c – 渲染到桌面

这里有一些代码可以让你获得一个窗口的句柄(HWND),可以用来绘制windows桌面的顶部.这是如何工作的主要问题是桌面图标仍然存在,但这将允许您绘制它们之上.如果你想让图标显示为正常(你的东西在它们后面),你需要在绘制完东西之后重新绘制它们,或者找到一种方法来避免首先绘制它们.这是非常重要的,我从未完全解决过.

这肯定适用于XP和Windows 7(使用Areo),以获得普通GDI绘图可以使用的东西.我从未使用DirectX对其进行测试,但我怀疑如果您使用hMainWnd作为演示窗口,它会起作用.

HWND hProgMan = NULL;
HWND hShell = NULL;
HWND hMainWnd = NULL;
unsigned int ScreenWidth = 0;
unsigned int ScreenHeight = 0;
int ScreenTop = 0;
int ScreenLeft = 0;
HRGN ValidRGN = NULL;

// ...

    ScreenWidth = GetSystemMetrics(SM_CXVIRTUALSCREEN);
    if ( ScreenWidth == 0 ) 
        ScreenWidth = GetSystemMetrics( SM_CXSCREEN );

    ScreenHeight = GetSystemMetrics(SM_CYVIRTUALSCREEN);
    if ( ScreenHeight == 0 ) 
        ScreenHeight = GetSystemMetrics(SM_CYSCREEN);

    ScreenTop = GetSystemMetrics(SM_YVIRTUALSCREEN);
    ScreenLeft = GetSystemMetrics(SM_XVIRTUALSCREEN);

    ValidRGN = CreateRectRgn(0,ScreenWidth,ScreenHeight);

    hProgMan = FindWindow("Progman","Program Manager");
    if(hProgMan != NULL)
    {
        hShell = FindWindowEx(hProgMan,"SHELLDLL_DefView",NULL);
    }
    else
    {
        hProgMan = FindWindow("DesktopBackgroundClass",NULL);
        if(hProgMan != NULL)
            hShell = FindWindowEx(hProgMan,"DeskFolder",NULL);
    }

    hMainWnd = CreateWindowEx( WS_EX_TRANSPARENT,"MyWindowClass","Window Title",WS_CHILDWINDOW | WS_OVERLAPPED | WS_CLIPCHILDREN,ScreenHeight,hShell,NULL,hInstance,NULL );
    EnableWindow(hMainWnd,FALSE);
    SetWindowPos(hMainWnd,HWND_BOTTOM,SWP_NOSIZE|SWP_NOMOVE);

…然后用于绘图(使用GDI),像这样……

HDC hDC = GetDC( hMainWnd );
    SelectClipRgn(hDC,ValidRGN);
    BitBlt( hDC,ScreenX,ScreenY,hBackBuffer,SRCCOPY );
    ReleaseDC( hMainWnd,hDC );

…并使用桌面图标的区域更新ValidRGN.通过Desktop的listview控制窗口可以找到一些工具.对于这个问题,这个问题相当复杂.