ui/events/keycodes/keyboard_code_conversion.h

   1 // Copyright (c) 2011 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_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_H_
   6 #define UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_H_
   7
   8 #include "base/strings/string16.h"
   9 #include "ui/events/events_base_export.h"
  10 #include "ui/events/keycodes/keyboard_codes.h"
  11
  12 namespace ui {
  13
  14 enum class DomKey;
  15
  16 // Helper functions to get the meaning of a Windows key code in a
  17 // platform independent way. It supports control characters as well.
  18 // It assumes a US keyboard layout is used, so it may only be used when there
  19 // is no native event or no better way to get the character.
  20 // For example, if a virtual keyboard implementation can only generate key
  21 // events with key_code and flags information, then there is no way for us to
  22 // determine the actual character that should be generate by the key. Because
  23 // a key_code only represents a physical key on the keyboard, it has nothing
  24 // to do with the actual character printed on that key. In such case, the only
  25 // thing we can do is to assume that we are using a US keyboard and get the
  26 // character according to US keyboard layout definition.
  27 // If a virtual keyboard implementation wants to support other keyboard
  28 // layouts, that may generate different text for a certain key than on a US
  29 // keyboard, a special native event object should be introduced to carry extra
  30 // information to help determine the correct character.
  31 // Take XKeyEvent as an example, it contains not only keycode and modifier
  32 // flags but also group and other extra XKB information to help determine the
  33 // correct character. That's why we can use XLookupString() function to get
  34 // the correct text generated by a X key event (See how is GetCharacter()
  35 // implemented in event_x.cc).
  36 EVENTS_BASE_EXPORT base::char16 GetCharacterFromKeyCode(KeyboardCode key_code,
  37                                                         int flags);
  38 EVENTS_BASE_EXPORT bool GetMeaningFromKeyCode(KeyboardCode key_code,
  39                                               int flags,
  40                                               DomKey* dom_key,
  41                                               base::char16* character);
  42
  43 }  // namespace ui
  44
  45 #endif  // UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_H_