WPF 多点触控跟踪触摸点

Question

我正在尝试做一个简单的应用程序，当用户触摸屏幕时，应用程序会创建简单的点、椭圆或 2d 对象，并且当用户移动手指时它应该跟随，而且当有 scond touch 同时还必须创建新对象，并针对用户的移动执行相同的操作。每当用户手指抬起时，对象就会被删除。

为此，我正在尝试从此链接http://www.cookingwithxaml.com/recipes/wpf4/wpf4touch.zip 更改触摸绘图代码，但我不知道应该更改哪种方法？

您能就此提出建议吗？

谢谢。

Answer 1

这是一些示例 xaml/C# 代码，可以满足我的需求：

MainWindow.xaml：

<Window x:Class="MultitouchExperiments.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Canvas
            x:Name="TouchCanvas"
            TouchDown="TouchCanvas_TouchDown" TouchUp="TouchCanvas_TouchUp"
            TouchMove="TouchCanvas_TouchMove" TouchLeave="TouchCanvas_TouchLeave"
            TouchEnter="TouchCanvas_TouchEnter"
            VerticalAlignment="Stretch" HorizontalAlignment="Stretch"
            Background="Black"
            IsManipulationEnabled="True" />
    </Grid>
</Window>

MainWindow.xaml.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Diagnostics;

namespace MultitouchExperiments
{
  /// <summary>
  /// Interaction logic for MainWindow.xaml
  /// </summary>
  public partial class MainWindow : Window
  {
    Dictionary<TouchDevice, Ellipse> _Followers = new Dictionary<TouchDevice, Ellipse>();

    public MainWindow()
    {
      InitializeComponent();
    }

    private void TouchCanvas_TouchDown(object sender, TouchEventArgs e)
    {
      TouchCanvas.CaptureTouch(e.TouchDevice);

      Ellipse follower = new Ellipse();
      follower.Width = follower.Height = 50;
      follower.Fill = Brushes.White;
      follower.Stroke = Brushes.White;

      TouchPoint point = e.GetTouchPoint(TouchCanvas);

      follower.RenderTransform = new TranslateTransform(point.Position.X, point.Position.Y);

      _Followers[e.TouchDevice] = follower;

      TouchCanvas.Children.Add(follower);
    }

    private void TouchCanvas_TouchUp(object sender, TouchEventArgs e)
    {
      TouchCanvas.ReleaseTouchCapture(e.TouchDevice);

      TouchCanvas.Children.Remove(_Followers[e.TouchDevice]);
      _Followers.Remove(e.TouchDevice);
    }

    private void TouchCanvas_TouchMove(object sender, TouchEventArgs e)
    {
      if (e.TouchDevice.Captured == TouchCanvas)
      {
        Ellipse follower = _Followers[e.TouchDevice];
        TranslateTransform transform = follower.RenderTransform as TranslateTransform;

        TouchPoint point = e.GetTouchPoint(TouchCanvas);

        transform.X = point.Position.X;
        transform.Y = point.Position.Y;
      }
    }

    private void TouchCanvas_TouchLeave(object sender, TouchEventArgs e)
    {
      //Debug.WriteLine("leave " + e.TouchDevice.Id);
    }

    private void TouchCanvas_TouchEnter(object sender, TouchEventArgs e)
    {
      //Debug.WriteLine("enter " + e.TouchDevice.Id);
    }
  }
}