smart_latex

Robust LaTeX rendering for Flutter. Renders mixed text and math, repairs malformed input, and works cleanly inside custom-font and right-to-left layouts.

Features

  • Renders inline ($...$, \(...\)) and display ($$...$$, \[...\]) math.
  • Repairs malformed LaTeX automatically:
    Input problem Fix applied
    \\right) (double backslash) \\command → \command
    \sqt{x} typo → \sqrt{x}
    Persian / Arabic digits ۱٫۵ → 1.5
    \text{0}\text{.}\text{5} → 0.5
    Unmatched { or } balanced automatically
  • RTL-safe: keeps KaTeX metrics isolated from the surrounding font/line-height so math renders correctly inside Persian/Arabic text and doesn't trigger flutter_math_fork layout assertions.
  • hideTrailingIncompleteMath flag for streaming / typewriter animations.
  • Selectable text, custom error builders, text scaling, and per-rule sanitizer options.

Installation

dependencies:
  smart_latex: ^1.0.0

Usage

import 'package:smart_latex/smart_latex.dart';

// Inline math mixed with text
SmartLatexText(r'The answer is $\frac{1}{2}$.')

// RTL text with a formula
SmartLatexText(
  r'قضیه فیثاغورس: $a^2 + b^2 = c^2$',
  textDirection: TextDirection.rtl,
  style: const TextStyle(fontSize: 16, height: 1.8),
)

// A single expression
SmartMath(r'e^{i\pi} + 1 = 0', display: true)

// Streaming / animated text — hides an unclosed formula while it is typed
SmartLatexText(currentStreamedText, hideTrailingIncompleteMath: true)

Sanitize without rendering

final clean = sanitizeLatex(r'\frac{{\text{0}\text{٫}\overline{\text{3}}}}{{1}}');
// → r'\frac{{0.\overline{3}}}{{1}}'

Pick which rules run:

sanitizeLatex(
  source,
  options: const LatexSanitizeOptions(
    normalizeDigits: false, // keep Persian digits
  ),
);

Configuration

SmartLatexText parameters:

Parameter Default Description
style null Base text style (merged over DefaultTextStyle).
textDirection ltr Text direction of the surrounding text.
textAlign start Alignment of the text.
selectable false Make plain-text runs selectable.
sanitize true Run sanitizeLatex on each math segment.
sanitizeOptions all on Which sanitizer rules to apply.
hideTrailingIncompleteMath false Hide an unclosed trailing $.
scrollDisplayMath true Horizontally scroll wide block equations.
errorBuilder null Custom widget when a formula fails to render.
textScaler inherited Scale factor for both text and math.

Using with gpt_markdown

smart_latex pairs well with full Markdown renderers. Provide a latexBuilder that forwards only fontSize/color to the math renderer and sanitize the input first:

import 'package:flutter_math_fork/flutter_math.dart';
import 'package:gpt_markdown/gpt_markdown.dart';
import 'package:smart_latex/smart_latex.dart';

GptMarkdown(
  source,
  useDollarSignsForLatex: true,
  latexWorkaround: sanitizeLatex,
  latexBuilder: (ctx, tex, style, inline) => Math.tex(
    sanitizeLatex(tex),
    mathStyle: inline ? MathStyle.text : MathStyle.display,
    textStyle: TextStyle(fontSize: style.fontSize, color: style.color),
    onErrorFallback: (_) => Text(tex, style: style),
  ),
)

Note on flutter_math_fork

flutter_math_fork can throw a layout assertion (RenderResetDimension does not meet its constraints) for some complex formulas. smart_latex minimises this by never forwarding the font family or line height to the renderer. If you still hit it with a specific expression, the root cause is in flutter_math_fork's layout code constraining child sizes; see its issue tracker.

License

MIT

Libraries

smart_latex
Robust LaTeX rendering for Flutter.