Separate TextMetrics advances from CharacterRanges (ligatures fixed).

Moving code to a separate function to avoid conflicting with svg code that uses CharacterRanges. Also fixed advances for ligatures and other edge cases. Similar to text selection approach, for ligatures the advances per character are distributed evenly along the glyph's actual width. In the case that one character has multiple glyphs, the advance for the next character will be the sum of all it's glyphs' widths. Bug:853376,277215 Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng Change-Id: I3a69d57dbb9f9c5cbc263da2d91f522f00ae4080 Reviewed-on: https://chromium-review.googlesource.com/1160874 Commit-Queue: David Quiroz Marin <davidqu@chromium.org> Reviewed-by: Fernando Serboncini <fserb@chromium.org> Cr-Commit-Position: refs/heads/master@{#583778}
Denger-Network · Aug 16, 2018 · 3c61aca · 3c61aca
1 parent 4098a12
commit 3c61aca
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Showing 8 changed files with 117 additions and 15 deletions.
diff --git a/third_party/WebKit/LayoutTests/fast/canvas-api/canvas-textMetrics-advances.html b/third_party/WebKit/LayoutTests/fast/canvas-api/canvas-textMetrics-advances.html
@@ -22,11 +22,11 @@
   { text: "ليس في اسمنا", rtl: true },
   { text: "\u202EHello", rtl: true },
   { text: "\u202EHello World", rtl: true },
-  // TODO(davidqu): Fix the following edge cases:
-  //{ text: "الله", rtl: true }, // Special ligatures.
-  //{ text: "🏁", rtl: false }, // One glyph with two "characters".
-  //{ text: "एक आम भाषा", rtl: false }, // Special post-modifying characters.
-  //{ text: "a\u0301", rtl: true }, // Combining diacritical marks
+  { text: "الله", rtl: true }, // Special ligatures.
+  { text: "اين المكتبة؟", rtl: true }, // Special ligatures.
+  { text: "🏁🎶🏁", rtl: false }, // One glyph with two "characters".
+  { text: "एक आम भाषा", rtl: false }, // Special post-modifying characters.
+  { text: "a\u0301", rtl: false }, // Combining diacritical marks
 ]
 
 function forEachExample(fn) {
@@ -75,7 +75,7 @@
   });
 }
 
-function testNonIncreasing(ctx) {
+function testNonIncreasingForRtl(ctx) {
   forEachExample((ex, align) => {
       if (ex.rtl) {
         const tm = getTextMetrics(ctx, ex.text, align, ex.rtl ? "rtl" : "ltr");
@@ -85,9 +85,9 @@
   });
 }
 
-function testNonDecreasing(ctx) {
+function testNonDecreasingForLtr(ctx) {
   forEachExample((ex, align) => {
-      if (ex.ltr) {
+      if (! ex.rtl) {
         const tm = getTextMetrics(ctx, ex.text, align, ex.rtl ? "rtl" : "ltr");
         assert_true(isNonDecreasing(tm.advances),
          "LTR advances must be non-decreasing (" + ex.text + ")");
@@ -106,7 +106,8 @@
 function testAdvances(ctx) {
   testEmptyStringReturnsEmptyAdvances(ctx);
   testAllPositive(ctx);
-  testNonDecreasing(ctx);
+  testNonIncreasingForRtl(ctx);
+  testNonDecreasingForLtr(ctx);
   testLastAdvanceLessThanWith(ctx);
 }
 

diff --git a/third_party/blink/renderer/core/html/canvas/text_metrics.cc b/third_party/blink/renderer/core/html/canvas/text_metrics.cc
@@ -66,11 +66,7 @@ void TextMetrics::Update(const Font& font,
   FloatRect bbox = font.BoundingBox(text_run);
   const FontMetrics& font_metrics = font_data->GetFontMetrics();
 
-  Vector<CharacterRange> ranges = font.IndividualCharacterRanges(text_run);
-  advances_.resize(ranges.size());
-  for (unsigned i = 0; i < ranges.size(); i++) {
-    advances_[i] = ranges[i].start;
-  }
+  advances_ = font.IndividualCharacterAdvances(text_run);
 
