TouchDevice.Id 属性

定义

命名空间:

System.Windows.Input

程序集:

PresentationCore.dll

获取由操作系统提供的 TouchDevice 的唯一标识符。

public:
 property int Id { int get(); };

public int Id { get; }

member this.Id : int

Public ReadOnly Property Id As Integer

属性值

Int32

TouchDevice 的唯一标识符。

示例

以下示例处理 TouchMove 上 Canvas发生的事件。 当触摸在 上 Canvas移动时， Id 将检查 。 如果移动来自第一次触摸，则会记录其位置。 如果移动来自第二次触摸，则从第一次触摸的位置到第二次触摸的位置绘制一条线。

此示例是类概述中提供的更大示例的一 TouchDevice 部分。

private void canvas_TouchMove(object sender, TouchEventArgs e)
{
    Canvas _canvas = (Canvas)sender as Canvas;
    if (_canvas != null)
    {
        TouchPoint tp = e.GetTouchPoint(_canvas);
        // This is the first touch point; just record its position.
        if (e.TouchDevice.Id == firstTouchId)
        {
            pt1.X = tp.Position.X;
            pt1.Y = tp.Position.Y;
        }
        // This is not the first touch point; draw a line from the first point to this one.
        else if (e.TouchDevice.Id != firstTouchId)
        {
            pt2.X = tp.Position.X;
            pt2.Y = tp.Position.Y;

            Line _line = new Line();
            _line.Stroke = new RadialGradientBrush(Colors.White, Colors.Black);
            _line.X1 = pt1.X;
            _line.X2 = pt2.X;
            _line.Y1 = pt1.Y;
            _line.Y2 = pt2.Y;

            _line.StrokeThickness = 2;
            _canvas.Children.Add(_line);
        }
    }
}

' Touch Move
Private Sub canvas_TouchMove(ByVal sender As System.Object, ByVal e As System.Windows.Input.TouchEventArgs)
    Dim _canvas As Canvas = CType(sender, Canvas)
    If (_canvas IsNot Nothing) Then
        Dim tp = e.GetTouchPoint(_canvas)
        ' This is the first touch point; just record its position.
        If e.TouchDevice.Id = firstTouchId Then
            pt1.X = tp.Position.X
            pt1.Y = tp.Position.Y

            ' This is not the first touch point; draw a line from the first point to this one.
        ElseIf e.TouchDevice.Id <> firstTouchId Then
            pt2.X = tp.Position.X
            pt2.Y = tp.Position.Y

            Dim _line As New Line()
            _line.Stroke = New RadialGradientBrush(Colors.White, Colors.Black)
            _line.X1 = pt1.X
            _line.X2 = pt2.X
            _line.Y1 = pt1.Y
            _line.Y2 = pt2.Y

            _line.StrokeThickness = 2
            _canvas.Children.Add(_line)
        End If
    End If
End Sub

注解

表示 TouchDevice 屏幕上的一次触摸。 如果存在多个触摸，请使用 Id 属性来区分它们。