Expose font fallback API in TextStyle, Roll engine 54a3577c0139..215ca1560088 (8 commits) (#25585)

bin/internal/engine.version

-54a3577c0139f659f5064d918057bc46b6cd0932
+215ca15600887ffeffef2df3f216e0189159150e

packages/flutter/lib/src/painting/text_style.dart

@@ -250,8 +250,11 @@ class TextStyle extends Diagnosticable {
     this.decorationStyle,
     this.debugLabel,
     String fontFamily,
+    List<String> fontFamilyFallback,
     String package,
   }) : fontFamily = package == null ? fontFamily : 'packages/$package/$fontFamily',
+       _fontFamilyFallback = fontFamilyFallback,
+       _package = package,
        assert(inherit != null),
        assert(color == null || foreground == null, _kColorForegroundWarning);
 
@@ -279,8 +282,43 @@ class TextStyle extends Diagnosticable {
   /// 'packages/package_name/' (e.g. 'packages/cool_fonts/Roboto'). The
   /// prefixing is done by the constructor when the `package` argument is
   /// provided.
+  ///
+  /// The value provided in [fontFamily] will act as the preferred/first font
+  /// family that glyphs are looked for in, followed in order by the font families
+  /// in [fontFamilyFallback]. When [fontFamily] is null or not provided, the
+  /// first value in [fontFamilyFallback] acts as the preferred/first font
+  /// family. When neither is provided, then the default platform font will
+  /// be used.
   final String fontFamily;
 
