Most of the times, I wondered how System Menu in Native Window has been replaced with custom Menu in WPF. Finally, I found the trick. I just want to share the idea here.
Normally, WPF does not allow direct customization to Non-client area of Window. But that can be done using native methods. We need to hook the
WndProc
method. WPF has no override method as Winforms does. The following code shows how to hook
WndProc();
private void OnLoaded(object sender, RoutedEventArgs e)
{
IntPtr windowhandle = new WindowInteropHelper(this).Handle;
HwndSource hwndSource = HwndSource.FromHwnd(windowhandle);
hwndSource.AddHook(new HwndSourceHook(WndProc));
}
private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
return IntPtr.Zero;
}
First, we should hide the default System Menu in Window.
To hide the default System Menu in Window, we should handle the particular message. Corresponding window message and parameter for opening System Menu is 0xa4 and 0x02 respectively.
private const uint WM_SYSTEMMENU = 0xa4;
private const uint WP_SYSTEMMENU = 0x02;
private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
if ((msg == WM_SYSTEMMENU) && (wParam.ToInt32() == WP_SYSTEMMENU))
{
ShowContextMenu();
handled = true;
}
return IntPtr.Zero;
}
ShowContextMenu()
method will show our custom Context Menu declared in Window resources.
<Window.Resources>
<ContextMenu x:Key="systemMenu">
<MenuItem Header="Help" InputGestureText="F1">
<MenuItem.Icon>
<Image Source="Help.png" Height="16"/>
</MenuItem.Icon>
</MenuItem>
<MenuItem Header="Choose theme">
<MenuItem.Icon>
<Image Source="ChooseColor.png" Height="16"/>
</MenuItem.Icon>
</MenuItem>
<MenuItem Header="Add Note">
<MenuItem.Icon>
<Image Source="NoteHS.png" Height="16"/>
</MenuItem.Icon>
</MenuItem>
<Separator />
<MenuItem Header="Exit"/>
</ContextMenu>
</Window.Resources>
Get the Context Menu in code behind through a property,
public ContextMenu SystemMenu
{
get
{
return Resources["systemMenu"] as ContextMenu;
}
}
Show the
ContextMenu
in code behind:
private void ShowContextMenu()
{
if (SystemMenu != null)
{
SystemMenu.IsOpen = true;
}
}
Jawahar working as a Senior Development Engineer in Aditi Technologies,Bangalore, India. Specialist in all XAML frameworks. Very passionate on UX Design and Development. Skilled in Expression Blend, Design, WPF, Silverlight, Windows Phone 7/8, Windows 8. Good knowledge in Entity Framework, SQLite and SQL Server also. Also had good experience with PRISM, MVVM, Caliiburn Micro and other design patterns.
He developed few products for Syncfusion Inc. Also working on some freelancing projects. Worked as a lead developer of Metro Studio from Syncfusion Inc.
An active freelancer. http://xamlfactory.elance.com
http://about.me/jawahars
http://wpfplayground.com/