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      1 /*
      2  * Copyright 2016 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef SkShaper_DEFINED
      9 #define SkShaper_DEFINED
     10 
     11 #include <memory>
     12 
     13 #include "SkPoint.h"
     14 #include "SkSpan.h"
     15 #include "SkTextBlob.h"
     16 #include "SkTypeface.h"
     17 
     18 class SkFont;
     19 
     20 /**
     21    Shapes text using HarfBuzz and places the shaped text into a
     22    client-managed buffer.
     23 
     24    If compiled without HarfBuzz, fall back on SkPaint::textToGlyphs.
     25  */
     26 class SkShaper {
     27 public:
     28     static std::unique_ptr<SkShaper> MakePrimitive();
     29     #ifdef SK_SHAPER_HARFBUZZ_AVAILABLE
     30     static std::unique_ptr<SkShaper> MakeHarfBuzz();
     31     #endif
     32 
     33     static std::unique_ptr<SkShaper> Make();
     34 
     35     SkShaper();
     36     virtual ~SkShaper();
     37 
     38     class RunHandler {
     39     public:
     40         virtual ~RunHandler() = default;
     41 
     42         struct RunInfo {
     43             SkVector fAdvance;
     44             SkScalar fAscent,
     45                      fDescent,
     46                      fLeading;
     47         };
     48 
     49         struct Buffer {
     50             SkGlyphID* glyphs;    // required
     51             SkPoint*   positions; // required
     52             uint32_t*  clusters;  // optional
     53         };
     54 
     55         // Callback per glyph run.
     56         virtual Buffer newRunBuffer(const RunInfo&, const SkFont&, int glyphCount,
     57                                     SkSpan<const char> utf8) = 0;
     58 
     59         // Called after run information is filled out.
     60         virtual void commitRun() = 0;
     61         // Callback per line.
     62         virtual void commitLine() = 0;
     63     };
     64 
     65     virtual SkPoint shape(RunHandler* handler,
     66                           const SkFont& srcFont,
     67                           const char* utf8text,
     68                           size_t textBytes,
     69                           bool leftToRight,
     70                           SkPoint point,
     71                           SkScalar width) const = 0;
     72 
     73 private:
     74     SkShaper(const SkShaper&) = delete;
     75     SkShaper& operator=(const SkShaper&) = delete;
     76 };
     77 
     78 /**
     79  * Helper for shaping text directly into a SkTextBlob.
     80  */
     81 class SkTextBlobBuilderRunHandler final : public SkShaper::RunHandler {
     82 public:
     83     SkTextBlobBuilderRunHandler(const char* utf8Text) : fUtf8Text(utf8Text) {}
     84     sk_sp<SkTextBlob> makeBlob();
     85 
     86     SkShaper::RunHandler::Buffer newRunBuffer(const RunInfo&, const SkFont&, int, SkSpan<const char>) override;
     87     void commitRun() override;
     88     void commitLine() override {}
     89 
     90 private:
     91     SkTextBlobBuilder fBuilder;
     92     char const * const fUtf8Text;
     93     uint32_t* fClusters;
     94     int fClusterOffset;
     95     int fGlyphCount;
     96 };
     97 
     98 #endif  // SkShaper_DEFINED
     99