Add ShapeResult::SubRange

A small utility function that creates a ShapeResult and CopyRange.

Used in one place, and another coming in line breaker WIP.

Also changed |primary_font_| field to const to eliminate a const_cast.

Bug: 636993
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: I293bf245a360841ddc5ce87e805b60770b2ec553
Reviewed-on: https://chromium-review.googlesource.com/846603
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526447}

third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaperTest.cpp

@@ -776,6 +776,19 @@ TEST_F(HarfBuzzShaperTest, ShapeResultCopyRangeSegmentGlyphBoundingBox) {
   EXPECT_NEAR(result->Width(), result->Bounds().Width(), result->Width() * .1);
 }
 
+TEST_F(HarfBuzzShaperTest, SubRange) {
+  String string(u"Hello world");
+  TextDirection direction = TextDirection::kRtl;
+  HarfBuzzShaper shaper(string.Characters16(), string.length());
+  scoped_refptr<ShapeResult> result = shaper.Shape(&font, direction);
+
+  scoped_refptr<ShapeResult> sub_range = result->SubRange(4, 7);
+  DCHECK_EQ(4u, sub_range->StartIndexForResult());
+  DCHECK_EQ(7u, sub_range->EndIndexForResult());
+  DCHECK_EQ(3u, sub_range->NumCharacters());
+  DCHECK_EQ(result->Direction(), sub_range->Direction());
+}
+
 TEST_F(HarfBuzzShaperTest, SafeToBreakLatinCommonLigatures) {
   FontDescription::VariantLigatures ligatures;
   ligatures.common = FontDescription::kEnabledLigaturesState;

third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.cpp

@@ -195,16 +195,21 @@ void ShapeResult::RunInfo::SetGlyphAndPositions(unsigned index,
   data.offset = FloatSize(offset_x, offset_y);
 }
 
-ShapeResult::ShapeResult(const Font* font,
+ShapeResult::ShapeResult(const SimpleFontData* font_data,
                          unsigned num_characters,
                          TextDirection direction)
     : width_(0),
-      primary_font_(const_cast<SimpleFontData*>(font->PrimaryFont())),
+      primary_font_(font_data),
       num_characters_(num_characters),
       num_glyphs_(0),
       direction_(static_cast<unsigned>(direction)),
       has_vertical_offsets_(0) {}
 
+ShapeResult::ShapeResult(const Font* font,
+                         unsigned num_characters,
+                         TextDirection direction)
+    : ShapeResult(font->PrimaryFont(), num_characters, direction) {}
+
 ShapeResult::ShapeResult(const ShapeResult& other)
     : width_(other.width_),
       glyph_bounding_box_(other.glyph_bounding_box_),
@@ -814,6 +819,14 @@ void ShapeResult::CopyRange(unsigned start_offset,
 #endif
 }
 
+scoped_refptr<ShapeResult> ShapeResult::SubRange(unsigned start_offset,
+                                                 unsigned end_offset) const {
+  scoped_refptr<ShapeResult> sub_range =
+      Create(primary_font_.get(), 0, Direction());
+  CopyRange(start_offset, end_offset, sub_range.get());
+  return sub_range;
+}
+
 #if DCHECK_IS_ON()
 void ShapeResult::CheckConsistency() const {
   if (runs_.IsEmpty()) {

third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.h

@@ -124,6 +124,8 @@ class PLATFORM_EXPORT ShapeResult : public RefCounted<ShapeResult> {
                                          const TextRun&) const;
 
   void CopyRange(unsigned start, unsigned end, ShapeResult*) const;
+  scoped_refptr<ShapeResult> SubRange(unsigned start_offset,
+                                      unsigned end_offset) const;
 
   String ToString() const;
   void ToString(StringBuilder*) const;
@@ -138,10 +140,16 @@ class PLATFORM_EXPORT ShapeResult : public RefCounted<ShapeResult> {
 #endif
 
  protected:
-
+  ShapeResult(const SimpleFontData*, unsigned num_characters, TextDirection);
   ShapeResult(const Font*, unsigned num_characters, TextDirection);
   ShapeResult(const ShapeResult&);
 
+  static scoped_refptr<ShapeResult> Create(const SimpleFontData* font_data,
+                                           unsigned num_characters,
+                                           TextDirection direction) {
+    return base::AdoptRef(
+        new ShapeResult(font_data, num_characters, direction));
+  }
   static scoped_refptr<ShapeResult> Create(const ShapeResult& other) {
     return base::AdoptRef(new ShapeResult(other));
   }
@@ -166,7 +174,7 @@ class PLATFORM_EXPORT ShapeResult : public RefCounted<ShapeResult> {
   float width_;
   FloatRect glyph_bounding_box_;
   Vector<std::unique_ptr<RunInfo>> runs_;
-  scoped_refptr<SimpleFontData> primary_font_;
+  scoped_refptr<const SimpleFontData> primary_font_;
 
   unsigned num_characters_;
   unsigned num_glyphs_ : 30;

third_party/WebKit/Source/platform/fonts/shaping/ShapingLineBreaker.cpp

@@ -387,8 +387,7 @@ scoped_refptr<ShapeResult> ShapingLineBreaker::ShapeToEnd(unsigned start,
   TextDirection direction = result_->Direction();
   if (first_safe == start) {
     // If |start| is safe-to-break no reshape is needed.
-    line_result = ShapeResult::Create(font_, 0, direction);
-    result_->CopyRange(start, range_end, line_result.get());
+    line_result = result_->SubRange(start, range_end);
   } else if (first_safe < range_end) {
     // Otherwise reshape to |first_safe|, then copy the rest.
     line_result = Shape(direction, start, first_safe);