이미지 또는 캔버스를 계속 회전하는 방법

Question

이 코드는 한 번만 실행되어 캔버스를 회전시킵니다. 사용자가 회전 버튼을 두 번째로 누를 때 왜 회전하지 않습니까?

XAML을 : 대신으로 RenderTransform마다 한 번으로 RenderTransform을 생성하고 재사용 교체

 
--update with button
 
<AppBarButton x:Name="CamRotate90" Margin="0,2,2,0" Width="90" Height="90" FontSize="16" Label="Rotate-Right" Icon="Rotate" Click="CamRotate90_Click"> 
</AppBarButton> 




<Canvas x:Name="canvas" Margin="231,28,321,111" Width="700" Height="525" Grid.Row="0" Grid.RowSpan="3" Grid.Column="0"> 
    <Image Canvas.Top="0" Canvas.Left="0" Margin="0" x:Name="preview" Width="700" Height="525" Stretch="UniformToFill" > 
    </Image> 
</Canvas> 


private void CamRotate90_Click(object sender, RoutedEventArgs e) 
     { 

      CompositeTransform ct = new CompositeTransform(); 
      ct.CenterX = canvas.ActualWidth/2; 
      ct.CenterY = canvas.ActualHeight/2; 
      ct.Rotation = 90; 

      canvas.RenderTransform = ct;   


     } 

Answer 1

<Canvas x:Name="canvas" Margin="231,28,321,111" Width="700" Height="525" Grid.Row="0" Grid.RowSpan="3" Grid.Column="0"> 
    <Canvas.RenderTransform> 
     <CompositeTransform /> 
    </Canvas.RenderTransform> 
    <Image Canvas.Top="0" Canvas.Left="0" Margin="0" x:Name="preview" Width="700" Height="525" Stretch="UniformToFill" > 
    </Image> 
</Canvas> 

코드 :

private void CamRotate90_Click(object sender, RoutedEventArgs e) 
{ 
    CompositeTransform ct = canvas.RenderTransform as CompositeTransform; 
    if (ct != null) // Just to make sure 
    { 
     ct.CenterX = canvas.ActualWidth/2; 
     ct.CenterY = canvas.ActualHeight/2; 
     ct.Rotation += 90; 
    } 
}