c# winforms: Getting the screenshot image that has

问题:

I have c# windows form which have several controls on it, part of the controls are located one on another. I want a function that will take for input a control from the form and will return the image that has to be behind the control. for ex: if the form has backgroundimage and contains a button on it - if I'll run this function I'll got the part of backgroundimage that located behind the button. any Idea - and code?

H-E-L-P!!!

回答1:

That's my initial guess, but have to test it.

• Put button invisible
• capture current screen
• Crop screen captured to the clientRectangle of the button

• Restablish button.

  public static Image GetBackImage(Control c) {   
      c.Visible = false;
      var bmp = GetScreen();
      var img = CropImage(bmp, c.ClientRectangle);
      c.Visible = true;
  }
  
  public static Bitmap GetScreen() {
      int width = SystemInformation.PrimaryMonitorSize.Width;
      int height = SystemInformation.PrimaryMonitorSize.Height;
  
      Rectangle screenRegion = Screen.AllScreens[0].Bounds;
      var bitmap = new Bitmap(width, height, PixelFormat.Format32bppArgb);
      Graphics graphics = Graphics.FromImage(bitmap);
      graphics.CopyFromScreen(screenRegion.Left, screenRegion.Top, 0, 0, screenRegion.Size);
      return bitmap;
  }
  public static void CropImage(Image imagenOriginal, Rectangle areaCortar) {
      Graphics g = null;
      try {
          //create the destination (cropped) bitmap
          var bmpCropped = new Bitmap(areaCortar.Width, areaCortar.Height);
          //create the graphics object to draw with
          g = Graphics.FromImage(bmpCropped);
  
          var rectDestination = new Rectangle(0, 0, bmpCropped.Width, bmpCropped.Height);
  
          //draw the areaCortar of the original image to the rectDestination of bmpCropped
          g.DrawImage(imagenOriginal, rectDestination, areaCortar, GraphicsUnit.Pixel);
          //release system resources
      } finally {
          if (g != null) {
              g.Dispose();
          }
      }
  }
  

回答2:

This is pretty easy to do. Each control on the form has a Size and a Location property, which you can use to instantiate a new Rectangle, like so:

Rectangle rect = new Rectangle(button1.Location, button1.Size);

To get a Bitmap that contains the portion of the background image located behind the control, you first create a Bitmap of the proper dimensions:

Bitmap bmp = new Bitmap(rect.Width, rect.Height);

You then create a Graphics object for the new Bitmap, and use that object's DrawImage method to copy a portion of the background image:

using (Graphics g = Graphics.FromImage(bmp))
{
    g.DrawImage(...); // sorry, I don't recall which of the 30 overloads
        // you need here, but it will be one that uses form1.Image as
        // the source, and rect for the coordinates of the source
}

This will leave you with the new Bitmap (bmp) containing the portion of the background image underneath that control.

Sorry I can't be more specific in the code - I'm at a public terminal. But the intellisense info will tell you what you need to pass in for the DrawImage method.