+  /// The ordered list of font families to fall back on when a glyph cannot be
+  /// found in a higher priority font family.
+  ///
+  /// The value provided in [fontFamily] will act as the preferred/first font
+  /// family that glyphs are looked for in, followed in order by the font families
+  /// in [fontFamilyFallback]. If all font families are exhausted and no match
+  /// was found, the default platform font family will be used instead.
+  ///
+  /// When [fontFamily] is null or not provided, the first value in [fontFamilyFallback]
+  /// acts as the preferred/first font family. When neither is provided, then
+  /// the default platform font will be used. Providing and empty list or null
+  /// for this property is the same as omitting it.
+  ///
+  /// For example, if a glyph is not found in [fontFamily], then each font family
+  /// in [fontFamilyFallback] will be searched in order until it is found. If it
+  /// is not found, then a box will be drawn in its place.
+  ///
+  /// If the font is defined in a package, each font family in the list will be
+  /// prefixed with 'packages/package_name/' (e.g. 'packages/cool_fonts/Roboto').
+  /// The package name should be provided by the `package` argument in the
+  /// constructor.
+  List<String> get fontFamilyFallback => _package != null && _fontFamilyFallback != null ? _fontFamilyFallback.map((String str) => 'packages/$_package/$str').toList() : _fontFamilyFallback;
+  final List<String> _fontFamilyFallback;
+
+  // This is stored in order to prefix the fontFamilies in _fontFamilyFallback
+  // in the [fontFamilyFallback] getter.
+  final String _package;
+
   /// The size of glyphs (in logical pixels) to use when painting the text.
   ///
   /// During painting, the [fontSize] is multiplied by the current
@@ -392,6 +430,7 @@ class TextStyle extends Diagnosticable {
   TextStyle copyWith({
     Color color,
     String fontFamily,
+    List<String> fontFamilyFallback,
     double fontSize,
     FontWeight fontWeight,
     FontStyle fontStyle,
@@ -419,6 +458,7 @@ class TextStyle extends Diagnosticable {
       inherit: inherit,
       color: this.foreground == null && foreground == null ? color ?? this.color : null,
       fontFamily: fontFamily ?? this.fontFamily,
+      fontFamilyFallback: fontFamilyFallback ?? this.fontFamilyFallback,
       fontSize: fontSize ?? this.fontSize,
       fontWeight: fontWeight ?? this.fontWeight,
       fontStyle: fontStyle ?? this.fontStyle,
@@ -469,6 +509,7 @@ class TextStyle extends Diagnosticable {
     Color decorationColor,
     TextDecorationStyle decorationStyle,
     String fontFamily,
+    List<String> fontFamilyFallback,
     double fontSizeFactor = 1.0,
     double fontSizeDelta = 0.0,
     int fontWeightDelta = 0,
@@ -505,6 +546,7 @@ class TextStyle extends Diagnosticable {
       inherit: inherit,
       color: foreground == null ? color ?? this.color : null,
       fontFamily: fontFamily ?? this.fontFamily,
+      fontFamilyFallback: fontFamilyFallback ?? this.fontFamilyFallback,
       fontSize: fontSize == null ? null : fontSize * fontSizeFactor + fontSizeDelta,
       fontWeight: fontWeight == null ? null : FontWeight.values[(fontWeight.index + fontWeightDelta).clamp(0, FontWeight.values.length - 1)],
       fontStyle: fontStyle,
@@ -556,6 +598,7 @@ class TextStyle extends Diagnosticable {
     return copyWith(
       color: other.color,
       fontFamily: other.fontFamily,
+      fontFamilyFallback: other.fontFamilyFallback,
       fontSize: other.fontSize,
       fontWeight: other.fontWeight,
       fontStyle: other.fontStyle,
@@ -601,6 +644,7 @@ class TextStyle extends Diagnosticable {
         inherit: b.inherit,
         color: Color.lerp(null, b.color, t),
         fontFamily: t < 0.5 ? null : b.fontFamily,
+        fontFamilyFallback: t < 0.5 ? null : b.fontFamilyFallback,
         fontSize: t < 0.5 ? null : b.fontSize,
         fontWeight: FontWeight.lerp(null, b.fontWeight, t),
         fontStyle: t < 0.5 ? null : b.fontStyle,
@@ -624,6 +668,7 @@ class TextStyle extends Diagnosticable {
         inherit: a.inherit,
         color: Color.lerp(a.color, null, t),
         fontFamily: t < 0.5 ? a.fontFamily : null,
+        fontFamilyFallback: t < 0.5 ? a.fontFamilyFallback : null,
         fontSize: t < 0.5 ? a.fontSize : null,
         fontWeight: FontWeight.lerp(a.fontWeight, null, t),
         fontStyle: t < 0.5 ? a.fontStyle : null,
@@ -646,6 +691,7 @@ class TextStyle extends Diagnosticable {
       inherit: b.inherit,
       color: a.foreground == null && b.foreground == null ? Color.lerp(a.color, b.color, t) : null,
       fontFamily: t < 0.5 ? a.fontFamily : b.fontFamily,
+      fontFamilyFallback: t < 0.5 ? a.fontFamilyFallback : b.fontFamilyFallback,
       fontSize: ui.lerpDouble(a.fontSize ?? b.fontSize, b.fontSize ?? a.fontSize, t),
       fontWeight: FontWeight.lerp(a.fontWeight, b.fontWeight, t),
       fontStyle: t < 0.5 ? a.fontStyle : b.fontStyle,
@@ -679,6 +725,7 @@ class TextStyle extends Diagnosticable {
       fontStyle: fontStyle,
       textBaseline: textBaseline,
       fontFamily: fontFamily,
+      fontFamilyFallback: fontFamilyFallback,
       fontSize: fontSize == null ? null : fontSize * textScaleFactor,
       letterSpacing: letterSpacing,
       wordSpacing: wordSpacing,
@@ -743,7 +790,8 @@ class TextStyle extends Diagnosticable {
         locale != other.locale ||
         foreground != other.foreground ||
         background != other.background ||
-        !listEquals(shadows, other.shadows))
+        !listEquals(shadows, other.shadows) ||
+        !listEquals(fontFamilyFallback, other.fontFamilyFallback))
       return RenderComparison.layout;
     if (color != other.color ||
         decoration != other.decoration ||
@@ -776,7 +824,8 @@ class TextStyle extends Diagnosticable {
            decoration == typedOther.decoration &&
            decorationColor == typedOther.decorationColor &&
            decorationStyle == typedOther.decorationStyle &&
-           listEquals(shadows, typedOther.shadows);
+           listEquals(shadows, typedOther.shadows) &&
+           listEquals(fontFamilyFallback, typedOther.fontFamilyFallback);
   }
 
   @override
@@ -785,6 +834,7 @@ class TextStyle extends Diagnosticable {
       inherit,
       color,
       fontFamily,
+      fontFamilyFallback,
       fontSize,
       fontWeight,
       fontStyle,
@@ -814,6 +864,7 @@ class TextStyle extends Diagnosticable {
     final List<DiagnosticsNode> styles = <DiagnosticsNode>[];
     styles.add(DiagnosticsProperty<Color>('${prefix}color', color, defaultValue: null));
     styles.add(StringProperty('${prefix}family', fontFamily, defaultValue: null, quoted: false));
+    styles.add(IterableProperty<String>('${prefix}familyFallback', fontFamilyFallback, defaultValue: null));
     styles.add(DoubleProperty('${prefix}size', fontSize, defaultValue: null));
     String weightDescription;
     if (fontWeight != null) {

packages/flutter/test/material/theme_test.dart

@@ -671,6 +671,7 @@ class _TextStyleProxy implements TextStyle {
   @override Color get decorationColor => _delegate.decorationColor;
   @override TextDecorationStyle get decorationStyle => _delegate.decorationStyle;
   @override String get fontFamily => _delegate.fontFamily;
+  @override List<String> get fontFamilyFallback => _delegate.fontFamilyFallback;
   @override double get fontSize => _delegate.fontSize;
   @override FontStyle get fontStyle => _delegate.fontStyle;
   @override FontWeight get fontWeight => _delegate.fontWeight;
@@ -699,7 +700,7 @@ class _TextStyleProxy implements TextStyle {
   }
 
