如何在WPF中处理WndProc消息？

using System;
using System.Runtime.InteropServices;
using System.Windows;

public class CustomWindow : Window
{
    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)
    {
        // 在此处处理消息
        switch (msg)
        {
            case (int)WindowsMessage.WM_ACTIVATE:
                // 窗口激活时的处理逻辑
                break;
            case (int)WindowsMessage.WM_CLOSE:
                // 窗口关闭时的处理逻辑
                break;
            // 其他消息处理逻辑
        }

        return IntPtr.Zero;
    }
}

private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    switch (msg)
    {
        case (int)WindowsMessage.WM_ACTIVATE:
            // 窗口激活时的处理逻辑
            break;
        case (int)WindowsMessage.WM_CLOSE:
            // 窗口关闭时的处理逻辑
            break;
        // 其他消息处理逻辑
    }

    return IntPtr.Zero;
}

public partial class App : Application
{
    protected override Window CreateWindow()
    {
        return new CustomWindow();
    }
}