#773 – A Rotation Center Point Can Be Outside an Element

When you use the RenderTransformOrigin property of an element to specify the point of origin for all render transforms, you typically express X and Y as normalized coordinates.  X and Y both range from 0.0 to 1.0 as the position moves from one side of the element to the other.

You can also specify X and Y values that are less than 0.0 or greater than 1.0, indicating a point that is outside the element’s boundaries.  (Possibly quite distant from the element).

In the example below, the origin for a rotation transform is set to be off to the right of a Button.  The Slider allows you to try out different rotation angles at runtime.

    <StackPanel Orientation="Vertical">
        <Button Content="Push Me" HorizontalAlignment="Center" Padding="10,5" Margin="5"/>
        <Button Content="And Me" HorizontalAlignment="Center" Padding="10,5" Margin="5"
                RenderTransformOrigin="3.0,1.0" >
            <Button.RenderTransform>
                <RotateTransform Angle="{Binding ElementName=sliAngle, Path=Value}" />
            </Button.RenderTransform>
        </Button>
        <Slider Name="sliAngle" Minimum="-180"  Maximum="180" Value="-20" Margin="25,100"/>
    </StackPanel>

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

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