flutter 3.38 broke my app bc of LaTeX (733 errors per frame!)

bro. i almost cried.

opened my app on the "tips & tricks" topic and the terminal EXPLODED. like, 733 errors per frame. the app became unusable, freezing, everything broken. i thought it was a bug in my checklist (bc it had issues before), but nope.

the investigation (spoiler: it was LaTeX)

spent ages fixing the checklist (NoteChecklistContent). found real bugs there:

• IntrinsicWidth fighting with Flexible (constraint conflict)
• Checkbox with messed up sizing inside a Row
• mainAxisSize: MainAxisSize.min on a Row with Flexible children

fixed everything. swapped Checkbox for Icon + GestureDetector, Flexible → Expanded, etc. valid fixes, but they didnt solve the main problem. (一_一)

then i redirected flutter run output to a log file and finally saw the real cascade:

the root cause

the topic had a note with inline LaTeX: $E = mc^2$. GptMarkdown converts $...$ to \(...\) and sends it to flutter_math_fork to render via Math.tex().

turns out flutter_math_fork v0.7.4 uses a RenderLine class (custom RenderBox) that doesnt implement computeDryBaseline, a method that became mandatory in flutter 3.38.

and the worst part: theres no new version of either package (gpt_markdown 1.1.5 and flutter_math_fork 0.7.4). both are abandoned and incompatible with flutter 3.38. (ꐦ°᷄д°᷅)

the workaround (yeah its a hack)

since we cant use Math.tex() without crashing, i made a safe builder that renders LaTeX as styled text (monospace + italic) instead of a pretty formula:

static Widget safeLatexBuilder(
  BuildContext context,
  String tex,
  TextStyle textStyle,
  bool inline,
) {
  final theme = Theme.of(context);
  return Text(
    tex,
    style: textStyle.copyWith(
      fontFamily: 'monospace',
      fontStyle: FontStyle.italic,
      color: theme.colorScheme.onSurface.withValues(alpha: 0.85),
    ),
  );
}

also made my own preprocessing to convert $...$ → \(...\) outside of GptMarkdown, bc its internal regex was generating malformed UTF-16 strings:

static String _convertDollarLatex(String text) {
  var result = text.replaceAllMapped(
    RegExp(r'(?<!\\)\$\$(.*?)(?<!\\)\$\$', dotAll: true),
    (match) => '\\[${match[1] ?? ""}\\]',
  );
  if (!result.contains(r'\(')) {
    result = result.replaceAllMapped(
      RegExp(r'(?<!\\)\$(.*?)(?<!\\)\$'),
      (match) => '\\(${match[1] ?? ""}\\)',
    );
  }
  return result;
}

then called GptMarkdown with useDollarSignsForLatex: false (since conversion was done manually) and applied the safe latexBuilder in all places that use GptMarkdown directly:

• study_session_screen.dart (3 uses)
• edit_note_dialog.dart (1 use)
• flashcard_bubble_content.dart (1 use)

results

the trade-off is that LaTeX doesnt render as a pretty formula anymore (it shows E = mc^2 in monospace instead of the formatted one). but at least the app works. when the package maintainers wake up and release an update, ill revert everything.

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