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我通过代码隐藏向 InkCanvas 添加了一个按钮。由于我无法理解的原因，

    HitTestResult result = VisualTreeHelper.HitTest(pe.InkCanvas.Children[2], point_MouseDown);

其中按钮的索引为 2，当我点击按钮时，结果总是为空。

有人知道如何确定是否单击了子元素吗？

任何帮助将不胜感激。（是的，我已经搜索了互联网但没有成功。如果这似乎是一个愚蠢的问题，我深表歉意）。

系统：Windows 7，.net4.0 WPF C#

编辑：如果我在 Children[0] 是 RichTextBox 的情况下做同样的事情，那么上面的 HitTest 返回非空值。有人知道为什么吗？

编辑： RichTextBox 和 Button 都在代码隐藏中添加，XAML 是：

 <Grid Height="{x:Static local:pe.heightCanvas}" >

            <!--NotepadCanvas. Canvas used to place user writing lines and borders.-->
            <Canvas Name="NotePadCanvas" Panel.ZIndex="0"
                     Width="{x:Static local:pe.widthCanvas}" 
                     Height="{x:Static local:pe.heightCanvas}" 
                     Background="{Binding documenttype, Converter={StaticResource inkCanvasBackgroundConverter}}" />

            <!--BackgroundCanvas. Canvas used for special highlighting of seleted items-->
            <Canvas Name="BackgroundCanvas" Panel.ZIndex="1"
                     Width="{x:Static local:pe.widthCanvas}" 
                     Height="{x:Static local:pe.heightCanvas}" 
                     Background="Transparent" />

            <!--FormsCanvas. Canvas used to place formatted text from lists, etc.-->
            <Canvas Name="FormsCanvas" Panel.ZIndex="2"
                     Width="{x:Static local:pe.widthCanvas}" 
                     Height="{x:Static local:pe.heightCanvas}" 
                     Background="Transparent" />

            <!--TranscriptionCanvas. Canvas used to place recognized ink from the InkAnalyzer-->
            <Canvas Name="TranscriptionCanvas" Panel.ZIndex="3"
                     Width="{x:Static local:pe.widthCanvas}" 
                     Height="{x:Static local:pe.heightCanvas}" 
                     Background="Transparent" />

            <!--InkCanv. Top most canvas used to gather handwritten ink strokes from the user. EditingMode="Ink"   Gesture="OnGesture" -->
            <local:CustomInkCanvas x:Name="InkCanvas" Panel.ZIndex="4" 
                       Width="{x:Static local:pe.widthCanvas}"
                       Height ="{x:Static local:pe.heightCanvas}" 
                       Background="Transparent" 
                       AllowDrop="True"  Drop="InkCanvas_Drop"/>

        </Grid>
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1 回答 1

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这可行，但看起来很复杂，我不知道为什么按钮显示为 TextBlock：

...........

  Button btn = new Button();
        btn.Name = "Cancel";
        btn.Content = "Cancel";
        btn.Background = Brushes.Red;
        btn.Width = 50;
        btn.Height = 25;
        btn.RenderTransform = new System.Windows.Media.TranslateTransform(pe.InkCanvas.ActualWidth-btn.Width,topmargin);

        btnCancel = btn;
        pe.InkCanvas.Children.Add(btnCancel);

然后，在 PreviewMouseLeftButtonDown() 中（代码从微软网站稍作修改）......

// Clear the contents of the list used for hit test results.
                hitResultsList.Clear();


                // Set up a callback to receive the hit test result enumeration.
                VisualTreeHelper.HitTest(pe.InkCanvas, null,
                    new HitTestResultCallback(MyHitTestResult),                        new PointHitTestParameters(point_MouseDown));

                for (int i = 0; i < hitResultsList.Count; i++)
                {
                    TextBlock tb = hitResultsList[i] as TextBlock;
                    if (tb == null) continue;
                    if (tb.Text == "Cancel")
                    {
                        Cancel_Click(); 
                    }
                }

.....................................................

List<DependencyObject> hitResultsList = new List<DependencyObject>();

    // Return the result of the hit test to the callback. 
    public HitTestResultBehavior MyHitTestResult(HitTestResult result)
    {
        // Add the hit test result to the list that will be processed after the enumeration.
        hitResultsList.Add(result.VisualHit);

        // Set the behavior to return visuals at all z-order levels. 
        return HitTestResultBehavior.Continue;
    }

有没有更好的办法？为什么按钮显示为 TextBlock？

于 2014-06-11T04:26:15.273 回答