simgear/canvas/CanvasEventManager.cxx

   1 // Manage event handling inside a Canvas similar to the DOM Level 3 Event Model
   2 //
   3 // Copyright (C) 2012  Thomas Geymayer <tomgey@gmail.com>
   4 //
   5 // This library is free software; you can redistribute it and/or
   6 // modify it under the terms of the GNU Library General Public
   7 // License as published by the Free Software Foundation; either
   8 // version 2 of the License, or (at your option) any later version.
   9 //
  10 // This library is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 // Library General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU Library General Public
  16 // License along with this library; if not, write to the Free Software
  17 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  18
  19 #include "CanvasEventManager.hxx"
  20 #include "MouseEvent.hxx"
  21 #include <simgear/canvas/elements/CanvasElement.hxx>
  22
  23 namespace simgear
  24 {
  25 namespace canvas
  26 {
  27
  28   const unsigned int drag_threshold = 8;
  29   const double multi_click_timeout = 0.4;
  30
  31   //----------------------------------------------------------------------------
  32   EventManager::StampedPropagationPath::StampedPropagationPath():
  33     time(0)
  34   {
  35
  36   }
  37
  38   //----------------------------------------------------------------------------
  39
  40   EventManager::StampedPropagationPath::StampedPropagationPath(
  41     const EventPropagationPath& path,
  42     double time
  43   ):
  44     path(path),
  45     time(time)
  46   {
  47
  48   }
  49
  50   //----------------------------------------------------------------------------
  51   void EventManager::StampedPropagationPath::clear()
  52   {
  53     path.clear();
  54     time = 0;
  55   }
  56
  57   //----------------------------------------------------------------------------
  58   bool EventManager::StampedPropagationPath::valid() const
  59   {
  60     return !path.empty() && time > 0;
  61   }
  62
  63   //----------------------------------------------------------------------------
  64   EventManager::EventManager():
  65     _current_click_count(0)
  66   {
  67
  68   }
  69
  70   //----------------------------------------------------------------------------
  71   bool EventManager::handleEvent( const MouseEventPtr& event,
  72                                   const EventPropagationPath& path )
  73   {
  74     switch( event->type )
  75     {
  76       case Event::MOUSE_DOWN:
  77         _last_mouse_down = StampedPropagationPath(path, event->getTime());
  78         break;
  79       case Event::MOUSE_UP:
  80       {
  81         if( _last_mouse_down.path.empty() )
  82           // Ignore mouse up without any previous mouse down
  83           return false;
  84
  85         // normal mouseup
  86         propagateEvent(event, path);
  87
  88         // now handle click/dblclick
  89         if( checkClickDistance(path, _last_mouse_down.path) )
  90           handleClick(event, getCommonAncestor(_last_mouse_down.path, path));
  91
  92         _last_mouse_down.clear();
  93
  94         return true;
  95       }
  96       case Event::DRAG:
  97         if( !_last_mouse_down.valid() )
  98           return false;
  99         else
 100           return propagateEvent(event, _last_mouse_down.path);
 101       case Event::MOUSE_MOVE:
 102         handleMove(event, path);
 103         break;
 104       case Event::MOUSE_LEAVE:
 105         // Mouse leaves window and therefore also current mouseover element
 106         handleMove(event, EventPropagationPath());
 107         return true;
 108       case Event::WHEEL:
 109         break;
 110       default:
 111         return false;
 112     }
 113
 114     return propagateEvent(event, path);
 115   }
 116
 117   //----------------------------------------------------------------------------
 118   void EventManager::handleClick( const MouseEventPtr& event,
 119                                   const EventPropagationPath& path )
 120   {
 121     MouseEventPtr click(new MouseEvent(*event));
 122     click->type = Event::CLICK;
 123
 124     if( event->getTime() > _last_click.time + multi_click_timeout )
 125       _current_click_count = 1;
 126     else
 127     {
 128       // Maximum current click count is 3
 129       _current_click_count = (_current_click_count % 3) + 1;
 130
 131       if( _current_click_count > 1 )
 132       {
 133         // Reset current click count if moved too far
 134         if( !checkClickDistance(path, _last_click.path) )
 135           _current_click_count = 1;
 136       }
 137     }
 138
 139     click->click_count = _current_click_count;
