ui/events/ozone/layout/keyboard_layout_engine.h

   1 // Copyright 2014 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_OZONE_PUBLIC_KEYBOARD_LAYOUT_ENGINE_H_
   6 #define UI_OZONE_PUBLIC_KEYBOARD_LAYOUT_ENGINE_H_
   7
   8 #include <string>
   9
  10 #include "base/strings/string16.h"
  11 #include "ui/events/keycodes/keyboard_codes.h"
  12 #include "ui/events/ozone/layout/events_ozone_layout_export.h"
  13
  14 namespace ui {
  15
  16 enum class DomCode;
  17 enum class DomKey;
  18
  19 // A KeyboardLayoutEngine provides a platform-independent interface to
  20 // key mapping. Key mapping provides a meaning (DomKey and character,
  21 // and optionally Windows key code) for a physical key press (DomCode
  22 // and modifier flags).
  23 //
  24 // This interface does not expose individual layouts because it must support
  25 // platforms that only provide for one active system layout, and/or platforms
  26 // where layouts have no accessible representation.
  27 class EVENTS_OZONE_LAYOUT_EXPORT KeyboardLayoutEngine {
  28  public:
  29   KeyboardLayoutEngine() {}
  30   virtual ~KeyboardLayoutEngine() {}
  31
  32   // Returns true if it is possible to change the current layout.
  33   virtual bool CanSetCurrentLayout() const = 0;
  34
  35   // Sets the current layout; returns true on success.
  36   // Drop-in replacement for ImeKeyboard::SetCurrentKeyboardLayoutByName();
  37   // the argument string is defined by that interface (crbug.com/362698).
  38   virtual bool SetCurrentLayoutByName(const std::string& layout_name) = 0;
  39
  40   // Returns true if the current layout makes use of the ISO Level 5 Shift key.
  41   // Drop-in replacement for ImeKeyboard::IsISOLevel5ShiftAvailable().
  42   virtual bool UsesISOLevel5Shift() const = 0;
  43
  44   // Returns true if the current layout makes use of the AltGr
  45   // (ISO Level 3 Shift) key.
  46   // Drop-in replacement for ImeKeyboard::IsAltGrAvailable().
  47   virtual bool UsesAltGr() const = 0;
  48
  49   // Provides the meaning of a physical key.
  50   //
  51   // The caller must supply valid addresses for all the output parameters;
  52   // the function must not use their initial values.
  53   //
  54   // Returns true if it can determine the DOM meaning (i.e. ui::DomKey and
  55   // character) and the corresponding legacy KeyboardCode from the given
  56   // physical state (ui::DomCode and ui::EventFlags), OR if it can determine
  57   // that there is no meaning in the current layout (e.g. the key is unbound).
  58   // In the latter case, the function sets *dom_key to UNIDENTIFIED, *character
  59   // to 0, and *key_code to VKEY_UNKNOWN.
  60   //
  61   // Returns false if it cannot determine the meaning (and cannot determine
  62   // that there is none); in this case it does not set any of the output
  63   // parameters.
  64   //
  65   // TODO(kpschoedel): remove the platform_keycode output. crbug.com/442757
  66   virtual bool Lookup(DomCode dom_code,
  67                       int event_flags,
  68                       DomKey* dom_key,
  69                       base::char16* character,
  70                       KeyboardCode* key_code,
  71                       uint32* platform_keycode) const = 0;
  72 };
  73
  74 }  // namespace ui
  75
  76 #endif  // UI_OZONE_PUBLIC_KEYBOARD_LAYOUT_ENGINE_H_