Completely fill a TextBlock with repeating text

Question

I need to create a textblock that is completely filled with a repeating text.

The font size should change as well so approximately the same number of characters are displayed no matter the textblock size.

I have the following code:

<TextBlock
    Name="Watermark"
    Background="White"
    FontSize="14"
    Foreground="DarkGray"
    TextWrapping="WrapWithOverflow" />

And the related code-behind:

// Really bad function...
void GenerateWatermarks()
{
    if (string.IsNullOrWhiteSpace(watermarkString))
    {
        return;
    }
    var builder = new StringBuilder();
    for(int i = 0; i < 50; i++)
    {
        builder.Append(watermarkString);
    }

    Watermark.Text = builder.ToString();
}

Here is an example of what I would like to get :

The text is generated in large quantity to fit the whole textblock, but if a resize occurs, the text nor the font size evolve

Answer 1

try placing TextBlock into a Viewbox with Stretch set to Fill or UniformToFill

<Viewbox StretchDirection="Both" Stretch="Fill">
    <TextBlock
        Name="Watermark"
        Background="White"
        FontSize="14"
        Foreground="DarkGray"
        TextWrapping="WrapWithOverflow" 
        Width="480" Height="320"/>
</Viewbox>