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/compiler_specific.h"
   9 #include "base/strings/string16.h"
  10 #include "ui/events/events_base_export.h"
  11 #include "ui/events/keycodes/keyboard_codes.h"
  12
  13 namespace ui {
  14
  15 enum class DomCode;
  16 enum class DomKey;
  17
  18 // Helper functions to get the meaning of a DOM |code| in a
  19 // platform independent way. It supports control characters as well.
  20 // It assumes a US keyboard layout is used, so it may only be used when there
  21 // is no native event or no better way to get the character.
  22 //
  23 // For example, if a virtual keyboard implementation can only generate key
  24 // events with key_code and flags information, then there is no way for us to
  25 // determine the actual character that should be generate by the key. Because
  26 // a key_code only represents a physical key on the keyboard, it has nothing
  27 // to do with the actual character printed on that key. In such case, the only
  28 // thing we can do is to assume that we are using a US keyboard and get the
  29 // character according to US keyboard layout definition. Preferably, such
  30 // events should be created using a full KeyEvent constructor, explicitly
  31 // specifying the character and DOM 3 values as well as the legacy VKEY.
  32
  33 // Helper function to map a physical key state (dom_code and flags)
  34 // to a meaning (dom_key and character, together corresponding to the
  35 // DOM keyboard event |key| value), along with a corresponding Windows-based
  36 // key_code.
  37 //
  38 // This follows a US keyboard layout, so it should only be used when there
  39 // is no other better way to obtain the meaning (e.g. actual keyboard layout).
  40 // Returns true and sets the output parameters if the (dom_code, flags) pair
  41 // has an interpretation in the US English layout; otherwise the output
  42 // parameters are untouched.
  43 EVENTS_BASE_EXPORT base::char16 DomCodeToUsLayoutCharacter(DomCode dom_code,
  44                                                            int flags);
  45 EVENTS_BASE_EXPORT bool DomCodeToUsLayoutMeaning(DomCode dom_code,
  46                                                  int flags,
  47                                                  DomKey* dom_key,
  48                                                  base::char16* character,
  49                                                  KeyboardCode* key_code)
  50     WARN_UNUSED_RESULT;
  51
  52 // Obtains the control character corresponding to a physical key;
  53 // that is, the meaning of the physical key state (dom_code, and flags
  54 // containing EF_CONTROL_DOWN) under the base US English layout.
  55 // Returns true and sets the output parameters if the (dom_code, flags) pair
  56 // is interpreted as a control character; otherwise the output parameters
  57 // are untouched.
  58 EVENTS_BASE_EXPORT bool DomCodeToControlCharacter(DomCode dom_code,
  59                                                   int flags,
  60                                                   DomKey* dom_key,
  61                                                   base::char16* character,
  62                                                   KeyboardCode* key_code)
  63     WARN_UNUSED_RESULT;
  64
  65 // Returns a Windows-based VKEY for a non-printable DOM Level 3 |key|.
  66 // The returned VKEY is non-located (e.g. VKEY_SHIFT).
  67 EVENTS_BASE_EXPORT KeyboardCode
  68 NonPrintableDomKeyToKeyboardCode(DomKey dom_key);
  69
  70 // Determine the non-located VKEY corresponding to a located VKEY.
  71 // Most modifier keys have two kinds of KeyboardCode: located (e.g.
  72 // VKEY_LSHIFT and VKEY_RSHIFT), that indentify one of two specific
  73 // physical keys, and non-located (e.g. VKEY_SHIFT) that identify
  74 // only the operation.
  75 EVENTS_BASE_EXPORT KeyboardCode
  76 LocatedToNonLocatedKeyboardCode(KeyboardCode key_code);
  77
  78 // Determine the located VKEY corresponding to a non-located VKEY.
  79 EVENTS_BASE_EXPORT KeyboardCode
  80 NonLocatedToLocatedKeyboardCode(KeyboardCode key_code, DomCode dom_code);
  81
  82 // Returns a DOM Level 3 |code| from a Windows-based VKEY value.
  83 // This assumes a US layout and should only be used when |code| cannot be
  84 // determined from a physical scan code, for example when a key event was
  85 // generated synthetically by JavaScript with only a VKEY value supplied.
  86 EVENTS_BASE_EXPORT DomCode UsLayoutKeyboardCodeToDomCode(KeyboardCode key_code);
  87
  88 }  // namespace ui
  89
  90 #endif  // UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_H_