_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$[, mode%])
Parameters
- filename$ is literal or variable STRING file name value.
- Optional mode% INTEGER values can be:
- 32 = 32-bit image
- 33 = 32-bit hardware image
- 256 = 8-bit (256 color) image using the QB64-PE master palette
- 257 = 8-bit (256 color) image using an adaptive palette
Description
- Various common image file formats like JPG, PNG, TGA, BMP, PSD, GIF, HDR, PIC, PNM and PCX are supported. A path can also be given.
- The mode% parameter can be 32, 33 (version 1.000 and up), 256 or 257 (version 3.1.0 and up). Omit to use the current graphic screen settings.
- Mode 33 images are hardware accelerated and are created using _LOADIMAGE or _COPYIMAGE (version 1.000 and up).
- Mode 256 images are loaded using the QB64-PE master palette. This is the same palette that is used for 256 color screens like SCREEN 13.
- Mode 257 images are loaded using an adaptive palette making these images look better than mode 256 when used with 32-bit color screens.
- 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.
- Returns -1 as an invalid handle if it can't load the image. Valid LONG handle returns are less than -1 (handle& < -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.
Errors
- Some picture file images may not load when a mode% value is designated. Try loading it without a mode% designation.
- It is important to free unused or discarded images with _FREEIMAGE to prevent CPU memory overflow errors.
- In text-only SCREEN 0, mode% 32 must be specified. When loading an _ICON image use 32 for the mode% too.
Availability
v0.800
all
yes
yes
yes
- The capability to load from memory was introduced in QB64-PE v3.6.0.
Examples
- Example 1
- To display an image in 32-bit color using its resolution as a program screen.
i& = _LOADIMAGE("mypic.jpg", 32) SCREEN i& |
- Example 2
- 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") 'use any 24/32 bit image 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$ > "" |
More examples
See also
- _FREEIMAGE, _ICON
- _PUTIMAGE, _MAPTRIANGLE
- _NEWIMAGE, _COPYIMAGE
- _PRINTIMAGE (printer)
- _PALETTECOLOR (function), _COPYPALETTE, _ICON
- SCREEN
- Hardware images
- Bitmaps, Icons and Cursors, GIF Images