Provide an SkPaint that describes the background of a text style (#5153)

Fixes https://github.com/flutter/flutter/issues/11961

lib/ui/painting/paint.cc

@@ -12,9 +12,7 @@
 #include "third_party/skia/include/core/SkShader.h"
 #include "third_party/skia/include/core/SkString.h"
 
-using namespace blink;
-
-namespace tonic {
+namespace blink {
 
 // Indices for 32bit values.
 constexpr int kIsAntiAliasIndex = 0;
@@ -52,17 +50,10 @@ constexpr double kStrokeMiterLimitDefault = 4.0;
 // Must be kept in sync with the MaskFilter private constants in painting.dart.
 enum MaskFilterType { Null, Blur };
 
-Paint DartConverter<Paint>::FromArguments(Dart_NativeArguments args,
-                                          int index,
-                                          Dart_Handle& exception) {
-  Dart_Handle paint_objects = Dart_GetNativeArgument(args, index);
-  FXL_DCHECK(!LogIfError(paint_objects));
-
-  Dart_Handle paint_data = Dart_GetNativeArgument(args, index + 1);
-  FXL_DCHECK(!LogIfError(paint_data));
-
-  Paint result;
-  SkPaint& paint = result.paint_;
+Paint::Paint(Dart_Handle paint_objects, Dart_Handle paint_data) {
+  is_null_ = Dart_IsNull(paint_data);
+  if (is_null_)
+    return;
 
   if (!Dart_IsNull(paint_objects)) {
     FXL_DCHECK(Dart_IsList(paint_objects));
@@ -72,12 +63,12 @@ Paint DartConverter<Paint>::FromArguments(Dart_NativeArguments args,
     FXL_CHECK(length == kObjectCount);
     Dart_Handle values[kObjectCount];
     if (Dart_IsError(Dart_ListGetRange(paint_objects, 0, kObjectCount, values)))
-      return result;
+      return;
 
     Dart_Handle shader = values[kShaderIndex];
     if (!Dart_IsNull(shader)) {
-      Shader* decoded = DartConverter<Shader*>::FromDart(shader);
-      paint.setShader(decoded->shader());
+      Shader* decoded = tonic::DartConverter<Shader*>::FromDart(shader);
+      paint_.setShader(decoded->shader());
     }
   }
 
@@ -87,49 +78,49 @@ Paint DartConverter<Paint>::FromArguments(Dart_NativeArguments args,
   const uint32_t* uint_data = static_cast<const uint32_t*>(byte_data.data());
   const float* float_data = static_cast<const float*>(byte_data.data());
 
-  paint.setAntiAlias(uint_data[kIsAntiAliasIndex] == 0);
+  paint_.setAntiAlias(uint_data[kIsAntiAliasIndex] == 0);
 
   uint32_t encoded_color = uint_data[kColorIndex];
   if (encoded_color) {
     SkColor color = encoded_color ^ kColorDefault;
-    paint.setColor(color);
+    paint_.setColor(color);
   }
 
   uint32_t encoded_blend_mode = uint_data[kBlendModeIndex];
   if (encoded_blend_mode) {
     uint32_t blend_mode = encoded_blend_mode ^ kBlendModeDefault;
-    paint.setBlendMode(static_cast<SkBlendMode>(blend_mode));
+    paint_.setBlendMode(static_cast<SkBlendMode>(blend_mode));
   }
 
   uint32_t style = uint_data[kStyleIndex];
   if (style)
-    paint.setStyle(static_cast<SkPaint::Style>(style));
+    paint_.setStyle(static_cast<SkPaint::Style>(style));
 
   float stroke_width = float_data[kStrokeWidthIndex];
   if (stroke_width != 0.0)
-    paint.setStrokeWidth(stroke_width);
+    paint_.setStrokeWidth(stroke_width);
 
   uint32_t stroke_cap = uint_data[kStrokeCapIndex];
   if (stroke_cap)
-    paint.setStrokeCap(static_cast<SkPaint::Cap>(stroke_cap));
+    paint_.setStrokeCap(static_cast<SkPaint::Cap>(stroke_cap));
 
   uint32_t stroke_join = uint_data[kStrokeJoinIndex];
   if (stroke_join)
-    paint.setStrokeJoin(static_cast<SkPaint::Join>(stroke_join));
+    paint_.setStrokeJoin(static_cast<SkPaint::Join>(stroke_join));
 
