feat: Support inline code blocks on markdown rich text (#3186)

Support inline code blocks on markdown rich text.

examples/lib/stories/rendering/rich_text_example.dart

@@ -58,14 +58,24 @@ class RichTextExample extends FlameGame {
           PlainTextNode('."'),
         ]),
       ]),
-      ParagraphNode.simple(
+      ParagraphNode.group([
+        PlainTextNode(
           'He pushed the thought under instantly. The fallacy was obvious. It '
           'presupposed that somewhere or other, outside oneself, there was a '
-        '"real" world where "real" things happened. But how could there be '
+          '"',
+        ),
+        CodeTextNode.simple('real'),
+        PlainTextNode(
+          '" world where "',
+        ),
+        CodeTextNode.simple('real'),
+        PlainTextNode(
+          '" things happened. But how could there be '
           'such a world? What knowledge have we of anything, save through our '
           'own minds? All happenings are in the mind. Whatever happens in all '
           'minds, truly happens.',
         ),
+      ]),
     ]);
 
     add(

packages/flame/lib/src/text/nodes/code_text_node.dart

@@ -0,0 +1,24 @@
+import 'package:flame/src/text/nodes/inline_text_node.dart';
+import 'package:flame/text.dart';
+
+class CodeTextNode extends InlineTextNode {
+  CodeTextNode(this.child);
+
+  CodeTextNode.simple(String text) : child = PlainTextNode(text);
+
+  CodeTextNode.group(List<InlineTextNode> children)
+      : child = GroupTextNode(children);
+
+  final InlineTextNode child;
+
+  static final defaultStyle = InlineTextStyle(fontFamily: 'monospace');
+
+  @override
+  void fillStyles(DocumentStyle stylesheet, InlineTextStyle parentTextStyle) {
+    style = FlameTextStyle.merge(parentTextStyle, stylesheet.codeText)!;
+    child.fillStyles(stylesheet, style);
+  }
+
+  @override
+  TextNodeLayoutBuilder get layoutBuilder => child.layoutBuilder;
+}

packages/flame/lib/src/text/styles/document_style.dart

@@ -20,6 +20,7 @@ class DocumentStyle extends FlameTextStyle {
     InlineTextStyle? text,
     InlineTextStyle? boldText,
     InlineTextStyle? italicText,
+    InlineTextStyle? codeText,
     BlockStyle? paragraph,
     BlockStyle? header1,
     BlockStyle? header2,
@@ -31,6 +32,7 @@ class DocumentStyle extends FlameTextStyle {
         _boldText = FlameTextStyle.merge(BoldTextNode.defaultStyle, boldText),
         _italicText =
             FlameTextStyle.merge(ItalicTextNode.defaultStyle, italicText),
+        _codeText = FlameTextStyle.merge(CodeTextNode.defaultStyle, codeText),
         _paragraph =
             FlameTextStyle.merge(ParagraphNode.defaultStyle, paragraph),
         _header1 = FlameTextStyle.merge(HeaderNode.defaultStyleH1, header1),
@@ -43,6 +45,7 @@ class DocumentStyle extends FlameTextStyle {
   final InlineTextStyle? _text;
   final InlineTextStyle? _boldText;
   final InlineTextStyle? _italicText;
+  final InlineTextStyle? _codeText;
   final BlockStyle? _paragraph;
   final BlockStyle? _header1;
   final BlockStyle? _header2;
@@ -94,6 +97,7 @@ class DocumentStyle extends FlameTextStyle {
   InlineTextStyle get text => _text!;
   InlineTextStyle get boldText => _boldText!;
   InlineTextStyle get italicText => _italicText!;
+  InlineTextStyle get codeText => _codeText!;
 
   /// Style for [ParagraphNode]s.
   BlockStyle get paragraph => _paragraph!;
@@ -117,6 +121,7 @@ class DocumentStyle extends FlameTextStyle {
       text: FlameTextStyle.merge(_text, other.text),
       boldText: FlameTextStyle.merge(_boldText, other.boldText),
       italicText: FlameTextStyle.merge(_italicText, other.italicText),
+      codeText: FlameTextStyle.merge(_codeText, other.codeText),
       background: merge(background, other.background) as BackgroundStyle?,
       paragraph: merge(paragraph, other.paragraph) as BlockStyle?,
       header1: merge(header1, other.header1) as BlockStyle?,

packages/flame/lib/text.dart

@@ -14,6 +14,7 @@ export 'src/text/elements/text_painter_text_element.dart'
     show TextPainterTextElement;
 export 'src/text/nodes/block_node.dart' show BlockNode;
 export 'src/text/nodes/bold_text_node.dart' show BoldTextNode;
+export 'src/text/nodes/code_text_node.dart' show CodeTextNode;
 export 'src/text/nodes/column_node.dart' show ColumnNode;
 export 'src/text/nodes/document_root.dart' show DocumentRoot;
 export 'src/text/nodes/group_text_node.dart' show GroupTextNode;

packages/flame_markdown/lib/flame_markdown.dart

@@ -55,6 +55,7 @@ class FlameMarkdown {
       'p' => ParagraphNode(child),
       'em' || 'i' => ItalicTextNode(child),
       'strong' || 'b' => BoldTextNode(child),
+      'code' => CodeTextNode(child),
       _ => throw Exception('Unknown element tag: ${element.tag}'),
     } as TextNode;
   }

packages/flame_markdown/test/flame_markdown_test.dart

@@ -29,6 +29,19 @@ void main() {
       ]);
     });
 
+    test('inline code block', () {
+      final doc = FlameMarkdown.toDocument('Flame: `var game = FlameGame();`');
+
+      _expectDocument(doc, [
+        (node) => _expectParagraph(node, (p) {
+              _expectGroup(p, [
+                (node) => _expectPlain(node, 'Flame: '),
+                (node) => _expectCode(node, 'var game = FlameGame();'),
+              ]);
+            }),
+      ]);
+    });
+
     test('all header levels', () {
       final doc = FlameMarkdown.toDocument(
         '# h1\n'
@@ -107,6 +120,13 @@ void _expectPlain(InlineTextNode node, String text) {
   expect(span.text, text);
 }
 
+void _expectCode(InlineTextNode node, String text) {
+  expect(node, isA<CodeTextNode>());
+  final content = (node as CodeTextNode).child;
+  expect(content, isA<PlainTextNode>());
+  expect((content as PlainTextNode).text, text);
+}
+
 void _expectParagraph(
   BlockNode node,
   void Function(InlineTextNode) expectChild,