ManipulationDelta - 只有翻译具有价值，缩放和旋转始终是“身份” [英] ManipulationDelta - Only Translation has values, Scale and Rotation is always 'Identity'

问题描述

我尝试实现了多点触控的用户界面（在棕地项目）的<一个href="http://msdn.microsoft.com/en-us/library/system.windows.uielement.manipulationdelta%28v=vs.110%29.aspx"相对=nofollow> ManipulationDelta事件 WPF的。但是我只得到了平移值，而从来不是规模或旋转。

I try to implement a multi-touch ui (in a brownfield project) with the ManipulationDelta event of wpf. But I only get values for translation, but never for scale or rotation.

我的测试code是这样的：

My test code looks like this:

        Private Sub ScrollViewerViewModelManipulationDelta(sender As Object, e As Input.ManipulationDeltaEventArgs) Handles Me.ManipulationDelta

        Dim transform As MatrixTransform = TryCast(RenderTransform, MatrixTransform)
        If transform Is Nothing Then transform = New MatrixTransform(RenderTransform.Value)
        Dim matrix As Matrix = transform.Matrix

        If e.DeltaManipulation.Scale.X <> 1 OrElse e.DeltaManipulation.Scale.Y <> 1 Then
            matrix.ScaleAt(e.DeltaManipulation.Scale.X,
                            e.DeltaManipulation.Scale.Y,
                            e.ManipulationOrigin.X,
                            e.ManipulationOrigin.Y)
        End If
        If e.DeltaManipulation.Translation.X <> 1 OrElse e.DeltaManipulation.Translation.Y <> 1 Then
            'matrix.Translate(e.DeltaManipulation.Translation.X,
            '                e.DeltaManipulation.Translation.Y)
        End If
        If e.DeltaManipulation.Rotation <> 0 Then
            matrix.RotateAt(e.DeltaManipulation.Rotation,
                 e.ManipulationOrigin.X,
                 e.ManipulationOrigin.Y)
        End If

        RenderTransform = New MatrixTransform(matrix)

        If e.IsInertial Then
            e.Complete()
        End If

        'e.Handled = True

    End Sub

任何想法，我在这里缺少什么？我试过手势缩放和旋转，但我只得到翻译...

Any idea what I'm missing here? I tried the gestures for zooming and rotating, but I only get translations...

谢谢！   斯特凡

推荐答案

您必须调用<一个href="http://msdn.microsoft.com/en-us/library/system.windows.input.manipulation.setmanipulationmode.aspx"相对=nofollow> Manipulation.SetManipulationMode 在在ManipulationStarted 事件处理程序：

You have to call Manipulation.SetManipulationMode in a ManipulationStartedevent handler:

private void ScrollViewerViewModelManipulationStarted(
    object sender, ManipulationStartedEventArgs e)
{
    Manipulation.SetManipulationMode((UIElement)sender, ManipulationModes.All);
}

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