我如何在ESRI中的线符上绑定上下文菜单

Question

我已经为lineSymbol创建了一个ControlTemplate：

            <esri:SimpleLineSymbol 
        x:Key="PolylineSymbol" 
        Width="3"
        >
        <esri:SimpleLineSymbol.ControlTemplate>
            <ControlTemplate>
                <Grid
                    >
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
    ...
                        </VisualStateGroup>
                        <VisualStateGroup x:Name="SelectionStates">
    ...
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <Path 
                        x:Name="Element" Fill="{x:Null}"
                        Stroke="Navy" StrokeThickness="3"
                                StrokeLineJoin="Round" StrokeStartLineCap="Round" StrokeEndLineCap="Round">
                        <Path.ContextMenu>
                            <ContextMenu 
                                x:Name="popUpMenu"
                                DataContext="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type esri:Graphic}}}">
                                <MenuItem 
                                    x:Name="miSelect"
                                    Header="Select" 
                                    IsCheckable="True"
                                    IsChecked="{Binding Selected, FallbackValue=False}"
                                    />
                                ...
                            </ContextMenu>
                        </Path.ContextMenu>
                    </Path>
                </Grid>
            </ControlTemplate>
        </esri:SimpleLineSymbol.ControlTemplate>
    </esri:SimpleLineSymbol>

一切正常，除了在"选择"菜单项上进行检查中的绑定：由于符号和图形从框架工作均未从框架上继承无绑定的表达式将我从这里带到此SimpleElinesembol的包含图形。

我还尝试了一个点击事件（它给出了发件人，一个命令（支持参数）或Mouserightbuttondown事件（在图形上） - 没有方法将我从右键点上的右键点上带走包含图形的符号...

菜单的dataContext在VS2012的设计器中看起来还不错，但是在运行时，菜单不起作用，因为菜单在符号的控制图中定义的路径内，该路径不是Frameworkelement的符号的控制图！

我添加了ContextMenu的名称，但是我无法从ViewModel检索它（在其中创建图形和符号；如果我能够做到这一点，我将能够添加所需的DataContext在代码中：

      var graphic = new Graphic { Symbol = Resources["PolylineSymbol"] as SimpleLineSymbol;
      var menu = graphic.Symbol.ControlTemplate.FindName("popUpMenu", graphic.Symbol); // ???
      menu.DataContext = graphic;

）

有什么想法？

Answer 1

如果我正确理解您的问题，似乎您在WPF中有一个常见的问题。解决方案是利用Path的Tag属性使用ContextMenu.PlacementTarget属性将DataContext传递到ContextMenu。此获得或设置了上下文Menu打开时将其放置的uielement 。尝试以下操作：

<Path x:Name="Element" Fill="{x:Null}" Stroke="Navy" StrokeThickness="3"
    StrokeLineJoin="Round" StrokeStartLineCap="Round" StrokeEndLineCap="Round"
    Tag="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type 
    esri:Graphic}}}"><!--Use Binding.Path that you need for data here-->
    <Path.ContextMenu>
        <ContextMenu x:Name="popUpMenu" DataContext="{Binding PlacementTarget.Tag, 
            RelativeSource={RelativeSource Self}}"><!--Use PlacementTarget.Tag-->
            <MenuItem x:Name="miSelect" Header="Select" IsCheckable="True"
                IsChecked="{Binding Selected, FallbackValue=False}" />
            ...
        </ContextMenu>
    </Path.ContextMenu>
</Path>

Answer 2

解决方案是实现上下文菜单的打开。在背后的代码中，我在其DataContext上分配了视图模型的实例。

    <Path.ContextMenu>
            <ContextMenu 
                    Opened="PopUpMenu_OnOpened"
            >

代码背后：

    private void PopUpMenu_OnOpened(object sender, RoutedEventArgs e)
    {
        var menu = sender as ContextMenu;
        if (menu != null)
        {
            menu.DataContext = ViewModel;
        }
    }

另一个挑战是获得单击的图形和点击点。解决方案是在视图模型中创建属性，并在左Mousedown和Rightmousedown上分配。

    private Graphic GetPolylineGraphic(ESRI.ArcGIS.Client.Geometry.Geometry geometry = null)
    {
        var drawLayer = Model.GetDrawLayer(MyMap, "Polyline");
        var graphic = new Graphic
        {
            // clone the resourced PolylineSymbol (from Model)
            Symbol = new SimpleLineSymbol 
                {
                    Color = PolylineSymbol.Color,
                    Width = PolylineSymbol.Width,
                    ControlTemplate = PolylineSymbol.ControlTemplate
                }
        };
        if (geometry != null) graphic.Geometry = geometry;
        graphic.MouseLeftButtonDown += GraphicOnMouseLeftButtonDown;
        graphic.MouseRightButtonDown += GraphicOnMouseRightButtonDown;
        drawLayer.Graphics.Add(graphic);
        return graphic;
    }
    private Graphic m_clickedGraphic;
    public Graphic ClickedGraphic
    {
        get { return m_clickedGraphic; }
        set
        {
            if (!Equals(m_clickedGraphic, value))
            {
                m_clickedGraphic = value;
                OnPropertyChanged(value);
            }
        }
    }
    private MapPoint m_clickedPoint;
    public MapPoint ClickedPoint
    {
        get { return m_clickedPoint; }
        set
        {
            if (m_clickedPoint != value)
            {
                m_clickedPoint = value;
                OnPropertyChanged(value);
            }
        }
    }
    private void GraphicOnMouseRightButtonDown(object sender, MouseButtonEventArgs args)
    {
        //// This does not work because GraphicElement is internal!!!
        //var s = args.Source; 
        //ClickedGraphic = ((GraphicElement)(e.Source)).Graphic;
        //ClickedPoint = ((GraphicElement)(e.Source)).Origin;
        ClickedGraphic = sender as Graphic;
        ClickedPoint = MyMap.ScreenToMap(args.GetPosition(MyMap));
        //// not here - else context menu won't pop!
        //args.Handled = true;
    }
    private void GraphicOnMouseLeftButtonDown(object sender, MouseButtonEventArgs args)
    {
        var g = sender as Graphic;
        if (g != null)
        {
            ClickedGraphic = g;
            ClickedPoint = MyMap.ScreenToMap(args.GetPosition(MyMap));
            // select/unselect the graphic on left click
            if (g.Selected) g.UnSelect();
            else g.Select();
            args.Handled = true;
        }
    }

要使一切正常工作，我不得不克隆符号。