Cody Cody - 29 days ago 8
C# Question

Determining if a form is completely off screen

I am developing an application that remembers the user's preferences as to where the form was last located on the screen. In some instances the user will have it on a secondary screen, and then fire the app up later without the second screen (sometimes having the form appear off screen). Other times the user will change their resolution resulting in a similar effect.

I was hoping to do this checking in the Form_Shown event handler. Basically I want to determine whether the form is completely off screen so I can re-position it.

Any advice?

Answer

Check with this function if Form is fully on screen:

public bool IsOnScreen( Form form )
{
   Screen[] screens = Screen.AllScreens;
   foreach( Screen screen in screens )
   {
      Rectangle formRectangle = new Rectangle( form.Left, form.Top, 
                                               form.Width, form.Height );

      if( screen.WorkingArea.Contains( formRectangle ) )
      {
         return true;
      }
   }

   return false;
}

Checking only top left point if it's on screen:

public bool IsOnScreen( Form form )
{
   Screen[] screens = Screen.AllScreens;
   foreach( Screen screen in screens )
   {
      Point formTopLeft = new Point( form.Left, form.Top );

      if( screen.WorkingArea.Contains( formTopLeft ) )
      {
         return true;
      }
   }

   return false;
}
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