BGRABitmap pixel formats
BGRABitmap offers a single type for pixels (TBGRAPixel), the format of which
is decided at compile-time. The format used depends on system details and
various compile-time definitions, which lead to the definition of the
BGRABITMAP_BGRAPIXEL or BGRABITMAP_RGBAPIXEL compile-time definitions.
If BGRABITMAP_BGRAPIXEL is defined or there is no format definition at all,
then the format used is an array format which is always stored in memory as the
bytes B, G, R, A (with B at the lowest address, A at the highest).
If BGRABITMAP_RGBAPIXEL is defined, then the format used is an array format
which is always stored in memory as the bytes R, G, B, A (with R at the lowest
address, A at the highest).