✨ added latex support. fixes #31

lib/home.dart

@@ -9,6 +9,7 @@ import 'package:markdown_editor/device_preference_notifier.dart';
 import 'package:markdown_editor/l10n/generated/app_localizations.dart';
 import 'package:markdown_editor/widgets/MarkdownBody/custom_image_config.dart';
 import 'package:markdown_editor/widgets/MarkdownBody/custom_text_node.dart';
+import 'package:markdown_editor/widgets/MarkdownBody/latex_node.dart';
 import 'package:markdown_editor/widgets/MarkdownTextInput/markdown_text_input.dart';
 import 'package:markdown_widget/markdown_widget.dart';
 
@@ -228,6 +229,8 @@ class _HomeState extends State<Home> {
             child: MarkdownBlock(
               data: _inputText,
               generator: MarkdownGenerator(
+                generators: [latexGenerator],
+                inlineSyntaxList: [LatexSyntax()],
                 textGenerator: (node, config, visitor) =>
                     CustomTextNode(node.textContent, config, visitor),
                 richTextBuilder: Text.rich,

lib/widgets/MarkdownBody/latex_node.dart

@@ -0,0 +1,77 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_math_fork/flutter_math.dart';
+import 'package:markdown/markdown.dart' as m;
+import 'package:markdown_widget/markdown_widget.dart';
+
+SpanNodeGeneratorWithTag latexGenerator = SpanNodeGeneratorWithTag(
+  tag: _latexTag,
+  generator: (e, config, visitor) =>
+      LatexNode(e.attributes, e.textContent, config),
+);
+
+const _latexTag = 'latex';
+
+class LatexSyntax extends m.InlineSyntax {
+  LatexSyntax() : super(r'(\$\$[\s\S]+\$\$)|(\$.+?\$)');
+
+  @override
+  bool onMatch(m.InlineParser parser, Match match) {
+    final input = match.input;
+    final matchValue = input.substring(match.start, match.end);
+    String content = '';
+    bool isInline = true;
+    const blockSyntax = '\$\$';
+    const inlineSyntax = '\$';
+    if (matchValue.startsWith(blockSyntax) &&
+        matchValue.endsWith(blockSyntax) &&
+        (matchValue != blockSyntax)) {
+      content = matchValue.substring(2, matchValue.length - 2);
+      isInline = false;
+    } else if (matchValue.startsWith(inlineSyntax) &&
+        matchValue.endsWith(inlineSyntax) &&
+        matchValue != inlineSyntax) {
+      content = matchValue.substring(1, matchValue.length - 1);
+    }
+    final m.Element el = m.Element.text(_latexTag, matchValue);
+    el.attributes['content'] = content;
+    el.attributes['isInline'] = '$isInline';
+    parser.addNode(el);
+    return true;
+  }
+}
+
+class LatexNode extends SpanNode {
+  final Map<String, String> attributes;
+  final String textContent;
+  final MarkdownConfig config;
+
+  LatexNode(this.attributes, this.textContent, this.config);
+
+  @override
+  InlineSpan build() {
+    final content = attributes['content'] ?? '';
+    final isInline = attributes['isInline'] == 'true';
+    final style = parentStyle ?? config.p.textStyle;
+    if (content.isEmpty) return TextSpan(style: style, text: textContent);
+
+    final latex = Math.tex(
+      content,
+      mathStyle: MathStyle.text,
+      textStyle: style,
+      textScaleFactor: 1,
+      onErrorFallback: (error) {
+        return Text(textContent, style: style.copyWith(color: Colors.red));
+      },
+    );
+    return WidgetSpan(
+      alignment: PlaceholderAlignment.middle,
+      child: !isInline
+          ? Container(
+              width: double.infinity,
+              margin: const EdgeInsets.symmetric(vertical: 16),
+              child: Center(child: latex),
+            )
+          : latex,
+    );
+  }
+}

pubspec.lock

@@ -139,6 +139,14 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_math_fork:
+    dependency: "direct main"
+    description:
+      name: flutter_math_fork
+      sha256: "6d5f2f1aa57ae539ffb0a04bb39d2da67af74601d685a161aff7ce5bda5fa407"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.4"
   flutter_plugin_android_lifecycle:
     dependency: transitive
     description:
@@ -293,6 +301,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.16.0"
+  nested:
+    dependency: transitive
+    description:
+      name: nested
+      sha256: "03bac4c528c64c95c722ec99280375a6f2fc708eec17c7b3f07253b626cd2a20"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
   path:
     dependency: transitive
     description:
@@ -405,6 +421,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.8"
+  provider:
+    dependency: transitive
+    description:
+      name: provider
+      sha256: "4e82183fa20e5ca25703ead7e05de9e4cceed1fbd1eadc1ac3cb6f565a09f272"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.1.5+1"
   scroll_to_index:
     dependency: transitive
     description:
@@ -522,6 +546,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.7.6"
+  tuple:
+    dependency: transitive
+    description:
+      name: tuple
+      sha256: a97ce2013f240b2f3807bcbaf218765b6f301c3eff91092bcfa23a039e7dd151
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.2"
   typed_data:
     dependency: transitive
     description:

pubspec.yaml

@@ -16,6 +16,7 @@ dependencies:
     sdk: flutter
   flutter_localizations:
     sdk: flutter
+  flutter_math_fork: ^0.7.4
   flutter_svg: ^2.2.1
   flutter_widget_from_html_core: ^0.17.0
   html: ^0.15.6