How Can I Override WndProc Functionality in WPF to Handle Windows Messages?

WPF Message Handling: An Alternative to WndProc

While Windows Forms developers commonly override WndProc to manage Windows messages, WPF doesn't offer a direct equivalent. Instead, the System.Windows.Interop namespace and its HwndSource class provide a mechanism to achieve similar functionality.

Intercepting Windows Messages in WPF

The following code illustrates how to use HwndSource to capture and process Windows messages within a WPF application:

<code class="language-csharp">using System;
using System.Windows;
using System.Windows.Interop;

namespace WpfApplication1
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        protected override void OnSourceInitialized(EventArgs e)
        {
            base.OnSourceInitialized(e);
            HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
            source.AddHook(WndProc);
        }

        private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            // Implement custom message handling logic here...

            return IntPtr.Zero;
        }
    }
}</code>

This code snippet hooks the WndProc method to the HwndSource object associated with the Window1 instance. The OnSourceInitialized event ensures this hook is established after the window's handle is created. This allows the WndProc method to intercept and process Windows messages before WPF's default handling.

This approach is beneficial for scenarios requiring custom message processing, such as intercepting low-level system messages or responding to specific keyboard or mouse events not directly exposed through WPF's standard event system.

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