Add sfntly library for font subsetting used in print preview.

third_party/sfntly/src/subsetter/font_subsetter.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 FONT_SUBSETTER_H_

[brettw, 2011/07/19 05:09:42]

If this is going to be our code, I'd like to have it use Google style, so full
include guards (THIRD_PARTY_SFNTLY_SRC_SUBSETTER_FONT_SUBSETTER_H_) and header
include paths (for the .cc files).

[arthurhsu, 2011/07/19 18:34:32]

Done.

+#define FONT_SUBSETTER_H_
+
+#include <cstddef>
+
+// Font subsetting API
+//
+// Input TTF/TTC/OTF fonts, specify the glyph IDs to subset, and the subset font
+// is returned in |output_buffer| (caller to delete[]).  Return value is the
+// length of output_buffer allocated.
+//
+// If subsetting failes, a negative value is returned.  If none of the glyph IDs
+// specified is found, the function will return 0.
+//
+// |font_name|      Font name of the font, required for TTC files.  If specified
+//                  NULL, the first available font is selected.
+// |original_font|  Original font file contents.
+// |font_size|      Size of |original_font| in bytes.
+// |glyph_ids|      Glyph IDs to subset.  If the specified glyph ID is not found
+//                  in the font file, it will be ignored silently.
+// |glyph_count|    Number of glyph IDs in |glyph_ids|
+// |output_buffer|  Generated subset font.
+extern int subsetFont(const char* font_name,

[brettw, 2011/07/18 22:57:52]

It's not clear to me what's going on here. This subsetter code isn't part of the
sfntly library? Is this coming from some other place? If Chrome is the canonial
repo, it doesn't seem like it should be in third_party.

[brettw, 2011/07/19 05:09:42]

Function names should be capital. I'm also wondering if there should be some
kind of namespace? This is a pretty generic name. I notice you used sfntly in
the implementation, I'd prefer that here. If you want to hide those other
functions, you can put it in sfntly::internal

[arthurhsu, 2011/07/19 18:34:32]

Done.  Wrapped as a static method in SfntlyWrapper class.

[arthurhsu, 2011/07/19 18:34:32]

sfntly disagreed the subsetter code to be upstream so we need to put them
somewhere in Chrome.  As mentioned, I've asked in Chromium-dev and the
suggestion from there is to stay in third_party.  Do you think I should move the
subsetter code to Chromium src/sfntly instead?

+                      const unsigned char* original_font,
+                      const size_t font_size,

[brettw, 2011/07/19 05:09:42]

Generally I don't see people writing const on copied POD input arguments.

[arthurhsu, 2011/07/19 18:34:32]

Done.

+                      const unsigned int* glyph_ids,
+                      const size_t glyph_count,
+                      unsigned char** output_buffer);
+
+#endif  // FONT_SUBSETTER_H_