   // x direction
   width_ = bbox.Width();

diff --git a/third_party/blink/renderer/platform/fonts/font.cc b/third_party/blink/renderer/platform/fonts/font.cc
@@ -505,6 +505,12 @@ Vector<CharacterRange> Font::IndividualCharacterRanges(
   return ranges;
 }
 
+Vector<double> Font::IndividualCharacterAdvances(const TextRun& run) const {
+  FontCachePurgePreventer purge_preventer;
+  CachingWordShaper shaper(*this);
+  return shaper.IndividualCharacterAdvances(run);
+}
+
 void Font::ExpandRangeToIncludePartialGlyphs(const TextRun& text_run,
                                              int* from,
                                              int* to) const {

diff --git a/third_party/blink/renderer/platform/fonts/font.h b/third_party/blink/renderer/platform/fonts/font.h
@@ -156,6 +156,11 @@ class PLATFORM_EXPORT Font {
                                    unsigned to) const;
   Vector<CharacterRange> IndividualCharacterRanges(const TextRun&) const;
 
+  // Returns a vector of same size as TextRun.length() with advances measured
+  // in pixels from the left bounding box of the full TextRun to the left bound
+  // of the glyph rendered by each character. Values should always be positive.
+  Vector<double> IndividualCharacterAdvances(const TextRun&) const;
+
   void ExpandRangeToIncludePartialGlyphs(const TextRun&,
                                          int* from,
                                          int* to) const;

diff --git a/third_party/blink/renderer/platform/fonts/shaping/caching_word_shaper.cc b/third_party/blink/renderer/platform/fonts/shaping/caching_word_shaper.cc
@@ -111,7 +111,6 @@ Vector<CharacterRange> CachingWordShaper::IndividualCharacterRanges(
     const TextRun& run) {
   ShapeResultBuffer buffer;
   float total_width = ShapeResultsForRun(GetShapeCache(), &font_, run, &buffer);
-
   auto ranges = buffer.IndividualCharacterRanges(run.Direction(), total_width);
   // The shaper can fail to return glyph metrics for all characters (see
   // crbug.com/613915 and crbug.com/615661) so add empty ranges to ensure all
@@ -121,6 +120,14 @@ Vector<CharacterRange> CachingWordShaper::IndividualCharacterRanges(
   return ranges;
 }
 
+Vector<double> CachingWordShaper::IndividualCharacterAdvances(
+    const TextRun& run) {
+  ShapeResultBuffer buffer;
+  float total_width = ShapeResultsForRun(GetShapeCache(), &font_, run, &buffer);
+  return buffer.IndividualCharacterAdvances(run.ToStringView(), run.Direction(),
+                                            total_width);
+}
+
 Vector<ShapeResult::RunFontData> CachingWordShaper::GetRunFontData(
     const TextRun& run) const {
   ShapeResultBuffer buffer;

diff --git a/third_party/blink/renderer/platform/fonts/shaping/caching_word_shaper.h b/third_party/blink/renderer/platform/fonts/shaping/caching_word_shaper.h
@@ -61,6 +61,7 @@ class PLATFORM_EXPORT CachingWordShaper final {
   void FillResultBuffer(const TextRunPaintInfo&, ShapeResultBuffer*);
   CharacterRange GetCharacterRange(const TextRun&, unsigned from, unsigned to);
   Vector<CharacterRange> IndividualCharacterRanges(const TextRun&);
+  Vector<double> IndividualCharacterAdvances(const TextRun&);
 
   Vector<ShapeResult::RunFontData> GetRunFontData(const TextRun&) const;
 

diff --git a/third_party/blink/renderer/platform/fonts/shaping/shape_result_buffer.cc b/third_party/blink/renderer/platform/fonts/shaping/shape_result_buffer.cc
@@ -199,6 +199,86 @@ Vector<CharacterRange> ShapeResultBuffer::IndividualCharacterRanges(
   return ranges;
 }
 
