Touch 类

定义

public ref class Touch abstract sealed

public static class Touch

type Touch = class

Public Class Touch

继承

Object

Touch

示例

以下示例使你能够通过在触摸屏上拖动两根手指来创建 Canvas 简单的模式。 每个触摸都由一个 TouchDevice。 通过绘制触摸提供的触摸点之间的线条来创建图案。 此示例需要Windows兼容触摸的屏幕。

以下标记创建用户界面，该用户界面由居中居中设置的Canvas用户界面组成Grid。

<Window x:Class="WpfTouchFrameSample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="525" Width="525">
    <Grid>
        <Canvas x:Name="canvas1"
                Width="500" Height="500"
                Background="Black" />     
    </Grid>
</Window>

以下代码处理 FrameReported 事件。 当触摸按下时 Canvas，会 TouchDevice 捕获到该控件 Canvas。 当触摸解除时，将 TouchDevice 释放触摸。 当触摸移动过 Canvas时， Id 将选中它。 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。

using System;
using System.Windows;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;

namespace WpfTouchFrameSample
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        // Variables for tracking the position of two points.
        Point pt1, pt2 = new Point();
        
        public MainWindow()
        {
            InitializeComponent();
            Touch.FrameReported += new TouchFrameEventHandler(Touch_FrameReported);
        }

        void Touch_FrameReported(object sender, TouchFrameEventArgs e)
        {
            if (this.canvas1 != null)
            {
                foreach (TouchPoint _touchPoint in e.GetTouchPoints(this.canvas1))
                {
                    if (_touchPoint.Action == TouchAction.Down)
                    {
                        // Clear the canvas and capture the touch to it.
                        this.canvas1.Children.Clear();
                        _touchPoint.TouchDevice.Capture(this.canvas1);
                    }

                    else if (_touchPoint.Action == TouchAction.Move && e.GetPrimaryTouchPoint(this.canvas1) != null)
                    {   
                        // This is the first (primary) touch point. Just record its position.
                        if (_touchPoint.TouchDevice.Id == e.GetPrimaryTouchPoint(this.canvas1).TouchDevice.Id)
                        {
                            pt1.X = _touchPoint.Position.X;
                            pt1.Y = _touchPoint.Position.Y;
                        }

                        // This is not the first touch point. Draw a line from the first point to this one.
                        else if (_touchPoint.TouchDevice.Id != e.GetPrimaryTouchPoint(this.canvas1).TouchDevice.Id)
                        {
                            pt2.X = _touchPoint.Position.X;
                            pt2.Y = _touchPoint.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;
                            this.canvas1.Children.Add(_line);
                        }
                    }

                    else if (_touchPoint.Action == TouchAction.Up)
                    {
                        // If this touch is captured to the canvas, release it.
                        if (_touchPoint.TouchDevice.Captured == this.canvas1)
                        {
                            this.canvas1.ReleaseTouchCapture(_touchPoint.TouchDevice);
                        }
                    }
                }                        
            }
        }
    }
}

Class MainWindow
    ' Variables for tracking the position of two points.
    Private pt1, pt2 As Point

    Public Sub New()
        InitializeComponent()
        AddHandler Touch.FrameReported, AddressOf Touch_FrameReported
    End Sub

    Private Sub Touch_FrameReported(ByVal sender As System.Object, ByVal e As System.Windows.Input.TouchFrameEventArgs)
        If (canvas1 IsNot Nothing) Then
            For Each _touchPoint In e.GetTouchPoints(Me.canvas1)

                If _touchPoint.Action = TouchAction.Down Then
                    ' Clear the canvas and capture the touch to it.
                    canvas1.Children.Clear()
                    _touchPoint.TouchDevice.Capture(canvas1)

                ElseIf _touchPoint.Action = TouchAction.Move Then
                    ' This is the first (primary) touch point. Just record its position.
                    If _touchPoint.TouchDevice.Id = e.GetPrimaryTouchPoint(Me.canvas1).TouchDevice.Id Then
                        pt1.X = _touchPoint.Position.X
                        pt1.Y = _touchPoint.Position.Y

                        ' This is not the first touch point; draw a line from the first point to this one.
                    ElseIf _touchPoint.TouchDevice.Id <> e.GetPrimaryTouchPoint(Me.canvas1).TouchDevice.Id Then
                        pt2.X = _touchPoint.Position.X
                        pt2.Y = _touchPoint.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
                        Me.canvas1.Children.Add(_line)
                    End If

                ElseIf _touchPoint.Action = TouchAction.Up Then
                    ' If this touch is captured to the canvas, release it.
                    If (_touchPoint.TouchDevice.Captured Is canvas1) Then
                        canvas1.ReleaseTouchCapture(_touchPoint.TouchDevice)
                    End If
                End If
            Next
        End If
    End Sub
End Class

注解

FrameReported 事件包含在 Windows Presentation Foundation （WPF） 中，以支持与 Silverlight 的兼容性。 如果不必确保与 Silverlight 的兼容性，请使用触摸事件，例如TouchDown，on 和、on TouchMoveUIElement或UIElement3D。ContentElement

FrameReported 事件不使用与其他WPF输入事件相同的事件模型，例如 TouchDown 和 TouchMove。 事件 FrameReported 不是公开为可能通过 UI 的对象树路由的特定于元素的事件，而是在应用程序级别处理的单个事件。 因此，不能使用 sender 事件处理程序的参数来确定触摸的元素。

使用此方法 TouchFrameEventArgs 获取 TouchPoint 与触摸事件相关的值。 从中 TouchPoint，你可以获取 Position 触摸并确定 TouchAction 是一个 Down， Move还是 Up 操作。 还可以使用该 TouchPoint 来获取 TouchDevice。 从中 TouchDevice，你可以确定设备 Id 并获取有关所触摸元素的信息。