xbmc从onKey到onAction创建CAction对象的过程

注我们以遥控器音量加键为说明例子

//xbmc/Application.cppbool CApplication::OnKey(const CKey& key){...  int iWin = GetActiveWindowID();  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);}

//xbmc/input/ButtonTranslator.cppCAction CButtonTranslator::GetAction(int window, const CKey &key, bool fallback){  std::string strAction;  // try to get the action from the current window  int actionID = GetActionCode(window, key, strAction);  // if it's invalid, try to get it from the global map  if (actionID == 0 && fallback)  {    int fallbackWindow = GetFallbackWindow(window);    if (fallbackWindow > -1)      actionID = GetActionCode(fallbackWindow, key, strAction);    // still no valid action? use global map    if (actionID == 0)      actionID = GetActionCode( -1, key, strAction);  }  CAction action(actionID, strAction, key);  return action;}

在此说明以下CAction的其一构造函数//xbmc/guilib/Key.h
CAction(int actionID, const CStdString &name, const CKey &key);
看样子我们要弄清楚actionID的由来

int CButtonTranslator::GetActionCode(int window, const CKey &key, std::string &strAction) const{  uint32_t code = key.GetButtonCode();  map<int, buttonMap>::const_iterator it = m_translatorMap.find(window);    ...  buttonMap::const_iterator it2 = (*it).second.find(code);  int action = 0;  if (it2 != (*it).second.end())  {    action = (*it2).second.id;    strAction = (*it2).second.strID;  }  return action;}

我们看看获取code的GetButtonCode代码

//xbmc/guilib/Key.h  inline uint32_t GetButtonCode() const { return m_buttonCode; }

看来似乎又要回到从OnEvent方法的g_Keyboard.ProcessKeyDown(newEvent.key.keysym)返回的key对象入手了

CKey::CKey(uint8_t vkey, wchar_t unicode, char ascii, uint32_t modifiers, unsigned int held){  Reset();  if (vkey) // FIXME: This needs cleaning up - should we always use the unicode key where available?    m_buttonCode = vkey | KEY_VKEY;  else    m_buttonCode = KEY_UNICODE;  m_buttonCode |= modifiers;  m_vkey = vkey;  m_unicode = unicode;  m_ascii = ascii;  m_modifiers = modifiers;  m_held = held;}

其中
#define KEY_VKEY 0xF000
至此，我们的m_buttonCode出来了,即0xF02b,从keyboard.xml等xml的读取过程中我们知道actionID 0xF02b对应的，
action为plus,strAction为ACTION_VOLUME_UP，至此key转化为action便完成。
actions的数组的内容如下

//xbmc/input/ButtonTranslator.cppstatic const ActionMapping actions[] ={    ...        {"volumeup"          , ACTION_VOLUME_UP},   //这是action名称和对应的值action.GetID()}

后续到Application.cpp的ExecuteInputAction(action);中处理