fix #107

lib/components/code.dart

@@ -0,0 +1,96 @@
+part of 'components.dart';
+
+class CodeEditor extends StatefulWidget {
+  const CodeEditor({super.key, this.initialValue, this.onChanged});
+
+  final String? initialValue;
+
+  final void Function(String value)? onChanged;
+
+  @override
+  State<CodeEditor> createState() => _CodeEditorState();
+}
+
+class _CodeEditorState extends State<CodeEditor> {
+  late TextEditingController _controller;
+  late FocusNode _focusNode;
+  var horizontalScrollController = ScrollController();
+  var verticalScrollController = ScrollController();
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = TextEditingController(text: widget.initialValue);
+    _focusNode = FocusNode()
+      ..onKeyEvent = (node, event) {
+        if (event.logicalKey == LogicalKeyboardKey.tab) {
+          if (event is KeyDownEvent) {
+            handleTab();
+          }
+          return KeyEventResult.handled;
+        }
+        return KeyEventResult.ignored;
+      };
+  }
+
+  void handleTab() {
+    var text = _controller.text;
+    var start = _controller.selection.start;
+    var end = _controller.selection.end;
+    _controller.text = '${text.substring(0, start)}    ${text.substring(end)}';
+    _controller.selection = TextSelection.collapsed(offset: start + 4);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scrollbar(
+      thumbVisibility: true,
+      controller: verticalScrollController,
+      notificationPredicate: (notif) => notif.metrics.axis == Axis.vertical,
+      child: Scrollbar(
+        thumbVisibility: true,
+        controller: horizontalScrollController,
+        notificationPredicate: (notif) => notif.metrics.axis == Axis.horizontal,
+        child: SizedBox.expand(
+          child: ScrollConfiguration(
+            behavior: _CustomScrollBehavior(),
+            child: SingleChildScrollView(
+              scrollDirection: Axis.horizontal,
+              controller: horizontalScrollController,
+              child: IntrinsicWidth(
+                stepWidth: 100,
+                child: TextField(
+                  style: TextStyle(
+                    fontFamily: 'consolas',
+                    fontFamilyFallback: ['Courier New', 'monospace'],
+                  ),
+                  controller: _controller,
+                  focusNode: _focusNode,
+                  maxLines: null,
+                  expands: true,
+                  decoration: InputDecoration(
+                    border: InputBorder.none,
+                    contentPadding: EdgeInsets.all(8),
+                  ),
+                  onChanged: (value) {
+                    widget.onChanged?.call(value);
+                  },
+                  scrollController: verticalScrollController,
+                ),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class _CustomScrollBehavior extends MaterialScrollBehavior {
+  const _CustomScrollBehavior();
+  @override
+  Widget buildScrollbar(
+      BuildContext context, Widget child, ScrollableDetails details) {
+    return child;
+  }
+}