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GeometryHitTestParameters Class

Specifies a Geometry as the parameter to be used for hit testing a visual tree.

Namespace:  System.Windows.Media
Assembly:  PresentationCore (in PresentationCore.dll)

public class GeometryHitTestParameters : HitTestParameters
You cannot directly create an instance of this class in XAML.

With the GeometryHitTestParameters class, you can use a Geometry value for hit testing, to determine whether any visual object intersects with the Geometry value.

You can also hit test with a Point value by creating a PointHitTestParameters object.

NoteNote:

Windows Presentation Foundation (WPF) hit testing only considers the filled area of a geometry during a hit test. If you create a point Geometry, the hit test would not intersect anything because a point has no area.

The following example shows how to set up a hit test using GeometryHitTestParameters for the HitTest method. The Point value that is passed to the OnMouseDown method is used to create a Geometry object in order to expand the range of the hit test.

// Respond to the mouse button down event by setting up a hit test results callback. 
private void OnMouseDown(object sender, MouseButtonEventArgs e)
{
    // Retrieve the coordinate of the mouse position.
    Point pt = e.GetPosition((UIElement)sender);

    // Expand the hit test area by creating a geometry centered on the hit test point.
    EllipseGeometry expandedHitTestArea = new EllipseGeometry(pt, 10.0, 10.0);

    // 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(myControl, null,
        new HitTestResultCallback(MyHitTestResultCallback),
        new GeometryHitTestParameters(expandedHitTestArea));

    // Perform actions on the hit test results list. 
    if (hitResultsList.Count > 0)
    {
        ProcessHitTestResultsList();
    }
}

The IntersectionDetail property of GeometryHitTestResult provides information about the results of a hit test that uses a Geometry as a hit test parameter. The following illustration shows the relationship between the hit test geometry (the blue circle) and the target object (the red square).

Intersection between hit test geometry and target object

Diagram of IntersectionDetail used in hit testing

System.Object
  System.Windows.Media.HitTestParameters
    System.Windows.Media.GeometryHitTestParameters

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0

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