如何使刷新时画面不闪烁

Posted 2021-05-17 skdev

  

创建位图内存，在内存里放置绘画数据，然后显示内存。为了避免内存在刷新时不断创建，所以内存只存窗口大小变化时创建。

HDC        hMemDC=0;//global variat

WM_PAINT:

if(hMemDC==0)

              CreateMemDC(Rect,hDC,hMemDC);       //Rect为窗体大小

       DrawBack(hDC,Rect,hMemDC);

WM_SIZE:

GetClientRect(hWnd,&Rect);

       if(Rect.right==0||Rect.bottom==0)

              return 0;

       if(hMemDC!=0)

              ReleaseMemDC(hWnd,hMemDC);

       hDC=GetDC(hWnd);

       CreateMemDC(Rect,hDC,hMemDC);

       DeleteDC(hDC);

WM_DESTROY:

       ReleaseMemDC(hWnd,hMemDC);

/*名称：CreateMemDC

 功能：创建显存hMemDC

 参数：hDC

*/

int CreateMemDC(RECT Rect,HDC hDC,HDC &hMemDC)

{

       hMemDC=CreateCompatibleDC(hDC);

       hMembitmap=CreateCompatibleBitmap(hDC,Rect.right-Rect.left,Rect.bottom-Rect.top);

       SelectObject(hMemDC,hMembitmap);

       BitBlt(hMemDC,Rect.left,Rect.top,Rect.right-Rect.left,Rect.bottom-Rect.top,hDC,0,0,SRCCOPY);

return 1;

}

/*名称：ReleaseMemDC

 功能：释放显存hMemDC

 参数：释放显存hMemDC

*/

int ReleaseMemDC(HWND hWnd,HDC &hMemDC)

{

       DeleteObject(hMembitmap);

       DeleteObject(hMemDC);         

       return 1;

}

/*名称：DrawBack

 功能：画波形

 参数：HDC,显存hMemDC数据

*/

int DrawBack(HDC hDC,RECT Rect,HDC hMemDC)

{

    TextOut(hMemDC,0,0,”hello”,5);//在内存写数据

BitBlt(hDC,Rect.left,Rect.top,Rect.right,Rect.bottom,hMemDC,0,0,SRCCOPY);//将hMemDC数据显示在hDC上。

Return 1;

}