旋转画布后X，Y位置错误

Question

在用故事板掠过画布之后，我不知道为什么我不能像我所做的那样移动画布。这是我的代码，请帮助我。

在xaml页面中：

<Canvas Name="pnEditor" Background="Transparent"  MouseLeftButtonUp="pnEditor_MouseLeftButtonUp" ManipulationDelta="PnEditor_OnManipulationDelta" ManipulationStarted="PnEditor_OnManipulationStarted" RenderTransformOrigin="0.5,0.5" Margin="-10,10,10,-10">
        <Border Name="adornerControl" BorderBrush="Green" BorderThickness="1"  MouseLeftButtonDown="adornerControl_MouseLeftButtonDown">
            <Border.RenderTransform>
                <CompositeTransform x:Name="ControlRotation" Rotation="0"/>
            </Border.RenderTransform>......
</Border>
</Canvas> 

在代码背后： 的修改

 private void PnEditor_OnManipulationDelta(object sender, ManipulationDeltaEventArgs e)
    {
        //I have a canvas with 5 holders
        if (mIsHolderPressed)
        {
            double deltaX = e.DeltaManipulation.Translation.X;
            double deltaY = e.DeltaManipulation.Translation.Y;

            //center -> move
            if (mSelectedHolder == holderCenter)
            {
                mCurrentX = Math.Max(0, mCurrentX + deltaX);
                mCurrentY = Math.Max(0, mCurrentY + deltaY);
                Canvas.SetLeft(adornerControl, mCurrentX);
                Canvas.SetTop(adornerControl, mCurrentY);
            }
            ...
            //hold it to rotate the canvas follow the mouse
            else if (mSelectedHolder == holderSouthWest)
            {

                var angel = (Math.Atan2(deltaY, deltaX)*180/Math.PI) - 45;
                if (deltaX < 0) angel -= 180;

                var currentAngel = ControlRotation.Rotation;
                CompositeTransform ct = new CompositeTransform();
                ct.TranslateX = Math.Max(0, mCurrentX + deltaX);
                ct.TranslateY = Math.Max(0, mCurrentY + deltaY);
                ct.Rotation = currentAngel + angel;

                adornerControl.RenderTransform = ct;
                adornerControl.RenderTransformOrigin = new Point(0.5, 0.5);
            }
        }
    }

通过此方法获取adornerControl的当前X，Y：

    private void PnEditor_OnManipulationStarted(object sender, ManipulationStartedEventArgs e)
    {
        mOriginalPoint = e.ManipulationOrigin;
        mCurrentX = Canvas.GetLeft(adornerControl);
        mCurrentY = Canvas.GetTop(adornerControl);

    }