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Integrating in Uno

The common integration pattern is:

1. Prepare content when the text or font changes.
2. Reuse the prepared object during measure or arrange.
3. Recompute only the line walk when available width changes.

Typical spots to call it

• Custom panels
• MeasureOverride
• Drawing code for chips, bubbles, and cards
• Responsive layouts that need minimum width or exact line counts

Example pattern

private PreparedTextWithSegments? _prepared;

void UpdateText(string text, string font)
{
    _prepared = PretextLayout.PrepareWithSegments(text, font);
}

Size MeasureBubble(double maxWidth, double lineHeight, Thickness padding)
{
    if (_prepared is null)
    {
        return Size.Empty;
    }

    var layout = PretextLayout.Layout(_prepared, maxWidth, lineHeight);
    return new Size(maxWidth + padding.Left + padding.Right, layout.Height + padding.Top + padding.Bottom);
}

Companion helpers

The Pretext.Uno package in this repository adds reusable helpers around the core engine:

• StretchScrollHost for page-like scrollable samples and viewport calculations
• UiRenderScheduler for coalesced redraw scheduling on DispatcherQueue
• PreparedTextMetrics for wrap metrics and tight-width calculations
• ColumnFlowLayout and ObstacleLayoutHelper for flowing lines into constrained regions

Use them when they match your layout model, but keep the core Pretext API as the main dependency.

Uno-specific advice

• Prepare text in view-model or control state, not inside every render callback.
• Reuse prepared text across SizeChanged or MeasureOverride passes.
• Keep line height in your Uno typography system rather than encoding it into the font string.
• Use Layout in measurement passes and LayoutWithLines or LayoutNextLine only when rendering needs richer output.

Further reading

For broader Uno renderer context, see How Uno Platform Works.