   @override
-  TextStyle apply({Color color, TextDecoration decoration, Color decorationColor, TextDecorationStyle decorationStyle, String fontFamily, double fontSizeFactor = 1.0, double fontSizeDelta = 0.0, int fontWeightDelta = 0, double letterSpacingFactor = 1.0, double letterSpacingDelta = 0.0, double wordSpacingFactor = 1.0, double wordSpacingDelta = 0.0, double heightFactor = 1.0, double heightDelta = 0.0}) {
+  TextStyle apply({Color color, TextDecoration decoration, Color decorationColor, TextDecorationStyle decorationStyle, String fontFamily, List<String> fontFamilyFallback, double fontSizeFactor = 1.0, double fontSizeDelta = 0.0, int fontWeightDelta = 0, double letterSpacingFactor = 1.0, double letterSpacingDelta = 0.0, double wordSpacingFactor = 1.0, double wordSpacingDelta = 0.0, double heightFactor = 1.0, double heightDelta = 0.0}) {
     throw UnimplementedError();
   }
 
@@ -709,7 +710,7 @@ class _TextStyleProxy implements TextStyle {
   }
 
   @override
-  TextStyle copyWith({Color color, String fontFamily, double fontSize, FontWeight fontWeight, FontStyle fontStyle, double letterSpacing, double wordSpacing, TextBaseline textBaseline, double height, Locale locale, ui.Paint foreground, ui.Paint background, List<Shadow> shadows, TextDecoration decoration, Color decorationColor, TextDecorationStyle decorationStyle, String debugLabel}) {
+  TextStyle copyWith({Color color, String fontFamily, List<String> fontFamilyFallback, double fontSize, FontWeight fontWeight, FontStyle fontStyle, double letterSpacing, double wordSpacing, TextBaseline textBaseline, double height, Locale locale, ui.Paint foreground, ui.Paint background, List<Shadow> shadows, TextDecoration decoration, Color decorationColor, TextDecorationStyle decorationStyle, String debugLabel}) {
     throw UnimplementedError();
   }
 

packages/flutter/test/painting/text_style_test.dart

@@ -163,10 +163,10 @@ void main() {
 
     final ui.TextStyle ts5 = s5.getTextStyle();
     expect(ts5, equals(ui.TextStyle(fontWeight: FontWeight.w700, fontSize: 12.0, height: 123.0)));
-    expect(ts5.toString(), 'TextStyle(color: unspecified, decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: FontWeight.w700, fontStyle: unspecified, textBaseline: unspecified, fontFamily: unspecified, fontSize: 12.0, letterSpacing: unspecified, wordSpacing: unspecified, height: 123.0x, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
+    expect(ts5.toString(), 'TextStyle(color: unspecified, decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: FontWeight.w700, fontStyle: unspecified, textBaseline: unspecified, fontFamily: unspecified, fontFamilyFallback: unspecified, fontSize: 12.0, letterSpacing: unspecified, wordSpacing: unspecified, height: 123.0x, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
     final ui.TextStyle ts2 = s2.getTextStyle();
     expect(ts2, equals(ui.TextStyle(color: const Color(0xFF00FF00), fontWeight: FontWeight.w800, fontSize: 10.0, height: 100.0)));
-    expect(ts2.toString(), 'TextStyle(color: Color(0xff00ff00), decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: FontWeight.w800, fontStyle: unspecified, textBaseline: unspecified, fontFamily: unspecified, fontSize: 10.0, letterSpacing: unspecified, wordSpacing: unspecified, height: 100.0x, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
+    expect(ts2.toString(), 'TextStyle(color: Color(0xff00ff00), decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: FontWeight.w800, fontStyle: unspecified, textBaseline: unspecified, fontFamily: unspecified, fontFamilyFallback: unspecified, fontSize: 10.0, letterSpacing: unspecified, wordSpacing: unspecified, height: 100.0x, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
 
     final ui.ParagraphStyle ps2 = s2.getParagraphStyle(textAlign: TextAlign.center);
     expect(ps2, equals(ui.ParagraphStyle(textAlign: TextAlign.center, fontWeight: FontWeight.w800, fontSize: 10.0, lineHeight: 100.0)));
@@ -176,6 +176,7 @@ void main() {
     expect(ps5.toString(), 'ParagraphStyle(textAlign: unspecified, textDirection: unspecified, fontWeight: FontWeight.w700, fontStyle: unspecified, maxLines: unspecified, fontFamily: unspecified, fontSize: 12.0, lineHeight: 123.0x, ellipsis: unspecified, locale: unspecified)');
   });
 
