IncrementalHitTester Class
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Dynamically performs hit testing on a Stroke.
public ref class IncrementalHitTester abstract
public abstract class IncrementalHitTester
type IncrementalHitTester = class
Public MustInherit Class IncrementalHitTester
- Inheritance
-
IncrementalHitTester
- Derived
The following example demonstrates how to add points to the IncrementalHitTester when the user inputs data with the stylus. 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.
// Prepare to collect stylus packets. Get the
// IncrementalHitTester from the InkPresenter's
// StrokeCollection and subscribe to its StrokeHitChanged event.
protected override void OnStylusDown(StylusDownEventArgs e)
{
base.OnStylusDown(e);
EllipseStylusShape eraserTip = new EllipseStylusShape(3, 3, 0);
eraseTester =
presenter.Strokes.GetIncrementalStrokeHitTester(eraserTip);
eraseTester.StrokeHit += new StrokeHitEventHandler(eraseTester_StrokeHit);
eraseTester.AddPoints(e.GetStylusPoints(this));
}
// Collect the StylusPackets as the stylus moves.
protected override void OnStylusMove(StylusEventArgs e)
{
if (eraseTester.IsValid)
{
eraseTester.AddPoints(e.GetStylusPoints(this));
}
}
// Unsubscribe from the StrokeHitChanged event when the
// user lifts the stylus.
protected override void OnStylusUp(StylusEventArgs e)
{
eraseTester.AddPoints(e.GetStylusPoints(this));
eraseTester.StrokeHit -= new
StrokeHitEventHandler(eraseTester_StrokeHit);
eraseTester.EndHitTesting();
}
// 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);
}
}
' Prepare to collect stylus packets. Get the
' IncrementalHitTester from the InkPresenter's
' StrokeCollection and subscribe to its StrokeHitChanged event.
Protected Overrides Sub OnStylusDown(ByVal e As StylusDownEventArgs)
MyBase.OnStylusDown(e)
Dim eraserTip As New EllipseStylusShape(3, 3, 0)
eraseTester = presenter.Strokes.GetIncrementalStrokeHitTester(eraserTip)
AddHandler eraseTester.StrokeHit, _
AddressOf eraseTester_StrokeHit
eraseTester.AddPoints(e.GetStylusPoints(Me))
End Sub
' Collect the StylusPackets as the stylus moves.
Protected Overrides Sub OnStylusMove(ByVal e As StylusEventArgs)
If eraseTester.IsValid Then
eraseTester.AddPoints(e.GetStylusPoints(Me))
End If
End Sub
' Unsubscribe from the StrokeHitChanged event when the
' user lifts the stylus.
Protected Overrides Sub OnStylusUp(ByVal e As StylusEventArgs)
eraseTester.AddPoints(e.GetStylusPoints(Me))
RemoveHandler eraseTester.StrokeHit, _
AddressOf eraseTester_StrokeHit
eraseTester.EndHitTesting()
End Sub
' 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.
Private Sub eraseTester_StrokeHit(ByVal sender As Object, _
ByVal args As StrokeHitEventArgs)
Dim eraseResult As StrokeCollection = _
args.GetPointEraseResults()
Dim strokesToReplace As New StrokeCollection()
strokesToReplace.Add(args.HitStroke)
' Replace the old stroke with the new one.
If eraseResult.Count > 0 Then
presenter.Strokes.Replace(strokesToReplace, eraseResult)
Else
presenter.Strokes.Remove(strokesToReplace)
End If
End Sub
The IncrementalHitTester dynamically determines whether the user "hits" a Stroke. This class enables you to provide immediate feedback to the user in situations such as selecting and erasing ink.
There are two classes that inherit from IncrementalHitTester:
The IncrementalLassoHitTester hit tests strokes by determining whether a lasso path surrounds it.
The IncrementalStrokeHitTester hit tests strokes by determining where an eraser path intersects it.
The following table lists where to learn how to manage digital ink on a custom control.
To do this… | See this article |
---|---|
Create a control that collects digital ink | Creating an Ink Input Control |
Create a control that enables the user to select ink | How to: Select Ink from a Custom Control |
Create a control that enables the user to point-erase ink | How to: Erase Ink on a Custom Control |
This class is not typically used in XAML.
Is |
Gets whether the IncrementalHitTester is hit testing. |
Add |
Adds a Point to the IncrementalHitTester. |
Add |
Adds points to the IncrementalHitTester. |
Add |
Adds the specified StylusPoint objects to the IncrementalHitTester. |
Add |
Adds points to the IncrementalHitTester. |
End |
Releases resources used by the IncrementalHitTester. |
Equals(Object) |
Determines whether the specified object is equal to the current object. (Inherited from Object) |
Get |
Serves as the default hash function. (Inherited from Object) |
Get |
Gets the Type of the current instance. (Inherited from Object) |
Memberwise |
Creates a shallow copy of the current Object. (Inherited from Object) |
To |
Returns a string that represents the current object. (Inherited from Object) |
Product | Versions |
---|---|
.NET Framework | 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
Windows Desktop | 3.0, 3.1, 5, 6, 7, 8, 9 |
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