[web] Some cleanup for text tests

lib/web_ui/lib/src/engine/engine_canvas.dart

@@ -264,7 +264,7 @@ DomElement drawParagraphElement(
 }) {
   assert(paragraph.isLaidOut);
 
-  final DomHTMLElement paragraphElement = paragraph.toDomElement();
+  final DomElement paragraphElement = paragraph.toDomElement();
 
   if (transform != null) {
     setElementTransform(

lib/web_ui/lib/src/engine/html/recording_canvas.dart

@@ -1246,7 +1246,7 @@ class PaintDrawParagraph extends DrawCommand {
   @override
   String toString() {
     if (assertionsEnabled) {
-      return 'DrawParagraph(${paragraph.toPlainText()}, $offset)';
+      return 'DrawParagraph(${paragraph.plainText}, $offset)';
     } else {
       return super.toString();
     }

lib/web_ui/lib/src/engine/text/canvas_paragraph.dart

@@ -17,7 +17,7 @@ import 'word_breaker.dart';
 
 const ui.Color _defaultTextColor = ui.Color(0xFFFF0000);
 
-final String _placeholderChar = String.fromCharCode(0xFFFC);
+final String placeholderChar = String.fromCharCode(0xFFFC);
 
 /// A paragraph made up of a flat list of text spans and placeholders.
 ///
@@ -33,7 +33,6 @@ class CanvasParagraph implements ui.Paragraph {
     this.spans, {
     required this.paragraphStyle,
     required this.plainText,
-    required this.placeholderCount,
     required this.canDrawOnCanvas,
   }) : assert(spans.isNotEmpty);
 
@@ -46,9 +45,6 @@ class CanvasParagraph implements ui.Paragraph {
   /// The full textual content of the paragraph.
   late String plainText;
 
-  /// The number of placeholders in this paragraph.
-  final int placeholderCount;
-
   /// Whether this paragraph can be drawn on a bitmap canvas.
   ///
   /// Some text features cannot be rendered into a 2D canvas and must use HTML,
@@ -87,8 +83,6 @@ class CanvasParagraph implements ui.Paragraph {
   /// Whether this paragraph has been laid out or not.
   bool isLaidOut = false;
 
-  bool get isRtl => paragraphStyle.effectiveTextDirection == ui.TextDirection.rtl;
-
   ui.ParagraphConstraints? _lastUsedConstraints;
 
   late final TextLayoutService _layoutService = TextLayoutService(this);
@@ -138,27 +132,23 @@ class CanvasParagraph implements ui.Paragraph {
     _paintService.paint(canvas, offset);
   }
 
-  /// Generates a flat string computed from all the spans of the paragraph.
-  String toPlainText() => plainText;
-
-  DomHTMLElement? _cachedDomElement;
+  DomElement? _cachedDomElement;
 
   /// Returns a DOM element that represents the entire paragraph and its
   /// children.
   ///
   /// Generates a new DOM element on every invocation.
-  DomHTMLElement toDomElement() {
+  DomElement toDomElement() {
     assert(isLaidOut);
-    final DomHTMLElement? domElement = _cachedDomElement;
+    final DomElement? domElement = _cachedDomElement;
     if (domElement == null) {
       return _cachedDomElement ??= _createDomElement();
     }
-    return domElement.cloneNode(true) as DomHTMLElement;
+    return domElement.cloneNode(true) as DomElement;
   }
 
-  DomHTMLElement _createDomElement() {
-    final DomHTMLElement rootElement =
-        domDocument.createElement('flt-paragraph') as DomHTMLElement;
+  DomElement _createDomElement() {
+    final DomElement rootElement = domDocument.createElement('flt-paragraph');
 
     // 1. Set paragraph-level styles.
 