   float stroke_miter_limit = float_data[kStrokeMiterLimitIndex];
   if (stroke_miter_limit != 0.0)
-    paint.setStrokeMiter(stroke_miter_limit + kStrokeMiterLimitDefault);
+    paint_.setStrokeMiter(stroke_miter_limit + kStrokeMiterLimitDefault);
 
   uint32_t filter_quality = uint_data[kFilterQualityIndex];
   if (filter_quality)
-    paint.setFilterQuality(static_cast<SkFilterQuality>(filter_quality));
+    paint_.setFilterQuality(static_cast<SkFilterQuality>(filter_quality));
 
   if (uint_data[kColorFilterIndex]) {
     SkColor color = uint_data[kColorFilterColorIndex];
     SkBlendMode blend_mode =
         static_cast<SkBlendMode>(uint_data[kColorFilterBlendModeIndex]);
-    paint.setColorFilter(SkColorFilter::MakeModeFilter(color, blend_mode));
+    paint_.setColorFilter(SkColorFilter::MakeModeFilter(color, blend_mode));
   }
 
   switch (uint_data[kMaskFilterIndex]) {
@@ -139,18 +130,29 @@ Paint DartConverter<Paint>::FromArguments(Dart_NativeArguments args,
       SkBlurStyle blur_style =
           static_cast<SkBlurStyle>(uint_data[kMaskFilterBlurStyleIndex]);
       double sigma = float_data[kMaskFilterSigmaIndex];
-      paint.setMaskFilter(SkMaskFilter::MakeBlur(blur_style, sigma));
+      paint_.setMaskFilter(SkMaskFilter::MakeBlur(blur_style, sigma));
       break;
   }
+}
+
+}  // namespace blink
+
+namespace tonic {
+
+blink::Paint DartConverter<blink::Paint>::FromArguments(
+    Dart_NativeArguments args, int index, Dart_Handle& exception) {
+  Dart_Handle paint_objects = Dart_GetNativeArgument(args, index);
+  FXL_DCHECK(!LogIfError(paint_objects));
+
+  Dart_Handle paint_data = Dart_GetNativeArgument(args, index + 1);
+  FXL_DCHECK(!LogIfError(paint_data));
 
-  result.is_null_ = false;
-  return result;
+  return blink::Paint(paint_objects, paint_data);
 }
 
-PaintData DartConverter<PaintData>::FromArguments(Dart_NativeArguments args,
-                                                  int index,
-                                                  Dart_Handle& exception) {
-  return PaintData();
+blink::PaintData DartConverter<blink::PaintData>::FromArguments(
+    Dart_NativeArguments args, int index, Dart_Handle& exception) {
+  return blink::PaintData();
 }
 
 }  // namespace tonic

lib/ui/painting/paint.h

@@ -12,13 +12,16 @@ namespace blink {
 
 class Paint {
  public:
+  Paint() = default;
+  Paint(Dart_Handle paint_objects, Dart_Handle paint_data);
+
   const SkPaint* paint() const { return is_null_ ? nullptr : &paint_; }
 
  private:
   friend struct tonic::DartConverter<Paint>;
 
   SkPaint paint_;
-  bool is_null_;
+  bool is_null_ = true;
 };
 
 // The PaintData argument is a placeholder to receive encoded data for Paint

lib/ui/text.dart

@@ -257,6 +257,7 @@ Int32List _encodeTextStyle(
   double wordSpacing,
   double height,
   Locale locale,
+  Paint background,
 ) {
   final Int32List result = new Int32List(8);
   if (color != null) {
@@ -311,6 +312,10 @@ Int32List _encodeTextStyle(
     result[0] |= 1 << 13;
     // Passed separately to native.
   }
+  if (background != null) {
+    result[0] |= 1 << 14;
+    // Passed separately to native.
+  }
   return result;
 }
 
