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:
SkTextBlobBuilderRunHandler(const char * utf8Text)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;
commitLine()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