Compass with an arrow wpf

Question

I have to show a compass with an arrow inside a circle

I have the following code:

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> 

<Page.Resources>
        <Pen x:Key="BlackPen1" Thickness="1" Brush="Black"></Pen>
  </Page.Resources> 
  <Grid>
        <!-- Image for the Circle -->
        <Image>
            <Image.Source>
                <DrawingImage>
                    <DrawingImage.Drawing>
                        <GeometryDrawing Pen="{StaticResource BlackPen1}" >
                            <GeometryDrawing.Geometry>
                                <GeometryGroup>
                                    <EllipseGeometry RadiusX="50" RadiusY="50"></EllipseGeometry>
                                </GeometryGroup>
                            </GeometryDrawing.Geometry>
                        </GeometryDrawing>
                    </DrawingImage.Drawing>
                </DrawingImage>
            </Image.Source>
        </Image>
        <Path Grid.Row="1" Data="M15,0 L30,40 L0,40Z" Stroke="Black" Fill="Black" StrokeThickness="1" HorizontalAlignment="Center" />
        <Line Grid.Row="0" Y1="40" Y2="400" X1="0" X2="0" Stroke="Black" StrokeThickness="5" HorizontalAlignment="Center" />

    </Grid>
</Page>

Now I have to transform this whole compass based on the input angle. One thing I know is If I move my arrow shape into Image type I can tans form this using the following

<Image.RenderTransform>
                <RotateTransform Angle="{Binding ElementName=root, Path=Angle}"/>
</Image.RenderTransform>

But I am not able to draw this geometry inside the Image tag. How to achieve this?

Answer 1

Why would you need to rotate the Ellipse? Surely only the arrow moves in a compass. In order to make that job easier, why don't you create the arrow in just one Path, instead of additionally using a Line element? You could define the same arrow with rotation like this:

<Path Grid.Row="1" Data="M15,0 30,40 18,40 18,400 12,400 12,40 0,40Z" Stroke="Black" 
    Fill="Black" StrokeThickness="1" HorizontalAlignment="Center" 
    RenderTransformOrigin="0.5,0.5">
    <Path.RenderTransform>
        <RotateTransform Angle="{Binding Angle, ElementName=root}" />
    </Path.RenderTransform>
</Path>

Answer 2

You can apply the rotation to the whole Grid That contains all of your controls. Don't forget to set RenderTransformOrigin="0.5,0.5" on the element you rotate so it rotates arround the center and not the top left corner.

Or you could add a RotationTransform to each of the elements Path, Line and Ellipse. However in this case Rotation centers will probably be different for each one and it makes it more complicated.