SaveImage SUB

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Starting with QB64-PE v3.9.0 the functionality described here was superseded by _SAVEIMAGE.

The SaveImage SUB program to create Bitmaps of other type Images or Screenshots Bitmaps are image files with the .BMP file name extension.

Bitmaps can be 1, 4, 8 or 24/32 bits per pixel(BPP) color palettes. QB64 is capable of working with high color bitmaps.
Screen or Image width and height calculations are automatically made using the image handle value.
Use an image handle value of 0(zero) to get a screen shot of the entire active program screen.
Note: SCREEN 0 text mode cannot be screen saved in QBasic or QB64 using this SUB.

Examples

Example

Using the SaveImage SUB program to save a loaded 32 bit PNG image as a bitmap (BMP) using QB64's graphic functions.

'load a 32 bit .PNG file image
i& = _LOADIMAGE("source\peLogo.png", 32)
IF i& < -1 THEN
    'load success: get image's width/height
    w& = _WIDTH(i&): h& = _HEIGHT(i&)
    'TEST-1: directly save the loaded image as .BMP file "logo.bmp"
    SaveImage i&, "logo"
    'TEST-2: make a new 4:3 program SCREEN of the loaded image's width/height
    SCREEN _NEWIMAGE((4 * w&), (3 * h&), 32)
    'now tile-fill the screen with the loaded image
    FOR x& = 0 TO (4 * w&) STEP w&
        FOR y& = 0 TO (3 * h&) STEP h&
            _PUTIMAGE (x&, y&), i&
        NEXT y&
    NEXT x&
    'and then save the entire program screen as "screenshot.bmp"
    SaveImage 0, "screenshot"
ELSE
    'load failure: print error
    PRINT "Cannot find/load the given image."
END IF
END

SUB SaveImage (image AS LONG, filename AS STRING)
bytesperpixel& = _PIXELSIZE(image&)
IF bytesperpixel& = 0 THEN PRINT "Text modes unsupported!": END
IF bytesperpixel& = 1 THEN bpp& = 8 ELSE bpp& = 24
x& = _WIDTH(image&)
y& = _HEIGHT(image&)
b$ = "BM????QB64????" + MKL$(40) + MKL$(x&) + MKL$(y&) + MKI$(1) + MKI$(bpp&) + MKL$(0) + "????" + STRING$(16, 0) 'partial BMP header info(???? to be filled later)
IF bytesperpixel& = 1 THEN
    FOR c& = 0 TO 255 ' read BGR color settings from JPG image + 1 byte spacer(CHR$(0))
        cv& = _PALETTECOLOR(c&, image&) ' color attribute to read.
        b$ = b$ + CHR$(_BLUE32(cv&)) + CHR$(_GREEN32(cv&)) + CHR$(_RED32(cv&)) + CHR$(0) 'spacer byte
    NEXT
END IF
MID$(b$, 11, 4) = MKL$(LEN(b$)) ' image pixel data offset(BMP header)
lastsource& = _SOURCE
_SOURCE image&
IF ((x& * 3) MOD 4) THEN padder$ = STRING$(4 - ((x& * 3) MOD 4), 0)
FOR py& = y& - 1 TO 0 STEP -1 ' read JPG image pixel color data
    r$ = ""
    FOR px& = 0 TO x& - 1
        c& = POINT(px&, py&) 'POINT 32 bit values are large LONG values
        IF bytesperpixel& = 1 THEN r$ = r$ + CHR$(c&) ELSE r$ = r$ + LEFT$(MKL$(c&), 3)
    NEXT px&
    d$ = d$ + r$ + padder$
NEXT py&
_SOURCE lastsource&
MID$(b$, 35, 4) = MKL$(LEN(d$)) ' image size(BMP header)
b$ = b$ + d$ ' total file data bytes to create file
MID$(b$, 3, 4) = MKL$(LEN(b$)) ' size of data file(BMP header)
IF LCASE$(RIGHT$(filename$, 4)) <> ".bmp" THEN ext$ = ".bmp"
f& = FREEFILE
OPEN filename$ + ext$ FOR OUTPUT AS #f&: CLOSE #f& ' erases an existing file
OPEN filename$ + ext$ FOR BINARY AS #f&
PUT #f&, , b$
CLOSE #f&
END SUB

Code by Galleon

SUB Explanation: b$ and d$ assemble the entire string of data to create a bitmap file. Some of the bitmap header info is placed later using a MID$ to add final header numerical data converted to ASCII characters by MKI$ or MKL$.

After the header, the RGB color settings are created using ASCII characters read backwards as Blue, Green, Red and CHR$(0) as a spacer. MKL$ places the byte values in reverse order too. Bitmaps and icons require that format. LEFT$ trims off the _ALPHA byte.

The actual image is read as pixel attributes from the image bottom to the top for proper formatting with zero padding when necessary.

Note: 32-bit images will be saved as 24-bit BMP files. All palette indexed images/modes will be saved as 256 color BMP files. Text modes cannot be saved.

SaveImage SUB

Examples

See also

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SaveImage SUB

Examples

See also

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