#782 – A RenderTransform Has Better Performance than a LayoutTransform

When you transform a 2D element, you specify the desired transform as either a layout transform (transform calculated before layout phase) or a render transform (transform calculated before rendering the element).

A render transform has better performance than a layout transform.  This is especially apparent when you are animating a transform.  Whenever a layout transform changes, the panel containing the element that is being transformed needs to recalculate the layout of the children within the panel.  With a render transform, by contrast, the element only needs to be re-rendered.  Because of the additional layout step, a layout transform is more compute intensive than a render transform.

Because of the performance differences, you should use a render transform by default, unless you need the layout of the elements to change when the transform changes.

 

#779 – Animating a Rotation Transform

Here’s one more example of an animation of a 2D transform.  In this case, we animate a rotation transform of an element so that the element continually spins around.

    <Grid>
        <Label Content="Gambling now legal in Nevada" Background="Plum"
               HorizontalAlignment="Center" VerticalAlignment="Center"
               Padding="20,10" FontSize="16"
               RenderTransformOrigin="0.5,0.5">
            <Label.RenderTransform>
                <RotateTransform x:Name="rotTransform" />
            </Label.RenderTransform>
            <Label.Triggers>
                <EventTrigger RoutedEvent="Label.Loaded">
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetName="rotTransform"
                                             Storyboard.TargetProperty="Angle"
                                             From="0" To="360" Duration="0:0:2.5"
                                             RepeatBehavior="Forever"/>
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </Label.Triggers>
        </Label>
    </Grid>

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#777 – Animating a Transform

You can animate any of the 2D transforms applied to an element by using a Storyboard that contains an object that derives from AnimationTimeline.

In the example below, we use two DoubleAnimation objects to animate the X and properties of a TranslateTransform, so that the TextBlock wanders around the screen.

For the X property of the transform, we specify that we want it to vary from -100 to 100 and then back again, taking 0.7 seconds and then repeating the pattern forever.  We do something similar for Y, but using a different time period.

    <Grid>
        <TextBlock Text="We shall overcome" HorizontalAlignment="Center" VerticalAlignment="Center"
                   Padding="20,10" Background="PaleGoldenrod" FontSize="16">
            <TextBlock.RenderTransform>
                <TranslateTransform x:Name="transTransform" X="-100" Y="-80"/>
            </TextBlock.RenderTransform>
            <TextBlock.Triggers>
                <EventTrigger RoutedEvent="TextBlock.Loaded">
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetName="transTransform"
                                             Storyboard.TargetProperty="X"
                                             From="-100" To="100" Duration="0:0:0.7"
                                             AutoReverse="True" RepeatBehavior="Forever"/>
                            <DoubleAnimation Storyboard.TargetName="transTransform"
                                             Storyboard.TargetProperty="Y"
                                             From="-80" To="80" Duration="0:0:1.5"
                                             AutoReverse="True" RepeatBehavior="Forever"/>
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </TextBlock.Triggers>
        </TextBlock>
    </Grid>

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