How to set the gradient fill of text in WPF?

In WPF, you can utilize LinearGradientBrush or RadialGradientBrush to achieve gradient fill for text. Here is an example of using LinearGradientBrush to implement gradient fill for text.

<TextBlock FontSize="36" FontWeight="Bold">
    <TextBlock.Foreground>
        <LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
            <GradientStop Color="Red" Offset="0" />
            <GradientStop Color="Blue" Offset="1" />
        </LinearGradientBrush>
    </TextBlock.Foreground>
    Hello World!
</TextBlock>

In the example above, the Foreground property of the TextBlock element is set to a LinearGradientBrush that contains two GradientStops, one for red and one for blue, each with offsets of 0 and 1, respectively, creating a gradient effect from red to blue.

To achieve gradient fill for text using RadialGradientBrush, you can replace the LinearGradientBrush in the example above with RadialGradientBrush and adjust the necessary properties.

I hope this helps you!