text: // Copyright (c) 2013 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef UI_BASE_KEYCODES_KEYCODE_CONVERTER_H_
  #define UI_BASE_KEYCODES_KEYCODE_CONVERTER_H_
  
  #include <stdint.h>
  #include "base/basictypes.h"
  #include "base/memory/singleton.h"
  
  // For reference, the W3C UI Event spec is located at:
  // http://www.w3.org/TR/uievents/
  
  namespace ui {
  
  // This structure is used to define the keycode mapping table.
  // It is defined here because the unittests need access to it.
  typedef struct {
    // USB keycode:
    //  Upper 16-bits: USB Usage Page.
    //  Lower 16-bits: USB Usage Id: Assigned ID within this usage page.
    uint32_t usb_keycode;
  
    // Contains one of the following:
    //  On Linux: XKB scancode
    //  On Windows: Windows OEM scancode
    //  On Mac: Mac keycode
    uint16_t native_keycode;
  
    // The UIEvents (aka: DOM4Events) |code| value as defined in:
    // https://dvcs.w3.org/hg/d4e/raw-file/tip/source_respec.htm
    const char* code;
  } KeycodeMapEntry;
  
  // A class to convert between the current platform's native keycode (scancode)
  // and platform-neutral |code| values (as defined in the W3C UI Events
  // spec (http://www.w3.org/TR/uievents/).
  class KeycodeConverter {
   public:
    static KeycodeConverter* GetInstance();
  
    // Return the value that identifies an invalid native keycode.
    uint16_t InvalidNativeKeycode();
  
    // Return the string that indentifies an invalid UI Event |code|.
    // The returned pointer references a static global string.
    const char* InvalidKeyboardEventCode();
  
    // Convert a native (Mac/Win/Linux) keycode into the |code| string.
    // The returned pointer references a static global string.
    const char* NativeKeycodeToCode(uint16_t native_keycode);
  
    // Convert a UI Events |code| string value into a native keycode.
    uint16_t CodeToNativeKeycode(const char* code);
  
    // The following methods relate to USB keycodes.
    // Note that USB keycodes are not part of any web standard.
    // Please don't use USB keycodes in new code.
  
    // Return the value that identifies an invalid USB keycode.
    uint16_t InvalidUsbKeycode();
  
    // Convert a USB keycode into an equivalent platform native keycode.
    uint16_t UsbKeycodeToNativeKeycode(uint32_t usb_keycode);
  
    // Convert a platform native keycode into an equivalent USB keycode.
    uint32_t NativeKeycodeToUsbKeycode(uint16_t native_keycode);
  
    // Convert a USB keycode into the string with the UI Event |code| value.
    // The returned pointer references a static global string.
    const char* UsbKeycodeToCode(uint32_t usb_keycode);
  
    // Static methods to support testing.
    size_t NumKeycodeMapEntriesForTest();
    const KeycodeMapEntry* GetKeycodeMapForTest();
  
   private:
    KeycodeConverter();
    friend struct DefaultSingletonTraits<KeycodeConverter>;
  
    DISALLOW_COPY_AND_ASSIGN(KeycodeConverter);
  };
  
  }  // namespace ui
  
  #endif  // UI_BASE_KEYCODE_CONVERTER_H_
  