disable text rounding hack by default

Author: LongCatIsLooong

lib/ui/text.dart

@@ -3026,11 +3026,14 @@ abstract class ParagraphBuilder {
   ///
   /// Do not rely on this getter as it exists for migration purposes only and
   /// will soon be removed.
+  @Deprecated('''
+    The shouldDisableRoundingHack flag is for internal migration purposes only and should not be used.
+  ''')
   static bool get shouldDisableRoundingHack {
-    return const bool.hasEnvironment('SKPARAGRAPH_REMOVE_ROUNDING_HACK')
+    return const bool.fromEnvironment('SKPARAGRAPH_REMOVE_ROUNDING_HACK', defaultValue: true)
         || _roundingHackDisabledInDebugMode;
   }
-  static bool _roundingHackDisabledInDebugMode = false;
+  static bool _roundingHackDisabledInDebugMode = true;
 
   /// Only works in debug mode. Do not call this method as it is for migration
   /// purposes only and will soon be removed.

lib/web_ui/test/canvaskit/text_test.dart

@@ -156,16 +156,16 @@ void testMain() {
       ui.ParagraphBuilder.setDisableRoundingHack(roundingHackWasDisabled);
     });
 
-    test('rounding hack applied by default', () {
+    test('rounding hack disabled by default', () {
       const double fontSize = 1.25;
       const String text = '12345';
       assert((fontSize * text.length).truncate() != fontSize * text.length);
-      expect(ui.ParagraphBuilder.shouldDisableRoundingHack, isFalse);
+      expect(ui.ParagraphBuilder.shouldDisableRoundingHack, isTrue);
       final ui.ParagraphBuilder builder = ui.ParagraphBuilder(ui.ParagraphStyle(fontSize: fontSize, fontFamily: 'FlutterTest'));
       builder.addText(text);
       final ui.Paragraph paragraph = builder.build()
         ..layout(const ui.ParagraphConstraints(width: text.length * fontSize));
-      expect(paragraph.computeLineMetrics().length, greaterThan(1));
+      expect(paragraph.computeLineMetrics().length, 1);
     });
 
     // TODO(hterkelsen): https://github.com/flutter/flutter/issues/71520

testing/dart/paragraph_test.dart

@@ -263,15 +263,15 @@ void main() {
     ParagraphBuilder.setDisableRoundingHack(roundingHackWasDisabled);
   });
 
-  test('rounding hack applied by default', () {
+  test('rounding hack disabled by default', () {
     const double fontSize = 1.25;
     const String text = '12345';
     assert((fontSize * text.length).truncate() != fontSize * text.length);
-    expect(ParagraphBuilder.shouldDisableRoundingHack, isFalse);
+    expect(ParagraphBuilder.shouldDisableRoundingHack, isTrue);
     final ParagraphBuilder builder = ParagraphBuilder(ParagraphStyle(fontSize: fontSize));
     builder.addText(text);
     final Paragraph paragraph = builder.build()
       ..layout(const ParagraphConstraints(width: text.length * fontSize));
-    expect(paragraph.computeLineMetrics().length, greaterThan(1));
+    expect(paragraph.computeLineMetrics().length, 1);
   });
 }