详解C# wpf如何嵌入hwnd窗口_C#

前言

wpf是direct ui，窗口中只有一个hwnd句柄，大部分控件都是直接在上面绘制的。当我们需要使用不同的渲染方式进行绘制时，就会和控件绘制产生冲突。比如使用opengl渲染3d图形或者视频时，直接在窗口绘制就会出现闪烁，与控件相互覆盖。要解决这个问题就需要，添加一个新的hwnd窗口或控件嵌入wpf窗口中，我们可以通过hwndhost就可以实现这样的功能。

一、如何实现

1、继承hwndhost

public class mywindowhost : hwndhost

2、实现抽象方法

只需实现下列2个方法

protected override handleref buildwindowcore(handleref hwndparent)
{
    handle =创建的窗口句柄
    return new handleref(this, handle);
}

protected override void destroywindowcore(handleref hwnd)
{
   hwnd.handle;//根据句柄销毁窗口
}

3、xaml中使用hwndhost控件

<local:mywindowhost width="100" height="100" >
</local:mywindowhost >

二、具体实现

1、win32窗口

我们可以通过win32 api创建一个窗口，封装成hwndhost对象，提供给xaml使用。

win32windowhost.cs

using system.runtime.interopservices;
using system.windows;
using system.windows.interop;
namespace wpfhwndelement
{
    /// <summary>
    /// 直接通过win32 api创建窗口
    /// </summary>
    public class win32windowhost : hwndhost
    {
        //重新定义handle为依赖属性，可以用于绑定
        new public intptr handle
        {
            get { return (intptr)getvalue(handleproperty); }
            private set { setvalue(handleproperty, value); }
        }
        // using a dependencyproperty as the backing store for hwnd.  this enables animation, styling, binding, etc...
        public static readonly dependencyproperty handleproperty =
            dependencyproperty.register("handle", typeof(intptr), typeof(win32windowhost), new propertymetadata(intptr.zero));
        protected override handleref buildwindowcore(handleref hwndparent)
        {
            handle = createwindowex(0, "static", "", ws_child | ws_visible | lbs_notify | ws_clipsiblings, 0, 0, (int)width, (int)height, hwndparent.handle, intptr.zero, intptr.zero, 0);
            return new handleref(this, handle);
        }
        [dllimport("user32.dll", setlasterror = true)]
        static extern system.intptr defwindowprocw(intptr hwnd, uint msg, intptr wparam, intptr lparam);

        protected override void destroywindowcore(handleref hwnd)
        {
            destroywindow(hwnd.handle);
        }
        const int ws_child = 0x40000000;
        const int ws_visible = 0x10000000;
        const int lbs_notify = 0x001;
        const int ws_clipsiblings = 0x04000000;
        [dllimport("user32.dll")]
        internal static extern intptr createwindowex(int exstyle, string classname, string windowname, int style, int x, int y, int width, int height, intptr hwndparent, intptr hmenu, intptr hinstance, [marshalas(unmanagedtype.asany)] object pvparam);
        [dllimport("user32.dll")]
        static extern bool destroywindow(intptr hwnd);
    }
}

2、hwndsource窗口

如果不想导入win32 api，则可以使用hwndsource对象创建句柄窗口。

using system.runtime.interopservices;
using system.windows;
using system.windows.interop;

namespace wpfhwndelement
{
    class hwndsourcehost : hwndhost
    {
        //重新定义handle为依赖属性，可以用于绑定
        new public intptr handle
        {
            get { return (intptr)getvalue(handleproperty); }
            private set { setvalue(handleproperty, value); }
        }
        // using a dependencyproperty as the backing store for hwnd.  this enables animation, styling, binding, etc...
        public static readonly dependencyproperty handleproperty =
            dependencyproperty.register("handle", typeof(intptr), typeof(hwndsourcehost), new propertymetadata(intptr.zero));
        hwndsource _source;
        protected override handleref buildwindowcore(handleref hwndparent)
        {
            _source = new hwndsource(0, ws_child | ws_visible | lbs_notify| ws_clipsiblings, 0, 0, 0, (int)width, (int)height, "nativehost", hwndparent.handle);
            handle = _source.handle;
            return new handleref(this, handle);
        }
        protected override void destroywindowcore(handleref hwnd)
        {
            _source.dispose();
        }
        const int ws_child = 0x40000000;
        const int ws_visible = 0x10000000;
        const int lbs_notify = 0x001;
        const int ws_clipsiblings = 0x04000000;
    }
}

3、wpf窗口

wpf窗口也可以进行嵌入，但需要导入win32对窗口属性进行设置，要设置ws_child 以及父窗口。

using system.runtime.interopservices;
using system.windows;
using system.windows.interop;

namespace wpfhwndelement
{   
    //重新定义handle为依赖属性，可以用于绑定
    public class wpfwindowhost : hwndhost
    {
        new public intptr handle
        {
            get { return (intptr)getvalue(handleproperty); }
            private set { setvalue(handleproperty, value); }
        }
        // using a dependencyproperty as the backing store for hwnd.  this enables animation, styling, binding, etc...
        public static readonly dependencyproperty handleproperty =
            dependencyproperty.register("handle", typeof(intptr), typeof(wpfwindowhost), new propertymetadata(intptr.zero));
        const int ws_child = 0x40000000;
        const int gwl_style = (-16);
        [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 = new window();   
            var hwnd = new windowinterophelper(window).ensurehandle();
            window.show();
            setwindowlong(hwnd, gwl_style, getwindowlong(hwnd, gwl_style) | ws_child);
            setparent(hwnd, hwndparent.handle);
            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

mainwindow.xaml

<window x:class="wpfhwndelement.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:wpfhwndelement"
        mc:ignorable="d"
        title="mainwindow" height="360" width="640"   
        >
    <stackpanel>
        <local:win32windowhost width="100" height="100"/>
        <local:hwndsourcehost margin="0,10,0,0" width="100" height="100"/>
        <local:wpfwindowhost margin="0,10,0,0" width="100" height="100"/>
    </stackpanel>
</window>

效果预览