如何在网格中选择一个孩子？

有人可以帮我解决我的问题 . 我正在创建一个可以在Image上绘制矩形的程序 . 我正在使用WPF和MVVM模式 .

要求是 . 观看者可以缩放和平移图像 . 使用调整大小绘制矩形并移动绘制的矩形 .

然后我从下面的链接中找到了这个答案

Pan & Zoom Image

我从答案中实现了ZoomBorder类 .

然后因为我还需要绘制矩形 . 我修改了代码并添加了返回Rect的Dependency Property

public Rect Rect
        {
            get { return (Rect)GetValue(RectProperty); }
            set { SetValue(RectProperty, value); }
        }

        // Using a DependencyProperty as the backing store for Rect.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty RectProperty =
            DependencyProperty.Register("Rect", typeof(Rect), typeof(ZoomBorder),
                new FrameworkPropertyMetadata(new Rect(), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, null));

这就是我使用它的方式

<Viewer:ZoomBorder x:Name="img" Rect="{Binding Rect}" IsDraw="{Binding IsDraw}">

            <Grid>

                <Image Height="{Binding ActualHeight, ElementName=img, UpdateSourceTrigger=PropertyChanged}" Width="{Binding ActualWidth, ElementName=img, UpdateSourceTrigger=PropertyChanged}" Stretch="None" Source="img_05_l.jpg"/>
                <ItemsControl ItemsSource="{Binding RectItems}">
                    <ItemsControl.ItemsPanel>
                        <ItemsPanelTemplate>
                            <Canvas  x:Name="canvas" Background="Transparent"  Height="{Binding ActualHeight, ElementName=img, UpdateSourceTrigger=PropertyChanged}" Width="{Binding ActualWidth, ElementName=img, UpdateSourceTrigger=PropertyChanged}" />
                        </ItemsPanelTemplate>
                    </ItemsControl.ItemsPanel>
                    <ItemsControl.ItemContainerStyle>
                        <Style TargetType="{x:Type ContentPresenter}">
                            <Setter Property="Canvas.Left" Value="{Binding X, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
                            <Setter Property="Canvas.Top" Value="{Binding Y, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>

                        </Style>
                    </ItemsControl.ItemContainerStyle>
                    <ItemsControl.ItemTemplate>
                        <DataTemplate>
                            <Rectangle Width="{Binding Width}"
                                       Height="{Binding Height}" 
                                       Fill="Transparent" 
                                       Stroke="Blue" 
                                       StrokeThickness="1"  />
                        </DataTemplate>
                    </ItemsControl.ItemTemplate>
                </ItemsControl>

            </Grid>
        </Viewer:ZoomBorder>

然后我有一个工作平移缩放和绘图 . 但是我仍然需要调整大小并移动绘制的矩形 .

然后经过几个小时的搜索，我发现这个博客调整大小并在画布中移动对象

http://www.voidcn.com/article/p-krlsqrhc-uw.html

但我的问题是 . 我无法在画布中选择绘制的矩形 .

以下是在画布中选择控件的代码

// Handler for element selection on the canvas providing resizing adorner
        void myCanvas_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            // Remove selection on clicking anywhere the window
            if (selected)
            {
                selected = false;
                if (selectedElement != null)
                {
                    // Remove the adorner from the selected element
                    aLayer.Remove(aLayer.GetAdorners(selectedElement)[0]);                    
                    selectedElement = null;
                }
            }

            // If any element except canvas is clicked, 
            // assign the selected element and add the adorner
            if (e.Source != myCanvas)
            {
                _isDown = true;
                _startPoint = e.GetPosition(myCanvas);

                selectedElement = e.Source as UIElement;

                _originalLeft = Canvas.GetLeft(selectedElement);
                _originalTop = Canvas.GetTop(selectedElement);

                aLayer = AdornerLayer.GetAdornerLayer(selectedElement);
                aLayer.Add(new ResizingAdorner(selectedElement));
                selected = true;
                e.Handled = true;
            }
        }

But my problem is how can I select the drawn rectangle? 问题是所选的控件是 Grid 而不是 Canvas - 我该如何解决这个问题？

如果我打算删除 Grid . 我会有一个错误"the property Child is set more than once" . 我需要画布和图像 . 我找不到解决方案所以我决定在这里问一下 .