动态更改以app.xaml中的样式指定的属性的值

Question

I am new to WPF . Recently i encountered an issue where i have to dynamically change the font size of a label.

To achieve this i created a test application and created a style with a key in my App.xaml .

Then gave this style to the label.

Style is as below:

<Style x:Key="myLbl" TargetType="Label">
    <Setter Property="FontSize" Value="20"/>
</Style>

Then I gave this Style to the Label in my Window XAML like :

<Label Name="lblDemo" Content="Test" Foreground="Black" Style="{DynamicResource myLbl}"/>

I want to change the value of the Property in the Style with the click of the button. I searched for it a little bit but havent found anything useful. Can anyone suggest me a right possible direction. Any help will be appreciated.

Thanks.

Answer 1

If you'd like to do this using XAML only, you could do it like so:

<StackPanel>
    <Label Name="lblDemo" Content="Test" Foreground="Black" FontSize="20"/>
    <Button x:Name="ClickMe" Content="Enlarge" />
    <StackPanel.Triggers>
        <EventTrigger RoutedEvent="Button.Click" SourceName="ClickMe">
            <EventTrigger.Actions>
                <BeginStoryboard>
                    <Storyboard>
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetName="lblDemo" Storyboard.TargetProperty="FontSize">
                            <DiscreteDoubleKeyFrame KeyTime="00:00:00.01" Value="48" />
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger.Actions>
        </EventTrigger>
    </StackPanel.Triggers>
</StackPanel>

OR you can use good old fashioned Click event handler in code behind with this code (using the Button above without StackPanel.Triggers section):

private void ClickMe_OnClick(object sender, RoutedEventArgs e) { lblDemo.FontSize = 48; }