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Stroke.HitTest Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Indicates whether a specified StylusPointCollection intersects with a Stroke object.

Namespace:  System.Windows.Ink
Assembly:  System.Windows (in System.Windows.dll)

Syntax

'Declaration
Public Function HitTest ( _
    stylusPointCollection As StylusPointCollection _
) As Boolean

public bool HitTest(
    StylusPointCollection stylusPointCollection
)

Parameters

Return Value

Type: System.Boolean
true if the specified StylusPointCollection intersects with the Stroke object; otherwise, false.

Examples

The following code demonstrates the HitTest method. If you draw a stroke that intersects an existing stroke, the color of the existing stroke changes to red.

Run this sample

    Private MyStroke As Stroke

    Public Sub New()
        MyBase.New()
        InitializeComponent()
        SetBoundary()
    End Sub

    'A new stroke object, MyStroke, is created and is added to the StrokeCollection object
    'of the InkPresenter, MyIP
    Private Sub MyIP_MouseLeftButtonDown(ByVal sender As Object, ByVal e As MouseEventArgs)
        MyIP.CaptureMouse()
        Dim MyStylusPointCollection As StylusPointCollection = New StylusPointCollection
        MyStylusPointCollection.Add(e.StylusDevice.GetStylusPoints(MyIP))
        MyStroke = New Stroke(MyStylusPointCollection)
        MyStroke.DrawingAttributes.Color = Colors.Yellow
        MyStroke.DrawingAttributes.Width = 8
        MyIP.Strokes.Add(MyStroke)
    End Sub

    'StylusPoint objects are collected from the MouseEventArgs and added to MyStroke. 
    Private Sub MyIP_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
        If (Not (MyStroke) Is Nothing) Then
            MyStroke.StylusPoints.Add(e.StylusDevice.GetStylusPoints(MyIP))
            'Iterate through the stroke collection
            Dim i As Integer = 0
            Do While (i _
                        < (MyIP.Strokes.Count - 1))
                Dim HitStroke As Stroke = MyIP.Strokes(i)
                'If the new stroke intersects with an existing stroke, the color of the 
                'existing stroke is changed to red.
                If HitStroke.HitTest(e.StylusDevice.GetStylusPoints(MyIP)) Then
                    HitStroke.DrawingAttributes.Color = Colors.Red
                End If
                i = (i + 1)
            Loop
        End If
    End Sub

    'MyStroke is completed
    Private Sub MyIP_LostMouseCapture(ByVal sender As Object, ByVal e As MouseEventArgs)
        MyStroke = Nothing
    End Sub


Stroke MyStroke;

//A new stroke object named MyStroke is created. MyStroke is added to the StrokeCollection of the InkPresenter named MyIP
private void MyIP_MouseLeftButtonDown(object sender, MouseEventArgs e)
{
    MyIP.CaptureMouse();

    StylusPointCollection MyStylusPointCollection = new StylusPointCollection();
    MyStylusPointCollection.Add(e.StylusDevice.GetStylusPoints(MyIP));

    MyStroke = new Stroke(MyStylusPointCollection);
    MyStroke.DrawingAttributes.Color = Colors.Yellow;
    MyStroke.DrawingAttributes.Width = 8;

    MyIP.Strokes.Add(MyStroke);
}

//StylusPoint objects are collected from the MouseEventArgs and added to MyStroke. 
private void MyIP_MouseMove(object sender, MouseEventArgs e)
{
    if (MyStroke != null)
    {
        MyStroke.StylusPoints.Add(e.StylusDevice.GetStylusPoints(MyIP));

        //Iterate through the stroke collection
        for (int i = 0; i < MyIP.Strokes.Count - 1; i++)
        {
            Stroke HitStroke = MyIP.Strokes[i];
            //If the new stroke intersects with an existing stroke, the color of the 
            //existing stroke is changed to red.
            if (HitStroke.HitTest(e.StylusDevice.GetStylusPoints(MyIP)))
                HitStroke.DrawingAttributes.Color = Colors.Red;
        }
    }
}

//MyStroke is completed
private void MyIP_LostMouseCapture(object sender, MouseEventArgs e)
{
    MyStroke = null;
}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.