用MASK方法传送不规则位图

#define FORE_ROP3(ROP4) (0x00FFFFFF&(ROP4))

#define BACK_ROP3(ROP4) (ROP3FromIndex(SwapROP3_SrcDst(BYTE((ROP4)>>24))))

#define DSTCOPY 0x00AA0029

#define DSTERASE 0x00220326 // dest = dest & (~src) : DSna

BOOL WINAPI MyMaskBlt(HDC hdcDest, int nXDest, int nYDest, int nWidth, int nHeight,

HDC hdcSrc, int nXSrc, int nYSrc,

HBITMAP hbmMask, int xMask, int yMask,

DWORD dwRop

)

{

if ( hbmMask == NULL )

return BitBlt(hdcDest, nXDest, nYDest, nWidth, nHeight, hdcSrc,

nXSrc, nYSrc, FORE_ROP3(dwRop));

// 1. make mask bitmap's dc

HDC hDCMask = ::CreateCompatibleDC(hdcDest);

HBITMAP hOldMaskBitmap = (HBITMAP)::SelectObject(hDCMask, hbmMask);

ASSERT ( hOldMaskBitmap );

// 2. make masked Background bitmap

// 2.1 make bitmap

HDC hDC1 = ::CreateCompatibleDC(hdcDest);

ASSERT ( hDC1 );

HBITMAP hBitmap2 = ::CreateCompatibleBitmap(hdcDest, nWidth, nHeight);

HBITMAP hOldBitmap2 = (HBITMAP)::SelectObject(hDC1, hBitmap2);

ASSERT ( hOldBitmap2 );

// 2.2 draw dest bitmap and mask

DWORD dwRop3 = BACK_ROP3(dwRop);

::BitBlt(hDC1, 0, 0, nWidth, nHeight, hdcSrc, nXSrc, nYSrc, SRCCOPY);

::BitBlt(hDC1, 0, 0, nWidth, nHeight, hdcDest, nXDest, nYDest, dwRop3);

::BitBlt(hDC1, 0, 0, nWidth, nHeight, hDCMask, xMask, yMask, DSTERASE);

// 3. make masked Foreground bitmap

// 3.1 make bitmap

HDC hDC2 = ::CreateCompatibleDC(hdcDest);

ASSERT ( hDC2 );

HBITMAP hBitmap3 = ::CreateCompatibleBitmap(hdcDest, nWidth, nHeight);

HBITMAP hOldBitmap3 = (HBITMAP)::SelectObject(hDC2, hBitmap3);

ASSERT ( hOldBitmap3 );

// 3.2 draw src bitmap and mask

dwRop3 = FORE_ROP3(dwRop);

::BitBlt(hDC2, 0, 0, nWidth, nHeight, hdcDest, nXDest, nYDest, SRCCOPY);

::BitBlt(hDC2, 0, 0, nWidth, nHeight, hdcSrc, nXSrc, nYSrc, dwRop3);

::BitBlt(hDC2, 0, 0, nWidth, nHeight, hDCMask, xMask, yMask, SRCAND);

// 4. combine two bitmap and copy it to hdcDest

::BitBlt(hDC1, 0, 0, nWidth, nHeight, hDC2, 0, 0, SRCPAINT);

::BitBlt(hdcDest, nXDest, nYDest, nWidth, nHeight, hDC1, 0, 0, SRCCOPY);

// 5. restore all object

::SelectObject(hDCMask, hOldMaskBitmap);

::SelectObject(hDC1, hOldBitmap2);

::SelectObject(hDC2, hOldBitmap3);

// 6. delete all temp object

DeleteObject(hBitmap2);

DeleteObject(hBitmap3);

DeleteDC(hDC1);

DeleteDC(hDC2);

DeleteDC(hDCMask);

return TRUE;

}