 140
 141     MouseEventPtr dbl_click;
 142     if( _current_click_count == 2 )
 143     {
 144       dbl_click.reset(new MouseEvent(*click));
 145       dbl_click->type = Event::DBL_CLICK;
 146     }
 147
 148     propagateEvent(click, path);
 149
 150     if( dbl_click )
 151       propagateEvent(dbl_click, getCommonAncestor(_last_click.path, path));
 152
 153     _last_click = StampedPropagationPath(path, event->getTime());
 154   }
 155
 156   //----------------------------------------------------------------------------
 157   void EventManager::handleMove( const MouseEventPtr& event,
 158                                  const EventPropagationPath& path )
 159   {
 160     if( _last_mouse_over.path == path )
 161       return;
 162
 163     if( !_last_mouse_over.path.empty() )
 164     {
 165       MouseEventPtr mouseout(new MouseEvent(*event));
 166       mouseout->type = Event::MOUSE_OUT;
 167       propagateEvent(mouseout, _last_mouse_over.path);
 168     }
 169
 170     if( !path.empty() )
 171     {
 172       MouseEventPtr mouseover(new MouseEvent(*event));
 173       mouseover->type = Event::MOUSE_OVER;
 174       propagateEvent(mouseover, path);
 175     }
 176
 177     _last_mouse_over.path = path;
 178   }
 179
 180   //----------------------------------------------------------------------------
 181   bool EventManager::propagateEvent( const EventPtr& event,
 182                                      const EventPropagationPath& path )
 183   {
 184     event->target = path.back().element;
 185     MouseEventPtr mouse_event = boost::dynamic_pointer_cast<MouseEvent>(event);
 186
 187     // Event propagation similar to DOM Level 3 event flow:
 188     // http://www.w3.org/TR/DOM-Level-3-Events/#event-flow
 189
 190     // Capturing phase
 191 //    for( EventPropagationPath::const_iterator it = path.begin();
 192 //                                              it != path.end();
 193 //                                            ++it )
 194 //    {
 195 //      if( !it->element.expired() )
 196 //        std::cout << it->element.lock()->getProps()->getPath() << std::endl;
 197 //    }
 198
 199     // Bubbling phase
 200     for( EventPropagationPath::const_reverse_iterator
 201            it = path.rbegin();
 202            it != path.rend();
 203          ++it )
 204     {
 205       ElementPtr el = it->element.lock();
 206
 207       if( !el )
 208         // Ignore element if it has been destroyed while traversing the event
 209         // (eg. removed by another event handler)
 210         continue;
 211
 212       // TODO provide functions to convert delta to local coordinates on demand.
 213       //      Maybe also provide a clone method for events as local coordinates
 214       //      might differ between different elements receiving the same event.
 215       if( mouse_event ) //&& event->type != Event::DRAG )
 216       {
 217         // TODO transform pos and delta for drag events. Maybe we should just
 218         //      store the global coordinates and convert to local coordinates
 219         //      on demand.
 220
 221         // Position and delta are specified in local coordinate system of
 222         // current element
 223         mouse_event->local_pos = it->local_pos;
 224         //mouse_event->delta = it->local_delta;
 225       }
 226
 227       el->handleEvent(event);
 228
 229       if( event->propagation_stopped )
 230         return true;
 231     }
 232
 233     return true;
 234   }
 235
 236   //----------------------------------------------------------------------------
 237   bool
 238   EventManager::checkClickDistance( const EventPropagationPath& path1,
 239                                     const EventPropagationPath& path2 ) const
 240   {
 241     osg::Vec2 delta = path1.front().local_pos - path2.front().local_pos;
 242     return delta.x() < drag_threshold
 243         && delta.y() < drag_threshold;
 244   }
 245
 246   //----------------------------------------------------------------------------
 247   EventPropagationPath
 248   EventManager::getCommonAncestor( const EventPropagationPath& path1,
 249                                    const EventPropagationPath& path2 ) const
 250   {
 251     if( path1.back().element.lock() == path2.back().element.lock() )
 252       return path2;
 253
 254     EventPropagationPath path;
 255
 256     for( size_t i = 0; i < path1.size() && i < path2.size(); ++i )
 257     {
 258       if( path1[i].element.lock() != path2[i].element.lock() )
 259         break;
 260
 261       path.push_back(path2[i]);
 262     }
 263
 264     return path;
 265   }
 266
 267 } // namespace canvas
 268 } // namespace simgear