更改旋转对象的 RenderTransformOrigin 属性

Question

当 RenderTransformOrigin 属性更改时，如何使旋转的对象保持静止？运行下面的代码后，您可以注意到，通过旋转对象（滑块执行此操作）、更改旋转原点（按钮）并再次旋转它，对象会轻微移动。我想要实现的目标是能够在不同的点上旋转对象，而每当我尝试在它们之间切换时，对象不会四处移动。

<UserControl x:Class="ObjrctRotation.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">

<Canvas x:Name="C" Background="White">
    <Path x:Name="thing" RenderTransformOrigin="0,0" Stretch="Fill" Stroke="Black" StrokeThickness="2" Height="93.153" HorizontalAlignment="Left" VerticalAlignment="Top" Width="106.357" UseLayoutRounding="False" Data="M48.723255,124.82815 C41.00029,80.999809 81.000046,65.000069 112.99985,89.000092 C144.99965,113.00011 168.9996,169.00061 136.99989,169.0002 C105.00018,168.99979 104.9999,145.00015 81.000053,145.00015 C57.000206,145.00015 56.44622,168.65649 48.723255,124.82815 z" Canvas.Left="69" Canvas.Top="24" />
    <Slider Value="0" Minimum="0" Maximum="360" Width="100" Margin="300,0,0,272" ValueChanged="Slider_ValueChanged" />
    <TextBlock x:Name="test" Width="100" Height="20" Canvas.Left="300" Canvas.Top="24" />
    <Button Canvas.Left="300" Canvas.Top="24" Content="ChangeCenter" Height="20" Name="button1" Width="100" Click="button1_Click"/>
</Canvas>

 public partial class MainPage : UserControl
{
    public MainPage()
    {
        InitializeComponent();
    }
    private void Slider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
    {
        RotateTransform rotate = new RotateTransform()
        {
            Angle=e.NewValue
        };         

        thing.RenderTransform = rotate;
    }
    private void button1_Click(object sender, RoutedEventArgs e)
    {
        thing.RenderTransformOrigin = new Point(thing.RenderTransformOrigin.X + 0.2, thing.RenderTransformOrigin.Y + 0.2);
    }
}

Answer 1

将 RenderTransformOrigin="0,0" 设置为 RenderTransformOrigin="0.5,0.5"，以便变换原点位于要旋转的对象的中间。