xbmc從onEvent到onkey創建CKey對象的過程

注我們以遙控器音量加鍵爲說明例子

//xbmc/Application.cpp
bool CApplication::OnEvent(XBMC_Event& newEvent)
{
  switch(newEvent.type)
  {
    case XBMC_QUIT: //退出xbmc
        ...
        CApplicationMessenger::Get().Quit();
    break;

    case XBMC_KEYDOWN:
        g_application.OnKey(g_Keyboard.ProcessKeyDown(newEvent.key.keysym));
    break;  
  }
}

/*
xbmc/input/KeyboardStat.cpp
*/
const CKey CKeyboardStat::ProcessKeyDown(XBMC_keysym& keysym)
{ uint8_t vkey;
  wchar_t unicode;
  char ascii;
  uint32_t modifiers;
  unsigned int held;
  XBMCKEYTABLE keytable;
  ...
   //這裏一句輸出了：Keyboard: scancode: 0x18, sym: 0x002b, unicode: 0x0000, modifier: 0x0
  CLog::Log(LOGDEBUG, "Keyboard: scancode: 0x%02x, sym: 0x%04x, unicode: 0x%04x, modifier: 0x%x", 
  keysym.scancode, keysym.sym, keysym.unicode, keysym.mod);

 if (LookupSymAndUnicodePeripherals(keysym, &vkey, &ascii))
  {
    CLog::Log(LOGDEBUG, "%s - keypress translated by a HID peripheral", __FUNCTION__);
  }

  // Continue by trying to match both the sym and unicode. This will identify
  else if (KeyTableLookupSymAndUnicode(keysym.sym, keysym.unicode, &keytable))
  {
    vkey = keytable.vkey;
    ascii = keytable.ascii;
  }

  // If we failed to match the sym and unicode try just the unicode. This
  else if (KeyTableLookupUnicode(keysym.unicode, &keytable))
  {
    vkey = keytable.vkey;
    ascii = keytable.ascii;
  }
  // If there is still no match try the sym我們按音量加進入了這裏
  else if (KeyTableLookupSym(keysym.sym, &keytable))
  {
    vkey = keytable.vkey;
    if (keytable.unicode == 0 && unicode != 0)
      unicode = 0;
    else if (keysym.unicode > 32 && keysym.unicode < 128)
      ascii = unicode & 0x7f;
  }
  ...
  //我們點擊遙控器音量加到這裏是 vkey:+, unicode:0x0000, ascii:null, modifiers:0x0000, held:0
  CKey key(vkey, unicode, ascii, modifiers, held);

  return key;
}

/*
xbmc/input/XBMC_keytable.cpp
*/
bool KeyTableLookupSym(uint16_t sym, XBMCKEYTABLE* keytable)
{
  ...
  // Look up the sym in XBMCKeyTable
  for (int i = 0; i < XBMCKeyTableSize; i++)
  { if (sym == XBMCKeyTable[i].sym)
    { *keytable = XBMCKeyTable[i];
      return true;
    }
  }
  return false;
}

這裏會查找XBMCKeyTable這個數組，以找到sym號相同的的數組。我們知道sym爲0x002b，這個
值是在AndroidKey.cpp將鍵盤scancode轉化爲sym而來。

/*
xbmc/input/XBMC_keytable.h
*/
typedef struct struct_XBMCKEYTABLE
{
  uint16_t sym;
  uint16_t unicode;
  char     ascii;
  uint32_t    vkey;
  const char* keyname;
}

static const XBMCKEYTABLE XBMCKeyTable[] =
{
  ...
  // Misc printing characters
  { XBMCK_PLUS,                 '+',  '+', XBMCVK_PLUS,            "plus" }
  ...
}

到此，我們就解析完了CKey對象的創建過程，然後它被傳遞給了

//xbmc/Application.cpp
bool CApplication::OnKey(const CKey& key)
{
  // get the current active window
  int iWin = GetActiveWindowID();
  // this will be checked for certain keycodes that need
  // special handling if the screensaver is active
  CAction action = CButtonTranslator::GetInstance().GetAction(iWin, key);
    ....

  if (!key.IsAnalogButton())
    CLog::LogF(LOGDEBUG, "%s pressed, action is %s", 
        g_Keyboard.GetKeyName((int) key.GetButtonCode()).c_str(), action.GetName().c_str());

  return ExecuteInputAction(action);
}