Add support for shaper-driven line breaking to HarfBuzzShaper

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

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 24 matching lines @@
 #include "platform/fonts/shaping/ShapeResult.h"
 #include "wtf/Allocator.h"
 #include "wtf/Deque.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class Font;
 class SimpleFontData;
 class HarfBuzzShaper;
+class LayoutUnit;
 struct HolesQueueItem;
+enum class LineBreakType;
 
 class PLATFORM_EXPORT HarfBuzzShaper final {
  public:
   HarfBuzzShaper(const UChar*, unsigned length);
 
   // Shape a range, defined by the start and end parameters, of the string
   // supplied to the constructor.
   // The start and end positions should represent boundaries where a break may
   // occur, such as at the beginning or end of lines or at element boundaries.
   // If given arbitrary positions the results are not guaranteed to be correct.
   // May be called multiple times; font and direction may vary between calls.
   PassRefPtr<ShapeResult> shape(const Font*,
                                 TextDirection,
                                 unsigned start,
                                 unsigned end) const;
 
   // Shape the entire string with a single font and direction.
   // Equivalent to calling the range version with a start offset of zero and an
   // end offset equal to the length.
   PassRefPtr<ShapeResult> shape(const Font*, TextDirection) const;
 
+  // Shapes a line of text by finding a valid and appropriate break opportunity
+  // based on the shaping results for the entire paragraph.
+  // The output parameter breakOffset indicates the resulting break offset.
+  PassRefPtr<ShapeResult> shapeLine(const Font*,
+                                    const ShapeResult*,
+                                    unsigned startOffset,
+                                    const AtomicString locale,

[jbroman, 2017/03/21 21:30:08]

drive-by: const AtomicString&? (this currently unnecessarily bumps the ref
count)

+                                    LineBreakType,
+                                    LayoutUnit availableSpace,
+                                    unsigned* breakOffset) const;
+
   ~HarfBuzzShaper() {}
 
  private:
   struct RangeData;
 
   // Shapes a single seqment, as identified by the RunSegmenterRange parameter,
   // one or more times taking font fallback into account. The start and end
   // parameters are for the entire text run, not the segment, and are used to
   // determine pre- and post-context for shaping.
   void shapeSegment(RangeData*,
@@ skipping 11 matching lines @@
   bool collectFallbackHintChars(const Deque<HolesQueueItem>&,
                                 Vector<UChar32>& hint) const;
 
   const UChar* m_text;
   unsigned m_textLength;
 };
 
 }  // namespace blink
 
 #endif  // HarfBuzzShaper_h