Visual C++中实现双缓冲的基本原理

CPen Pen;

Pen.CreatePen(PS_INSIDEFRAME,1,RGB(225,225,0));

CBrush Brush;

Brush.CreateSolidBrush(RGB(225,225,0));

CDC dcMem;

CBitmap bm;

CRect rc;

GetClientRect(&rc);

// Step 1:为屏幕DC创建兼容的内存DC :CreateCompatibleDC()

dcMem.CreateCompatibleDC(pDC);

// Step 2:创建位图：CreateCompatibleBitmap()

bm.CreateCompatibleBitmap(pDC,rc.Width(),rc.Height());

// Step 3:把位图选入设备环境：SelectObject()，可以理解为选择画布

dcMem.SelectObject(&bm); 

dcMem.SelectObject(Pen);

dcMem.SelectObject(Brush);

dcMem.Ellipse(0,0,50,50);//画椭圆

// Step 4:把绘制好的图形“拷贝“到屏幕上:BitBlt()

pDC->BitBlt(0,0,rc.Width(),rc.Height(),&dcMem,0,0,SRCCOPY);

dcMem.DeleteDC();

bm.DeleteObject();