WPF inkcanvas 多点触控？

Question

我正在为触摸屏创建一个简单的绘图应用程序，并且我一直在努力使用多点触控手势在 inkcanvas 内进行缩放和旋转，但我还没有找到解决方案。

有没有一种在 inkcanvas 中提供多点触控手势的简单方法？

Answer 1

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    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;

    namespace WpfApplication1
    {
        /// <summary>
        /// Interaction logic for MainWindow.xaml
        /// </summary>
        public partial class MainWindow : Window
        {
            Dictionary<int, System.Windows.Ink.Stroke> myStrokes;
            public MainWindow()
            {
                InitializeComponent();
                myStrokes = new Dictionary<int, System.Windows.Ink.Stroke>();
                this.WindowState = System.Windows.WindowState.Maximized;
                SandyCanvas.TouchDown += SandyCanvas_OnTouchDown;
                SandyCanvas.TouchUp += SandyCanvas_OnTouchUp;
                SandyCanvas.TouchMove += SandyCanvas_OnTouchMove;
            }
            private void SandyCanvas_OnTouchMove(object sender, TouchEventArgs e)
            {
                var touchPoint = e.GetTouchPoint(this);
                var point = touchPoint.Position;

                if (myStrokes.ContainsKey(touchPoint.TouchDevice.Id))
                {
                    var stroke = myStrokes[touchPoint.TouchDevice.Id];
                    var nearbyPoint = CheckPointNearby(stroke, point);
                    if (!nearbyPoint)
                    {
                        stroke.StylusPoints.Add(new StylusPoint(point.X, point.Y));
                    }
                }
            }
            private static bool CheckPointNearby(System.Windows.Ink.Stroke stroke, Point point)
            {
                return stroke.StylusPoints.Any(p => (Math.Abs(p.X - point.X) <= 1) && (Math.Abs(p.Y - point.Y) <= 1));                
            }
            private void SandyCanvas_OnTouchUp(object sender, TouchEventArgs e)
            {
                var touchPoint = e.GetTouchPoint(this);
                myStrokes.Remove(touchPoint.TouchDevice.Id);
            }        
            private void SandyCanvas_OnTouchDown(object sender, TouchEventArgs e)
            {
                var touchPoint = e.GetTouchPoint(this);
                var point = touchPoint.Position;
                System.Windows.Ink.Stroke newStroke = new System.Windows.Ink.Stroke(new StylusPointCollection(new List<Point> { point }), SandyCanvas.DefaultDrawingAttributes);
                if (!myStrokes.ContainsKey(touchPoint.TouchDevice.Id))
                {
                    myStrokes.Add(touchPoint.TouchDevice.Id, newStroke);
                    SandyCanvas.Strokes.Add(newStroke);
                }
            }
        }
    }

/////////////////////Designer Page////////////////////
<Window x:Class="WpfApplication1.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>
        <InkCanvas x:Name="SandyCanvas"></InkCanvas>
    </Grid>
</Window>