CODEWITHSUNDEEP
c#wpfxaml
yaho cho
yaho cho

Reputation: 1779

WPF's Storyboard Name in behind code can not be accessed

I want to make blinking TextBlock's Text. But, Storyboard is not accessed. Please review code as below:

XAML

<Page.Resources>
    <Storyboard x:Name="BlinkLabelStoryBoard" x:Key="BlinkLabel" Duration="0:0:2" RepeatBehavior="Forever">
        <ColorAnimationUsingKeyFrames
                                Storyboard.TargetName="DeviceState"
                                Storyboard.TargetProperty="Foreground.(SolidColorBrush.Color)">
            <DiscreteColorKeyFrame KeyTime="0:0:0" Value="White"/>
            <DiscreteColorKeyFrame KeyTime="0:0:1" Value="OrangeRed"/>
        </ColorAnimationUsingKeyFrames>
    </Storyboard>
</Page.Resources>

<TextBlock x:Name="DeviceState" Text="{Binding RunMode}" FontWeight="Bold" FontSize="16" HorizontalAlignment="Center" Loaded="Start_Animation">

Behind Code

private void Start_Animation(object sender, RoutedEventArgs e)
{
    Storyboard board = (FindResource("BlinkLabelStoryBoard") as Storyboard);
    board.Begin();
}

But, An error happens BlinkLabelStoryBoard resource not found. And, Another error happens DeviceState resource not found.

Upvotes: 0

Views: 256

Answers (2)

yaho cho
yaho cho

Reputation: 1779

There was some mistakes in my code.

  1. (Thanks for Emo de Weerd) FindResource was not able to find BlinkLabelStoryBoard because FindResource expects a Key not a Name. So, I changed a code in Start_Animation handler and Deleted a Storyboard's Name in Xaml.

    Storyboard board = (FindResource("BlinkLabel") as Storyboard);

  2. Storyboard.TargetName was not able to find the name of Target TextBlock. So, I changed Storyboard.TargetName to {Binding ElementName=DeviceState}.

  3. board.Begin required a target element. So, I changed a related code to board.Begin(sender as TextBlock)

Finally, Please refer full code as below:

XAML

<Page.Resources>
    <Storyboard x:Key="BlinkLabel" Duration="0:0:2" RepeatBehavior="Forever">
       <ColorAnimationUsingKeyFrames
                                Storyboard.TargetName="{Binding ElementName=DeviceState}"
                                Storyboard.TargetProperty="(TextBlock.Foreground).(SolidColorBrush.Color)">
            <DiscreteColorKeyFrame KeyTime="0:0:0" Value="White"/>
            <DiscreteColorKeyFrame KeyTime="0:0:1" Value="OrangeRed"/>
        </ColorAnimationUsingKeyFrames>
    </Storyboard>
</Page.Resources>

...

<TextBlock x:Name="DeviceState" Text="{Binding RunMode}" FontWeight="Bold" FontSize="16" HorizontalAlignment="Center" Loaded="Start_Animation">

Behind Code

private void Start_Animation(object sender, RoutedEventArgs e)
{
    Storyboard board = (FindResource("BlinkLabel") as Storyboard);
    board.Begin(sender as TextBlock);
}

Upvotes: 0

Emond
Emond

Reputation: 50672

FindResource expects a Key not a Name.

XAML

<Page.Resources>
    <Storyboard x:Key="BlinkLabel" Duration="0:0:2" RepeatBehavior="Forever">
        <ColorAnimationUsingKeyFrames

C#

private void Start_Animation(object sender, RoutedEventArgs e)
{
    Storyboard board = (FindResource("BlinkLabel") as Storyboard);

A Name turns into an identifier in the C# code. A Key is an index in a dictionary, a ResourceDictionary in this case.

See https://learn.microsoft.com/en-us/dotnet/api/system.windows.frameworkelement.findresource?view=netframework-4.8

Upvotes: 1

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