1 files changed, 65 insertions, 0 deletions
diff --git a/gfx/skia/skia/src/utils/SkCharToGlyphCache.h b/gfx/skia/skia/src/utils/SkCharToGlyphCache.h
new file mode 100644
index 0000000000..8137131587
--- /dev/null
+++ b/gfx/skia/skia/src/utils/SkCharToGlyphCache.h
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2019 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkCharToGlyphCache_DEFINED
+#define SkCharToGlyphCache_DEFINED
+
+#include "include/core/SkTypes.h"
+#include "include/private/base/SkTDArray.h"
+#include "include/private/base/SkTo.h"
+
+#include <cstdint>
+
+class SkCharToGlyphCache {
+public:
+    SkCharToGlyphCache();
+    ~SkCharToGlyphCache();
+
+    // return number of unichars cached
+    int count() const {
+        return fK32.size();
+    }
+
+    void reset();       // forget all cache entries (to save memory)
+
+    /**
+     *  Given a unichar, return its glyphID (if the return value is positive), else return
+     *  ~index of where to insert the computed glyphID.
+     *
+     *  int result = cache.charToGlyph(unichar);
+     *  if (result >= 0) {
+     *      glyphID = result;
+     *  } else {
+     *      glyphID = compute_glyph_using_typeface(unichar);
+     *      cache.insertCharAndGlyph(~result, unichar, glyphID);
+     *  }
+     */
+    int findGlyphIndex(SkUnichar c) const;
+
+    /**
+     *  Insert a new char/glyph pair into the cache at the specified index.
+     *  See charToGlyph() for how to compute the bit-not of the index.
+     */
+    void insertCharAndGlyph(int index, SkUnichar, SkGlyphID);
+
+    // helper to pre-seed an entry in the cache
+    void addCharAndGlyph(SkUnichar unichar, SkGlyphID glyph) {
+        int index = this->findGlyphIndex(unichar);
+        if (index >= 0) {
+            SkASSERT(SkToU16(index) == glyph);
+        } else {
+            this->insertCharAndGlyph(~index, unichar, glyph);
+        }
+    }
+
+private:
+    SkTDArray<int32_t>   fK32;
+    SkTDArray<uint16_t>  fV16;
+    double               fDenom;
+};
+
+#endif