活用C#截取计算机屏幕

 ///
/// 截取部分屏幕
///
/// 左上角
/// 右下角
/// 是否全屏幕
/// 返回值Bitmap
public static Bitmap GetPartScreen(Point P1,Point P2,bool Full)
{
    IntPtr hscrdc,hmemdc;
    IntPtr hbitmap,holdbitmap;
    int nx,ny,nx2,ny2;
    nx=ny=nx2=ny2=0;
    int nwidth, nheight;
    int xscrn, yscrn;
    hscrdc = CreateDC("DISPLAY", null, null, 0);//创建DC句柄
    hmemdc = CreateCompatibleDC(hscrdc);//创建一个内存DC
    xscrn = GetDeviceCaps(hscrdc, GetDeviceCapsIndex.HORZRES);//获取屏幕宽度
    yscrn = GetDeviceCaps(hscrdc, GetDeviceCapsIndex.VERTRES);//获取屏幕高度
    if(Full)//如果是截取整个屏幕
    {
        nx = 0;
        ny = 0;
        nx2 = xscrn;
        ny2 = yscrn;
    }
    else
    {
        nx = P1.X;
        ny = P1.Y;
        nx2 =P2.X;
        ny2 =P2.Y;
        //检查数值合法性
        if(nx<0)nx = 0;
        if(ny<0)ny = 0;
        if(nx2>xscrn)nx2 = xscrn;
        if(ny2>yscrn)ny2 = yscrn;
    }
    nwidth = nx2 - nx;//截取范围的宽度
    nheight = ny2 - ny;//截取范围的高度
    hbitmap = CreateCompatibleBitmap(hscrdc, nwidth, nheight);//从内存DC复制到hbitmap句柄
    holdbitmap = SelectObject(hmemdc, hbitmap);
    BitBlt(hmemdc, 0, 0, nwidth, nheight,hscrdc, nx, ny,(UInt32)0xcc0020);
    hbitmap = SelectObject(hmemdc, holdbitmap);
    DeleteDC(hscrdc);//删除用过的对象
    DeleteDC(hmemdc);//删除用过的对象
    return Bitmap.FromHbitmap(hbitmap);//用Bitmap.FromHbitmap从hbitmap返回Bitmap
}