WidgetSpan order in right-to-left text

WidgetSpan widgets in right-to-left (RTL) and mixed-direction text now follow the visual order determined by the Unicode bidirectional algorithm. Apps that compensated for the previous incorrect order might display inline widgets in the wrong positions after upgrading.

Skia's paragraph layout previously placed inline widget placeholders in source order, even when the surrounding text was visually reordered. This caused inline widgets in Arabic, Hebrew, and mixed-direction text to appear in the wrong positions.

Paragraph layout now places inline widget placeholders in bidirectional visual order. Your WidgetSpan children stay in logical reading order in your Dart code, and layout returns placeholder boxes with the corrected visual coordinates. No public API signatures changed.

The following example shows the corrected positions of inline widgets in mixed-direction text:

Before	After

If your app uses WidgetSpan widgets without compensating for the old layout, no code changes are needed. Otherwise, remove workarounds added specifically for this issue:

• Translating or swapping widgets on the same line using Transform.translate offsets or GlobalKey measurements.
• Reversing the source order of WidgetSpan widgets for RTL text. Keep spans in the logical order of the content and let text layout determine their visual positions.
• Mirroring placeholder-box x-coordinates in custom layout code. Use the returned coordinates directly.

For example, remove a translation that compensated for the old RTL order. Here, rtlSwapOffset is an offset calculated by the app's workaround, and inlineWidget is the widget embedded in the text.

Code before migration:

WidgetSpan(
  child: Transform.translate(
    offset: rtlSwapOffset,
    child: inlineWidget,
  ),
)

Code after migration:

WidgetSpan(child: inlineWidget)

Also remove the code that calculated the compensating offsets. Check RTL and mixed-direction text, including wrapped lines, and update golden tests that captured the incorrect layout.

Landed in version: 3.50.0-0.1.pre
In stable release: Not yet

GitHub issue:

• Issue 54400

Relevant PRs:

• Skia CL 1366676