@@ -331,6 +336,7 @@ class TextStyle {
   /// * `textBaseline`: The common baseline that should be aligned between this text span and its parent text span, or, for the root text spans, with the line box.
   /// * `height`: The height of this text span, as a multiple of the font size.
   /// * `locale`: The locale used to select region-specific glyphs.
+  /// * `background`: The paint drawn as a background for the text.
   TextStyle({
     Color color,
     TextDecoration decoration,
@@ -345,6 +351,7 @@ class TextStyle {
     double wordSpacing,
     double height,
     Locale locale,
+    Paint background,
   }) : _encoded = _encodeTextStyle(
          color,
          decoration,
@@ -359,13 +366,15 @@ class TextStyle {
          wordSpacing,
          height,
          locale,
+         background,
        ),
        _fontFamily = fontFamily ?? '',
        _fontSize = fontSize,
        _letterSpacing = letterSpacing,
        _wordSpacing = wordSpacing,
        _height = height,
-       _locale = locale;
+       _locale = locale,
+       _background = background;
 
   final Int32List _encoded;
   final String _fontFamily;
@@ -374,6 +383,7 @@ class TextStyle {
   final double _wordSpacing;
   final double _height;
   final Locale _locale;
+  final Paint _background;
 
   @override
   bool operator ==(dynamic other) {
@@ -387,7 +397,8 @@ class TextStyle {
         _letterSpacing != typedOther._letterSpacing ||
         _wordSpacing != typedOther._wordSpacing ||
         _height != typedOther._height ||
-        _locale != typedOther._locale)
+        _locale != typedOther._locale ||
+        _background != typedOther._background)
      return false;
     for (int index = 0; index < _encoded.length; index += 1) {
       if (_encoded[index] != typedOther._encoded[index])
@@ -397,7 +408,7 @@ class TextStyle {
   }
 
   @override
-  int get hashCode => hashValues(hashList(_encoded), _fontFamily, _fontSize, _letterSpacing, _wordSpacing, _height, _locale);
+  int get hashCode => hashValues(hashList(_encoded), _fontFamily, _fontSize, _letterSpacing, _wordSpacing, _height, _locale, _background);
 
   @override
   String toString() {
@@ -414,7 +425,8 @@ class TextStyle {
              'letterSpacing: ${  _encoded[0] & 0x0400 == 0x0400 ? "${_letterSpacing}x"                    : "unspecified"}, '
              'wordSpacing: ${    _encoded[0] & 0x0800 == 0x0800 ? "${_wordSpacing}x"                      : "unspecified"}, '
              'height: ${         _encoded[0] & 0x1000 == 0x1000 ? "${_height}x"                           : "unspecified"}, '
-             'locale: ${         _encoded[0] & 0x2000 == 0x2000 ? _locale                                 : "unspecified"}'
+             'locale: ${         _encoded[0] & 0x2000 == 0x2000 ? _locale                                 : "unspecified"}, '
+             'background: ${     _encoded[0] & 0x4000 == 0x4000 ? _background                             : "unspecified"}'
            ')';
   }
 }
@@ -1013,8 +1025,8 @@ class ParagraphBuilder extends NativeFieldWrapperClass2 {
   /// Applies the given style to the added text until [pop] is called.
   ///
   /// See [pop] for details.
-  void pushStyle(TextStyle style) => _pushStyle(style._encoded, style._fontFamily, style._fontSize, style._letterSpacing, style._wordSpacing, style._height, _encodeLocale(style._locale));
-  void _pushStyle(Int32List encoded, String fontFamily, double fontSize, double letterSpacing, double wordSpacing, double height, String locale) native 'ParagraphBuilder_pushStyle';
+  void pushStyle(TextStyle style) => _pushStyle(style._encoded, style._fontFamily, style._fontSize, style._letterSpacing, style._wordSpacing, style._height, _encodeLocale(style._locale), style._background?._objects, style._background?._data);
+  void _pushStyle(Int32List encoded, String fontFamily, double fontSize, double letterSpacing, double wordSpacing, double height, String locale, List<dynamic> backgroundObjects, ByteData backgroundData) native 'ParagraphBuilder_pushStyle';
 
   static String _encodeLocale(Locale locale) => locale?.toString() ?? '';
 

lib/ui/text/paragraph_builder.cc

@@ -42,6 +42,7 @@ const int tsLetterSpacingIndex = 10;
 const int tsWordSpacingIndex = 11;
 const int tsHeightIndex = 12;
 const int tsLocaleIndex = 13;
+const int tsBackgroundIndex = 14;
 
 const int tsColorMask = 1 << tsColorIndex;
 const int tsTextDecorationMask = 1 << tsTextDecorationIndex;
@@ -56,6 +57,7 @@ const int tsLetterSpacingMask = 1 << tsLetterSpacingIndex;
 const int tsWordSpacingMask = 1 << tsWordSpacingIndex;
 const int tsHeightMask = 1 << tsHeightIndex;
 const int tsLocaleMask = 1 << tsLocaleIndex;
+const int tsBackgroundMask = 1 << tsBackgroundIndex;
 
