Determining if a form is completely off screen

user_40527 0
Viewed 18832

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?

screen winforms c#
7 Answers

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;
}
user_848520

Old thread, but still helpful! Cody and Andrija- thanks for the code. I had to make a couple of minor adjustments: Instead of screen.WorkingArea.Intersect(formRectangle); I used formRectangle.Intersect(screen.WorkingArea); since Intersect() replaces its object with the intersection. If the form is completely off the screen, formRectangle after the intersection is (0,0,0,0), and Contains() returns true. So I also check to see if formRectangle Top, Left, Width and Height are not all 0 before returning true. Now the code returns true if any part of the form is on screen, and false if no part is on screen.

user_5453910

None of these work if a monitor happens to be off. The Screen.AllScreens function will always return the number of screens even if one is off.

user_28604050

Check the screens resolution before you position the window. That will allow you to figure out if you where going to place it outside the bounds of the resolution, before you actually do it.

user_498850
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