BITMAP resource

• Win32 RC compiler allows any DIB with header size >= 40 or exactly 12 (Win 2.0). DIBs with unknown or BITMAPV4HEADER/BITMAPV5HEADER headers will fail to be loaded at runtime by LoadBitmap/LoadImage, but they are not a compile error.
• Does not support PNG at all. Side note: If a .png file is specified in a .xml file run through uicc.exe, it will generate a .rc file with e.g. <id> IMAGE "image.png" which is a custom resource with the type as the string IMAGE, while for .bmp files it will use BITMAP.
• Win32 rc.exe will always try to write numColorPaletteBytes (<number of bytes per color palette index> * numColors) bytes to the .res, filling in any bytes past the end of the file with the pixel data (this is a miscompilation I believe), and then 0x00 if it starts reading past the end of the file (note: numColors is biClrUsed from the BITMAPINFOHEADER).
  • If numColorPaletteBytes is >= 2 GiB, then rc.exe will fail with out of memory, e.g. if numColors is 0x262C8ACF, then rc.exe will attempt to allocate 0x98B22B3C bytes (2.386 GiB) and fail.
    • Certain values where numColorPaletteBytes is >= 2 GiB seem avoid the out of memory and have extremely long runtime (it seems like an infinite loop but will eventually finish), but I’m not sure exactly what the conditions are that avoid the out of memory.
  • If numColorPaletteBytes is < 2 GiB, then rc.exe will succeed (but may take a while)
• Win32 rc.exe will miscompile bitmaps where the bfOffBits field of the bitmap file header is set larger than <the size of the bmp file> + <size of the DIB header>, in which case the ‘size’ of the resource will become negative and a resource with the size set to the underflowed size (e.g. -1 will underflow/wrap to 0xFFFFFFFF) but with no actual data.