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I'm trying to toggle the display of a small window based on the click of a notify icon in a system tray app. This is simple enough to implement, however when the small window is displayed and another application takes focus and therefore moves in front of it (z-order) I want the toggle to assume that the small window is now hidden, even though it's visibility is still set to visible. Otherwise, clicking the icon would set the windows visiblity to hidden even though it is already hidden behind another. I've tried catching / overriding the activate and deactive methods to keep track but clicking the notify icon will always cause the deactive event to fire first. A similar approach using focus / lost focus didn't work either as the window seemed to think it still had focus even when hidden behind another applications window in active use. In the end I had to resort to native code and the WindowFromPoint method as follows:
using System.Windows.Interop;
using System.Runtime.InteropServices;
using System.Drawing;
[DllImport("user32.dll")]
public static extern IntPtr WindowFromPoint(Point lpPoint);
public static bool IsWindowVisible(System.Windows.Window window) {
WindowInteropHelper win = new WindowInteropHelper(window);
int x = (int)(window.Left + (window.Width / 2));
int y = (int)(window.Top + (window.Height / 2));
Point p = new Point(x, y);
return (win.Handle == WindowFromPoint(p));
}
This checks if the window returned at the coordinates of the centre of the window in question matches said window. i.e. the centre of the window in question is visible.
This seems a little hacky, is there a nicer way to achieve the same result?
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In WPF there is a collection of the open Windows in the Application class, you could make a helper method to check if the window is open. Here is an example that will check if any Window of a certain Type or if a Window with a certain name is open, or both. Show activity on this post. Show activity on this post.
If you want to show and hide a window multiple times during the lifetime of an application, and you don't want to re-instantiate the window each time you show it, you can handle the Closing event, cancel it, and call the Hide method. Then, you can call Show on the same instance to re-open it.
When a Window is created at run-time using the Window object, it is not visible by default. To make it visible, we can use Show or ShowDialog method. Show method of Window class is responsible for displaying a window.
Window is the root control that must be used to hold/host other controls (e.g. Button) as container. Page is a control which can be hosted in other container controls like NavigationWindow or Frame. Page control has its own goal to serve like other controls (e.g. Button). Page is to create browser like applications.
You may not want to rely on whether a window is obstructed as there are many factors that can change the window size, positing, etc. and all of them tie into accessibility features which add even more complexities.
Instead, you may want to check whether or not the window has focus. This is how MSN Messenger knows whether or not to flash orange in the taskbar; it fires a notification and if it doesn't have focus, the taskbar flashes.
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