用wpf實現顯示攝像頭畫面，並且能拍照，標注，切換畫面等等

1、能拍照能書寫的話，就是在攝像頭控件上面套一個InkCanvas了，這個寫成一個自定義控件，命名為：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、拍照后能書寫的話，就是在圖片控件上面套一個InkCanvas了，這個也寫成一個自定義控件，命名為：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、需要切換攝像頭和拍出來的照片，那我用一個list將用戶控件丟進去，當然為了統一操作的話，我就寫一個Class1類將CameraControl和ImgControl放進去。你需要有什么操作直接寫在Class1里面就能通用了，比如移動，修改InkCanvas狀態（書寫，擦除等），放大縮小等等。

    #region ------構造函數------
    /// <summary>
    /// 添加攝像頭頁面
    /// </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();//初始化幻燈片縮略圖
        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;//初始化旋轉
    }/// <summary>
    /// 添加圖片頁面
    /// </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();  //初始化幻燈片縮略圖
        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;//初始化旋轉
    }
    #endregion ------構造函數------

4、需要切換顯示哪個的時候就在主界面的Grid里面操作

Grid.Children.Clear();

Grid.Children.Add(list[你要顯示的頁]);

做到這里你以為就完成了么？然后你會發現切換到圖片后，在切回去攝像頭，攝像頭是空白的，因為VideoCaptureElement 這個控件是不能被Remove再Add的，不然就需要重新加載，而且它本身加載就是比較慢的，有時候沒釋放完全還沒發加載（VideoCaptureElement 控件只能加載一個空閑中的攝像頭）

解決方案目前有2個，一個就是換控件咯，就不用VideoCaptureElement 了嘛，用C#的AForge，雖然他是C#的控件，雖然AForge在wpf嵌進去比較丑（沒有wpf的特性了：穿透），並且嵌進去步驟比較麻煩。