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      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef UI_BASE_IME_CHROMEOS_CHARACTER_COMPOSER_H_
      6 #define UI_BASE_IME_CHROMEOS_CHARACTER_COMPOSER_H_
      7 
      8 #include <vector>
      9 
     10 #include "base/strings/string_util.h"
     11 #include "ui/base/ui_base_export.h"
     12 
     13 namespace ui {
     14 class KeyEvent;
     15 
     16 // A class to recognize compose and dead key sequence.
     17 // Outputs composed character.
     18 class UI_BASE_EXPORT CharacterComposer {
     19  public:
     20   CharacterComposer();
     21   ~CharacterComposer();
     22 
     23   void Reset();
     24 
     25   // Filters keypress.
     26   // Returns true if the keypress is recognized as a part of composition
     27   // sequence.
     28   // Fabricated events which don't have the native event, are not supported.
     29   bool FilterKeyPress(const ui::KeyEvent& event);
     30 
     31   // Returns a string consisting of composed character.
     32   // Empty string is returned when there is no composition result.
     33   const base::string16& composed_character() const {
     34     return composed_character_;
     35   }
     36 
     37   // Returns the preedit string.
     38   const base::string16& preedit_string() const { return preedit_string_; }
     39 
     40  private:
     41   friend class CharacterComposerTest;
     42 
     43   // An enum to describe composition mode.
     44   enum CompositionMode {
     45     // This is the initial state.
     46     // Composite a character with dead-keys and compose-key.
     47     KEY_SEQUENCE_MODE,
     48     // Composite a character with a hexadecimal unicode sequence.
     49     HEX_MODE,
     50   };
     51 
     52   // Filters keypress using IBus defined value.
     53   // Returns true if the keypress is recognized as a part of composition
     54   // sequence.
     55   // |keyval| must be a GDK_KEY_* constant.
     56   // |keycode| must be a X key code.
     57   // |flags| must be a combination of ui::EF_* flags.
     58   //
     59   // composed_character() returns non empty string when there is a character
     60   // composed after this method returns true.
     61   // preedit_string() returns non empty string when there is a preedit string
     62   // after this method returns true.
     63   // Return values of preedit_string() is empty after this method returns false.
     64   // composed_character() may have some characters which are consumed in this
     65   // composing session.
     66   //
     67   //
     68   // TODO(nona): Actually a X KeySym is passed to |keyval|, so we should use
     69   // XK_* rather than GDK_KEY_*.
     70   bool FilterKeyPressInternal(unsigned int keyval, unsigned int keycode,
     71                               int flags);
     72 
     73   // Filters keypress in key sequence mode.
     74   bool FilterKeyPressSequenceMode(unsigned int keyval, int flags);
     75 
     76   // Filters keypress in hexadecimal mode.
     77   bool FilterKeyPressHexMode(unsigned int keyval, unsigned int keycode,
     78                              int flags);
     79 
     80   // Commit a character composed from hexadecimal uncode sequence
     81   void CommitHex();
     82 
     83   // Updates preedit string in hexadecimal mode.
     84   void UpdatePreeditStringHexMode();
     85 
     86   // Remembers keypresses previously filtered.
     87   std::vector<unsigned int> compose_buffer_;
     88 
     89   // A string representing the composed character.
     90   base::string16 composed_character_;
     91 
     92   // Preedit string.
     93   base::string16 preedit_string_;
     94 
     95   // Composition mode which this instance is in.
     96   CompositionMode composition_mode_;
     97 
     98   DISALLOW_COPY_AND_ASSIGN(CharacterComposer);
     99 };
    100 
    101 }  // namespace ui
    102 
    103 #endif  // UI_BASE_IME_CHROMEOS_CHARACTER_COMPOSER_H_
    104