ui/gfx/font_fallback_win.h

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_GFX_FONT_FALLBACK_WIN_H_
#define UI_GFX_FONT_FALLBACK_WIN_H_

#include <stddef.h>

#include <string>
#include <vector>

#include "base/macros.h"
#include "ui/gfx/font.h"
#include "ui/gfx/font_fallback.h"

namespace gfx {

// Internals of font_fallback_win.cc exposed for testing.
namespace internal {

// Parses comma separated SystemLink |entry|, per the format described here:
// http://msdn.microsoft.com/en-us/goglobal/bb688134.aspx
//
// Sets |filename| and |font_name| respectively. If a field is not present
// or could not be parsed, the corresponding parameter will be cleared.
void GFX_EXPORT ParseFontLinkEntry(const std::string& entry,
                                  std::string* filename,
                                  std::string* font_name);

// Parses a font |family| in the format "FamilyFoo & FamilyBar (TrueType)".
// Splits by '&' and strips off the trailing parenthesized expression.
void GFX_EXPORT ParseFontFamilyString(const std::string& family,
                                     std::vector<std::string>* font_names);

// Iterator over linked fallback fonts for a given font. The linked font chain
// comes from the Windows registry, but gets cached between uses.
class GFX_EXPORT LinkedFontsIterator {
 public:
  // Instantiates the iterator over the linked font chain for |font|. The first
  // item will be |font| itself.
  explicit LinkedFontsIterator(Font font);
  virtual ~LinkedFontsIterator();

  // Sets the font that would be returned by the next call to |NextFont()|,
  // useful for inserting one-time entries into the iterator chain.
  void SetNextFont(Font font);

  // Gets the next font in the link chain, if available, and increments the
  // iterator. Returns |true| on success or |false| if the iterator is past
  // last item (in that case, the value of |font| should not be used). If
  // |SetNextFont()| was called, returns the font set that way and clears it.
  bool NextFont(Font* font);

 protected:
  // Retrieves the list of linked fonts. Protected and virtual so that it may
  // be overridden by tests.
  virtual const std::vector<Font>* GetLinkedFonts() const;

 private:
  // Original font whose linked fonts are being iterated over.
  Font original_font_;

  // Font that was set via |SetNextFont()|.
  Font next_font_;

  // Indicates whether |SetNextFont()| was called.
  bool next_font_set_;

  // The font most recently returned by |NextFont()|.
  Font current_font_;

  // List of linked fonts; weak pointer.
  const std::vector<Font>* linked_fonts_;

  // Index of the current entry in the |linked_fonts_| list.
  size_t linked_font_index_;

  DISALLOW_COPY_AND_ASSIGN(LinkedFontsIterator);
};

}  // namespace internal

// Finds a fallback font to render the specified |text| with respect to an
// initial |font|. Returns the resulting font via out param |result|. Returns
// |true| if a fallback font was found.
bool GFX_EXPORT GetFallbackFont(const Font& font,
                                const wchar_t* text,
                                int text_length,
                                Font* result);

}  // namespace gfx

#endif  // UI_GFX_FONT_FALLBACK_WIN_H_