程序中图片透明函数（使用SetBkColor API函数）

void DrawTransparentBitmap(HDC hdc, HBITMAP hBitmap, short xStart, short yStart, COLORREF cTransparentColor);

函数的实现:

void CLoginPanel::DrawTransparentBitmap(HDC hdc, HBITMAP hBitmap, short xStart, short yStart, COLORREF cTransparentColor)
     {
     BITMAP          bm;
     COLORREF      cColor;
     HBITMAP        bmAndBack, bmAndObject, bmAndMem, bmSave;
     HBITMAP        bmBackOld, bmObjectOld, bmMemOld, bmSaveOld;
     HDC                hdcMem, hdcBack, hdcObject, hdcTemp, hdcSave;
     POINT            ptSize;

     hdcTemp = CreateCompatibleDC(hdc);
     SelectObject(hdcTemp, hBitmap);      // Select the bitmap

     GetObject(hBitmap, sizeof(BITMAP), (LPSTR)&bm);
     ptSize.x = bm.bmWidth;                        // Get width of bitmap
     ptSize.y = bm.bmHeight;                      // Get height of bitmap
     DPtoLP(hdcTemp, &ptSize, 1);            // Convert from device

                                                                         // to logical points

     // Create some DCs to hold temporary data.
     hdcBack      = CreateCompatibleDC(hdc);
     hdcObject = CreateCompatibleDC(hdc);
     hdcMem        = CreateCompatibleDC(hdc);
     hdcSave      = CreateCompatibleDC(hdc);

     // Create a bitmap for each DC. DCs are required for a number of
     // GDI functions.

     // Monochrome DC
     bmAndBack      = CreateBitmap(ptSize.x, ptSize.y, 1, 1, NULL);

     // Monochrome DC
     bmAndObject = CreateBitmap(ptSize.x, ptSize.y, 1, 1, NULL);

     bmAndMem        = CreateCompatibleBitmap(hdc, ptSize.x, ptSize.y);
     bmSave            = CreateCompatibleBitmap(hdc, ptSize.x, ptSize.y);

     // Each DC must select a bitmap object to store pixel data.
     bmBackOld      = (HBITMAP)SelectObject(hdcBack, bmAndBack);
     bmObjectOld = (HBITMAP)SelectObject(hdcObject, bmAndObject);
     bmMemOld        = (HBITMAP)SelectObject(hdcMem, bmAndMem);
     bmSaveOld      = (HBITMAP)SelectObject(hdcSave, bmSave);

     // Set proper mapping mode.
     SetMapMode(hdcTemp, GetMapMode(hdc));

     // Save the bitmap sent here, because it will be overwritten.
     BitBlt(hdcSave, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0, SRCCOPY);

     // Set the background color of the source DC to the color.
     // contained in the parts of the bitmap that should be transparent
     cColor = SetBkColor(hdcTemp, cTransparentColor);

     // Create the object mask for the bitmap by performing a BitBlt
     // from the source bitmap to a monochrome bitmap.
     BitBlt(hdcObject, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0,
                   SRCCOPY);

     // Set the background color of the source DC back to the original
     // color.
     SetBkColor(hdcTemp, cColor);

     // Create the inverse of the object mask.
     BitBlt(hdcBack, 0, 0, ptSize.x, ptSize.y, hdcObject, 0, 0,
                   NOTSRCCOPY);

     // Copy the background of the main DC to the destination.
     BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdc, xStart, yStart,
                   SRCCOPY);

     // Mask out the places where the bitmap will be placed.
     BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdcObject, 0, 0, SRCAND);

     // Mask out the transparent colored pixels on the bitmap.
     BitBlt(hdcTemp, 0, 0, ptSize.x, ptSize.y, hdcBack, 0, 0, SRCAND);

     // XOR the bitmap with the background on the destination DC.
     BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0, SRCPAINT);

     // Copy the destination to the screen.
     BitBlt(hdc, xStart, yStart, ptSize.x, ptSize.y, hdcMem, 0, 0,
                   SRCCOPY);

     // Place the original bitmap back into the bitmap sent here.
     BitBlt(hdcTemp, 0, 0, ptSize.x, ptSize.y, hdcSave, 0, 0, SRCCOPY);

     // Delete the memory bitmaps.
     DeleteObject(SelectObject(hdcBack, bmBackOld));
     DeleteObject(SelectObject(hdcObject, bmObjectOld));
     DeleteObject(SelectObject(hdcMem, bmMemOld));
     DeleteObject(SelectObject(hdcSave, bmSaveOld));

     // Delete the memory DCs.
     DeleteDC(hdcMem);
     DeleteDC(hdcBack);
     DeleteDC(hdcObject);
     DeleteDC(hdcSave);
     DeleteDC(hdcTemp);
     }

https://blog.csdn.net/goodowxy/article/details/2038014

巴特西

程序中图片透明函数（使用SetBkColor API函数）

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巴特西

程序中图片透明 函数（使用SetBkColor API函数）

最新文章

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程序中图片透明函数（使用SetBkColor API函数）