 // ParagraphStyle
 
@@ -290,7 +292,9 @@ void ParagraphBuilder::pushStyle(tonic::Int32List& encoded,
                                  double letterSpacing,
                                  double wordSpacing,
                                  double height,
-                                 const std::string& locale) {
+                                 const std::string& locale,
+                                 Dart_Handle background_objects,
+                                 Dart_Handle background_data) {
   FXL_DCHECK(encoded.num_elements() == 8);
 
   int32_t mask = encoded[0];
@@ -351,6 +355,14 @@ void ParagraphBuilder::pushStyle(tonic::Int32List& encoded,
       style.locale = locale;
     }
 
+    if (mask & tsBackgroundMask) {
+      Paint background(background_objects, background_data);
+      if (background.paint()) {
+        style.has_background = true;
+        style.background = *background.paint();
+      }
+    }
+
     m_paragraphBuilder->PushStyle(style);
   } else {
     // Blink Version.

lib/ui/text/paragraph_builder.h

@@ -6,6 +6,7 @@
 #define FLUTTER_LIB_UI_TEXT_PARAGRAPH_BUILDER_H_
 
 #include <memory>
+#include "flutter/lib/ui/painting/paint.h"
 #include "flutter/lib/ui/text/paragraph.h"
 #include "flutter/sky/engine/core/rendering/RenderObject.h"
 #include "flutter/sky/engine/wtf/OwnPtr.h"
@@ -43,7 +44,9 @@ class ParagraphBuilder : public fxl::RefCountedThreadSafe<ParagraphBuilder>,
                  double letterSpacing,
                  double wordSpacing,
                  double height,
-                 const std::string& locale);
+                 const std::string& locale,
+                 Dart_Handle background_objects,
+                 Dart_Handle background_data);
 
   void pop();
 

third_party/txt/src/txt/paragraph.cc

@@ -862,6 +862,7 @@ void Paragraph::Paint(SkCanvas* canvas, double x, double y) {
   for (const PaintRecord& record : records_) {
     paint.setColor(record.style().color);
     SkPoint offset = record.offset();
+    PaintBackground(canvas, record);
     canvas->drawTextBlob(record.text(), offset.x(), offset.y(), paint);
     PaintDecorations(canvas, record);
   }
@@ -1026,6 +1027,17 @@ void Paragraph::PaintDecorations(SkCanvas* canvas, const PaintRecord& record) {
   }
 }
 
+void Paragraph::PaintBackground(SkCanvas* canvas, const PaintRecord& record) {
+  if (!record.style().has_background)
+    return;
+
+  const SkPaint::FontMetrics& metrics = record.metrics();
+  SkRect rect(SkRect::MakeLTRB(0, metrics.fAscent,
+                               record.GetRunWidth(), metrics.fDescent));
+  rect.offset(record.offset());
+  canvas->drawRect(rect, record.style().background);
+}
+
 std::vector<Paragraph::TextBox> Paragraph::GetRectsForRange(size_t start,
                                                             size_t end) const {
   std::map<size_t, std::vector<Paragraph::TextBox>> line_boxes;

third_party/txt/src/txt/paragraph.h

@@ -310,6 +310,9 @@ class Paragraph {
   // Creates and draws the decorations onto the canvas.
   void PaintDecorations(SkCanvas* canvas, const PaintRecord& record);
 
+  // Draws the background onto the canvas.
+  void PaintBackground(SkCanvas* canvas, const PaintRecord& record);
+
   FXL_DISALLOW_COPY_AND_ASSIGN(Paragraph);
 };
 

third_party/txt/src/txt/text_style.h

@@ -24,6 +24,7 @@
 #include "text_baseline.h"
 #include "text_decoration.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "third_party/skia/include/core/SkPaint.h"
 
 namespace txt {
 
@@ -46,6 +47,8 @@ class TextStyle {
   double word_spacing = 0.0;
   double height = 1.0;
   std::string locale;
+  bool has_background = false;
+  SkPaint background;
 
   TextStyle();