feat: implement TeX plugin

frontend/app_flowy/packages/appflowy_editor/example/assets/example.json

@@ -9,6 +9,12 @@
           "align": "center"
         }
       },
+      {
+        "type": "tex",
+        "attributes": {
+          "tex": "x = 2"
+        }
+      },
       {
         "type": "text",
         "attributes": { "subtype": "heading", "heading": "h1" },

frontend/app_flowy/packages/appflowy_editor/example/lib/main.dart

@@ -2,6 +2,7 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:example/plugin/code_block_node_widget.dart';
+import 'package:example/plugin/tex_block_node_widget.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
@@ -119,6 +120,7 @@ class _MyHomePageState extends State<MyHomePage> {
               editable: true,
               customBuilders: {
                 'text/code_block': CodeBlockNodeWidgetBuilder(),
+                'tex': TeXBlockNodeWidgetBuidler(),
               },
               shortcutEvents: [
                 enterInCodeBlock,
@@ -126,7 +128,8 @@ class _MyHomePageState extends State<MyHomePage> {
                 underscoreToItalic,
               ],
               selectionMenuItems: [
-                codeBlockItem,
+                codeBlockMenuItem,
+                teXBlockMenuItem,
               ],
             ),
           );

frontend/app_flowy/packages/appflowy_editor/example/lib/plugin/code_block_node_widget.dart

@@ -44,7 +44,7 @@ ShortcutEventHandler _ignorekHandler = (editorState, event) {
   return KeyEventResult.ignored;
 };
 
-SelectionMenuItem codeBlockItem = SelectionMenuItem(
+SelectionMenuItem codeBlockMenuItem = SelectionMenuItem(
   name: 'Code Block',
   icon: const Icon(Icons.abc),
   keywords: ['code block'],

frontend/app_flowy/packages/appflowy_editor/example/lib/plugin/tex_block_node_widget.dart

@@ -0,0 +1,189 @@
+import 'dart:collection';
+
+import 'package:appflowy_editor/appflowy_editor.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_math_fork/flutter_math.dart';
+
+SelectionMenuItem teXBlockMenuItem = SelectionMenuItem(
+  name: 'Tex',
+  icon: const Icon(Icons.text_fields_rounded),
+  keywords: ['tex, latex, katex'],
+  handler: (editorState, _, __) {
+    final selection =
+        editorState.service.selectionService.currentSelection.value;
+    final textNodes = editorState.service.selectionService.currentSelectedNodes
+        .whereType<TextNode>();
+    if (selection == null || !selection.isCollapsed || textNodes.isEmpty) {
+      return;
+    }
+    final Path texNodePath;
+    if (textNodes.first.toRawString().isEmpty) {
+      texNodePath = selection.end.path;
+      TransactionBuilder(editorState)
+        ..insertNode(
+          selection.end.path,
+          Node(
+            type: 'tex',
+            children: LinkedList(),
+            attributes: {'tex': ''},
+          ),
+        )
+        ..deleteNode(textNodes.first)
+        ..afterSelection = selection
+        ..commit();
+    } else {
+      texNodePath = selection.end.path.next;
+      TransactionBuilder(editorState)
+        ..insertNode(
+          selection.end.path.next,
+          Node(
+            type: 'tex',
+            children: LinkedList(),
+            attributes: {'tex': ''},
+          ),
+        )
+        ..afterSelection = selection
+        ..commit();
+    }
+    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
+      final texState =
+          editorState.document.nodeAtPath(texNodePath)?.key?.currentState;
+      if (texState != null && texState is __TeXBlockNodeWidgetState) {
+        texState.showEditingDialog();
+      }
+    });
+  },
+);
+
+class TeXBlockNodeWidgetBuidler extends NodeWidgetBuilder<Node> {
+  @override
+  Widget build(NodeWidgetContext<Node> context) {
+    return _TeXBlockNodeWidget(
+      key: context.node.key,
+      node: context.node,
+      editorState: context.editorState,
+    );
+  }
+
+  @override
+  NodeValidator<Node> get nodeValidator => (node) {
+        return node.attributes['tex'] is String;
+      };
+}
+
+class _TeXBlockNodeWidget extends StatefulWidget {
+  const _TeXBlockNodeWidget({
+    Key? key,
+    required this.node,
+    required this.editorState,
+  }) : super(key: key);
+
+  final Node node;
+  final EditorState editorState;
+
+  @override
+  State<_TeXBlockNodeWidget> createState() => __TeXBlockNodeWidgetState();
+}
+
+class __TeXBlockNodeWidgetState extends State<_TeXBlockNodeWidget> {
+  String get _tex => widget.node.attributes['tex'] as String;
+  bool _isHover = false;
+
+  @override
+  Widget build(BuildContext context) {
+    return InkWell(
+      onHover: (value) {
+        setState(() {
+          _isHover = value;
+        });
+      },
+      onTap: () {
+        showEditingDialog();
+      },
+      child: Stack(
+        children: [
+          _buildTex(context),
+          if (_isHover) _buildDeleteButton(context),
+        ],
+      ),
+    );
+  }
+
+  Widget _buildTex(BuildContext context) {
+    return Container(
+      width: MediaQuery.of(context).size.width,
+      padding: const EdgeInsets.symmetric(vertical: 20),
+      decoration: BoxDecoration(
+        borderRadius: const BorderRadius.all(Radius.circular(8.0)),
+        color: _isHover ? Colors.grey[200] : Colors.transparent,
+      ),
+      child: Center(
+        child: Math.tex(
+          _tex,
+          textStyle: const TextStyle(fontSize: 20),
+          mathStyle: MathStyle.display,
+        ),
+      ),
+    );
+  }
+
+  Widget _buildDeleteButton(BuildContext context) {
+    return Positioned(
+      top: -5,
+      right: -5,
+      child: IconButton(
+        icon: Icon(
+          Icons.delete_outline,
+          color: Colors.blue[400],
+          size: 16,
+        ),
+        onPressed: () {
+          TransactionBuilder(widget.editorState)
+            ..deleteNode(widget.node)
+            ..commit();
+        },
+      ),
+    );
+  }
+
+  void showEditingDialog() {
+    showDialog(
+      context: context,
+      builder: (context) {
+        final controller = TextEditingController(text: _tex);
+        return AlertDialog(
+          title: const Text('Edit Katex'),
+          content: TextField(
+            controller: controller,
+            maxLines: null,
+            decoration: const InputDecoration(
+              border: OutlineInputBorder(),
+            ),
+          ),
+          actions: [
+            TextButton(
+              onPressed: () {
+                Navigator.of(context).pop();
+              },
+              child: const Text('Cancel'),
+            ),
+            TextButton(
+              onPressed: () {
+                Navigator.of(context).pop();
+                if (controller.text != _tex) {
+                  TransactionBuilder(widget.editorState)
+                    ..updateNode(
+                      widget.node,
+                      {'tex': controller.text},
+                    )
+                    ..commit();
+                }
+              },
+              child: const Text('OK'),
+            ),
+          ],
+        );
+      },
+    );
+  }
+}

frontend/app_flowy/packages/appflowy_editor/example/pubspec.yaml

@@ -44,6 +44,7 @@ dependencies:
   file_picker: ^5.0.1
   universal_html: ^2.0.8
   highlight: ^0.7.0
+  flutter_math_fork: ^0.6.3+1
 
 dev_dependencies:
   flutter_test: