Matteo Bruni (@Mystral) commented about dlls/d3dx9_36/tests/surface.c:
}, }, /* - * We don't match formats here because we encode our BMP headers - * differently. Native encodes with the same header as - * D3DFMT_X8R8G8B8, it just sets the values in the alpha channel. The - * format is distinguished by checking the image. We encode a bitmap - * V4 header with a dedicated alpha mask, so we'll always report - * D3DFMT_A8R8G8B8, regardless of whether or not any alpha channel - * values are non-zero. + * For BMP/DIB, these encode as D3DFMT_X8R8G8B8. If there's a single + * pixel with a non-zero alpha channel, it reports as D3DFMT_A8R8G8B8.
Nitpick, "If there's at least one pixel..." -- https://gitlab.winehq.org/wine/wine/-/merge_requests/7436#note_96708