求助大神啊，ImageViewer 控件该如何支持在触摸屏电脑上，实现双指捏合/展开进行缩放 单指拖动进行平移功能。

[jimmypeng92]

我在imageViewer的基础上，封装了个TouchImageViewer，不仅图片无法显示，还不能缩放了，该怎么办求助大神，下面是我做的尝试，但是不行。

<Grid  >
    <Grid.RowDefinitions>
        <RowDefinition Height="50"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>          
            <Border  Grid.Row="1">
             <local:TouchImageViewer
              x:Name="mainImageViewer" 
              ImageSource="{Binding CurrentImageSource}" 
              ShowToolBar="True"
              Background="White"
              Margin="10"
              IsManipulationEnabled="True"
              ManipulationStarting="MainImageViewer_ManipulationStarting"
              ManipulationDelta="MainImageViewer_ManipulationDelta"/>
            </Border>
        </Grid>
    </Border>
</Grid>

using HandyControl.Controls;
using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;

namespace 安灯系统
{

public class TouchImageViewer : HandyControl.Controls.ImageViewer
{
private MatrixTransform _matrixTransform;
private Image _imageMain;
private Point _lastPoint;

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate(); // 必须调用基类方法

        // 获取内部的Image部件
        _imageMain = GetTemplateChild("PART_ImageMain") as Image;

        if (_imageMain != null)
        {
            Debug.WriteLine("成功获取 PART_ImageMain");

            // 初始化矩阵变换
            _matrixTransform = new MatrixTransform();
            _imageMain.RenderTransform = _matrixTransform;

            // 启用手势操作
            this.IsManipulationEnabled = true;
            this.ManipulationDelta += OnManipulationDelta;
            this.ManipulationStarting += OnManipulationStarting;

            Debug.WriteLine("TouchImageViewer 初始化完成");
        }
        else
        {
            Debug.WriteLine("警告：未能找到 PART_ImageMain");

            // 如果找不到内部Image，回退到对整个控件应用变换
            _matrixTransform = new MatrixTransform();
            this.RenderTransform = _matrixTransform;

            this.IsManipulationEnabled = true;
            this.ManipulationDelta += OnManipulationDelta;
            this.ManipulationStarting += OnManipulationStarting;
        }
    }

    private void OnManipulationStarting(object sender, ManipulationStartingEventArgs e)
    {
        e.ManipulationContainer = this;
        e.Mode = ManipulationModes.Scale | ManipulationModes.Translate;
        e.Handled = true;
    }

    private void OnManipulationDelta(object sender, ManipulationDeltaEventArgs e)
    {
        if (_matrixTransform == null) return;

        Matrix matrix = _matrixTransform.Matrix;

        // 获取操作中心点 - 这里使用 ManipulationOrigin（在 ManipulationDeltaEventArgs 中）
        Point center = e.ManipulationOrigin;

        // 处理缩放
        if (e.DeltaManipulation.Scale != null)
        {
            double scaleX = e.DeltaManipulation.Scale.X;
            double scaleY = e.DeltaManipulation.Scale.Y;

            // 添加缩放限制
            double currentScale = Math.Sqrt(matrix.M11 * matrix.M11 + matrix.M12 * matrix.M12);
            double newScale = currentScale * scaleX;

            // 限制缩放范围在 0.1 到 10 倍之间
            if (newScale >= 0.1 && newScale <= 10.0)
            {
                matrix.ScaleAt(scaleX, scaleY, center.X, center.Y);
            }
        }

        // 处理平移
        matrix.Translate(e.DeltaManipulation.Translation.X, e.DeltaManipulation.Translation.Y);

        // 应用变换
        _matrixTransform.Matrix = matrix;
        e.Handled = true;
    }

    // 重置视图到初始状态
    public void ResetView()
    {
        if (_matrixTransform != null)
        {
            _matrixTransform.Matrix = Matrix.Identity;
        }
    }

    // 双击重置视图
    protected override void OnMouseDoubleClick(MouseButtonEventArgs e)
    {
        base.OnMouseDoubleClick(e);
        ResetView();
        e.Handled = true;
    }

    // 添加鼠标滚轮缩放支持
    protected override void OnMouseWheel(MouseWheelEventArgs e)
    {
        if (_matrixTransform == null) return;

        Matrix matrix = _matrixTransform.Matrix;
        Point center = e.GetPosition(this);

        double scaleFactor = e.Delta > 0 ? 1.1 : 0.9; // 滚轮向上放大，向下缩小
        double currentScale = Math.Sqrt(matrix.M11 * matrix.M11 + matrix.M12 * matrix.M12);
        double newScale = currentScale * scaleFactor;

        // 限制缩放范围
        if (newScale >= 0.1 && newScale <= 10.0)
        {
            matrix.ScaleAt(scaleFactor, scaleFactor, center.X, center.Y);
            _matrixTransform.Matrix = matrix;
        }

        e.Handled = true;
    }

}
}