学步园

在贴一些大点的图片,或者要又叠加多张图片在一起的时候,最好用双缓存.

下面是双缓存的代码,是一个播放进度条,一共三个图片.在缓存画好后一起搬到前台DC上显示

 

//双缓冲绘图
 HDC hdc=GetDC(hWnd);

 HDC hdcMem1 = CreateCompatibleDC(hdc);
 HDC hdcMem2 = CreateCompatibleDC(hdc);
 HBITMAP hBit=CreateCompatibleBitmap(hdc,
                                  rcVolBarBk.right-rcVolBarBk.left,
          rcVolBarBk.bottom-rcVolBarBk.top);
 HBITMAP hOldSel1 = (HBITMAP)SelectObject(hdcMem1,hBit);
                               
 HBITMAP hBmp=LoadBitmap(hInst,MAKEINTRESOURCE(IDB_APVOLBARBK));
 HBITMAP hOldSel2 = (HBITMAP)SelectObject(hdcMem2,hBmp);
 BitBlt(hdcMem1,0,0,rcVolBarBk.right-rcVolBarBk.left,rcVolBarBk.bottom-rcVolBarBk.top,
     hdcMem2,0,0,SRCCOPY);
 SelectObject(hdcMem2,hOldSel2);
 DeleteObject(hBmp);

 hBmp=LoadBitmap(hInst,MAKEINTRESOURCE(IDB_APVOLBAR));
 hOldSel2 = (HBITMAP)SelectObject(hdcMem2,hBmp);
 BitBlt(hdcMem1,0,0,rcVolBar.right-rcVolBar.left,rcVolBar.bottom-rcVolBar.top,
     hdcMem2,0,0,SRCCOPY);
 SelectObject(hdcMem2,hOldSel2);
 DeleteObject(hBmp);

 hBmp=LoadBitmap(hInst,MAKEINTRESOURCE(IDB_APVOLBARTHUMB));
 hOldSel2 = (HBITMAP)SelectObject(hdcMem2,hBmp);
 COLORREF Tcolor=RGB(255,0,255);
 TransparentBlt(hdcMem1,rcVolBarThumb.left-rcVolBarBk.left,rcVolBarThumb.top-rcVolBarBk.top,
             rcVolBarThumb.right-rcVolBarThumb.left,rcVolBarThumb.bottom-rcVolBarThumb.top,
       hdcMem2,0,0,rcVolBarThumb.right-rcVolBarThumb.left,rcVolBarThumb.bottom-rcVolBarThumb.top,Tcolor);
 SelectObject(hdcMem2,hOldSel2);
 DeleteObject(hBmp);
 
 BitBlt(hdc,rcVolBarBk.left,rcVolBarBk.top,rcVolBarBk.right-rcVolBarBk.left,rcVolBarBk.bottom-rcVolBarBk.top,
     hdcMem1,0,0,SRCCOPY);
 SelectObject(hdcMem1,hOldSel1);
 DeleteObject(hBit);
 DeleteDC(hdcMem2);
 DeleteDC(hdcMem1);

    ReleaseDC(hWnd,hdc);