Creating Icons from Bitmaps

The following program can create a single icon from square bitmaps up to 128 X 128. Best to use sizes 32 X 32 or 64 X 64.

CONST dat = 14~& DIM Dword AS _UNSIGNED LONG DIM size AS _UNSIGNED LONG DIM wide AS _UNSIGNED LONG DIM high AS _UNSIGNED LONG DIM Word AS _UNSIGNED INTEGER DIM Byte AS _UNSIGNED _BYTE DO LINE INPUT "Enter existing BMP file name to convert to icon: ", BMP$ LOOP UNTIL _FILEEXISTS(BMP$) DO LINE INPUT "Enter ICO file name to create (must not exist): ", ICO$ LOOP UNTIL _FILEEXISTS(ICO$) = 0 OPEN BMP$ FOR BINARY ACCESS READ AS 1 'BITMAP name OPEN ICO$ FOR OUTPUT AS 2 'destination icon name CLOSE 2 OPEN ICO$ FOR BINARY AS 2 GET 1, 1 + 2, size 'skip "BM" in bitmap size = size - 14 '14 bytes not used Word = 0 PUT 2, 1, Word 'reserved Word = 1 PUT 2, , Word 'resource id 1 as icon, 2 as cursor PUT 2, , Word 'icon count in resource GET 1, 1 + dat + 4, wide 'skip header size in BMP SELECT CASE wide CASE IS < &H100: Byte = wide '< 256 CASE &H100: Byte = 0 CASE ELSE: PRINT "bitmap is larger than 256 pixels.": END END SELECT PUT 2, , Byte 'width GET 1, , high SELECT CASE high CASE IS < &H100: Byte = high '< 256 CASE &H100: Byte = 0 '256 = 0 CASE ELSE: PRINT "bitmap is larger than 256 pixels.": END END SELECT PUT 2, , Byte 'height Byte = 0 GET 1, 1 + dat + 14, Word 'number of colors from BPP IF Word < 8 THEN Byte = 2 ^ Word ELSE Byte = 0 '256 colors = 0, 4BPP = 16 PUT 2, , Byte 'num of colors Byte = 0 Dword = 0 PUT 2, , Byte 'reserved as byte PUT 2, , Dword 'reserved 2 hotspots = 0 Dword = size + (((wide * high) + 7) \ 8) PUT 2, , Dword 'size of data Dword = 22 '6 byte header + 16 PUT 2, , Dword 'offset 'copy bitmap header down 14 bytes, palette and image info, but double height SEEK 1, 1 + dat 'BMP info header size FOR Dword = 1 TO size 'actual BMP data from Header size on GET 1, , Byte IF Dword = 1 + 8 THEN Word = high * 2 ' 2 times height PUT 2, , Word Dword = Dword + 1 GET 1, , Byte ELSE PUT 2, , Byte END IF NEXT 'add null AND bitmask for full square image Byte = 0 BitsOver& = wide MOD 32 'pad the AND mask for minimum of 4 byte width IF BitsOver& THEN ANDpad& = (32 - BitsOver&) ELSE ANDpad& = 0 FOR Dword = 1 TO high * (wide + ANDpad&) \ 8 PUT 2, , Byte NEXT CLOSE SYSTEM

Adapted from code by Michael Calkins, Public domain, November 2011

See also:

• _ICON, $EXEICON
• SaveIcon32 (saves any image to icon)
• Icons and Cursors
• Bitmaps

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