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#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_SHAPING_HARFBUZZ_SHAPER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_SHAPING_HARFBUZZ_SHAPER_H_

#include "third_party/blink/renderer/platform/fonts/font_fallback_iterator.h"
#include "third_party/blink/renderer/platform/fonts/shaping/run_segmenter.h"
#include "third_party/blink/renderer/platform/fonts/shaping/shape_options.h"
#include "third_party/blink/renderer/platform/fonts/shaping/shape_result.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"

namespace blink {

class Font;
class SimpleFontData;
class HarfBuzzShaper;
struct ReshapeQueueItem;
struct RangeContext;
struct BufferSlice;

class PLATFORM_EXPORT HarfBuzzShaper final {
  DISALLOW_NEW();

 public:
  explicit HarfBuzzShaper(String text) : text_(std::move(text)) {}

  // 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.
  ShapeResult* Shape(const Font*,
                     TextDirection,
                     unsigned start,
                     unsigned end) const;

  // Shape a range that has already been pre-segmented. Start and end positions
  // must match the positions defined by the ranges and must be at valid break
  // positions.
  ShapeResult* Shape(const Font*,
                     TextDirection,
                     unsigned start,
                     unsigned end,
                     const Vector<RunSegmenter::RunSegmenterRange>&,
                     ShapeOptions = ShapeOptions()) const;

  // Shape a single range. Start and end positions defined by the range.
  ShapeResult* Shape(const Font*,
                     TextDirection,
                     unsigned start,
                     unsigned end,
                     const RunSegmenter::RunSegmenterRange,
                     ShapeOptions = ShapeOptions()) 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.
  ShapeResult* Shape(const Font*, TextDirection) const;

  const String& GetText() const { return text_; }
  unsigned TextLength() const { return text_.length(); }

  // This function is between `Shape` and `SimpleFontData::GlyphForCharacter`.
  //
  // Unlike `Shape`, it works only for one `SimpleFontData`, not `Font`, without
  // cascading nor fallback. Missing glyphs are reported as `.notdef` (0). Also
  // it's a lot less expensive than `Shape`.
  //
  // Unlike `SimpleFontData::GlyphForCharacter`, it shapes, taking locale,
  // script, and OpenType features into account.
  struct GlyphData {
    unsigned cluster;
    Glyph glyph;
    gfx::PointF advance;
    gfx::PointF offset;
  };
  using GlyphDataList = Vector<GlyphData, 16>;
  void GetGlyphData(const SimpleFontData& font_data,
                    const LayoutLocale& locale,
                    UScriptCode script,
                    bool is_horizontal,
                    TextDirection direction,
                    GlyphDataList& glyphs);
  enum FallbackFontStage {
    // There were no unshaped variation sequences found, so we don't need to
    // perform second fallback fonts list pass.
    kIntermediate,
    kLast,
    // Found unshaped variation sequences and we are on the first fallback pass,
    // so we are including variation selectors during shaping.
    kIntermediateWithVS,
    kLastWithVS,
    // Found unshaped variation sequences and we are on the second and last
    // fallback pass, so we are ignoring variation selectors during shaping.
    kIntermediateIgnoreVS,
    kLastIgnoreVS
  };

  ~HarfBuzzShaper() = default;

 private:
  using HintCharList = FontFallbackIterator::HintCharList;

  // 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(RangeContext*,
                    const RunSegmenter::RunSegmenterRange&,
                    ShapeResult*) const;

  void ExtractShapeResults(RangeContext*,
                           bool& font_cycle_queued,
                           const ReshapeQueueItem&,
                           const SimpleFontData*,
                           UScriptCode,
                           CanvasRotationInVertical,
                           FallbackFontStage& fallback_stage,
                           ShapeResult*) const;

  bool CollectFallbackHintChars(const Deque<ReshapeQueueItem>&,
                                bool needs_hint_list,
                                HintCharList& hint) const;

  void CommitGlyphs(RangeContext*,
                    const SimpleFontData* current_font,
                    UScriptCode current_run_script,
                    CanvasRotationInVertical,
                    FallbackFontStage fallback_stage,
                    const BufferSlice&,
                    ShapeResult*) const;

  void CheckTextLen(unsigned start, unsigned length) const;
  void CheckTextEnd(unsigned start, unsigned end) const;

  const String text_;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_SHAPING_HARFBUZZ_SHAPER_H_