Missing standard 32bppBGRA BMP

[rysavyjan]

I noticed Paint.NET cannot properly open transparent samples such as q\rgba32.bmp:

Paint.NET is using standard Windows Imaging Component (WIC) for BMP loading and saving. WIC is used by GDI+, WPF, .NET. The problem with mentioned q\rgba32.bmp is in channels order. I created a modified version of this image with BGRA order:

    defaultbmp(glctx, c);
    c->filename = "q/rgba32win.bmp";
    c->headersize = 124;
    c->bpp = 32;
    c->compression = BI_BITFIELDS;
    c->bf[I_R] = 0x00ff0000; c->nbits[I_R] = 8; c->bf_shift[I_R] = 16;
    c->bf[I_G] = 0x0000ff00; c->nbits[I_G] = 8; c->bf_shift[I_G] = 8;
    c->bf[I_B] = 0x000000ff; c->nbits[I_B] = 8; c->bf_shift[I_B] = 0;
    c->bf[I_A] = 0xff000000; c->nbits[I_A] = 8; c->bf_shift[I_A] = 24;
    c->pal_entries = 0;
    set_calculated_fields(c);
    if (!make_bmp_file(c)) goto done;

It works fine with Paint.NET and all applications based on WIC.

Note that GIMP is also saving 32bpp alpha transparent BMP with BGRA channels order.

Would you accept pull request with this image?

[rysavyjan]

Small update after some tests. To enable WIC saving alpha transparent BMP, WIC2 (Windows 7 Platform Update and later) must be used and EnableV5Header32bppBGRA option enabled in BMP encoder:

https://docs.microsoft.com/en-us/windows/win32/wic/bmp-format-overview#enablev5header32bppbgra

https://github.com/Munemori/Windows_Classic_Sample/blob/96f883e4c900948e39660ec14a200a5164a3c7b7/Samples/DirectXTextureConverter/Cpp/DirectXTexWIC.cpp#L651

[jsummers]

Thanks. I agree, there should be such a file. I'll update the project soon.