Gewusst wie: Löschen von Freihandeingaben auf einem benutzerdefinierten Steuerelement
IncrementalStrokeHitTester bestimmt, ob sich der aktuell gezeichnete Strich mit einem anderen Strich kreuzt. Dies ist nützlich für das Erstellen eines Steuerelements, mit dem Benutzer Teile eines Strichs löschen können, wie es bei InkCanvas möglich ist, wenn EditingMode auf EraseByPoint festgelegt ist.
Beispiel
Im folgenden Beispiel wird ein benutzerdefiniertes Steuerelement erstellt, mit dem Benutzer Teile von Strichen löschen können. In diesem Beispiel wird ein Steuerelement erstellt, das beim Initialisieren Freihandeingaben enthält. Informationen zum Erstellen eines Steuerelements, das Freihandeingaben erfasst, finden Sie unter Erstellen eines Freihandeingabesteuerelements.
using System.Windows;
using System.Windows.Controls;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.IO;
// This control initializes with ink already on it and allows the
// user to erase the ink with the tablet pen or mouse.
public class InkEraser : Label
{
IncrementalStrokeHitTester eraseTester;
InkPresenter presenter;
string strokesString =
@"ALwHAxdIEETLgIgERYQBGwIAJAFGhAEbAgAkAQUBOBkgMgkA9P8CAekiOkUzCQD4n"
+ "wIBWiA6RTgIAP4DAAAAgH8RAACAPx8JEQAAAAAAAPA/CiUHh/A6N4HR0AivFX8Vs"
+ "IfsiuyLSaIeDSLwabiHm0GgUDi+KZkACjsQh/A9t4IC5VJpfLhaIxyxXIh7Dncnh"
+ "+6e7qODwoERlPAw8EpGoJAgh61IKjCYXBYDA4DAIHF67KIHAAojB4fwMteBn+RKB"
+ "lziaIfwWTeCwePqbM8WgIeeQCDQOFRvcIAKNA+H8B8XgQHkUbjQTTnGuaZns3l4h"
+ "/DWt4a0YKBBOA94D6HRCAiGnp5CS8LExMLB1tOgYIAKUBOH8KnXhU7lMold+tcbi"
+ "kChkqu2EtPYxp9bmYCH8HDHg4ZhMIwRyMHH+4Jt8nleX8c0/D/AkYwxJGiHkkQgM"
+ "Ch9CqcFhMDQCBwWAwuR2eAACmgdh/EpF4lA6XMUfhMXgMHgVDxBFpRKpZII5EINA"
+ "OA64M+J4Lw1CIoAh/B2x4PS4bQodAopEI5IJBki4waEx2Qy+dy+ayHgleEmmHH8c"
+ "e3MZOCGw5TWd3CwsHAwMCgRAEAgElKwOHZKBApaGIfxezeL0uN02N8IzwaGEpNIJ"
+ "ZxHnELyOj0GfyuU6FgmhplIgIfwYgeDHeaI1vjOtZgcHgHAYb9hUCgEFgsPm1xnM"
+ "ZkYhsnYJgZeZh4uAgCgnSBIOJv4OAgwCmkgh/GrR41X4dGoRJL9EKra5HKY7IZ3C"
+ "4fj/M06olSoU8kkehUbh8jkMdCH8IJXhAXhMCk8JuNlmNyh0YiEumUwn2wMRxyHw"
+ "2TzWmzeb02OzGKxMITwIhnrjzbb44zRhGEKRhCM4zrr6sQKXRWH8kuXkmPj0DiXC"
+ "gcJbC9HZZgkKgUG4bLh3YrwJHAYw2CAh/CiN4Tq7DOZr4BB/AFtdOWW5P2h1Wkzv"
+ "l4+YwqXf8d5fZ7ih51QKbB4LQrLAYDBIDABA4BO4nAICApvIIfy4BeXA2DRSrQlL"
+ "oHHsYQ/KMXlsvl8rn8Xkcdg+G9NVaUWimUDYk9Ah/BoF4M0YBCqZPYqk8dwLf7hD"
+ "YNBJFLKBNqZTqNubWshl9VoM1reFYZYQEBGUsDAwKEjYuDQKBgICBgCAgIOAg4nI"
+ "8OACloSh/BFl4Gf/IOt6FXfF8F4ToPCZzlPwP4+B+DHmQO847rfDeCcG8eKh/EZV"
+ "4i9eZt8A9nUF8VzxaUe5grl7YrPaHfpRKJNx4yHmUuj1vicwmMBEAjUVgKB61A=";
public InkEraser()
{
presenter = new InkPresenter();
this.Content = presenter;
// Create a StrokeCollection the string and add it to
StrokeCollectionConverter converter =
new StrokeCollectionConverter();
if (converter.CanConvertFrom(typeof(string)))
{
StrokeCollection newStrokes =
converter.ConvertFrom(strokesString) as StrokeCollection;
presenter.Strokes.Clear();
presenter.Strokes.Add(newStrokes);
}
}
protected override void OnStylusDown(StylusDownEventArgs e)
{
base.OnStylusDown(e);
StylusPointCollection points = e.GetStylusPoints(this);
InitializeEraserHitTester(points);
}
protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
{
base.OnMouseLeftButtonDown(e);
if (e.StylusDevice != null)
{
return;
}
Point pt = e.GetPosition(this);
StylusPointCollection collectedPoints = new StylusPointCollection(new Point[] { pt });
InitializeEraserHitTester(collectedPoints);
}
// Prepare to collect stylus packets. Get the
// IncrementalHitTester from the InkPresenter's
// StrokeCollection and subscribe to its StrokeHitChanged event.
