GDI螢幕輸出，在當前電腦的案頭上進行繪畫

現在可以在案頭上進行繪畫了，但是當何時進行重繪，現在還沒有解決方案。

using System;
using System.Runtime.InteropServices;
using System.Drawing;
namespace WindowsApplication2
{
 public class WinScreen
 {
  [DllImport("gdi32.dll")]
  static extern IntPtr CreateDC(string lpDriverName, string lpDeviceName, string lpOutput, string lpInitData);

  [DllImport("gdi32.dll")]
  static extern IntPtr CreateCompatibleDC(IntPtr hDC);

  [DllImport("gdi32.dll")]
  static extern IntPtr CreateCompatibleBitmap(IntPtr hDC, int nWidth, int nHeight);

  [DllImport("gdi32.dll")]
  static extern int GetDeviceCaps(IntPtr hdc, int nIndex);

  [DllImport("gdi32.dll")]
  static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);

  [DllImport("gdi32.dll")]
  static extern int BitBlt(IntPtr desthDC, int srcX, int srcY, int srcW, int srcH, IntPtr srchDC, int destX, int destY, int op);

  [DllImport("gdi32.dll")]
  static extern int DeleteDC(IntPtr hDC);

  [DllImport("gdi32.dll")]
  static extern int DeleteObject(IntPtr hObj);
 　　　
 
  public static Bitmap CaptureControl(IntPtr SourceDC,int SourceWidth,int SourceHeight)
  {
   return Capture(SourceDC,SourceWidth,SourceHeight);
  }

  public static  Bitmap CaptureScreen()
  {
   IntPtr screen=CreateDC("DISPLAY", "", "", "");
   int sourceWidth=GetDeviceCaps(screen, 8);
   int sourceHeight=GetDeviceCaps(screen, 10);
   Capture(screen,sourceWidth,sourceHeight);
   Bitmap ret=Capture(screen,sourceWidth,sourceHeight);
   DeleteDC(screen);
   return ret;
  }

  static  Bitmap Capture(IntPtr SourceDC,int SourceWidth,int SourceHeight)
  {
   IntPtr destDC;
   IntPtr BMP, BMPOld;
   destDC = CreateCompatibleDC(SourceDC);
   BMP = CreateCompatibleBitmap(SourceDC, SourceWidth, SourceHeight);
   BMPOld = SelectObject(destDC, BMP);
   BitBlt(destDC, 0, 0, SourceWidth, SourceHeight, SourceDC, 0, 0, 13369376);
   BMP = SelectObject(destDC, BMPOld);
   DeleteDC(destDC);
   Bitmap ret = Image.FromHbitmap(BMP);
   DeleteObject(BMP);
   return ret;
  }

//在案頭上進行輸出的代碼

  public static void PrintScreen()
  {
   System.Windows.Forms.SendKeys.Send("{PRTSC}");
   System.Windows.Forms.IDataObject obj=System.Windows.Forms.Clipboard.GetDataObject();
   if(obj==null) return;
   if(obj.GetDataPresent(System.Windows.Forms.DataFormats.Bitmap))
   {
    Image img=(Bitmap)obj.GetData(System.Windows.Forms.DataFormats.Bitmap);
    IntPtr screen=CreateDC("DISPLAY", "", "", "");
    IntPtr destDC;
    
    destDC = CreateCompatibleDC(screen);
    Graphics g=Graphics.FromHdc(screen,destDC);
    g.DrawImage(img,200,100);
    DeleteDC(screen);
   }
  }
 }

}

//調用代碼

private void button1_Click(object sender, System.EventArgs e)
  {
   Bitmap bitmap=WinScreen.CaptureControl(button1.CreateGraphics().GetHdc(),button1.Width,button1.Height);
   bitmap.Save(@"c:/1.bmp");
   bitmap=WinScreen.CaptureScreen();
   bitmap.Save(@"c:/2.bmp");
   WinScreen.PrintScreen();
  }

可以試一下來看看