+void ShapeResultBuffer::AddRunInfoAdvances(const ShapeResult::RunInfo& run_info,
+                                           float offset,
+                                           Vector<double>& advances) {
+  const unsigned num_glyphs = run_info.glyph_data_.size();
+  const unsigned num_chars = run_info.num_characters_;
+
+  if (run_info.Rtl())
+    offset += run_info.width_;
+
+  double current_width = 0;
+  for (unsigned glyph_id = 0; glyph_id < num_glyphs; glyph_id++) {
+    unsigned gid = run_info.Rtl() ? num_glyphs - glyph_id - 1 : glyph_id;
+    unsigned next_gid =
+        run_info.Rtl() ? num_glyphs - glyph_id - 2 : glyph_id + 1;
+    const HarfBuzzRunGlyphData& glyph = run_info.glyph_data_[gid];
+
+    unsigned char_id = glyph.character_index;
+    unsigned next_char_id =
+        (glyph_id + 1 == num_glyphs)
+            ? num_chars
+            : run_info.glyph_data_[next_gid].character_index;
+
+    current_width += glyph.advance;
+
+    if (char_id == next_char_id)
+      continue;
+
+    unsigned num_graphemes = run_info.NumGraphemes(char_id, next_char_id);
+
+    for (unsigned i = char_id; i < next_char_id; i++) {
+      if (run_info.Rtl()) {
+        advances.push_back(offset - (current_width / num_graphemes));
+      } else {
+        advances.push_back(offset);
+      }
+
+      if (num_graphemes == next_char_id - char_id) {
+        offset += (current_width / num_graphemes) * (run_info.Rtl() ? -1 : 1);
+      }
+    }
+
+    if (num_graphemes != next_char_id - char_id) {
+      offset += current_width * (run_info.Rtl() ? -1 : 1);
+    }
+
+    current_width = 0;
+  }
+}
+
+Vector<double> ShapeResultBuffer::IndividualCharacterAdvances(
+    const StringView& text,
+    TextDirection direction,
+    float total_width) const {
+  unsigned character_offset = 0;
+  Vector<double> advances;
+  float current_x = direction == TextDirection::kRtl ? total_width : 0;
+
+  for (const scoped_refptr<const ShapeResult> result : results_) {
+    unsigned run_count = result->runs_.size();
+
+    result->EnsureGraphemes(
+        StringView(text, character_offset, result->NumCharacters()));
+
+    if (result->Rtl()) {
+      for (int index = run_count - 1; index >= 0; index--) {
+        current_x -= result->runs_[index]->width_;
+        AddRunInfoAdvances(*result->runs_[index], current_x, advances);
+      }
+    } else {
+      for (unsigned index = 0; index < run_count; index++) {
+        AddRunInfoAdvances(*result->runs_[index], current_x, advances);
+        current_x += result->runs_[index]->width_;
+      }
+    }
+
+    character_offset += result->NumCharacters();
+  }
+  return advances;
+}
+
 int ShapeResultBuffer::OffsetForPosition(
     const TextRun& run,
     float target_x,

diff --git a/third_party/blink/renderer/platform/fonts/shaping/shape_result_buffer.h b/third_party/blink/renderer/platform/fonts/shaping/shape_result_buffer.h
@@ -44,6 +44,9 @@ class PLATFORM_EXPORT ShapeResultBuffer {
                                    unsigned to) const;
   Vector<CharacterRange> IndividualCharacterRanges(TextDirection,
                                                    float total_width) const;
+  Vector<double> IndividualCharacterAdvances(const StringView&,
+                                             TextDirection,
+                                             float total_width) const;
 
   static CharacterRange GetCharacterRange(scoped_refptr<const ShapeResult>,
                                           const StringView& text,
@@ -68,6 +71,9 @@ class PLATFORM_EXPORT ShapeResultBuffer {
       unsigned from,
       unsigned to);
 
+  static void AddRunInfoAdvances(const ShapeResult::RunInfo& run_info,
+                                 float offset,
+                                 Vector<double>& advances);
   static void AddRunInfoRanges(const ShapeResult::RunInfo&,
                                float offset,
                                Vector<CharacterRange>&);