CODEWITHSUNDEEP
c#.netwpfxamlanimation
Paul Michaels
Paul Michaels

Reputation: 16705

Starting a XAML animation in WPF

I'm using this as a basis to make an animation start using code behind. Based on the contents of the article, I have the following:

<Window.Resources>
    <Storyboard x:Key="sbdLabelRotation">
        <DoubleAnimation
          Storyboard.TargetName="lblHello"
          Storyboard.TargetProperty="(TextBlock.RenderTransform).(RotateTransform.Angle)"
          From="0"
          To="360"
          Duration="0:0:0.5"
          RepeatBehavior="4x" />
    </Storyboard>

</Window.Resources>

I have the following XAML (obviously):

    <Label x:Name="lblHello" Content="test" Margin="20"/>

And the code behind:

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();            
    }

    public void AnimateLabelRotation()
    {
        Storyboard sbdLabelRotation = (Storyboard)FindResource("sbdLabelRotation");

        sbdLabelRotation.Begin(this);
    }

Which I call from a button click event. The FindResource works and finds the storyboard, but nothing happens. I have managed to get the animation to work on an event trigger, but clearly I'm missing something for the code behind.

Upvotes: 2

Views: 6318

Answers (2)

outofdabox
outofdabox

Reputation: 3

There is a link to download the whole project http://www.galasoft.ch/mydotnet/articles/resources/article-2006102701/GalaSoftLb.Article2006102701.zip

You can study the code and see it running. Sometimes it's more helpful. Also in your code the part:

sbdLabelRotation.Begin(this);

could be wrong. As you know the this keyword references the class itself, in your case the MainWindow class. You should try without the this keyword.

Upvotes: 0

XAMeLi
XAMeLi

Reputation: 6289

This:

<Label x:Name="lblHello" Content="test" Margin="20"/>

and this:

Storyboard.TargetProperty="(TextBlock.RenderTransform).(RotateTransform.Angle)"

are not compatible.

When the animation tries to find the property to animate, it goes to (TextBlock.RenderTransform) and finds null since you didn't declare it (actually it doesn't since you say TextBlock but apply it to Label, more on that later in the answer). Thus it cannot find .(RotateTransform.Angle).

To remedy the issue:

<Label x:Name="lblHello"
        Content="test"
        Margin="20"
        RenderTransformOrigin="0.5,0.5">
    <Label.RenderTransform>
        <RotateTransform />
    </Label.RenderTransform>
</Label>

Notice RenderTransformOrigin setting - this means that the axis of rotation will be in the center of the object (X and Y).

Also, in the animation it should be:

Storyboard.TargetProperty="(Label.RenderTransform).(RotateTransform.Angle)"

Upvotes: 2

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