给窗体中控件绘图的几种方法

方法一：WINDOWS API画法

//获取要绘制的控件句柄
Image img = GetWindow(this.tabPage12.Handle);
//在母容器上创建图形对象
Graphics gOut = mOut.pnlOut.CreateGraphics();
//在指定位置按指定大小绘出image
gOut.DrawImage((Image)img, form1.pnlImage.DisplayRectangle, this.tabPage12.DisplayRectangle, GraphicsUnit.Pixel);
//释放图形对象所有资源
gOut.Dispose();
img.Dispose();
GC.Collect();
form1.pnlImage.BringToFront();

#region 截图函数
    [DllImport("gdi32.dll")]
    public static extern IntPtr CreateDC(
     string lpszDriver, // driver name驱动名
     string lpszDevice, // device name设备名
     string lpszOutput, // not used; should be NULL
     IntPtr lpInitData // optional printer data
     );
    [DllImport("gdi32.dll")]
    public static extern int BitBlt(
     IntPtr hdcDest, // handle to destination DC目标设备的句柄
     int nXDest, // x-coord of destination upper-left corner目标对象的左上角的X坐标
     int nYDest, // y-coord of destination upper-left corner目标对象的左上角的Y坐标
     int nWidth, // width of destination rectangle目标对象的矩形宽度
     int nHeight, // height of destination rectangle目标对象的矩形长度
     IntPtr hdcSrc, // handle to source DC源设备的句柄
     int nXSrc, // x-coordinate of source upper-left corner源对象的左上角的X坐标
     int nYSrc, // y-coordinate of source upper-left corner源对象的左上角的Y坐标
     UInt32 dwRop // raster operation code光栅的操作值
     );
    [DllImport("gdi32.dll")]
    public static extern IntPtr CreateCompatibleDC(
     IntPtr hdc // handle to DC
     );
    [DllImport("gdi32.dll")]
    public static extern IntPtr CreateCompatibleBitmap(
     IntPtr hdc, // handle to DC
     int nWidth, // width of bitmap, in pixels
     int nHeight // height of bitmap, in pixels
     );
    [DllImport("gdi32.dll")]
    public static extern IntPtr SelectObject(
     IntPtr hdc, // handle to DC
     IntPtr hgdiobj // handle to object
     );
    [DllImport("gdi32.dll")]
    public static extern int DeleteDC(
     IntPtr hdc // handle to DC
     );
    [DllImport("user32.dll")]
    public static extern bool PrintWindow(
     IntPtr hwnd, // Window to copy,Handle to the window that will be copied.
     IntPtr hdcBlt, // HDC to print into,Handle to the device context.
     UInt32 nFlags // Optional flags,Specifies the drawing options. It can be one of the following values.
     );
    [DllImport("user32.dll")]
    public static extern IntPtr GetWindowDC(
     IntPtr hwnd
     );
    public Bitmap GetWindow(IntPtr hWnd)
    {
        IntPtr hscrdc = GetWindowDC(hWnd);
        Control control = Control.FromHandle(hWnd);
        IntPtr hbitmap = CreateCompatibleBitmap(hscrdc, control.Width, control.Height);
        IntPtr hmemdc = CreateCompatibleDC(hscrdc);
        SelectObject(hmemdc, hbitmap);
        PrintWindow(hWnd, hmemdc, 0);
        Bitmap bmp = Bitmap.FromHbitmap(hbitmap);
        DeleteDC(hscrdc);//删除用过的对象
        DeleteDC(hmemdc);//删除用过的对象
        return bmp;
    }
    #endregion

方法二、给background赋值

Bitmap bmp = new Bitmap(this.tabPage12.Width, this.tabPage12.Height);
//将控件区域显呈到指定位图
this.tabPage12.DrawToBitmap(bmp, this.tabPage12.DisplayRectangle);
form1.pnlImage.BackgroundImage = (Image)bmp;
/* 分屏显示座席 */
form1.pnlImage.BackColor = Color.White;
form1.pnlImage.BringToFront();

方法三、将某个屏幕位置拷贝到image

Image img = new Bitmap(tabPage13.Width, tabPage13.Height);
Graphics g = Graphics.FromImage(img);
g.CopyFromScreen(Obj.PointToScreen(Point.Empty), Point.Empty, tabPage13.Size);
IntPtr dc1 = g.GetHdc();
g.ReleaseHdc(dc1);
form1.pnlImage.BackgroundImage = img;
form1.pnlImage.BringToFront();