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/dom/dom_key.h"
  12 #include "ui/events/keycodes/keyboard_codes.h"
  13
  14 namespace ui {
  15
  16 enum class DomCode;
  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 non-located
  36 // Windows-based 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 DomCodeToUsLayoutDomKey(DomCode dom_code,
  46                                                 int flags,
  47                                                 DomKey* dom_key,
  48                                                 KeyboardCode* key_code)
  49     WARN_UNUSED_RESULT;
  50
  51 // Obtains the control character corresponding to a physical key;
  52 // that is, the meaning of the physical key state (dom_code, and flags
  53 // containing EF_CONTROL_DOWN) under the base US English layout.
  54 // Returns true and sets the output parameters if the (dom_code, flags) pair
  55 // is interpreted as a control character; otherwise the output parameters
  56 // are untouched.
  57 EVENTS_BASE_EXPORT bool DomCodeToControlCharacter(DomCode dom_code,
  58                                                   int flags,
  59                                                   DomKey* dom_key,
  60                                                   KeyboardCode* key_code)
  61     WARN_UNUSED_RESULT;
  62
  63 // Returns a Windows-based VKEY for a non-printable DOM Level 3 |key|.
  64 // The returned VKEY is non-located (e.g. VKEY_SHIFT).
  65 EVENTS_BASE_EXPORT KeyboardCode
  66 NonPrintableDomKeyToKeyboardCode(DomKey dom_key);
  67
  68 // Determine the non-located VKEY corresponding to a located VKEY.
  69 // Most modifier keys have two kinds of KeyboardCode: located (e.g.
  70 // VKEY_LSHIFT and VKEY_RSHIFT), that indentify one of two specific
  71 // physical keys, and non-located (e.g. VKEY_SHIFT) that identify
  72 // only the operation. Similarly digit keys have a number-pad variant
  73 // (e.g. VKEY_NUMPAD1 on the number pad vs VKEY_1 on the main keyboard),
  74 // except that in this case the main keyboard code doubles as the
  75 // non-located value.
  76 EVENTS_BASE_EXPORT KeyboardCode
  77 LocatedToNonLocatedKeyboardCode(KeyboardCode key_code);
  78
  79 // Determine the located VKEY corresponding to a non-located VKEY.
  80 EVENTS_BASE_EXPORT KeyboardCode
  81 NonLocatedToLocatedKeyboardCode(KeyboardCode key_code, DomCode dom_code);
  82
  83 // Returns a DOM Level 3 |code| from a Windows-based VKEY value.
  84 // This assumes a US layout and should only be used when |code| cannot be
  85 // determined from a physical scan code, for example when a key event was
  86 // generated synthetically by JavaScript with only a VKEY value supplied.
  87 EVENTS_BASE_EXPORT DomCode UsLayoutKeyboardCodeToDomCode(KeyboardCode key_code);
  88
  89 // Returns the Windows-based VKEY value corresponding to a DOM Level 3 |code|,
  90 // assuming a base US English layout. The returned VKEY is located
  91 // (e.g. VKEY_LSHIFT).
  92 EVENTS_BASE_EXPORT KeyboardCode DomCodeToUsLayoutKeyboardCode(DomCode dom_code);
  93
  94 }  // namespace ui
  95
  96 #endif  // UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_H_