@@ -183,12 +173,8 @@ class CanvasParagraph implements ui.Paragraph {
           continue;
         }
 
-        final DomHTMLElement spanElement = domDocument.createElement('flt-span') as DomHTMLElement;
-        applyTextStyleToElement(
-          element: spanElement,
-          style: fragment.style,
-          isSpan: true,
-        );
+        final DomElement spanElement = domDocument.createElement('flt-span');
+        applyTextStyleToElement(element: spanElement, style: fragment.style);
         _positionSpanElement(spanElement, line, fragment);
 
         spanElement.appendText(text);
@@ -221,7 +207,6 @@ class CanvasParagraph implements ui.Paragraph {
 
   @override
   ui.TextRange getWordBoundary(ui.TextPosition position) {
-    final String text = toPlainText();
     final int characterPosition;
     switch (position.affinity) {
       case ui.TextAffinity.upstream:
@@ -231,8 +216,8 @@ class CanvasParagraph implements ui.Paragraph {
         characterPosition = position.offset;
         break;
     }
-    final int start = WordBreaker.prevBreakIndex(text, characterPosition + 1);
-    final int end = WordBreaker.nextBreakIndex(text, characterPosition);
+    final int start = WordBreaker.prevBreakIndex(plainText, characterPosition + 1);
+    final int end = WordBreaker.nextBreakIndex(plainText, characterPosition);
     return ui.TextRange(start: start, end: end);
   }
 
@@ -288,51 +273,30 @@ void _positionSpanElement(DomElement element, ParagraphLine line, LayoutFragment
     ..lineHeight = '${boxRect.height}px';
 }
 
-/// A common interface for all types of spans that make up a paragraph.
-///
-/// These spans are stored as a flat list in the paragraph object.
-abstract class ParagraphSpan {
-  /// The index of the beginning of the range of text represented by this span.
-  int get start;
-
-  /// The index of the end of the range of text represented by this span.
-  int get end;
-
-  /// The resolved style of the span.
-  EngineTextStyle get style;
-}
-
-/// Represent a span of text in the paragraph.
-///
-/// It's a "flat" text span as opposed to the framework text spans that are
-/// hierarchical.
+/// Represents a span in the paragraph.
 ///
 /// Instead of keeping spans and styles in a tree hierarchy like the framework
 /// does, we flatten the structure and resolve/merge all the styles from parent
 /// nodes.
-class FlatTextSpan implements ParagraphSpan {
-  /// Creates a [FlatTextSpan] with the given [style], representing the span of
+///
+/// These spans are stored as a flat list in the paragraph object.
+class ParagraphSpan {
+  /// Creates a [ParagraphSpan] with the given [style], representing the span of
   /// text in the range between [start] and [end].
-  FlatTextSpan({
+  ParagraphSpan({
     required this.style,
     required this.start,
     required this.end,
   });
 
-  @override
+  /// The resolved style of the span.
   final EngineTextStyle style;
 
-  @override
+  /// The index of the beginning of the range of text represented by this span.
   final int start;
 
-  @override
+  /// The index of the end of the range of text represented by this span.
   final int end;
-
-  String textOf(CanvasParagraph paragraph) {
-    final String text = paragraph.toPlainText();
-    assert(end <= text.length);
-    return text.substring(start, end);
-  }
 }
 
 class PlaceholderSpan extends ParagraphPlaceholder implements ParagraphSpan {
@@ -622,16 +586,13 @@ class CanvasParagraphBuilder implements ui.ParagraphBuilder {
     double? baselineOffset,
     ui.TextBaseline? baseline,
   }) {
-    // TODO(mdebbar): for measurement of placeholders, look at:
-    // - https://github.com/flutter/engine/blob/c0f7e8acf9318d264ad6a235facd097de597ffcc/third_party/txt/src/txt/paragraph_txt.cc#L325-L350
-
     // Require a baseline to be specified if using a baseline-based alignment.
     assert(!(alignment == ui.PlaceholderAlignment.aboveBaseline ||
             alignment == ui.PlaceholderAlignment.belowBaseline ||
             alignment == ui.PlaceholderAlignment.baseline) || baseline != null);
 
     final int start = _plainTextBuffer.length;
-    _plainTextBuffer.write(_placeholderChar);
+    _plainTextBuffer.write(placeholderChar);
     final int end = _plainTextBuffer.length;
 
     final EngineTextStyle style = _currentStyleNode.resolveStyle();
@@ -674,7 +635,7 @@ class CanvasParagraphBuilder implements ui.ParagraphBuilder {
     final EngineTextStyle style = _currentStyleNode.resolveStyle();
     _updateCanDrawOnCanvas(style);
 
