WPF從鼠標位置獲取視覺

我有一個畫布，其中繪製一些GraphNodes並將它們作爲ContentControls添加到畫布。所有圖形節點都有一個裝飾器，我用它來繪製從一個節點到另一個節點的連接線。裝飾器具有的方法OnMouseUp：WPF從鼠標位置獲取視覺

protected override void OnMouseUp(System.Windows.Input.MouseButtonEventArgs e) 
{ 
    var SourceNode = AdornedElement; 
    Point pt = PointToScreen(Mouse.GetPosition(this)); 
    var DestinationNode = ??? 
}

此時我有從那裏我開始畫在AdornedElement線作爲初始GraphNode源節點。另外，我還有鼠標釋放的座標。在這一點下是另一個GraphNode。如何找到這一點下的節點？

謝謝。

來源

2012-10-03 alexandrudicu

不[e.OriginalSource]（http://msdn.microsoft.com/en-us/library/system.windows.routedeventargs.originalsource.aspx）或[e.Source]（HTTP：// msdn.microsoft.com/en-us/library/system.windows.routedeventargs.source.aspx）有幫助嗎？ – LPL

不是。它始終是AdornedElement，它是源代碼。我想找到目標節點，我在哪裏生成MouseUpEvent。 – alexandrudicu

然後在此處查看：[在可視層中擊中測試]（http://msdn.microsoft.com/zh-cn/library/ms752097.aspx） – LPL

OK，許多研究後，我找到了解決辦法：

protected override void OnMouseUp(System.Windows.Input.MouseButtonEventArgs e) 
{ 
    Point pt = PointToScreen(Mouse.GetPosition(this)); 
    UIElement canvas = LogicalTreeHelper.GetParent(AdornedElement) as UIElement; 
    // This is important to get the mouse position relative to the canvas, otherwise it won't work 
    pt = canvas.PointFromScreen(pt); 
    VisualTreeHelper.HitTest(canvas, null, HitTestResultCallbackHandler, new PointHitTestParameters(pt));    
}

然後是的HitTest方法找到GraphNode。請記住GraphNode是一個自定義對象。

public HitTestResultBehavior HitTestResultCallbackHandler(HitTestResult result) 
{ 
    if (result != null) 
    { 
     // Search for elements that have GraphNode as parent 
     DependencyObject dobj = VisualTreeHelper.GetParent(result.VisualHit); 
     while (dobj != null && !(dobj is ContentControl)) 
     { 
     dobj = VisualTreeHelper.GetParent(dobj); 
     } 
     ContentControl cc = dobj as ContentControl; 
     if (!ReferenceEquals(cc, null)) 
     { 
     IEnumerable<DependencyObject> dependencyObjects = cc.GetSelfAndAncestors(); 
     if (dependencyObjects.Count() > 0) 
      { 
       IEnumerable<ContentControl> contentControls = dependencyObjects.Where(x => x.GetType() == typeof(ContentControl)).Cast<ContentControl>(); 
       if (contentControls.Count() > 0) 
        { 
         ContentControl cControl = contentControls.FirstOrDefault(x => x.Content.GetType() == typeof(GraphNode)); 
         if (cControl != null) 
         { 
          var graphNode = cControl.Content as GraphNode; 
          if (!ReferenceEquals(graphNode, null)) 
          { 
           // Keep the result in a local variable 
           m_DestinationNode = graphNode; 
           return HitTestResultBehavior.Stop; 
          } 
         }       
        } 
       } 
      }    
     } 
    m_DestinationNode = null; 
    return HitTestResultBehavior.Continue; 
}

來源

2012-10-08 08:57:33 alexandrudicu

WPF從鼠標位置獲取視覺

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