[libTxt] resolve null leading distribution in dart:ui.

lib/ui/text/paragraph_builder.cc

@@ -32,26 +32,27 @@ namespace {
 
 // TextStyle
 
+const int tsLeadingDistributionIndex = 0;
 const int tsColorIndex = 1;
 const int tsTextDecorationIndex = 2;
 const int tsTextDecorationColorIndex = 3;
 const int tsTextDecorationStyleIndex = 4;
 const int tsFontWeightIndex = 5;
 const int tsFontStyleIndex = 6;
 const int tsTextBaselineIndex = 7;
-const int tsLeadingDistributionIndex = 8;
-const int tsTextDecorationThicknessIndex = 9;
-const int tsFontFamilyIndex = 10;
-const int tsFontSizeIndex = 11;
-const int tsLetterSpacingIndex = 12;
-const int tsWordSpacingIndex = 13;
-const int tsHeightIndex = 14;
-const int tsLocaleIndex = 15;
-const int tsBackgroundIndex = 16;
-const int tsForegroundIndex = 17;
-const int tsTextShadowsIndex = 18;
-const int tsFontFeaturesIndex = 19;
+const int tsTextDecorationThicknessIndex = 8;
+const int tsFontFamilyIndex = 9;
+const int tsFontSizeIndex = 10;
+const int tsLetterSpacingIndex = 11;
+const int tsWordSpacingIndex = 12;
+const int tsHeightIndex = 13;
+const int tsLocaleIndex = 14;
+const int tsBackgroundIndex = 15;
+const int tsForegroundIndex = 16;
+const int tsTextShadowsIndex = 17;
+const int tsFontFeaturesIndex = 18;
 
+const int tsLeadingDistributionMask = 1 << tsLeadingDistributionIndex;
 const int tsColorMask = 1 << tsColorIndex;
 const int tsTextDecorationMask = 1 << tsTextDecorationIndex;
 const int tsTextDecorationColorMask = 1 << tsTextDecorationColorIndex;
@@ -60,7 +61,6 @@ const int tsTextDecorationThicknessMask = 1 << tsTextDecorationThicknessIndex;
 const int tsFontWeightMask = 1 << tsFontWeightIndex;
 const int tsFontStyleMask = 1 << tsFontStyleIndex;
 const int tsTextBaselineMask = 1 << tsTextBaselineIndex;
-const int tsLeadingDistributionMask = 1 << tsLeadingDistributionIndex;
 const int tsFontFamilyMask = 1 << tsFontFamilyIndex;
 const int tsFontSizeMask = 1 << tsFontSizeIndex;
 const int tsLetterSpacingMask = 1 << tsLetterSpacingIndex;
@@ -201,10 +201,8 @@ void decodeStrut(Dart_Handle strut_data,
     paragraph_style.strut_font_style =
         static_cast<txt::FontStyle>(uint8_data[byte_count++]);
   }
-  if (mask & sLeadingDistributionMask) {
-    paragraph_style.strut_has_leading_distribution_override = true;
-    paragraph_style.strut_half_leading = uint8_data[byte_count++];
-  }
+
+  paragraph_style.strut_half_leading = mask & sLeadingDistributionMask;
 
   std::vector<float> float_data;
   float_data.resize((byte_data.length_in_bytes() - byte_count) / 4);
@@ -389,6 +387,7 @@ void ParagraphBuilder::pushStyle(tonic::Int32List& encoded,
   // explicitly given.
   txt::TextStyle style = m_paragraphBuilder->PeekStyle();
 
+  style.half_leading = mask & tsLeadingDistributionMask;
   // Only change the style property from the previous value if a new explicitly
   // set value is available
   if (mask & tsColorMask) {
@@ -418,11 +417,6 @@ void ParagraphBuilder::pushStyle(tonic::Int32List& encoded,
     // property wasn't wired up either.
   }
 
-  style.has_leading_distribution_override = mask & tsLeadingDistributionMask;
-  if (mask & tsLeadingDistributionMask) {
-    style.half_leading = encoded[tsLeadingDistributionIndex];
-  }
-
   if (mask & (tsFontWeightMask | tsFontStyleMask | tsFontSizeMask |
               tsLetterSpacingMask | tsWordSpacingMask)) {
     if (mask & tsFontWeightMask) {

