08-16-2024, 07:22 PM
I turned Steve's code into a useful function that I just added to my goodies library:
Code: (Select All)
DIM a(4)
a(1) = _NEWIMAGE(640, 480, 32) ' 32 bit color
a(2) = _NEWIMAGE(640, 480, 256) ' 256 color
a(3) = _NEWIMAGE(640, 480, 12) ' 16 color
a(4) = _NEWIMAGE(80, 25, 0) ' text (16 color)
PRINT IMG_ColorDepth(a(1)) ' 32 bit color return
PRINT IMG_ColorDepth(a(2)) ' 256 color return
PRINT IMG_ColorDepth(a(3)) ' 16 color return
PRINT IMG_ColorDepth(a(4)) ' text color return
'PRINT IMG_ColorDepth(-30) ' this line will cause the error described in the function's documentation
FUNCTION IMG_ColorDepth% (i AS LONG)
'+------------------------------------------------+
'| Returns the color depth of an image passed in. |
'| |
'| i - the image handle |
'| |
'| Returns: 0 : not an image |
'| 32 : 32 bit color image |
'| 256 : 256 color image |
'| 16 : 16 color image (or text only) |
'| |
'| Note: this function will fail if an image |
'| handle value passed in is less than -1 |
'| but does not belong to an actual image. |
'+------------------------------------------------+
DIM c AS INTEGER ' color counter
DIM p AS INTEGER ' palette counter
IF i > -2 THEN EXIT FUNCTION ' not an image, return 0
IF _PIXELSIZE(i) = 4 THEN ' 4 bytes per pixel?
IMG_ColorDepth% = 32 ' yes, 32 bit color image
ELSE ' no, 1 byte per pixel
p = 0 ' reset palette counter
c = 0 ' reset color counter
DO ' begin palette search
IF _PALETTECOLOR(p, i) <> &HFF000000 THEN c = c + 1 ' increment color counter if color found
p = p + 1 ' increment palette counter
LOOP UNTIL p = 256 ' leave when entire palette searched
IF c <= 16 THEN ' 16 colors or less?
IMG_ColorDepth% = 16 ' yes, 16 color image
ELSE ' no, greater than 16
IMG_ColorDepth% = 256 ' 256 color image
END IF
END IF
END FUNCTION