102 lines
3.0 KiB
Dart
102 lines
3.0 KiB
Dart
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import 'package:flutter/material.dart';
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import 'package:flutter_math_fork/flutter_math.dart';
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import 'package:markdown/markdown.dart' as m;
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import 'package:markdown_widget/markdown_widget.dart';
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import '../../theme/theme_extensions.dart';
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const String _latexTag = 'latex';
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/// Provides LaTeX parsing support for markdown_widget.
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class ConduitLatex {
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const ConduitLatex();
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/// Returns the inline syntax used to identify LaTeX segments.
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m.InlineSyntax syntax() => _LatexSyntax();
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/// Returns the span generator that renders LaTeX expressions.
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SpanNodeGeneratorWithTag generator({required bool isDark}) {
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return SpanNodeGeneratorWithTag(
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tag: _latexTag,
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generator: (element, config, visitor) {
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return _LatexNode(
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attributes: element.attributes,
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rawText: element.textContent,
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config: config,
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isDark: isDark,
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);
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},
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);
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}
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}
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class _LatexSyntax extends m.InlineSyntax {
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_LatexSyntax() : super(r'(\$\$[\s\S]+?\$\$)|(\$[^\n]+?\$)');
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@override
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bool onMatch(m.InlineParser parser, Match match) {
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final raw = match.input.substring(match.start, match.end);
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final element = m.Element.text(_latexTag, raw);
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if (raw.startsWith(r'$$') && raw.endsWith(r'$$') && raw.length > 4) {
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element.attributes['content'] = raw.substring(2, raw.length - 2);
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element.attributes['isInline'] = 'false';
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} else if (raw.startsWith(r'$') && raw.endsWith(r'$') && raw.length > 2) {
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element.attributes['content'] = raw.substring(1, raw.length - 1);
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element.attributes['isInline'] = 'true';
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} else {
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element.attributes['content'] = raw;
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element.attributes['isInline'] = 'true';
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}
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parser.addNode(element);
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return true;
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}
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}
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class _LatexNode extends SpanNode {
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_LatexNode({
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required this.attributes,
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required this.rawText,
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required this.config,
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required this.isDark,
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});
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final Map<String, String> attributes;
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final String rawText;
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final MarkdownConfig config;
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final bool isDark;
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@override
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InlineSpan build() {
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final content = attributes['content']?.trim();
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final isInline = attributes['isInline'] == 'true';
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final baseStyle = (parentStyle ?? config.p.textStyle).copyWith(
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color:
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(parentStyle ?? config.p.textStyle).color ??
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(isDark ? Colors.white : Colors.black),
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);
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if (content == null || content.isEmpty) {
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return TextSpan(text: rawText, style: baseStyle);
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}
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final latexWidget = Math.tex(
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content,
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mathStyle: MathStyle.text,
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textStyle: baseStyle,
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textScaleFactor: 1,
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onErrorFallback: (error) {
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return Text(rawText, style: baseStyle.copyWith(color: Colors.red));
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},
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);
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final widget = isInline
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? latexWidget
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: Padding(
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padding: const EdgeInsets.symmetric(vertical: Spacing.xs),
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child: Center(child: latexWidget),
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);
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return WidgetSpan(alignment: PlaceholderAlignment.middle, child: widget);
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}
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}
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