画布在平移时“摇晃”

简介

我是 WPF 的新手，我正在尝试自己实现画布平移。

我已经设法弄清楚了必须应用的逻辑和机制，但是在实现它们时，我得到了一种奇怪的行为。

问题

我的平移代码"工作"得很好，这意味着图像正在朝着正确的方向移动，但它在移动时会"摇晃"(如果您愿意，可以"跳舞"(。

问题

• 为什么会这样？
• 如何解决？

相关信息：

下面是一个说明问题的小型演示应用程序。

XAML：

<Window x:Class="CanvasPanning.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 Background="Beige">
        <Canvas Name="canvas" 
                Width="200" 
                Height="200" 
                Background="Aqua"
                MouseLeftButtonDown="canvas_MouseLeftButtonDown" 
                MouseLeftButtonUp="canvas_MouseLeftButtonUp" 
                LostMouseCapture="canvas_LostMouseCapture" 
                MouseMove="canvas_MouseMove">
            <Ellipse Stroke="Black" Fill="Beige" Canvas.Left="50" Canvas.Top="50" Width="100" Height="50" />
            <Rectangle Stroke="Black" Fill="Red" Canvas.Left="50" Canvas.Top="120" Width="100" Height="50" />
        </Canvas>
    </Grid>
</Window>

代码隐藏：

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 CanvasPanning
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private Matrix m;
        private bool isPanning;
        private Point ptOldPanningPosition;
        public MainWindow()
        {
            InitializeComponent();
            isPanning = false;
            m = canvas.RenderTransform.Value;
        }
        private void canvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonDown(e);
            if (isPanning) return;
            isPanning = canvas.CaptureMouse();
            if(isPanning)
            {
                ptOldPanningPosition = e.GetPosition(canvas);
            }
        }
        private void canvas_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonUp(e);
            if (isPanning)
            {
                isPanning = false;
                canvas.ReleaseMouseCapture();
            }
        }
        private void canvas_LostMouseCapture(object sender, MouseEventArgs e)
        {
            isPanning = false;
            base.OnLostMouseCapture(e);
        }
        private void canvas_MouseMove(object sender, MouseEventArgs e)
        {
            base.OnMouseMove(e);
            if(isPanning)
            {
                Point ptNewPanningPosition = e.GetPosition(canvas);
                Vector offset = ptNewPanningPosition - ptOldPanningPosition;
                m.OffsetX += offset.X;
                m.OffsetY += offset.Y;
                ptOldPanningPosition = ptNewPanningPosition;
                canvas.RenderTransform = new MatrixTransform(m);
            }
        }
    }
}

if(isPanning)
{
    ptOldPanningPosition = e.GetPosition(this);
}

if(isPanning)
{
    Point ptNewPanningPosition = e.GetPosition(this);
}