private void InitializeEraserHitTester(StylusPointCollection points)
{
EllipseStylusShape eraserTip = new EllipseStylusShape(3, 3, 0);
eraseTester =
presenter.Strokes.GetIncrementalStrokeHitTester(eraserTip);
eraseTester.StrokeHit += new StrokeHitEventHandler(eraseTester_StrokeHit);
eraseTester.AddPoints(points);
}
protected override void OnStylusMove(StylusEventArgs e)
{
StylusPointCollection points = e.GetStylusPoints(this);
AddPointsToEraserHitTester(points);
}
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
if (e.StylusDevice != null)
{
return;
}
if (e.LeftButton == MouseButtonState.Released)
{
return;
}
Point pt = e.GetPosition(this);
StylusPointCollection collectedPoints = new StylusPointCollection(new Point[] { pt });
AddPointsToEraserHitTester(collectedPoints);
}
// Collect the StylusPackets as the stylus moves.
private void AddPointsToEraserHitTester(StylusPointCollection points)
{
if (eraseTester.IsValid)
{
eraseTester.AddPoints(points);
}
}
// Unsubscribe from the StrokeHitChanged event when the
// user lifts the stylus.
protected override void OnStylusUp(StylusEventArgs e)
{
StylusPointCollection points = e.GetStylusPoints(this);
StopEraseHitTesting(points);
}
protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
{
base.OnMouseLeftButtonUp(e);
if (e.StylusDevice != null)
{
return;
}
Point pt = e.GetPosition(this);
StylusPointCollection collectedPoints = new StylusPointCollection(new Point[] { pt });
StopEraseHitTesting(collectedPoints);
}
private void StopEraseHitTesting(StylusPointCollection points)
{
eraseTester.AddPoints(points);
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);
}
}
}
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Ink
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.IO
' This control initializes with ink already on it and allows the
' user to erase the ink with the tablet pen or mouse.
Public Class InkEraser
Inherits Label
Private eraseTester As IncrementalStrokeHitTester
Private presenter As InkPresenter
' The base-64 encoded string that contains ink data
' in ink serialized format (ISF).
Private strokesString As String = _
"ALwHAxdIEETLgIgERYQBGwIAJAFGhAEbAgAkAQUBOBkgMgkA9P8CAekiOkUzCQD4n" _
& "wIBWiA6RTgIAP4DAAAAgH8RAACAPx8JEQAAAAAAAPA/CiUHh/A6N4HR0AivFX8Vs" _
& "IfsiuyLSaIeDSLwabiHm0GgUDi+KZkACjsQh/A9t4IC5VJpfLhaIxyxXIh7Dncnh" _
& "+6e7qODwoERlPAw8EpGoJAgh61IKjCYXBYDA4DAIHF67KIHAAojB4fwMteBn+RKB" _
& "lziaIfwWTeCwePqbM8WgIeeQCDQOFRvcIAKNA+H8B8XgQHkUbjQTTnGuaZns3l4h" _
& "/DWt4a0YKBBOA94D6HRCAiGnp5CS8LExMLB1tOgYIAKUBOH8KnXhU7lMold+tcbi" _
& "kChkqu2EtPYxp9bmYCH8HDHg4ZhMIwRyMHH+4Jt8nleX8c0/D/AkYwxJGiHkkQgM" _
& "Ch9CqcFhMDQCBwWAwuR2eAACmgdh/EpF4lA6XMUfhMXgMHgVDxBFpRKpZII5EINA" _
& "OA64M+J4Lw1CIoAh/B2x4PS4bQodAopEI5IJBki4waEx2Qy+dy+ayHgleEmmHH8c" _
& "e3MZOCGw5TWd3CwsHAwMCgRAEAgElKwOHZKBApaGIfxezeL0uN02N8IzwaGEpNIJ" _
& "ZxHnELyOj0GfyuU6FgmhplIgIfwYgeDHeaI1vjOtZgcHgHAYb9hUCgEFgsPm1xnM" _
& "ZkYhsnYJgZeZh4uAgCgnSBIOJv4OAgwCmkgh/GrR41X4dGoRJL9EKra5HKY7IZ3C" _
& "4fj/M06olSoU8kkehUbh8jkMdCH8IJXhAXhMCk8JuNlmNyh0YiEumUwn2wMRxyHw" _
& "2TzWmzeb02OzGKxMITwIhnrjzbb44zRhGEKRhCM4zrr6sQKXRWH8kuXkmPj0DiXC" _
& "gcJbC9HZZgkKgUG4bLh3YrwJHAYw2CAh/CiN4Tq7DOZr4BB/AFtdOWW5P2h1Wkzv" _
