#781 – Transform Order Matters

When you combine several 2D transforms into a transform group, the order in which you list the constituent transforms matters.  The transforms are applied in the order that you list them in the TransformGroup.  The order that they are applied in makes a difference, because if you translate and then rotate an object, you get a different result than if you rotate the object first and then translate it.

In the example below, the labels start out on top of each other, but end up at different positions, because the order of their transforms is different.

    <Grid>
        <Label Content="Dr. Livingstone, I presume?"
               Style="{StaticResource styAfrica}">
            <Label.RenderTransform>
                <TransformGroup>
                    <TranslateTransform X="70" />
                    <RotateTransform Angle="60" />
                </TransformGroup>
            </Label.RenderTransform>
        </Label>
        <Label Content="Dr. Livingstone, I presume?"
               Style="{StaticResource styAfrica}">
            <Label.RenderTransform>
                <TransformGroup>
                    <RotateTransform Angle="60" />
                    <TranslateTransform X="70" />
                </TransformGroup>
            </Label.RenderTransform>
        </Label>
    </Grid>

#780 – Combining Transforms

When you apply a 2D transform to an element, you use the RenderTransform or LayoutTransform properties to specify the  transform to apply.  You set the value of these properties to a single instance of the Transform type.

Often, the value of the Transform type will be a specific transform, like ScaleTransform.  However, you can combine multiple transforms by setting the property to an instance of a TransformGroup, which in turn contains a collection of Transform elements.

In the example below, we first apply a rotate transform to the middle label, followed by a translation transform.

    <StackPanel>
        <Label Content="We few, we happy few, we band of brothers"
               Style="{StaticResource styRoyal}"/>
        <Label Content="For he to-day that sheds his blood with me"
               Style="{StaticResource styRoyal}">
            <Label.RenderTransform>
                <TransformGroup>
                    <RotateTransform Angle="20" />
                    <TranslateTransform X="50" />
                </TransformGroup>
            </Label.RenderTransform>
        </Label>
        <Label Content="Shall be my brother; be he ne'er so vile"
               Style="{StaticResource styRoyal}"/>
    </StackPanel>