int GetStretchBltMode() const;
Retrieves the current bitmap-stretching mode. The bitmap-stretching mode defines how information is removed from bitmaps that are stretched or compressed by using StretchBlt.
The BLACKONWHITE and WHITEONBLACK modes are typically used to preserve foreground pixels in monochrome bitmaps.
The COLORONCOLOR mode is typically used to preserve color in color bitmaps.
The current bitmap-stretching mode. It can be WHITEONBLACK, BLACKONWHITE, or COLORONCOLOR.
CDC::StretchBlt, CDC::SetStretchBltMode, ::GetStretchBltMode