Add sfntly library for font subsetting used in print preview.

third_party/sfntly/src/subsetter/subsetter_impl.h

+/*
+ * Copyright 2011 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef THIRD_PARTY_SFNTLY_SRC_SUBSETTER_SUBSETTER_IMPL_H_
+#define THIRD_PARTY_SFNTLY_SRC_SUBSETTER_SUBSETTER_IMPL_H_
+
+#include "third_party/sfntly/src/sfntly/font.h"
+#include "third_party/sfntly/src/sfntly/font_factory.h"
+
+namespace sfntly {
+
+// Smart pointer usage in sfntly:
+//
+// sfntly carries a smart pointer implementation like COM.  Ref-countable object
+// type inherits from RefCounted<>, which have AddRef and Release just like
+// IUnknown (but no QueryInterface).  Use a Ptr<> based smart pointer to hold
+// the object so that the object ref count is handled correctly.
+//
+// class Foo : public RefCounted<Foo> {
+//  public:
+//   static Foo* CreateInstance() {
+//     Ptr<Foo> obj = new Foo();  // ref count = 1
+//     return obj.detach();
+//   }
+// };
+// typedef Ptr<Foo> FooPtr;  // common short-hand notation
+// FooPtr obj;
+// obj.attach(Foo::CreatedInstance());  // ref count = 1
+// {
+//   FooPtr obj2 = obj;  // ref count = 2
+// }  // ref count = 1, obj2 out of scope
+// obj.release();  // ref count = 0, object destroyed
+
+class SubsetterImpl {
+ public:
+  SubsetterImpl();
+  ~SubsetterImpl();
+
+  bool LoadFont(const char* font_name,
+                const unsigned char* original_font,
+                size_t font_size);
+  int SubsetFont(const unsigned int* glyph_ids,
+                 size_t glyph_count,
+                 unsigned char** output_buffer);
+
+ private:
+  Font* FindFont(const char* font_name, const FontArray& font_array);
+  bool HasName(const char* font_name, Font* font);
+  CALLER_ATTACH Font* Subset(const unsigned int* glyph_ids,
+                             size_t glyph_count);
+
+  FontFactoryPtr factory_;
+  FontPtr font_;
+};
+
+}  // namespace sfntly
+
+#endif  // THIRD_PARTY_SFNTLY_SRC_SUBSETTER_SUBSETTER_IMPL_H_