src/hotkey/x11hotkeywrapper.cc

#ifdef WITH_X11
  #include "hotkeywrapper.hh"
  #include <X11/keysym.h>
  #include <QTimer>

//
/// Previously impletended with XGrabKey
/// Then reimplemented with X Record Extension Library
///

HotkeyWrapper::HotkeyWrapper( QObject * parent ):
  QThread( parent ),
  state2( false )
{
  init();
}

HotkeyWrapper::~HotkeyWrapper()
{
  unregister();
}

void HotkeyWrapper::waitKey2()
{
  state2 = false;

  if ( keyToUngrab != grabbedKeys.end() ) {
    ungrabKey( keyToUngrab );
    keyToUngrab = grabbedKeys.end();
  }
}

bool HotkeyWrapper::checkState( quint32 vk, quint32 mod )
{
  if ( state2 ) { // wait for 2nd key

    waitKey2(); // Cancel the 2nd-key wait stage

    if ( state2waiter.key2 == vk && state2waiter.modifier == mod ) {
      emit hotkeyActivated( state2waiter.handle );
      return true;
    }
  }

  for ( int i = 0; i < hotkeys.count(); i++ ) {

    const HotkeyStruct & hs = hotkeys.at( i );

    if ( hs.key == vk && hs.modifier == mod ) {

      if ( hs.key2 == 0 ) {
        emit hotkeyActivated( hs.handle );
        return true;
      }

      state2       = true;
      state2waiter = hs;
      QTimer::singleShot( 500, this, &HotkeyWrapper::waitKey2 );

      // Grab the second key, unless it's grabbed already
      // Note that we only grab the clipboard key only if
      // the sequence didn't begin with it

      if ( ( isCopyToClipboardKey( hs.key, hs.modifier ) || !isCopyToClipboardKey( hs.key2, hs.modifier ) )
           && !isKeyGrabbed( hs.key2, hs.modifier ) )
        keyToUngrab = grabKey( hs.key2, hs.modifier );

      return true;
    }
  }

  state2 = false;
  return false;
}

void HotkeyWrapper::init()
{
  keyToUngrab = grabbedKeys.end();

  QNativeInterface::QX11Application * x11AppInfo = qApp->nativeInterface< QNativeInterface::QX11Application >();
  Display * displayID                            = x11AppInfo->display();

  // We use RECORD extension instead of XGrabKey. That's because XGrabKey
  // prevents other clients from getting their input if it's grabbed.

  Display * display = displayID;

  lShiftCode = XKeysymToKeycode( display, XK_Shift_L );
  rShiftCode = XKeysymToKeycode( display, XK_Shift_R );

  lCtrlCode = XKeysymToKeycode( display, XK_Control_L );
  rCtrlCode = XKeysymToKeycode( display, XK_Control_R );

  lAltCode = XKeysymToKeycode( display, XK_Alt_L );
  rAltCode = XKeysymToKeycode( display, XK_Alt_R );

  lMetaCode = XKeysymToKeycode( display, XK_Super_L );
  rMetaCode = XKeysymToKeycode( display, XK_Super_R );

  cCode        = XKeysymToKeycode( display, XK_c );
  insertCode   = XKeysymToKeycode( display, XK_Insert );
  kpInsertCode = XKeysymToKeycode( display, XK_KP_Insert );

  currentModifiers = 0;

  // This one will be used to read the recorded content
  dataDisplay = XOpenDisplay( 0 );

  if ( !dataDisplay )
    throw exInit();

  recordRange = XRecordAllocRange();

  if ( !recordRange ) {
    XCloseDisplay( dataDisplay );
    throw exInit();
  }

  recordRange->device_events.first = KeyPress;
  recordRange->device_events.last  = KeyRelease;
  recordClientSpec                 = XRecordAllClients;

  recordContext = XRecordCreateContext( display, 0, &recordClientSpec, 1, &recordRange, 1 );

  if ( !recordContext ) {
    XFree( recordRange );
    XCloseDisplay( dataDisplay );
    throw exInit();
  }

