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    <p>You could add a mouse down event handler to the Canvas, instead of the Shape objects, and then do <a href="http://msdn.microsoft.com/en-us/library/ms752097.aspx" rel="nofollow">Hit Testing in the Visual Layer</a> (although the API is a bit strange) with a <a href="http://msdn.microsoft.com/en-us/library/system.windows.media.geometryhittestparameters.aspx" rel="nofollow">hit test geometry</a>, for example an ellipse. The Canvas needs to have its <code>Background</code> set (e.g. to <code>Transparent</code>) to receive mouse events.</p> <p>Sorry that this is C#, but i don't speak VB:</p> <pre><code>private void Canvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { Canvas canvas = sender as Canvas; EllipseGeometry hitTestGeometry = new EllipseGeometry(e.GetPosition(canvas), 10d, 10d); Shape hitShape = null; HitTestResultCallback hitTestCallback = result =&gt; { hitShape = result.VisualHit as Shape; return hitShape != null ? HitTestResultBehavior.Stop : HitTestResultBehavior.Continue; }; VisualTreeHelper.HitTest(canvas, null, hitTestCallback, new GeometryHitTestParameters(hitTestGeometry)); if (hitShape != null) { System.Diagnostics.Trace.TraceInformation("hit shape: {0}", hitShape); } } </code></pre> <p><strong>EDIT:</strong></p> <p>Here is the equivalent VB code. VB does not support multiline lambda expressions so the hit test callback has to be declared explicitly</p> <pre><code>Private Function htCallback(ByVal result As HitTestResult) _ As HitTestResultBehavior Dim hitShape As Shape = Nothing hitShape = TryCast(result.VisualHit, Shape) If hitShape IsNot Nothing Then 'do something End If Return If(hitShape IsNot Nothing, HitTestResultBehavior.[Stop], _ HitTestResultBehavior.[Continue]) End Function Private Sub Canvas_MouseLeftButtonDown(ByVal sender As Object, _ ByVal e As MouseButtonEventArgs) Handles Canvas1.MouseRightButtonDown Dim canvas As Canvas = TryCast(sender, Canvas) Dim hitTestGeometry As New EllipseGeometry(e.GetPosition(canvas), 10.0, 10.0) Dim hitTestCallback As HitTestResultCallback = _ New HitTestResultCallback(AddressOf htCallback) VisualTreeHelper.HitTest(canvas, Nothing, hitTestCallback, _ New GeometryHitTestParameters(hitTestGeometry)) End Sub </code></pre>
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    1. COedited to add VB code for the above, pending approval ;)
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    2. CODoes hit test have better performance than using the method described below?
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    3. CO@DavidVdd - with the hit test you can specify how large an area around the mouse you wish to look for the line (here it is a 10x10 ellipse) so you can have a larger tolerance area without making the line too much larger. They are both fast/light operations, in any case, I don't think you should feel a performance hit from them.
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