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wernsey / bitmap

A C module for manipulating bitmap/raster graphics
MIT No Attribution
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Support for loading 1-bit and 32-bit bitmaps + compression type BI_BITFIELDS #2

Closed nptr closed 5 years ago

nptr commented 5 years ago

Hello, i was playing around with your bitmap library and added support for loading 1-bit and 32-bit bitmaps in the process. Also for compression type 3: BI_BITFIELDS because its used on many 32-bit bmps.

I tested with a variety of formats from Jason Summers awesome collection at: http://entropymine.com/jason/bmpsuite/bmpsuite/html/bmpsuite.html

Successfully loaded all the files my browser did: -pal1.bmp -pal1bg.bmp -pal1p1.bmp -pal1wb.bmp

-rgb32.bmp -rgb32-7187.bmp -rgb32-111110.bmp -rgb32bf.bmp -rgb32bfdef.bmp -rgb32fakealpha.bmp -rgb32h52.bmp -rgb32-xbgr.bmp -rgba32.bmp -rgba32-61754.bmp -rgba32-81284.bmp -rgba32-1010102.bmp *

* I currently load just the RGB components, without interpret the remaining bits of 32-bit bitmaps as alpha channel. Neither do i support the V4 / V5 headers which seem to add alpha channel support. Altough i might add this another time.

Also, since the library keeps colors as R8G8B8A8, we loose some information when loading for example R11G11B10 because i have to downscale the channel to 8bit.

Furthermore, i compiled the library only from within VS2017 (MSVC++ 19.12.25830.2) so I cannot say if other compilers will be happy with the code.

Last but not least, I tried to stick to your coding style and conventions, but i might have missed something.

Let me know if i need to fix or improve something in order to have the changes merged!

wernsey commented 5 years ago

This is awesome! Thanks a lot for your effort!