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

@@ -131,7 +131,8 @@ class CkParagraphStyle implements ui.ParagraphStyle {
     }
 
     if (textHeightBehavior != null) {
-      properties.textHeightBehavior = textHeightBehavior.encode();
+      properties.textHeightBehavior = (textHeightBehavior.applyHeightToFirstAscent ? 0 : 1 << 0)
+                                    | (textHeightBehavior.applyHeightToLastDescent ? 0 : 1 << 1);
     }
 
     if (ellipsis != null) {

lib/web_ui/lib/src/ui/text.dart

@@ -214,20 +214,10 @@ class TextHeightBehavior {
     this.applyHeightToLastDescent = true,
     this.leadingDistribution = TextLeadingDistribution.proportional,
   });
-  TextHeightBehavior.fromEncoded(int encoded)
-    : applyHeightToFirstAscent = (encoded & 0x1) == 0,
-      applyHeightToLastDescent = (encoded & 0x2) == 0,
-      leadingDistribution = TextLeadingDistribution.values[encoded >> 2];
   final bool applyHeightToFirstAscent;
   final bool applyHeightToLastDescent;
   final TextLeadingDistribution leadingDistribution;
 
-  int encode() {
-    return (applyHeightToFirstAscent ? 0 : 1 << 0)
-         | (applyHeightToLastDescent ? 0 : 1 << 1)
-         | (leadingDistribution.index << 2);
-  }
-
   @override
   bool operator ==(Object other) {
     if (other.runtimeType != runtimeType)

lib/web_ui/test/canvaskit/canvaskit_api_test.dart

@@ -1273,7 +1273,7 @@ void _paragraphTests() {
     props.textAlign = canvasKit.TextAlign.Center;
     props.textDirection = canvasKit.TextDirection.RTL;
     props.heightMultiplier = 3;
-    props.textHeightBehavior = ui.TextHeightBehavior().encode();
+    props.textHeightBehavior = 0;
     props.maxLines = 4;
     props.ellipsis = '___';
     props.textStyle = SkTextStyleProperties()

testing/dart/text_test.dart

@@ -107,22 +107,6 @@ void main() {
       expect(behavior4.leadingDistribution, equals(TextLeadingDistribution.even));
     });
 
-    test('encode works', () {
-      expect(behavior0.encode(), equals(0));
-      expect(behavior1.encode(), equals(3));
-      expect(behavior2.encode(), equals(1));
-      expect(behavior3.encode(), equals(2));
-      expect(behavior4.encode(), equals(6));
-    });
-
-    test('decode works', () {
-      expect(TextHeightBehavior.fromEncoded(0), equals(behavior0));
-      expect(TextHeightBehavior.fromEncoded(3), equals(behavior1));
-      expect(TextHeightBehavior.fromEncoded(1), equals(behavior2));
-      expect(TextHeightBehavior.fromEncoded(2), equals(behavior3));
-      expect(TextHeightBehavior.fromEncoded(6), equals(behavior4));
-    });
-
     test('toString works', () {
       expect(behavior0.toString(), equals('TextHeightBehavior(applyHeightToFirstAscent: true, applyHeightToLastDescent: true, leadingDistribution: TextLeadingDistribution.proportional)'));
       expect(behavior1.toString(), equals('TextHeightBehavior(applyHeightToFirstAscent: false, applyHeightToLastDescent: false, leadingDistribution: TextLeadingDistribution.proportional)'));

third_party/txt/src/skia/paragraph_builder_skia.cc

@@ -107,6 +107,7 @@ skt::TextStyle TxtToSkia(const TextStyle& txt) {
   skia.setWordSpacing(SkDoubleToScalar(txt.word_spacing));
   skia.setHeight(SkDoubleToScalar(txt.height));
   skia.setHeightOverride(txt.has_height_override);
+  skia.setHalfLeading(txt.half_leading);
 
