Location Coordinates On Computer Showing X=-32000, Y=-32000

Question

I have a C# application that saves its state when it is closed and then reads in the saved state when it starts up. One item that is saved is the location of the main form. Normally this works great - in my code there is a line like this that saves the location to a file that is then read back in on startup:

streamWriter.WriteLine("location:" + this.Location.X + "," + this.Location.Y);

Normally, the location coordinates look like this on my machine with multiple monitors:

location:-1069,283

Occasionally I'll see coordinates that are saved like this:

location:-32000,-32000

And then when the user brings the app back up, the form is way off the desktop and can't (easily) be retrieved by an average user.

What is happening to make the coordinates be read this way and are there suggestions to prevent this situation?

Answer 1

The coordinates you're seeing are due to the fact that the application is minimized when it is closed. Windows "hides" your form by actually moving it from its coordinates to some ridiculously large negative X,Y coordinates.

Verified programmatically:

Output from a form app on Vista:

Current coordinates X: 184 Y: 184 *Default Location
Current coordinates X: -32000 Y: -32000 *Minimized Location

From the code:

System.Diagnostics.Debug.WriteLine("Current coordinates X: " + Location.X + "  Y: " + Location.Y );

To solve this I would simply check for such a value when your app is closing and not actually save it to file.

If you don't want to mess with doing math on arbitrary coordinate values you could also check the WindowState. See here on MSDN

Answer 2

Use the RestoreBounds property on your Form.

Edit: here's a copy/paste from some of my code (could probably use a bit of cleanup, but it gets the point across). This is from my main form's FormClosing event handler:

// Save the last form state
Program.AppSettings.MainWindowFormState = this.WindowState;

// Check if the window is minimized or maximized
if ((this.WindowState == FormWindowState.Minimized) ||
    (this.WindowState == FormWindowState.Maximized))
{
    // Use the restored state values
    Program.AppSettings.MainWindowX = this.RestoreBounds.Left;
    Program.AppSettings.MainWindowY = this.RestoreBounds.Top;
    Program.AppSettings.MainWindowWidth = this.RestoreBounds.Width;
    Program.AppSettings.MainWindowHeight = this.RestoreBounds.Height;
}
else
{
    // Use the normal state values
    Program.AppSettings.MainWindowX = this.Left;
    Program.AppSettings.MainWindowY = this.Top;
    Program.AppSettings.MainWindowWidth = this.Width;
    Program.AppSettings.MainWindowHeight = this.Height;
}

And here is how to restore the state on load (remember to set your form's initial position mode to Manual to avoid flicker):

// Set the initial form state
this.WindowState = Program.AppSettings.MainWindowFormState;
this.Left = Program.AppSettings.MainWindowX;
this.Top = Program.AppSettings.MainWindowY;
this.Width = Program.AppSettings.MainWindowWidth;
this.Height = Program.AppSettings.MainWindowHeight;