Screen Capture Problem?

Raysefo

Hi,

I am screen capturing as follows:

Bitmap b = new Bitmap(ScreenWidth, ScreenHeight);             g = Graphics.FromImage(b);             g.CopyFromScreen(Point.Empty, Point.Empty, Screen.PrimaryScreen.Bounds.Size);               b.Save(@"S:\\shot" + i.ToString() + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);             i = i + 1;

The problem is when I lock the computer, it gives The handle is invalid exception for the line below:

g.CopyFromScreen(Point.Empty, Point.Empty, Screen.PrimaryScreen.Bounds.Size);

How can I fix this?

Best Regards.

3 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
It'll tell you when the session has been locked and so it's not safe to call Graphics.CopyFromScreen.

A cruder way would be to simply place the code in a 'try' block and catch (and swallow) the exception if the desktop is locked.
Raysefo14y ago
thanks Vulpes

Raysefo14y ago

I hope this will work

Microsoft.Win32.SystemEvents.SessionSwitch += new Microsoft.Win32.SessionSwitchEventHandler(SystemEvents_SessionSwitch);

    void SystemEvents_SessionSwitch(object sender, Microsoft.Win32.SessionSwitchEventArgs e)
    {
        if (e.Reason == SessionSwitchReason.SessionLock)
        { 
            //I left my desk
        }
        else if (e.Reason == SessionSwitchReason.SessionUnlock)
        { 
            //I returned to my desk
        }
    }