useing MaskBit Function

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MaskBlt The MaskBlt function combines the color data for the source and destination bitmaps using the specified mask and raster operation. BOOL MaskBlt( HDC hdcDest, // handle to destination device context int nXDest, // x-coord. of upper-left corner of // destination rectangle int nYDest, // y-coord. of upper-left corner of // destination rectangle int nWidth, // width of source and destination rectangles int nHeight, // height of source and destination rectangles HDC hdcSrc, // handle to source device context int nXSrc, // x-coord. of upper-left corner of source rectangle int nYSrc, // y-coord. of upper-left corner of source rectangle HBITMAP hbmMask, // handle to monochrome bit mask int xMask, // horizontal pixel offset into the mask bitmap int yMask, // vertical pixel offset into the mask bitmap DWORD dwRop // raster operation code ); Parameters hdcDest Handle to the destination device context. nXDest Specifies the logical x-coordinate of the upper-left corner of the destination rectangle. nYDest Specifies the logical y-coordinate of the upper-left corner of the destination rectangle. nWidth Specifies the width, in logical units, of the destination rectangle and source bitmap. nHeight Specifies the height, in logical units, of the destination rectangle and source bitmap. hdcSrc Handle to the device context from which the bitmap is to be copied. It must be zero if the dwRop parameter specifies a raster operation that does not include a source. nXSrc Specifies the logical x-coordinate of the upper-left corner of the source bitmap. nYSrc Specifies the logical y-coordinate of the upper-left corner of the source bitmap. hbmMask Handle to the monochrome mask bitmap combined with the color bitmap in the source device context. xMask Specifies the horizontal pixel offset for the mask bitmap specified by the hbmMask parameter. yMask Specifies the vertical pixel offset for the mask bitmap specified by the hbmMask parameter. dwRop Specifies both foreground and background ternary raster operation codes that the function uses to control the combination of source and destination data. The background raster operation code is stored in the high-order byte of the high-order word of this value; the foreground raster operation code is stored in the low-order byte of the high-order word of this value; the low-order word of this value is ignored, and should be zero. The macro MAKEROP4 creates such combinations of foreground and background raster operation codes. For a discussion of foreground and background in the context of this function, see the following Remarks section. For a list of common raster operation codes, see the BitBlt function. Return Values If the function succeeds, the return value is nonzero. If the function fails, the return value is zero. Windows NT: To get extended error information, callGetLastError. Remarks A value of 1 in the mask specified by hbmMask indicates that the foreground raster operation code specified by dwRop should be applied at that location. A value of 0 in the mask indicates that the background raster operation code specified by dwRop should be applied at that location. If the raster operations require a source, the mask rectangle must cover the source rectangle. If it does not, the function will fail. If the raster operations do not require a source, the mask rectangle must cover the destination rectangle. If it does not, the function will fail. If a rotation or shear transformation is in effect for the source device context when this function is called, an error occurs. However, other types of transformation are allowed. If the color formats of the source, pattern, and destination bitmaps differ, this function converts the pattern or source format, or both, to match the destination format. If the mask bitmap is not a monochrome bitmap, an error occurs. When an enhanced metafile is being recorded, an error occurs (and the function returns FALSE) if the source device context identifies an enhanced-metafile device context. Not all devices support the MaskBlt function. An application should call the GetDeviceCaps function to determine whether a device supports this function. If no mask bitmap is supplied, this function behaves exactly like BitBlt, using the foreground raster operation code.