IncrementalHitTester.AddPoint(Point) Method

Definition

Namespace:

System.Windows.Ink

Assembly:

PresentationCore.dll

Adds a Point to the IncrementalHitTester.

C#

public void AddPoint(System.Windows.Point point);

Parameters

point

Point

The Point to add to the IncrementalHitTester.

Examples

The following example demonstrates how to add points to the IncrementalHitTester when the user inputs data with the mouse. The example includes a StrokeHit event handler that erases the part of the Stroke that the user intersects. To create a control that enables a user to erase ink, see How to: Erase Ink on a Custom Control.

C#

protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
{
    base.OnMouseLeftButtonDown(e);

    if (e.StylusDevice != null)
    {
        return;
    }

    EllipseStylusShape eraserTip = new EllipseStylusShape(3, 3, 0);
    eraseTester =
        presenter.Strokes.GetIncrementalStrokeHitTester(eraserTip);
    eraseTester.StrokeHit += new StrokeHitEventHandler(eraseTester_StrokeHit);
    eraseTester.AddPoint(e.GetPosition(this));
}

protected override void OnMouseMove(MouseEventArgs e)
{
    base.OnMouseMove(e);
    
    if (e.StylusDevice != null || eraseTester == null)
    {
        return;
    }

    if (eraseTester.IsValid)
    {
        eraseTester.AddPoint(e.GetPosition(this));
    }
}

protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
{
    base.OnMouseLeftButtonUp(e);

    if (e.StylusDevice != null)
    {
        return;
    }

    eraseTester.AddPoint(e.GetPosition(this));
    eraseTester.StrokeHit -= new
        StrokeHitEventHandler(eraseTester_StrokeHit);
    eraseTester.EndHitTesting();
}

C#

// When the stylus intersects a stroke, erase that part of
// the stroke.  When the stylus dissects a stoke, the 
// Stroke.Erase method returns a StrokeCollection that contains
// the two new strokes.
void eraseTester_StrokeHit(object sender,
    StrokeHitEventArgs args)
{
    StrokeCollection eraseResult =
        args.GetPointEraseResults();
    StrokeCollection strokesToReplace = new StrokeCollection();
    strokesToReplace.Add(args.HitStroke);
   
    // Replace the old stroke with the new one.
    if (eraseResult.Count > 0)
    {
        presenter.Strokes.Replace(strokesToReplace, eraseResult);
    }
    else
    {
        presenter.Strokes.Remove(strokesToReplace);
    }
}

Applies to