+
   test('TextStyle with text direction', () {
     final ui.ParagraphStyle ps6 = const TextStyle().getParagraphStyle(textDirection: TextDirection.ltr);
     expect(ps6, equals(ui.ParagraphStyle(textDirection: TextDirection.ltr, fontSize: 14.0)));
@@ -189,11 +190,47 @@ void main() {
   test('TextStyle using package font', () {
     const TextStyle s6 = TextStyle(fontFamily: 'test');
     expect(s6.fontFamily, 'test');
-    expect(s6.getTextStyle().toString(), 'TextStyle(color: unspecified, decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: unspecified, fontStyle: unspecified, textBaseline: unspecified, fontFamily: test, fontSize: unspecified, letterSpacing: unspecified, wordSpacing: unspecified, height: unspecified, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
+    expect(s6.getTextStyle().toString(), 'TextStyle(color: unspecified, decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: unspecified, fontStyle: unspecified, textBaseline: unspecified, fontFamily: test, fontFamilyFallback: unspecified, fontSize: unspecified, letterSpacing: unspecified, wordSpacing: unspecified, height: unspecified, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
 
     const TextStyle s7 = TextStyle(fontFamily: 'test', package: 'p');
     expect(s7.fontFamily, 'packages/p/test');
-    expect(s7.getTextStyle().toString(), 'TextStyle(color: unspecified, decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: unspecified, fontStyle: unspecified, textBaseline: unspecified, fontFamily: packages/p/test, fontSize: unspecified, letterSpacing: unspecified, wordSpacing: unspecified, height: unspecified, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
+    expect(s7.getTextStyle().toString(), 'TextStyle(color: unspecified, decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: unspecified, fontStyle: unspecified, textBaseline: unspecified, fontFamily: packages/p/test, fontFamilyFallback: unspecified, fontSize: unspecified, letterSpacing: unspecified, wordSpacing: unspecified, height: unspecified, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
+
+    const TextStyle s8 = TextStyle(fontFamilyFallback: <String>['test', 'test2'], package: 'p');
+    expect(s8.fontFamilyFallback[0], 'packages/p/test');
+    expect(s8.fontFamilyFallback[1], 'packages/p/test2');
+    expect(s8.fontFamilyFallback.length, 2);
+
+    const TextStyle s9 = TextStyle(package: 'p');
+    expect(s9.fontFamilyFallback, null);
+
+    const TextStyle s10 = TextStyle(fontFamilyFallback: <String>[], package: 'p');
+    expect(s10.fontFamilyFallback, <String>[]);
+  });
+
+  test('TextStyle font family fallback', () {
+    const TextStyle s1 = TextStyle(fontFamilyFallback: <String>['Roboto', 'test']);
+    expect(s1.fontFamilyFallback[0], 'Roboto');
+    expect(s1.fontFamilyFallback[1], 'test');
+    expect(s1.fontFamilyFallback.length, 2);
+
+    const TextStyle s2 = TextStyle(fontFamily: 'foo', fontFamilyFallback: <String>['Roboto', 'test']);
+    expect(s2.fontFamilyFallback[0], 'Roboto');
+    expect(s2.fontFamilyFallback[1], 'test');
+    expect(s2.fontFamily, 'foo');
+    expect(s2.fontFamilyFallback.length, 2);
+
+    const TextStyle s3 = TextStyle(fontFamily: 'foo');
+    expect(s3.fontFamily, 'foo');
+    expect(s3.fontFamilyFallback, null);
+
+    const TextStyle s4 = TextStyle(fontFamily: 'foo', fontFamilyFallback: <String>[]);
+    expect(s4.fontFamily, 'foo');
+    expect(s4.fontFamilyFallback, <String>[]);
+    expect(s4.fontFamilyFallback.isEmpty, true);
+
+    final ui.TextStyle uis1 = s2.getTextStyle();
+    expect(uis1.toString(), 'TextStyle(color: unspecified, decoration: unspecified, decorationColor: unspecified, decorationStyle: unspecified, fontWeight: unspecified, fontStyle: unspecified, textBaseline: unspecified, fontFamily: foo, fontFamilyFallback: [Roboto, test], fontSize: unspecified, letterSpacing: unspecified, wordSpacing: unspecified, height: unspecified, locale: unspecified, background: unspecified, foreground: unspecified, shadows: unspecified)');
   });
 
   test('TextStyle.debugLabel', () {