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c#uwpricheditbox

Paragraph mark of UWP RichEditBox is not resized

With this code (Editor.Document.Selection.CharacterFormat.Size = 20;) I change the font size of a UWP RichEditBox in the Page_Loaded-handle. When I start typing some characters, everything works fine. But when I select the paragraph mark and then type something, this text appears in the wrong font size (10.5).

What I've tried is to expand the selection before setting the font size, but it seems that there is no paragraph mark when there's no text. But when the rich edit box is empty and I press Shift+Right Arrow ⟶ (as I would normally select the paragraph mark), the font size is set back to 10.5.

Is there any workaround to prevent that the font size is set back to 10.5 in any case?

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <TextBlock x:Name="FontSizeBlock" Grid.Row="0"></TextBlock>
    <RichEditBox x:Name="Editor" Grid.Row="1" SelectionChanged="HandleRichEditBox_SelectionChanged"></RichEditBox>
</Grid>


public sealed partial class MainPage : Page {
    public MainPage() {
        this.InitializeComponent();
        this.Loaded += Page_Loaded;
    }

    private void Page_Loaded(object sender, RoutedEventArgs e) {
        Editor.Document.Selection.SetRange(0, 1);
        Editor.Document.Selection.CharacterFormat.Size = 20;
    }

    private void HandleRichEditBox_SelectionChanged(object sender, RoutedEventArgs e) {
        FontSizeBlock.Text = "FontSize: " + Editor.Document.Selection.CharacterFormat.Size;
    }
}

enter image description here

Solution

  • When further investigating my problem, I noted that my issue doesn't occur when there has already been some text in the RichEditBox which was deleted.

    Therefore, I have tried to programmatically append, select and remove characters in the Page_Loaded-handle, and this approach worked for me. 

    private void Page_Loaded(object sender, RoutedEventArgs e) {
    // set any character
    Editor.Document.SetText(Windows.UI.Text.TextSetOptions.None, "a");
    Editor.Document.Selection.Expand(Windows.UI.Text.TextRangeUnit.Paragraph);
    Editor.Document.Selection.CharacterFormat.Size = 20;
    Editor.Document.SetText(Windows.UI.Text.TextSetOptions.None, "");

}