通过

IncrementalHitTester 类

  • 参考

定义

命名空间:
System.Windows.Ink
程序集:
PresentationCore.dll

对 Stroke 动态执行命中测试。

public ref class IncrementalHitTester abstract
public abstract class IncrementalHitTester
type IncrementalHitTester = class
Public MustInherit Class IncrementalHitTester
继承
Object
IncrementalHitTester
派生

示例

以下示例演示如何在用户使用触笔输入数据时向 添加点 IncrementalHitTester 。 该示例包含一个 StrokeHit 事件处理程序，用于清除用户相交的 部分 Stroke 。 若要创建允许用户擦除墨迹的控件，请参阅 如何：擦除自定义控件上的墨迹。


// 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

注解

动态 IncrementalHitTester 确定用户是否“命中”了 Stroke。 此类使你能够在选择和擦除墨迹等情况下向用户提供即时反馈。

有两个继承自 IncrementalHitTester的类：

下表列出了在何处了解如何管理自定义控件上的数字墨迹。

要实现的目的… 参考文章
创建用于收集数字墨迹的控件 创建墨迹输入控件
创建允许用户选择墨迹的控件 如何：从自定义控件选择墨迹
创建允许用户对墨迹进行点擦除的控件 如何：清除自定义控件上的墨迹

XAML 文本用法

此类通常不在 XAML 中使用。

属性

IsValid

获取 IncrementalHitTester 是否在进行命中测试。

方法

AddPoint(Point)

向 Point 中添加一个 IncrementalHitTester。
AddPoints(IEnumerable<Point>)

向 IncrementalHitTester 添加点。
AddPoints(StylusPointCollection)

将指定的 StylusPoint 对象添加到 IncrementalHitTester 中。
AddPointsCore(IEnumerable<Point>)

向 IncrementalHitTester 添加点。
EndHitTesting()

释放由 IncrementalHitTester 使用的资源。
Equals(Object)

确定指定对象是否等于当前对象。

(继承自 Object)
GetHashCode()

作为默认哈希函数。

(继承自 Object)
GetType()

获取当前实例的 Type。

(继承自 Object)
MemberwiseClone()

创建当前 Object 的浅表副本。

(继承自 Object)
ToString()

返回表示当前对象的字符串。

(继承自 Object)

适用于