1 /*
2  * Copyright 2019 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 SkCharToGlyphCache_DEFINED
9 #define SkCharToGlyphCache_DEFINED
10 
11 #include "include/core/SkTypes.h"
12 #include "include/private/SkTDArray.h"
13 
14 class SkCharToGlyphCache {
15 public:
16     SkCharToGlyphCache();
17     ~SkCharToGlyphCache();
18 
19     // return number of unichars cached
count()20     int count() const {
21         return fK32.count();
22     }
23 
24     void reset();       // forget all cache entries (to save memory)
25 
26     /**
27      *  Given a unichar, return its glyphID (if the return value is positive), else return
28      *  ~index of where to insert the computed glyphID.
29      *
30      *  int result = cache.charToGlyph(unichar);
31      *  if (result >= 0) {
32      *      glyphID = result;
33      *  } else {
34      *      glyphID = compute_glyph_using_typeface(unichar);
35      *      cache.insertCharAndGlyph(~result, unichar, glyphID);
36      *  }
37      */
38     int findGlyphIndex(SkUnichar c) const;
39 
40     /**
41      *  Insert a new char/glyph pair into the cache at the specified index.
42      *  See charToGlyph() for how to compute the bit-not of the index.
43      */
44     void insertCharAndGlyph(int index, SkUnichar, SkGlyphID);
45 
46     // helper to pre-seed an entry in the cache
addCharAndGlyph(SkUnichar unichar,SkGlyphID glyph)47     void addCharAndGlyph(SkUnichar unichar, SkGlyphID glyph) {
48         int index = this->findGlyphIndex(unichar);
49         if (index >= 0) {
50             SkASSERT(SkToU16(index) == glyph);
51         } else {
52             this->insertCharAndGlyph(~index, unichar, glyph);
53         }
54     }
55 
56 private:
57     SkTDArray<int32_t>   fK32;
58     SkTDArray<uint16_t>  fV16;
59     double               fDenom;
60 };
61 
62 #endif
63