C# WPF-旋转后平移时的触摸操作问题

我对通过操纵事件（更准确地说是矩阵）进行对象转换有问题

问题：在第一次成功旋转/缩放/平移我的对象（顺便说一句：矩形）后，第二次操作（本例中为平移）将沿其新角度的方向移动对象。 例如，如果在第一次旋转（新角度为45°）后，我从右向左触摸屏幕，则对象将遵循45°的对角线路径，而不是我绘制的路径

期望值：我希望我的对象完全按照我在屏幕上所做的路径移动，而不管其旋转如何

情境：我通过代码在画布中放置一个矩形，这个矩形有“IsManipulationEnabled=true”和“renderTransferorMorigin=new Point（.5.5）”和“mySuperRectangle.ManipulationDelta+=Container\u ManipulationDelta；”

这是我使用的代码：

    private void Container_ManipulationDelta(object sender, ManipulationDeltaEventArgs e)
    {
        try
        {
            if (e.OriginalSource != null)
            {
                Rectangle image = e.OriginalSource as Rectangle;


                Point center = new Point(image.ActualWidth / 2.0, image.ActualHeight / 2.0);
                Matrix imageMatrix = ((MatrixTransform)image.RenderTransform).Matrix;
                center = imageMatrix.Transform(center);

                // Move the Rectangle.
                imageMatrix.Translate(e.DeltaManipulation.Translation.X,
                                            e.DeltaManipulation.Translation.Y);

                // Rotate the Rectangle.
                imageMatrix.RotateAt(e.DeltaManipulation.Rotation,
                                     center.X,
                                     center.Y);

                // Resize the Rectangle. Keep it square 
                // so use only the X value of Scale.
                imageMatrix.ScaleAt(e.DeltaManipulation.Scale.X,
                                    e.DeltaManipulation.Scale.X,
                                    center.X,
                                    center.Y);

                // Apply changes
                image.RenderTransform = new MatrixTransform(imageMatrix);

                Rect containingRect =
                    new Rect(((FrameworkElement)e.ManipulationContainer).RenderSize);

                Rect shapeBounds =
                    image.RenderTransform.TransformBounds(
                        new Rect(image.RenderSize));

                // Check if the rectangle is completely in the window.
                // If it is not and intertia is occuring, stop the manipulation.
                if (e.IsInertial && !containingRect.Contains(shapeBounds))
                {
                    e.Complete();
                }

                e.Handled = true;
            }
        }
        catch (Exception)
        {
           throw;
        }
    }

有什么想法吗

---

Thanx很多。

您应该在画布上处理操纵事件，因为操纵的原点应该相对于固定的画布，而不是移动的矩形

<Canvas IsManipulationEnabled="True"
        ManipulationDelta="CanvasManipulationDelta">
    <Rectangle x:Name="rectangle" Width="200" Height="200" Fill="Red">
        <Rectangle.RenderTransform>
            <MatrixTransform/>
        </Rectangle.RenderTransform>
    </Rectangle>
</Canvas>

我的最终代码：

private void CanvasManipulationDelta(object sender, ManipulationDeltaEventArgs e)
{
    var transform = rectangle.RenderTransform as MatrixTransform;
    var matrix = transform.Matrix;
    Point center = new Point(rectangle.ActualWidth / 2.0, rectangle.ActualHeight / 2.0);
    center = matrix.Transform(center);

    matrix.ScaleAt(e.DeltaManipulation.Scale.X , e.DeltaManipulation.Scale.X, center.X, center.Y);
    matrix.RotateAt(e.DeltaManipulation.Rotation, center.X, center.Y);
    matrix.Translate(e.DeltaManipulation.Translation.X, e.DeltaManipulation.Translation.Y);

    rectangle.RenderTransform = new MatrixTransform(matrix);
}

---

编辑：在未检查

null

结果的情况下，不要将

用作

运算符。在这种情况下，如果

transform

为空，则创建一个新的MatrixTransform并将其分配给

RenderTransform

属性。然后，重用转换并只更新其

矩阵

属性

改进代码：

private void CanvasManipulationDelta(object sender, ManipulationDeltaEventArgs e)
{
    var transform = rectangle.RenderTransform as MatrixTransform;

    if (transform == null) // here 
    {
        transform = new MatrixTransform();
        rectangle.RenderTransform = transform;
    }

    var matrix = transform.Matrix;
    var center = new Point(rectangle.ActualWidth / 2.0, rectangle.ActualHeight / 2.0);
    center = matrix.Transform(center);

    matrix.ScaleAt(e.DeltaManipulation.Scale.X , e.DeltaManipulation.Scale.X, center.X, center.Y);
    matrix.RotateAt(e.DeltaManipulation.Rotation, center.X, center.Y);
    matrix.Translate(e.DeltaManipulation.Translation.X, e.DeltaManipulation.Translation.Y);

    transform.Matrix = matrix; // here
}

---

谢谢你@Clemens！你帮了我很大的忙！

private void CanvasManipulationDelta(object sender, ManipulationDeltaEventArgs e)
{
    var transform = rectangle.RenderTransform as MatrixTransform;

    if (transform == null) // here 
    {
        transform = new MatrixTransform();
        rectangle.RenderTransform = transform;
    }

    var matrix = transform.Matrix;
    var center = new Point(rectangle.ActualWidth / 2.0, rectangle.ActualHeight / 2.0);
    center = matrix.Transform(center);

    matrix.ScaleAt(e.DeltaManipulation.Scale.X , e.DeltaManipulation.Scale.X, center.X, center.Y);
    matrix.RotateAt(e.DeltaManipulation.Rotation, center.X, center.Y);
    matrix.Translate(e.DeltaManipulation.Translation.X, e.DeltaManipulation.Translation.Y);

    transform.Matrix = matrix; // here
}