| int SetStretchBltMode(hdc, iStretchMode) | |||||
| HDC hdc; | /* handle of device context | */ | |||
| int iStretchMode; | /* bitmap stretching-mode | */ | |||
The SetStretchBltMode function sets the bitmap stretching-mode in the given device-context.
hdc
Identifies the device context.
iStretchMode
Specifies the stretching mode. It can be one of the following values:
| Value | Meaning |
| BLACKONWHITE | ||
| Performs a Boolean AND operation using the color values for the eliminated and existing pixels. If the bitmap is a monochrome bitmap, this mode preserves black pixels at the expense of white pixels. | ||
| COLORONCOLOR | ||
| Deletes the pixels. This mode deletes all eliminated lines of pixels without trying to preserve their information. | ||
| WHITEONBLACK | ||
| Performs a Boolean OR operation using the color values for the eliminated and existing pixels. If the bitmap is a monochrome bitmap, this mode preserves white pixels at the expense of black pixels. | ||
| HALFTONE | ||
| Pixels from the source are mapped into blocks of pixels in the destination. The average color over the destination block of pixels approximates the color of the source pixels. | ||
The return value specifies the previous stretching-mode if the function is successful; otherwise it is 0.
The stretching mode defines how Windows combines rows or columns of a bitmap with existing pixels on a display when an application calls the StretchBlt function.
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 HALFTONE mode requires more processing of the source image than the other three modes; it is slower than the others, but produces higher quality images.
StretchBlt