print current form using CreateGraphics, but the message box is also printed

Question

I'm printing my actived form (formMain) using CreateGraphics function as code below

Printing the Form (Visual C#)

Environment: windows 7 professional in classical mode, VisuaStudio 2008

[System.Runtime.InteropServices.DllImport("gdi32.dll")]
public static extern long BitBlt (IntPtr hdcDest, int nXDest, int nYDest, int nWidth, int nHeight, IntPtr hdcSrc, int nXSrc, int nYSrc, int dwRop);
private Bitmap memoryImage;
private void CaptureScreen()
{
   Graphics mygraphics = this.CreateGraphics();
   Size s = this.Size;
   memoryImage = new Bitmap(s.Width, s.Height, mygraphics);
   Graphics memoryGraphics = Graphics.FromImage(memoryImage);
   IntPtr dc1 = mygraphics.GetHdc();
   IntPtr dc2 = memoryGraphics.GetHdc();
   BitBlt(dc2, 0, 0, this.ClientRectangle.Width, this.ClientRectangle.Height, dc1, 0, 0, 13369376);
   mygraphics.ReleaseHdc(dc1);
   memoryGraphics.ReleaseHdc(dc2);
}
private void printDocument1_PrintPage(System.Object sender, System.Drawing.Printing.PrintPageEventArgs e)
{
   e.Graphics.DrawImage(memoryImage, 0, 0);
}
private void printButton_Click(System.Object sender, System.EventArgs e)
{
   if (MessageBox.Show("test", "test", MessageBoxButtons.YesNo) == DialogResult.Yes)
   {
        CaptureScreen();
        printDocument1.Print();
   }
}

case1: When MessageBox show by default location, formMain is can printed clearly

case 2: but, if using mouse to move messageBox out of default location, then the print's result is be dirty. It's now having messageBox (graph) include in mainForm.

Answer 1

Instead of using the WinAPI directly (BitBlt, ...) try using this:

Bitmap bmp = new Bitmap(this.Width, this.Height);
this.DrawToBitmap(bmp, this.Bounds);
bmp.Save(@"c:\temp\test.png", System.Drawing.Imaging.ImageFormat.Png); // For testing

This should only draw the contents of your form.
I tested this with another top-most form with success.

Place it in your code:

private void CaptureScreen() {
    memoryImage = new Bitmap(this.Width, this.Height);
    this.DrawToBitmap(memoryImage, this.Bounds);
}

Answer 2

like XP. A counter-measure is to put this.Update();before the CaptureScreen() call.

i think my system is windows 7 , but with classical mode -> as windows xp