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     bool handled = false;
  75     switch( event->type )
  76     {
  77       case Event::MOUSE_DOWN:
  78         _last_mouse_down = StampedPropagationPath(path, event->getTime());
  79         break;
  80       case Event::MOUSE_UP:
  81       {
  82         // If the mouse has moved while a button was down (aka. dragging) we
  83         // need to notify the original element that the mouse has left it, and
  84         // the new element that it has been entered
  85         if( _last_mouse_down.path != path )
  86           handled |= handleMove(event, path);
  87
  88         // normal mouseup
  89         handled |= propagateEvent(event, path);
  90
  91         if( _last_mouse_down.path.empty() )
  92           // Ignore mouse up without any previous mouse down
  93           return handled;
  94
  95         // now handle click/dblclick
  96         if( checkClickDistance(path, _last_mouse_down.path) )
  97           handled |=
  98             handleClick(event, getCommonAncestor(_last_mouse_down.path, path));
  99
 100         _last_mouse_down.clear();
 101
 102         return handled;
 103       }
 104       case Event::DRAG:
 105         if( !_last_mouse_down.valid() )
 106           return false;
 107         else
 108           return propagateEvent(event, _last_mouse_down.path);
 109       case Event::MOUSE_MOVE:
 110         handled |= handleMove(event, path);
 111         break;
 112       case Event::MOUSE_LEAVE:
 113         // Mouse leaves window and therefore also current mouseover element
 114         handleMove(event, EventPropagationPath());
 115         return true;
 116       case Event::WHEEL:
 117         break;
 118       default:
 119         return false;
 120     }
 121
 122     return handled | propagateEvent(event, path);
 123   }
 124
 125   //----------------------------------------------------------------------------
 126   bool EventManager::handleClick( const MouseEventPtr& event,
 127                                   const EventPropagationPath& path )
 128   {
 129     MouseEventPtr click(new MouseEvent(*event));
 130     click->type = Event::CLICK;
 131
 132     if( event->getTime() > _last_click.time + multi_click_timeout )
 133       _current_click_count = 1;
 134     else
 135     {
 136       // Maximum current click count is 3
 137       _current_click_count = (_current_click_count % 3) + 1;
 138
 139       if( _current_click_count > 1 )
 140       {
 141         // Reset current click count if moved too far
 142         if( !checkClickDistance(path, _last_click.path) )
 143           _current_click_count = 1;
 144       }
 145     }
 146
 147     click->click_count = _current_click_count;
 148
 149     MouseEventPtr dbl_click;
 150     if( _current_click_count == 2 )
 151     {
 152       dbl_click.reset(new MouseEvent(*click));
 153       dbl_click->type = Event::DBL_CLICK;
 154     }
 155
 156     bool handled = propagateEvent(click, path);
 157
 158     if( dbl_click )
 159       handled |= propagateEvent( dbl_click,
 160                                  getCommonAncestor(_last_click.path, path) );
 161
 162     _last_click = StampedPropagationPath(path, event->getTime());
 163
 164     return handled;
 165   }
 166
 167   //----------------------------------------------------------------------------
 168   bool EventManager::handleMove( const MouseEventPtr& event,
 169                                  const EventPropagationPath& path )
 170   {
 171     EventPropagationPath& last_path = _last_mouse_over.path;
 172     if( last_path == path )
 173       return false;
 174
 175     bool handled = false;
 176
 177     // Leave old element
 178     if( !last_path.empty() )
 179     {
 180       MouseEventPtr mouseout(new MouseEvent(*event));
 181       mouseout->type = Event::MOUSE_OUT;
 182       handled |= propagateEvent(mouseout, last_path);
 183
 184       // Send a mouseleave event to all ancestors of the currently left element
 185       // which are not ancestor of the new element currently entered
 186       EventPropagationPath path_leave = last_path;
 187       for(size_t i = path_leave.size() - 1; i > 0; --i)
 188       {
 189         if( i < path.size() && path[i] == path_leave[i] )
 190           break;
 191
 192         MouseEventPtr mouseleave(new MouseEvent(*event));
 193         mouseleave->type = Event::MOUSE_LEAVE;
 194         handled |= propagateEvent(mouseleave, path_leave);
 195
 196         path_leave.pop_back();
 197       }