  // This is required to ensure context was indeed created
  XSync( display, False );

  connect( this, &HotkeyWrapper::keyRecorded, this, &HotkeyWrapper::checkState, Qt::QueuedConnection );

  start();
}

void HotkeyWrapper::run() // Runs in a separate thread
{
  if ( !XRecordEnableContext( dataDisplay, recordContext, recordEventCallback, (XPointer)this ) )
    qDebug( "Failed to enable record context" );
}


void HotkeyWrapper::recordEventCallback( XPointer ptr, XRecordInterceptData * data )
{
  ( (HotkeyWrapper *)ptr )->handleRecordEvent( data );
}

void HotkeyWrapper::handleRecordEvent( XRecordInterceptData * data )
{
  if ( data->category == XRecordFromServer ) {
    xEvent * event = (xEvent *)data->data;

    if ( event->u.u.type == KeyPress ) {
      KeyCode key = event->u.u.detail;

      if ( key == lShiftCode || key == rShiftCode )
        currentModifiers |= ShiftMask;
      else if ( key == lCtrlCode || key == rCtrlCode )
        currentModifiers |= ControlMask;
      else if ( key == lAltCode || key == rAltCode )
        currentModifiers |= Mod1Mask;
      else if ( key == lMetaCode || key == rMetaCode )
        currentModifiers |= Mod4Mask;
      else {
        // Here we employ a kind of hack translating KP_Insert key
        // to just Insert. This allows reacting to both Insert keys.
        if ( key == kpInsertCode )
          key = insertCode;

        emit keyRecorded( key, currentModifiers );
      }
    }
    else if ( event->u.u.type == KeyRelease ) {
      KeyCode key = event->u.u.detail;

      if ( key == lShiftCode || key == rShiftCode )
        currentModifiers &= ~ShiftMask;
      else if ( key == lCtrlCode || key == rCtrlCode )
        currentModifiers &= ~ControlMask;
      else if ( key == lAltCode || key == rAltCode )
        currentModifiers &= ~Mod1Mask;
      else if ( key == lMetaCode || key == rMetaCode )
        currentModifiers &= ~Mod4Mask;
    }
  }

  XRecordFreeData( data );
}

bool HotkeyWrapper::setGlobalKey( const QKeySequence & seq, int handle )
{
  Config::HotKey hk( seq );
  int key                        = hk.key1;
  int key2                       = hk.key2;
  Qt::KeyboardModifiers modifier = hk.modifiers;

  if ( !key )
    return false; // We don't monitor empty combinations

  int vk  = nativeKey( key );
  int vk2 = key2 ? nativeKey( key2 ) : 0;

  quint32 mod = 0;
  if ( modifier & Qt::ShiftModifier )
    mod |= ShiftMask;
  if ( modifier & Qt::ControlModifier )
    mod |= ControlMask;
  if ( modifier & Qt::AltModifier )
    mod |= Mod1Mask;
  if ( modifier & Qt::MetaModifier )
    mod |= Mod4Mask;

  hotkeys.append( HotkeyStruct( vk, vk2, mod, handle, 0 ) );

  if ( !isCopyToClipboardKey( vk, mod ) )
    grabKey( vk, mod ); // Make sure it doesn't get caught by other apps

  return true;
}

bool HotkeyWrapper::isCopyToClipboardKey( quint32 keyCode, quint32 modifiers ) const
{
  return modifiers == ControlMask && ( keyCode == cCode || keyCode == insertCode || keyCode == kpInsertCode );
}

bool HotkeyWrapper::isKeyGrabbed( quint32 keyCode, quint32 modifiers ) const
{
  GrabbedKeys::const_iterator i = grabbedKeys.find( std::make_pair( keyCode, modifiers ) );

  return i != grabbedKeys.end();
}

namespace {

using X11ErrorHandler = int ( * )( Display * display, XErrorEvent * event );

class X11GrabUngrabErrorHandler
{
public:
  static bool error;

  static int grab_ungrab_error_handler( Display *, XErrorEvent * event )
  {
    qDebug() << "grab_ungrab_error_handler is invoked";
    switch ( event->error_code ) {
      case BadAccess:
      case BadValue:
      case BadWindow:
        if ( event->request_code == 33 /* X_GrabKey */ || event->request_code == 34 /* X_UngrabKey */ ) {
          error = true;
        }
    }
    return 0;
  }

