Add MouseTrackerAnnotationTextSpan for hovering support

lib/src/_code_field.dart

@@ -681,6 +681,19 @@ class _CodeFieldRender extends RenderBox implements MouseTrackerAnnotation {
     bool hitTarget = false;
     if (size.contains(position)) {
       result.add(BoxHitTestEntry(this, position));
+      final CodeLineRenderParagraph? paragraph = _findDisplayRenderParagraph(position + paintOffset);
+      final InlineSpan? span = paragraph?.getSpanForPosition(position - paragraph.offset + paintOffset);
+      if (span is MouseTrackerAnnotationTextSpan) {
+        result.add(HitTestEntry(_MouseTrackerAnnotationTextSpan(
+          id: paragraph!.index,
+          rects: paragraph.getRangeRects(paragraph.getRangeForSpan(span)).map((rect) {
+            return Rect.fromPoints(localToGlobal(rect.topLeft + paragraph.offset - paintOffset), localToGlobal(rect.bottomRight + paragraph.offset - paintOffset));
+          }).toList(),
+          span: span,
+        )));
+      } else if (span is HitTestTarget) {
+        result.add(HitTestEntry(span as HitTestTarget));
+      }
       if (_chunkIndicators.where((element) => element.region.contains(position)).isNotEmpty) {
         _cursor = SystemMouseCursors.click;
       } else {

lib/src/_code_highlight.dart

@@ -122,7 +122,7 @@ class _CodeHighlighter extends ValueNotifier<List<_HighlightResult>> {
     ], style);
   }
 
-  TextSpan _buildSpanFromNodes(List<_HighlightNode> nodes, TextStyle? baseStyle) {
+  TextSpan _buildSpanFromNodes(List<_HighlightNode> nodes, TextStyle baseStyle) {
     return TextSpan(
       children: nodes.map((e) => TextSpan(
           text: e.value,

lib/src/_code_paragraph.dart

@@ -6,6 +6,7 @@ class _ParagraphImpl extends IParagraph {
   static const int _zwjUtf16 = 0x200d;
 
   final String text;
+  final TextSpan span;
   final ui.Paragraph paragraph;
   final double _preferredLineHeight;
   final int _lineCount;
@@ -15,6 +16,7 @@ class _ParagraphImpl extends IParagraph {
 
   _ParagraphImpl({
     required this.text,
+    required this.span,
     required this.paragraph,
     required double preferredLineHeight,
   }) : _preferredLineHeight = preferredLineHeight,
@@ -51,7 +53,32 @@ class _ParagraphImpl extends IParagraph {
 
   @override
   TextPosition getPosition(Offset offset) {
-    return paragraph.getPositionForOffset(offset);
+    final TextPosition position = paragraph.getPositionForOffset(offset);
+    return position;
+  }
+
+  @override
+  InlineSpan? getSpanForPosition(TextPosition position) {
+    if (position.offset >= length - 1) {
+      return null;
+    }
+    return span.getSpanForPosition(position);
+  }
+
+  @override
+  TextRange getRangeForSpan(InlineSpan span) {
+    int offset = 0;
+    this.span.visitChildren((child) {
+      if (identical(child, span)) {
+        return false;
+      }
+      offset += child.length;
+      return true;
+    });
+    return TextRange(
+      start: offset,
+      end: offset + span.length
+    );
   }
 
   @override
@@ -225,6 +252,7 @@ class _CodeParagraphProvider {
     paragraph.layout(_constraints!);
     return _ParagraphImpl(
       text: span.toPlainText(),
+      span: span,
       paragraph: paragraph,
       preferredLineHeight: _preferredLineHeight!
     );

lib/src/_code_span.dart

@@ -0,0 +1,38 @@
+part of re_editor;
+
+@immutable
+class _MouseTrackerAnnotationTextSpan extends TextSpan {
+
+  final int id;
+  final MouseTrackerAnnotationTextSpan span;
+  final List<Rect> rects;
+
+  const _MouseTrackerAnnotationTextSpan({
+    required this.id,
+    required this.rects,
+    required this.span,
+  });
+
+  @override
+  PointerEnterEventListener? get onEnter => (event) {
+    span.onEnterWithRect(event, id, rects);
+  };
+
+  @override
+  PointerExitEventListener? get onExit => (event) {
+    span.onExitWithRect(event, id, rects);
+  };
+
+  @override
+  int get hashCode => span.hashCode;
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) {
+      return true;
+    }
+    return other is _MouseTrackerAnnotationTextSpan && span == other.span &&
+      id == other.id;
+  }
+
+}

lib/src/code_line.dart

@@ -1076,6 +1076,10 @@ class CodeLineRenderParagraph {
     range: paragraph.getWord(offset)
   );
 
+  InlineSpan? getSpanForPosition(Offset offset) => paragraph.getSpanForPosition(getPosition(offset));
+
+  TextRange getRangeForSpan(InlineSpan span) => paragraph.getRangeForSpan(span);
+
   Offset? getOffset(TextPosition position) => paragraph.getOffset(position);
 
   List<Rect> getRangeRects(TextRange range) => paragraph.getRangeRects(range);

lib/src/code_paragraph.dart

@@ -13,6 +13,10 @@ abstract class IParagraph {
   TextPosition getPosition(Offset offset);
 
   TextRange getWord(Offset offset);
+
+  InlineSpan? getSpanForPosition(TextPosition position);
+
+  TextRange getRangeForSpan(InlineSpan span);
 
   TextRange getLineBoundary(TextPosition position);
 

lib/src/code_span.dart

@@ -0,0 +1,26 @@
+part of re_editor;
+
+typedef PointerEnterEventWithRectListener = void Function(PointerEnterEvent event, int id, List<Rect> rects);
+
+typedef PointerExitEventWithRectListener = void Function(PointerExitEvent event, int id, List<Rect> rects);
+
+@immutable
+class MouseTrackerAnnotationTextSpan extends TextSpan {
+
+  final PointerEnterEventWithRectListener onEnterWithRect;
+  final PointerExitEventWithRectListener onExitWithRect;
+
+  const MouseTrackerAnnotationTextSpan({
+    super.text,
+    super.children,
+    super.style,
+    super.recognizer,
+    super.mouseCursor,
+    super.semanticsLabel,
+    super.locale,
+    super.spellOut,
+    required this.onEnterWithRect,
+    required this.onExitWithRect,
+  });
+
+}

lib/src/re_editor.dart

@@ -31,6 +31,7 @@ part '_code_paragraph.dart';
 part '_code_scroll.dart';
 part '_code_selection.dart';
 part '_code_shortcuts.dart';
+part '_code_span.dart';
 part '_isolate.dart';
 part 'code_autocomplete.dart';
 part 'code_chunk.dart';
@@ -43,6 +44,7 @@ part 'code_lines.dart';
 part 'code_paragraph.dart';
 part 'code_shortcuts.dart';
 part 'code_scroll.dart';
+part 'code_span.dart';
 part 'code_theme.dart';
 part 'code_toolbar.dart';
 part 'debug/_trace.dart';