 198     }
 199
 200     // Enter new element
 201     if( !path.empty() )
 202     {
 203       MouseEventPtr mouseover(new MouseEvent(*event));
 204       mouseover->type = Event::MOUSE_OVER;
 205       handled |= propagateEvent(mouseover, path);
 206
 207       // Send a mouseenter event to all ancestors of the currently entered
 208       // element which are not ancestor of the old element currently being
 209       // left
 210       EventPropagationPath path_enter;
 211       for(size_t i = 0; i < path.size(); ++i)
 212       {
 213         path_enter.push_back(path[i]);
 214
 215         if( i < last_path.size() && path[i] == last_path[i] )
 216           continue;
 217
 218         MouseEventPtr mouseenter(new MouseEvent(*event));
 219         mouseenter->type = Event::MOUSE_ENTER;
 220         handled |= propagateEvent(mouseenter, path_enter);
 221       }
 222     }
 223
 224     _last_mouse_over.path = path;
 225     return handled;
 226   }
 227
 228   //----------------------------------------------------------------------------
 229   bool EventManager::propagateEvent( const EventPtr& event,
 230                                      const EventPropagationPath& path )
 231   {
 232     event->target = path.back().element;
 233     MouseEventPtr mouse_event = boost::dynamic_pointer_cast<MouseEvent>(event);
 234
 235     // Event propagation similar to DOM Level 3 event flow:
 236     // http://www.w3.org/TR/DOM-Level-3-Events/#event-flow
 237
 238     // Capturing phase
 239 //    for( EventPropagationPath::const_iterator it = path.begin();
 240 //                                              it != path.end();
 241 //                                            ++it )
 242 //    {
 243 //      if( !it->element.expired() )
 244 //        std::cout << it->element.lock()->getProps()->getPath() << std::endl;
 245 //    }
 246
 247     // Bubbling phase
 248     for( EventPropagationPath::const_reverse_iterator
 249            it = path.rbegin();
 250            it != path.rend();
 251          ++it )
 252     {
 253       ElementPtr el = it->element.lock();
 254
 255       if( !el )
 256         // Ignore element if it has been destroyed while traversing the event
 257         // (eg. removed by another event handler)
 258         continue;
 259
 260       // TODO provide functions to convert delta to local coordinates on demand.
 261       //      Maybe also provide a clone method for events as local coordinates
 262       //      might differ between different elements receiving the same event.
 263       if( mouse_event ) //&& event->type != Event::DRAG )
 264       {
 265         // TODO transform pos and delta for drag events. Maybe we should just
 266         //      store the global coordinates and convert to local coordinates
 267         //      on demand.
 268
 269         // Position and delta are specified in local coordinate system of
 270         // current element
 271         mouse_event->local_pos = it->local_pos;
 272         //mouse_event->delta = it->local_delta;
 273       }
 274
 275       el->handleEvent(event);
 276
 277       if( event->propagation_stopped )
 278         return true;
 279     }
 280
 281     return true;
 282   }
 283
 284   //----------------------------------------------------------------------------
 285   bool
 286   EventManager::checkClickDistance( const EventPropagationPath& path1,
 287                                     const EventPropagationPath& path2 ) const
 288   {
 289     osg::Vec2 delta = path1.front().local_pos - path2.front().local_pos;
 290     return std::fabs(delta.x()) < drag_threshold
 291         && std::fabs(delta.y()) < drag_threshold;
 292   }
 293
 294   //----------------------------------------------------------------------------
 295   EventPropagationPath
 296   EventManager::getCommonAncestor( const EventPropagationPath& path1,
 297                                    const EventPropagationPath& path2 ) const
 298   {
 299     if( path1.empty() || path2.empty() )
 300       return EventPropagationPath();
 301
 302     if( path1.back().element.lock() == path2.back().element.lock() )
 303       return path2;
 304
 305     EventPropagationPath path;
 306
 307     for( size_t i = 0; i < path1.size() && i < path2.size(); ++i )
 308     {
 309       if( path1[i].element.lock() != path2[i].element.lock() )
 310         break;
 311
 312       path.push_back(path2[i]);
 313     }
 314
 315     return path;
 316   }
 317
 318 } // namespace canvas
 319 } // namespace simgear