loaded images can be read invisibly using POINT. Image coordinates start at 0 up to the _WIDTH - 1 and _HEIGHT - 1.
  • Images can be made into a program SCREEN or page adopting the size and palette settings or placed using _PUTIMAGE.
  • When you are in SCREEN 0 a mode& must be designated. When loading an _ICON use 32 for the mode.
  • Returns -1 as an invalid handle if it could not load the image. Valid LONG handle returns are less than -1.
  • Valid images only need to be loaded ONCE! The handle can be used repeatedly until freed.
  • Images are not deallocated when the SUB or FUNCTION they are created in ends. Free them with _FREEIMAGE.
  • It is IMPORTANT to free unused or discarded images with _FREEIMAGE to prevent CPU memory overflow errors!
  • QB64 currently does not support icon files! A bad handle value will occur using _LOADIMAGE! See _ICON example 2.


Code Examples:

Example 1: Already in SCREEN 13 and want computer to match the 32-bit jpg/etc. colors to the current palette:

SCREEN 13 i& = _LOADIMAGE("mypic.jpg") _PUTIMAGE, i&


Example 2: Already in SCREEN 13 but want to load an 8-bit image and adopt its palette as the current palette:

SCREEN 13 i& = _LOADIMAGE("mypic256col.bmp", 256) _COPYPALETTE i&, 0 _PUTIMAGE, i&


Example 3: Want to display an image in 32-bit color using its resolution as a program screen:

i& = _LOADIMAGE("mypic.jpg", 32) SCREEN i&


Example 4: DRAWing and rotating an image 360 degrees using Turn Angle. POINT is used to read the invisible image source.

SCREEN _NEWIMAGE(800, 600, 32) img& = _LOADIMAGE("QB64.PNG") 'load the image file to be drawn wide% = _WIDTH(img&): deep% = _HEIGHT(img&) TLC$ = "BL" + STR$(wide% \ 2) + "BU" + STR$(deep% \ 2) 'start draw at top left corner RET$ = "BD BL" + STR$(wide%) 'return to left side of image _SOURCE img& _DEST 0 DO FOR angle% = 0 TO 360 STEP 15 CLS DRAW "BM400, 300" + "TA=" + VARPTR$(angle%) + TLC$ FOR y = 0 TO deep% - 1 FOR x = 0 TO wide% - 1 DRAW "C" + STR$(POINT(x, y)) + "R1" 'color and DRAW each pixel NEXT DRAW RET$ NEXT _DISPLAY 'NOTE: CPU usage will be HIGH! NEXT LOOP UNTIL INKEY$ > ""

Code by Ted Weissgerber
NOTE: The QB64.PNG file picturing the QB64 bee can saved from the top of the QB64 forum. Speed varies with image size.


See Examples:

  • SAVEIMAGE (QB64 Image to Bitmap SUB by Galleon)
  • Program ScreenShots (Member program for legacy screen modes)
  • ThirtyTwoBit SUB (QB64 Image area to bitmap)


See also:

  • _FREEIMAGE, _PUTIMAGE, _NEWIMAGE, _COPYIMAGE, _PRINTIMAGE (printer)
  • _PALETTECOLOR (function), _COPYPALETTE, _ICON
  • SCREEN (statement)
  • Bitmaps, Icons and Cursors, GIF Images



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