-    _spans.add(FlatTextSpan(style: style, start: start, end: end));
+    _spans.add(ParagraphSpan(style: style, start: start, end: end));
   }
 
   void _updateCanDrawOnCanvas(EngineTextStyle style) {
@@ -708,18 +669,15 @@ class CanvasParagraphBuilder implements ui.ParagraphBuilder {
       //
       // We want the paragraph to always have a non-empty list of spans to match
       // the expectations of the [LayoutFragmenter].
-      _spans.add(FlatTextSpan(
-        style: _rootStyleNode.resolveStyle(),
-        start: 0,
-        end: 0,
-      ));
+      _spans.add(
+        ParagraphSpan(style: _rootStyleNode.resolveStyle(), start: 0, end: 0),
+      );
     }
 
     return CanvasParagraph(
       _spans,
       paragraphStyle: _paragraphStyle,
       plainText: _plainTextBuffer.toString(),
-      placeholderCount: _placeholderCount,
       canDrawOnCanvas: _canDrawOnCanvas,
     );
   }

lib/web_ui/lib/src/engine/text/layout_service.dart

@@ -360,7 +360,7 @@ class TextLayoutService {
       return <ui.TextBox>[];
     }
 
-    final int length = paragraph.toPlainText().length;
+    final int length = paragraph.plainText.length;
     // Ranges that are out of bounds should return an empty list.
     if (start > length || end > length) {
       return <ui.TextBox>[];
@@ -1046,10 +1046,9 @@ class Spanometer {
     assert(start >= currentSpan.start && start <= currentSpan.end);
     assert(end >= currentSpan.start && end <= currentSpan.end);
 
-    final String text = paragraph.toPlainText();
     return measureSubstring(
       context,
-      text,
+      paragraph.plainText,
       start,
       end,
       letterSpacing: letterSpacing,

lib/web_ui/lib/src/engine/text/paint_service.dart

@@ -36,15 +36,16 @@ class TextPaintService {
     ui.Offset offset,
     LayoutFragment fragment,
   ) {
-    final ParagraphSpan span = fragment.span;
-    if (span is FlatTextSpan) {
-      // Paint the background of the box, if the span has a background.
-      final SurfacePaint? background = span.style.background as SurfacePaint?;
-      if (background != null) {
-        final ui.Rect rect = fragment.toPaintingTextBox().toRect();
-        if (!rect.isEmpty) {
-          canvas.drawRect(rect.shift(offset), background.paintData);
-        }
+    if (fragment.isPlaceholder) {
+      return;
+    }
+
+    // Paint the background of the box, if the span has a background.
+    final SurfacePaint? background = fragment.style.background as SurfacePaint?;
+    if (background != null) {
+      final ui.Rect rect = fragment.toPaintingTextBox().toRect();
+      if (!rect.isEmpty) {
+        canvas.drawRect(rect.shift(offset), background.paintData);
       }
     }
   }

lib/web_ui/lib/src/engine/text/paragraph.dart

@@ -774,13 +774,9 @@ String fontWeightIndexToCss({int fontWeightIndex = 3}) {
 
 /// Applies a text [style] to an [element], translating the properties to their
 /// corresponding CSS equivalents.
-///
-/// If [isSpan] is true, the text element is a span within richtext and
-/// should not assign effectiveFontFamily if fontFamily was not specified.
 void applyTextStyleToElement({
-  required DomHTMLElement element,
+  required DomElement element,
   required EngineTextStyle style,
-  bool isSpan = false,
 }) {
   assert(element != null);
   assert(style != null);
@@ -822,10 +818,10 @@ void applyTextStyleToElement({
   }
   // For test environment use effectiveFontFamily since we need to
   // consistently use Ahem font.
-  if (isSpan && !ui.debugEmulateFlutterTesterEnvironment) {
-    cssStyle.fontFamily = canonicalizeFontFamily(style.fontFamily)!;
-  } else {
+  if (ui.debugEmulateFlutterTesterEnvironment) {
     cssStyle.fontFamily = canonicalizeFontFamily(style.effectiveFontFamily)!;
+  } else {
+    cssStyle.fontFamily = canonicalizeFontFamily(style.fontFamily)!;
   }
   if (style.letterSpacing != null) {
     cssStyle.letterSpacing = '${style.letterSpacing}px';