& "l4+YwqXf8d5fZ7ih51QKbB4LQrLAYDBIDABA4BO4nAICApvIIfy4BeXA2DRSrQlL" _
& "oHHsYQ/KMXlsvl8rn8Xkcdg+G9NVaUWimUDYk9Ah/BoF4M0YBCqZPYqk8dwLf7hD" _
& "YNBJFLKBNqZTqNubWshl9VoM1reFYZYQEBGUsDAwKEjYuDQKBgICBgCAgIOAg4nI" _
& "8OACloSh/BFl4Gf/IOt6FXfF8F4ToPCZzlPwP4+B+DHmQO847rfDeCcG8eKh/EZV" _
& "4i9eZt8A9nUF8VzxaUe5grl7YrPaHfpRKJNx4yHmUuj1vicwmMBEAjUVgKB61A="
Public Sub New()
presenter = New InkPresenter()
Me.Content = presenter
' Create a StrokeCollection the string and add it to
Dim converter As New StrokeCollectionConverter()
If converter.CanConvertFrom(GetType(String)) Then
Dim newStrokes As StrokeCollection = converter.ConvertFrom(strokesString)
presenter.Strokes.Clear()
presenter.Strokes.Add(newStrokes)
End If
End Sub
Protected Overrides Sub OnStylusDown(ByVal e As StylusDownEventArgs)
MyBase.OnStylusDown(e)
Dim points As StylusPointCollection = e.GetStylusPoints(Me)
InitializeEraserHitTester(points)
End Sub
Protected Overrides Sub OnMouseLeftButtonDown(ByVal e As MouseButtonEventArgs)
MyBase.OnMouseLeftButtonDown(e)
If Not (e.StylusDevice Is Nothing) Then
Return
End If
Dim pt As Point = e.GetPosition(Me)
Dim collectedPoints As New StylusPointCollection(New Point() {pt})
InitializeEraserHitTester(collectedPoints)
End Sub
' Get the IncrementalHitTester from the InkPresenter's
' StrokeCollection and subscribe to its StrokeHitChanged event.
Private Sub InitializeEraserHitTester(ByVal points As StylusPointCollection)
Dim eraserTip As New EllipseStylusShape(3, 3, 0)
eraseTester = presenter.Strokes.GetIncrementalStrokeHitTester(eraserTip)
AddHandler eraseTester.StrokeHit, AddressOf eraseTester_StrokeHit
eraseTester.AddPoints(points)
End Sub
Protected Overrides Sub OnStylusMove(ByVal e As StylusEventArgs)
Dim points As StylusPointCollection = e.GetStylusPoints(Me)
AddPointsToEraserHitTester(points)
End Sub
Protected Overrides Sub OnMouseMove(ByVal e As MouseEventArgs)
MyBase.OnMouseMove(e)
If Not (e.StylusDevice Is Nothing) Then
Return
End If
If e.LeftButton = MouseButtonState.Released Then
Return
End If
Dim pt As Point = e.GetPosition(Me)
Dim collectedPoints As New StylusPointCollection(New Point() {pt})
AddPointsToEraserHitTester(collectedPoints)
End Sub
' Collect the StylusPackets as the stylus moves.
Private Sub AddPointsToEraserHitTester(ByVal points As StylusPointCollection)
If eraseTester.IsValid Then
eraseTester.AddPoints(points)
End If
End Sub
' Unsubscribe from the StrokeHitChanged event when the
' user lifts the stylus.
Protected Overrides Sub OnStylusUp(ByVal e As StylusEventArgs)
Dim points As StylusPointCollection = e.GetStylusPoints(Me)
StopEraseHitTesting(points)
End Sub
Protected Overrides Sub OnMouseLeftButtonUp(ByVal e As MouseButtonEventArgs)
MyBase.OnMouseLeftButtonUp(e)
If Not (e.StylusDevice Is Nothing) Then
Return
End If
Dim pt As Point = e.GetPosition(Me)
Dim collectedPoints As New StylusPointCollection(New Point() {pt})
StopEraseHitTesting(collectedPoints)
End Sub
Private Sub StopEraseHitTesting(ByVal points As StylusPointCollection)
eraseTester.AddPoints(points)
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
End Class
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