   skia.setLocale(SkString(txt.locale.c_str()));
   if (txt.has_background) {

third_party/txt/src/txt/paragraph_style.h

@@ -48,12 +48,6 @@ enum class TextDirection {
 // the line will use the default font metric provided ascent/descent and
 // ParagraphStyle.height or TextStyle.height will not take effect.
 //
-// kEvenLeading determines how the leading is distributed over and under the
-// text. When true, half of the leading is added to the top of the text and the
-// other half is added to the bottom of the text. Otherwise, instead of
-// distributing the space evenly, it's distributed proportionally to the font's
-// ascent/descent ratio.
-//
 // The default behavior is kAll where height adjustments are enabled for all
 // lines.
 //
@@ -66,7 +60,6 @@ enum TextHeightBehavior {
   kDisableFirstAscent = 0x1,
   kDisableLastDescent = 0x2,
   kDisableAll = 0x1 | 0x2,
-  kEvenLeading = 0x1 << 2,
 };
 
 class ParagraphStyle {
@@ -92,7 +85,6 @@ class ParagraphStyle {
   double strut_height = 1;
   bool strut_has_height_override = false;
   bool strut_half_leading = false;
-  bool strut_has_leading_distribution_override = false;
   double strut_leading = -1;  // Negative to use font's default leading. [0,inf)
                               // to use custom leading as a ratio of font size.
   bool force_strut_height = false;

third_party/txt/src/txt/paragraph_txt.cc

@@ -566,14 +566,8 @@ void ParagraphTxt::ComputeStrut(StrutMetrics* strut, SkFont& font) {
               : (paragraph_style_.strut_leading *
                  paragraph_style_.strut_font_size);
 
-      const bool half_leading_enabled =
-          paragraph_style_.strut_has_leading_distribution_override
-              ? paragraph_style_.strut_half_leading
-              : paragraph_style_.text_height_behavior &
-                    TextHeightBehavior::kEvenLeading;
-
       const double available_height =
-          half_leading_enabled ? metrics_height : strut_height;
+          paragraph_style_.strut_half_leading ? metrics_height : strut_height;
 
       strut->ascent =
           (-strut_metrics.fAscent / metrics_height) * available_height;
@@ -1213,11 +1207,6 @@ void ParagraphTxt::UpdateLineMetrics(const SkFontMetrics& metrics,
     const double blob_height = style.has_height_override
                                    ? style.height * style.font_size
                                    : metrics_font_height + metrics.fLeading;
-    const bool half_leading_enabled =
-        style.has_leading_distribution_override
-            ? style.half_leading
-            : paragraph_style_.text_height_behavior &
-                  TextHeightBehavior::kEvenLeading;
 
     // Scale the ascent and descent such that the sum of ascent and
     // descent is `style.height * style.font_size`.
@@ -1266,14 +1255,14 @@ void ParagraphTxt::UpdateLineMetrics(const SkFontMetrics& metrics,
     // a sane, consistent, and reasonable "blob_height" to be specified,
     // though it breaks with what is done by any of the platforms above.
     const bool shouldNormalizeFont =
-        style.has_height_override && !half_leading_enabled;
+        style.has_height_override && !style.half_leading;
     const double font_height =
         shouldNormalizeFont ? style.font_size : metrics_font_height;
 
     // Reserve the outermost vertical space we want to distribute evenly over
     // and under the text ("half-leading").
     double leading;
-    if (half_leading_enabled) {
+    if (style.half_leading) {
       leading = blob_height - font_height;
     } else {
       leading = style.has_height_override ? 0.0 : metrics.fLeading;

third_party/txt/src/txt/text_style.cc

@@ -48,9 +48,6 @@ bool TextStyle::equals(const TextStyle& other) const {
     return false;
   if (has_height_override != other.has_height_override)
     return false;
-  if (has_leading_distribution_override !=
-      other.has_leading_distribution_override)
-    return false;
   if (half_leading != other.half_leading)
     return false;
   if (locale != other.locale)

third_party/txt/src/txt/text_style.h

@@ -45,9 +45,6 @@ class TextStyle {
   FontStyle font_style = FontStyle::normal;
   TextBaseline text_baseline = TextBaseline::kAlphabetic;
   bool half_leading = false;
-  // whether TextStyle.half_leading should be applied or we should defer to
-  // ParagraphStyle.half_leading.
-  bool has_leading_distribution_override = false;
   // An ordered list of fonts in order of priority. The first font is more
   // highly preferred than the last font.
   std::vector<std::string> font_families;