用wpf实现显示摄像头画面，并且能拍照，标注，切换画面等等

1、能拍照能书写的话，就是在摄像头控件上面套一个InkCanvas了，这个写成一个自定义控件，命名为：CameraControl。

<UserControl x:Class="MediaKit.CameraControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-MediaKit"
         xmlns:wpfmedia="clr-namespace:WPFMediaKit.DirectShow.Controls;assembly=WPFMediaKit"
         mc:Ignorable="d" 
         x:Name="window">
    <Canvas Height="{Binding Height, ElementName=window, Mode=OneWay}" Width="{Binding Width, ElementName=window, Mode=OneWay}"   HorizontalAlignment="Center">
        <InkCanvas Name="ink" Canvas.Left="0" Canvas.Top="0"  RenderTransformOrigin="0.5,0.5"  VerticalAlignment="Center" HorizontalAlignment="Center"  Height="{Binding ElementName=vce,Path=ActualHeight,Mode=OneWay}" Width="{Binding ElementName=vce,Path=ActualWidth,Mode=OneWay}">
            <InkCanvas.RenderTransform>
                <TransformGroup>
                    <ScaleTransform/>
                    <SkewTransform/>
                    <RotateTransform/>
                    <TranslateTransform/>
                </TransformGroup>
            </InkCanvas.RenderTransform>
        <wpfmedia:VideoCaptureElement  Height="1080"  x:Name="vce" Stretch="Fill"   RenderTransformOrigin="0.5,0.5"  >
                
            </wpfmedia:VideoCaptureElement>
        </InkCanvas>
    </Canvas>

2、拍照后能书写的话，就是在图片控件上面套一个InkCanvas了，这个也写成一个自定义控件，命名为：ImgControl。

  <UserControl x:Class="MediaKit.ImgControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:MediaKit"
         mc:Ignorable="d" 
         x:Name="window">
<Canvas Height="{Binding Height, ElementName=window, Mode=OneWay}" Width="{Binding Width, ElementName=window, Mode=OneWay}"   HorizontalAlignment="Center">
    <InkCanvas Name="ink" Canvas.Left="0" Canvas.Top="0"  RenderTransformOrigin="0.5,0.5"   VerticalAlignment="Center" HorizontalAlignment="Center"  Height="{Binding ElementName=img,Path=ActualHeight}" Width="{Binding ElementName=img,Path=ActualWidth}" >
        <InkCanvas.RenderTransform>
            <TransformGroup>
                <ScaleTransform/>
                <SkewTransform/>
                <RotateTransform />
                <TranslateTransform/>
            </TransformGroup>
        </InkCanvas.RenderTransform>
        <Image Name="img" VerticalAlignment="Center"  HorizontalAlignment="Center" Height="{Binding Height, ElementName=window, Mode=OneWay}"  Stretch="UniformToFill">
            
        </Image>
    </InkCanvas>
</Canvas>

3、需要切换摄像头和拍出来的照片，那我用一个list将用户控件丢进去，当然为了统一操作的话，我就写一个Class1类将CameraControl和ImgControl放进去。你需要有什么操作直接写在Class1里面就能通用了，比如移动，修改InkCanvas状态（书写，擦除等），放大缩小等等。

    #region ------构造函数------
    /// <summary>
    /// 添加摄像头页面
    /// </summary>
    public Class1()
    {
        pageIndex = 0;
        camera = new CameraControl();
        camera.ink.DefaultDrawingAttributes = PageManager.GetInstance()._defaultAttribuate;
        camera.ink.EditingMode = PageManager.GetInstance().editingMode;
        _inkCanvas = camera.ink;
        _vce = camera.vce;
        InitCameraThumb();//初始化幻灯片缩略图
        this.Children.Add(camera);

        _inkCanvas.IsManipulationEnabled = true;
        _inkCanvas.Focusable = true;
        _inkCanvas.PreviewMouseDown += _inkCanvas_PreviewMouseDown;
        (((TransformGroup)_inkCanvas.RenderTransform).Children[2] as RotateTransform).Angle = CommonMethod.s_angle;//初始化旋转
    }/// <summary>
    /// 添加图片页面
    /// </summary>
    /// <param name="source"></param>
    public Class1(ImageSource source, int index)
    {
        pageIndex = index;
        pic = new ImgControl(source);
        pic.ink.DefaultDrawingAttributes = PageManager.GetInstance()._defaultAttribuate;
        pic.ink.EditingMode = PageManager.GetInstance().editingMode;
        _inkCanvas = pic.ink;
        InitPageThumb();  //初始化幻灯片缩略图
        pageThumb.contentSource = source;
        this.Children.Add(pic);

        _inkCanvas.IsManipulationEnabled = true;
        _inkCanvas.Focusable = true;
        _inkCanvas.PreviewMouseDown += _inkCanvas_PreviewMouseDown;
        (((TransformGroup)_inkCanvas.RenderTransform).Children[2] as RotateTransform).Angle = CommonMethod.s_angle;//初始化旋转
    }
    #endregion ------构造函数------

4、需要切换显示哪个的时候就在主界面的Grid里面操作

Grid.Children.Clear();

Grid.Children.Add(list[你要显示的页]);

做到这里你以为就完成了么？然后你会发现切换到图片后，在切回去摄像头，摄像头是空白的，因为VideoCaptureElement 这个控件是不能被Remove再Add的，不然就需要重新加载，而且它本身加载就是比较慢的，有时候没释放完全还没发加载（VideoCaptureElement 控件只能加载一个空闲中的摄像头）

解决方案目前有2个，一个就是换控件咯，就不用VideoCaptureElement 了嘛，用C#的AForge，虽然他是C#的控件，虽然AForge在wpf嵌进去比较丑（没有wpf的特性了：穿透），并且嵌进去步骤比较麻烦。