lib/web_ui/test/html/paragraph/bidi_golden_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:async';
-
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine.dart';
@@ -12,8 +10,6 @@ import 'package:ui/ui.dart' hide window;
 import '../screenshot.dart';
 import 'helper.dart';
 
-typedef CanvasTest = FutureOr<void> Function(EngineCanvas canvas);
-
 const String _rtlWord1 = 'واحد';
 const String _rtlWord2 = 'اثنان';
 

lib/web_ui/test/html/paragraph/general_golden_test.dart

@@ -13,8 +13,6 @@ import 'package:ui/ui.dart' hide window;
 import '../screenshot.dart';
 import 'helper.dart';
 
-typedef CanvasTest = FutureOr<void> Function(EngineCanvas canvas);
-
 const Rect bounds = Rect.fromLTWH(0, 0, 800, 600);
 
 void main() {

lib/web_ui/test/html/paragraph/helper.dart

@@ -2,10 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:ui/src/engine.dart';
 import 'package:ui/ui.dart';
 import 'package:web_engine_tester/golden_tester.dart';
 
+typedef CanvasTest = FutureOr<void> Function(EngineCanvas canvas);
+
 const LineBreakType prohibited = LineBreakType.prohibited;
 const LineBreakType opportunity = LineBreakType.opportunity;
 const LineBreakType mandatory = LineBreakType.mandatory;
@@ -32,6 +36,11 @@ const Color blue = Color(0xFF0000FF);
 const Color yellow = Color(0xFFFFEB3B);
 const Color lightPurple = Color(0xFFE1BEE7);
 
+final EngineParagraphStyle ahemStyle = EngineParagraphStyle(
+  fontFamily: 'ahem',
+  fontSize: 10,
+);
+
 ParagraphConstraints constrain(double width) {
   return ParagraphConstraints(width: width);
 }
@@ -73,10 +82,7 @@ Future<void> takeScreenshot(
   try {
     sceneElement.append(canvas.rootElement);
     domDocument.body!.append(sceneElement);
-    await matchGoldenFile(
-      '$fileName.png',
-      region: region,
-    );
+    await matchGoldenFile('$fileName.png', region: region);
   } finally {
     // The page is reused across tests, so remove the element after taking the
     // Scuba screenshot.
@@ -109,3 +115,7 @@ void fillBoxes(EngineCanvas canvas, Offset offset, List<TextBox> boxes, Color co
     canvas.drawRect(rect, SurfacePaintData()..color = color);
   }
 }
+
+String getSpanText(CanvasParagraph paragraph, ParagraphSpan span) {
+  return paragraph.plainText.substring(span.start, span.end);
+}

lib/web_ui/test/html/paragraph/overflow_golden_test.dart

@@ -12,8 +12,6 @@ import 'package:ui/ui.dart' hide window;
 import '../screenshot.dart';
 import 'helper.dart';
 
-typedef CanvasTest = FutureOr<void> Function(EngineCanvas canvas);
-
 void main() {
   internalBootstrapBrowserTest(() => testMain);
 }

lib/web_ui/test/html/paragraph/placeholders_golden_test.dart

@@ -12,8 +12,6 @@ import 'package:ui/ui.dart' hide window;
 import '../screenshot.dart';
 import 'helper.dart';
 
-typedef CanvasTest = FutureOr<void> Function(EngineCanvas canvas);
-
 const Rect bounds = Rect.fromLTWH(0, 0, 800, 600);
 
 void main() {