WPF Hwnd窗口互操作系列

第一章 嵌入Hwnd窗口
第二章 嵌入WinForm控件
第三章 嵌入WPF控件（本章）
第四章 底部嵌入HwndHost

---

---

前言

通过前面的章节我们了解到了如何嵌入Hwnd窗口以及WinForm控件，但是嵌入的控件存在覆盖wpf控件的情况，嵌入控件上面无法显示王鹏飞控件，对UI的布局有一定的影响。本文提供一种解决方法，
将wpf控件通过HwndHost的方式嵌入到wpf界面中，以实现HwndHost控件上显示wpf控件的功能。

---

一、如何实现？

1、继承HwndHost

和其他嵌入方式一样，需要先继承HwndHost。

public class WpfElementHost : HwndHost

2、添加Content属性

添加一个Content属性，提供给xaml使用。这个Content属性就是需要嵌入的wpf控件。

[ContentProperty("Content")]
public class WpfElementHost : HwndHost
{
    public UIElement Content
    {
        get { return (UIElement)GetValue(ContentProperty); }
        set { SetValue(ContentProperty, value); }
    }
    public static readonly DependencyProperty ContentProperty =
        DependencyProperty.RegisterAttached("Content", typeof(UIElement), typeof(WpfElementHost), new PropertyMetadata(null));
}

3、创建wpf窗口并设置Content

实现抽象方法窗口wpf窗口，这里参考第一章的嵌入wpf窗口，以及给窗口设置Content属性。

protected override HandleRef BuildWindowCore(HandleRef hwndParent)
{
    var window = Content is Window ? Content as Window : new Window { WindowStyle = WindowStyle.None, ResizeMode = ResizeMode.NoResize, Focusable = false, Width = 0, Height = 0, ShowInTaskbar = false, ShowActivated = false, Background = Brushes.Transparent, Content = Content, AllowsTransparency = true };
    var hwnd = new WindowInteropHelper(window).EnsureHandle();
    SetWindowLong(hwnd, GWL_STYLE, GetWindowLong(hwnd, GWL_STYLE) | WS_CHILD);
    User32.SetParent(hwnd, hwndParent.Handle);
    window!.Show();
    return new HandleRef(this, hwnd);
}

4、关闭wpf窗口

实现抽象方法，关闭窗口

protected override void DestroyWindowCore(HandleRef hwnd)
{
    var window = HwndSource.FromHwnd(hwnd.Handle)?.RootVisual as Window;
    window?.Close();
}

---

二、完整代码

WpfElementHost.cs

using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Markup;
using Brushes = System.Windows.Media.Brushes;
namespace WpfHwndElement
{
    [ContentProperty("Content")]
    public class WpfElementHost : HwndHost
    {
        public UIElement Content
        {
            get { return (UIElement)GetValue(ContentProperty); }
            set { SetValue(ContentProperty, value); }
        }
        public static readonly DependencyProperty ContentProperty =
            DependencyProperty.RegisterAttached("Content", typeof(UIElement), typeof(WpfElementHost), new PropertyMetadata(null));
        const int GWL_STYLE = (-16);
        const int WS_CHILD = 0x40000000;
        [DllImport("user32.dll", EntryPoint = "GetWindowLongW")]
        static extern int GetWindowLong(IntPtr hwnd, int nIndex);
        [DllImport("user32.dll", EntryPoint = "SetWindowLongW")]
        static extern int SetWindowLong(IntPtr hwnd, int nIndex, int dwNewLong);
        [DllImport("user32.dll")]
        public static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
        protected override HandleRef BuildWindowCore(HandleRef hwndParent)
        {
            var window = Content is Window ? Content as Window : new Window { WindowStyle = WindowStyle.None, ResizeMode = ResizeMode.NoResize, Focusable = false, Width = 0, Height = 0, ShowInTaskbar = false, ShowActivated = false, Background = Brushes.Transparent, Content = Content, AllowsTransparency = true };
            var hwnd = new WindowInteropHelper(window).EnsureHandle();
            SetWindowLong(hwnd, GWL_STYLE, GetWindowLong(hwnd, GWL_STYLE) | WS_CHILD);
            SetParent(hwnd, hwndParent.Handle);
            window!.Show();
            return new HandleRef(this, hwnd);
        }
        protected override void DestroyWindowCore(HandleRef hwnd)
        {
            var window = HwndSource.FromHwnd(hwnd.Handle)?.RootVisual as Window;
            window?.Close();
        }
    }
}

---

三、使用示例

1、嵌入控件

<Window x:Class="WpfApp6.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp6"
        mc:Ignorable="d"
        Title="MainWindow" Height="360" Width="640">
    <Grid>
        <local:WpfElementHost Width="400" Height="200">
            <TextBox Background="RoyalBlue" Foreground="White" FontSize="24" ></TextBox>
        </local:WpfElementHost>
    </Grid>
</Window>

效果预览

2、嵌入Window

（1）xaml中定义Window

因为默认嵌入控件的承载Window使用了AllowsTransparency，如果需要自己定制窗口属性则可以直接使用Window

<Window x:Class="WpfApp6.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp6"
        mc:Ignorable="d"
        Title="MainWindow" Height="360" Width="640">
    <Grid>
        <local:WpfElementHost Width="400" Height="200">
            <Window Title="WPF窗口">
                <TextBox Background="RoyalBlue" Foreground="White" FontSize="24" ></TextBox>
            </Window>
        </local:WpfElementHost>
    </Grid>
</Window>

效果预览

（2）嵌入已有的Window

创建一个新的Window1

<Window x:Class="WpfApp6.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp6"
        mc:Ignorable="d"
        Title="MainWindow" Height="360" Width="640"
        >
    <Grid>
        <local:WpfElementHost Width="400" Height="200">
            <local:Window1 >
            </local:Window1>
        </local:WpfElementHost>
    </Grid>
</Window>

效果预览

3、显示在WinForm控件上面

<Window x:Class="WpfApp6.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp6"
        xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <WindowsFormsHost Width="300" Height="80" >
            <wf:TextBox  Text="WinForm TextBox" BackColor="255,192,192,192" />
        </WindowsFormsHost>
        <local:WpfElementHost Width="200" Height="100">
            <TextBox Opacity="0.6" Background="RoyalBlue" Foreground="White" FontSize="24" Text="WPF TextBox" ></TextBox>
        </local:WpfElementHost>
    </Grid>
</Window>

效果预览

---

总结

以上就是今天要讲的内容，整体的代码实现是比较简单的，关键是在win32 api设置窗口属性。这个功能的作用还是不小的，比如在嵌入网页上显示wpf控件，或者hwnd播放控件上放一些按钮。这种实现方式也不会有性能问题，绘制都是以窗口为单位的，其实和WinForm有点类似了，每个控件都是一个窗口。