  X11GrabUngrabErrorHandler()
  {
    error                 = false;
    previousErrorHandler_ = XSetErrorHandler( grab_ungrab_error_handler );
  }

  ~X11GrabUngrabErrorHandler()
  {

    QNativeInterface::QX11Application * x11AppInfo = qApp->nativeInterface< QNativeInterface::QX11Application >();

    Display * displayID = x11AppInfo->display();

    XFlush( displayID );
    (void)XSetErrorHandler( previousErrorHandler_ );
  }

  bool isError() const
  {

    QNativeInterface::QX11Application * x11AppInfo = qApp->nativeInterface< QNativeInterface::QX11Application >();

    Display * displayID = x11AppInfo->display();

    XFlush( displayID );
    return error;
  }

private:
  X11ErrorHandler previousErrorHandler_;
};

bool X11GrabUngrabErrorHandler::error = false;

} // anonymous namespace


HotkeyWrapper::GrabbedKeys::iterator HotkeyWrapper::grabKey( quint32 keyCode, quint32 modifiers )
{
  std::pair< GrabbedKeys::iterator, bool > result = grabbedKeys.insert( std::make_pair( keyCode, modifiers ) );

  if ( result.second ) {

    QNativeInterface::QX11Application * x11AppInfo = qApp->nativeInterface< QNativeInterface::QX11Application >();

    Display * displayID = x11AppInfo->display();

    X11GrabUngrabErrorHandler errorHandler;
    XGrabKey( displayID, keyCode, modifiers, DefaultRootWindow( displayID ), True, GrabModeAsync, GrabModeAsync );

    if ( errorHandler.isError() ) {
      qWarning( "Possible hotkeys conflict. Check your hotkeys options." );
      ungrabKey( result.first );
    }
  }

  return result.first;
}

void HotkeyWrapper::ungrabKey( GrabbedKeys::iterator i )
{

  QNativeInterface::QX11Application * x11AppInfo = qApp->nativeInterface< QNativeInterface::QX11Application >();

  Display * displayID = x11AppInfo->display();
  X11GrabUngrabErrorHandler errorHandler;
  XUngrabKey( displayID, i->first, i->second, XDefaultRootWindow( displayID ) );

  grabbedKeys.erase( i );

  if ( errorHandler.isError() ) {
    qWarning( "Cannot ungrab the hotkey" );
  }
}

quint32 HotkeyWrapper::nativeKey( int key )
{
  QString keySymName;

  switch ( key ) {
    case Qt::Key_Insert:
      keySymName = "Insert";
      break;
    case Qt::Key_Meta:
      // QKeySequenceEdit might not recognize the Super key, but we can handle it.
      keySymName = "Super_L";
      break;
    default:
      keySymName = QKeySequence( key ).toString();
      break;
  }

  QNativeInterface::QX11Application * x11AppInfo = qApp->nativeInterface< QNativeInterface::QX11Application >();

  Display * display = x11AppInfo->display();
  return XKeysymToKeycode( display, XStringToKeysym( keySymName.toLatin1().data() ) );
}

void HotkeyWrapper::unregister()
{
  QNativeInterface::QX11Application * x11AppInfo = qApp->nativeInterface< QNativeInterface::QX11Application >();
  Display * display                              = x11AppInfo->display();

  XRecordDisableContext( display, recordContext );
  XSync( display, False );

  wait();

  XRecordFreeContext( display, recordContext );
  XFree( recordRange );
  XCloseDisplay( dataDisplay );

  while ( grabbedKeys.size() )
    ungrabKey( grabbedKeys.begin() );
}

#endif