MSDN解释：StretchBlt The StretchBlt function copies a bitmap from a source rectangle into a destination rectangle, stretching or compressing the bitmap to fit the dimensions of the destination rectangle, if necessary. The system stretches or compresses the bitmap according to the stretching mode currently set in the destination device context. BOOL StretchBlt( HDC hdcDest, // handle to destination DC int nXOriginDest, // x-coord of destination upper-left corner int nYOriginDest, // y-coord of destination upper-left corner int nWidthDest, // width of destination rectangle int nHeightDest, // height of destination rectangle HDC hdcSrc, // handle to source DC int nXOriginSrc, // x-coord of source upper-left corner int nYOriginSrc, // y-coord of source upper-left corner int nWidthSrc, // width of source rectangle int nHeightSrc, // height of source rectangle DWORD dwRop // raster operation code ); Parameters hdcDest [in] Handle to the destination device context. nXOriginDest [in] Specifies the x-coordinate, in logical units, of the upper-left corner of the destination rectangle. nYOriginDest [in] Specifies the y-coordinate, in logical units, of the upper-left corner of the destination rectangle. nWidthDest [in] Specifies the width, in logical units, of the destination rectangle. nHeightDest [in] Specifies the height, in logical units, of the destination rectangle. hdcSrc [in] Handle to the source device context. nXOriginSrc [in] Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle. nYOriginSrc [in] Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle. nWidthSrc [in] Specifies the width, in logical units, of the source rectangle. nHeightSrc [in] Specifies the height, in logical units, of the source rectangle. dwRop [in] Specifies the raster operation to be performed. Raster operation codes define how the system combines colors in output operations that involve a brush, a source bitmap, and a destination bitmap. See BitBlt for a list of common raster operation codes.
The StretchBlt function copies a bitmap from a source rectangle into a destination rectangle, stretching or compressing the bitmap to fit the dimensions of the destination rectangle, if necessary. The system stretches or compresses the bitmap according to the stretching mode currently set in the destination device context. BOOL StretchBlt(
HDC hdcDest, // handle to destination DC
int nXOriginDest, // x-coord of destination upper-left corner
int nYOriginDest, // y-coord of destination upper-left corner
int nWidthDest, // width of destination rectangle
int nHeightDest, // height of destination rectangle
HDC hdcSrc, // handle to source DC
int nXOriginSrc, // x-coord of source upper-left corner
int nYOriginSrc, // y-coord of source upper-left corner
int nWidthSrc, // width of source rectangle
int nHeightSrc, // height of source rectangle
DWORD dwRop // raster operation code
);
Parameters
hdcDest
[in] Handle to the destination device context.
nXOriginDest
[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the destination rectangle.
nYOriginDest
[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the destination rectangle.
nWidthDest
[in] Specifies the width, in logical units, of the destination rectangle.
nHeightDest
[in] Specifies the height, in logical units, of the destination rectangle.
hdcSrc
[in] Handle to the source device context.
nXOriginSrc
[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle.
nYOriginSrc
[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle.
nWidthSrc
[in] Specifies the width, in logical units, of the source rectangle.
nHeightSrc
[in] Specifies the height, in logical units, of the source rectangle.
dwRop
[in] Specifies the raster operation to be performed. Raster operation codes define how the system combines colors in output operations that involve a brush, a source bitmap, and a destination bitmap.
See BitBlt for a list of common raster operation codes.
的回答是对的Featured(我握着爱情的门票静静排队……)
我想楼主的意思是对图片文件进行物理的转换,而不仅仅是缩小显示
我已经说明了不能用StretchBlt的,要自己写算法实现位图的缩放
可以用StretchBlt,但这个函数是在显存里画的
保存是有点问题了，尤其是大图片的时候。
一般是采用插值的