How to Retrieve the Viewable Area of a Window or Control

Environment: Visual Studio .NET / C#

How to Retrieve the Viewable (Client) Area of a Window or Control

The ClientRectangle Property doesnt always give you a true viewable area of a window. For example, this occurs when the window is an MDI child window or child window of an MDI child window because the MDI parent may not be large enough to display all of the MDI child.

To get the viewable area, you need to call a Win32 function named GetClipBox(). Following is a function that calls GetClipBox() and converts the results to something that .NET can use.

public static Rectangle GetViewableRect( Control control )
{
  //! Get a graphic from the control; we need the HDC.
  Graphics graphics = Graphics.FromHwnd(control.Handle);

  //! Get the hDC. (Remember to call ReleaseHdc() 
  //  when finished.)
  IntPtr hDC = graphics.GetHdc();

  //! Create a rectangle to receive the viewable 
  //  area of the control.
  WIN32Rect r = new WIN32Rect();

  //! Call the Win32 method that receives the viewable area.
  GetClipBox(hDC, ref r);

  //! Convert that to a .NET rectangle.
  Rectangle rectangle = new Rectangle( r.left, 
                                       r.top,
                                       r.right - r.left,
                                       r.bottom - r.top );

  //! Release the HDC. (If you don't, the CLR throws an 
  //  exception when it tries to Finalize/Dispose it.)

  graphics.ReleaseHdc(hDC);

  //! Dispose of the graphic; we don't need it any more.
  graphics.Dispose();
  graphics = null;

  return rectangle;
}

Downloads

Download demo project -- 11.13 KB


Comments

  • A long waited solution!!

    Posted by Legacy on 11/09/2003 12:00am

    Originally posted by: Arik Solomon

    Thanks to you, I finally managed to overcome a very nasty behavior of .NET Controls - they do not report the actual viewable size.


    Thanks again,

    Arik.

    Reply
Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • Live Event Date: December 11, 2014 @ 1:00 p.m. ET / 10:00 a.m. PT Market pressures to move more quickly and develop innovative applications are forcing organizations to rethink how they develop and release applications. The combination of public clouds and physical back-end infrastructures are a means to get applications out faster. However, these hybrid solutions complicate DevOps adoption, with application delivery pipelines that span across complex hybrid cloud and non-cloud environments. Check out this …

  • CentreCorp is a fully integrated and diversified property management and real estate service company, specializing in the "shopping center" segment, and is one of the premier retail service providers in North America. Company executives travel a great deal, carrying a number of traveling laptops with critical current business data, and no easy way to back up to the network outside the office. Read this case study to learn how CentreCorp implemented a suite of business continuity services that included …

Most Popular Programming Stories

More for Developers

RSS Feeds