dali/internal/event/events/pan-gesture/pan-gesture-processor.cpp

   1 /*
   2  * Copyright (c) 2019 Samsung Electronics Co., Ltd.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  *
  16  */
  17
  18 // CLASS HEADER
  19 #include <dali/internal/event/events/pan-gesture/pan-gesture-processor.h>
  20
  21 #if defined(DEBUG_ENABLED)
  22 #include <sstream>
  23 #endif
  24
  25 // EXTERNAL INCLUDES
  26 #include <algorithm>
  27
  28 // INTERNAL INCLUDES
  29 #include <dali/public-api/actors/actor.h>
  30 #include <dali/public-api/common/dali-common.h>
  31 #include <dali/public-api/events/pan-gesture.h>
  32 #include <dali/public-api/math/vector2.h>
  33 #include <dali/internal/event/events/pan-gesture/pan-gesture-event.h>
  34 #include <dali/integration-api/debug.h>
  35 #include <dali/internal/event/common/scene-impl.h>
  36 #include <dali/internal/event/render-tasks/render-task-impl.h>
  37 #include <dali/internal/update/gestures/scene-graph-pan-gesture.h>
  38 #include <dali/internal/event/events/multi-point-event-util.h>
  39 #include <dali/internal/event/events/pan-gesture/pan-gesture-recognizer.h>
  40 #include <dali/internal/event/events/gesture-requests.h>
  41
  42 namespace Dali
  43 {
  44
  45 namespace Internal
  46 {
  47
  48 namespace // unnamed namespace
  49 {
  50
  51 #if defined(DEBUG_ENABLED)
  52 Debug::Filter* gLogFilter = Debug::Filter::New(Debug::NoLogging, false, "LOG_PAN_PROCESSOR" );
  53
  54 const char * GESTURE_STATES[ 6 ] =
  55 {
  56   "Clear",
  57   "Started",
  58   "Continuing",
  59   "Finished",
  60   "Cancelled",
  61   "Possible"
  62 };
  63
  64 #endif // defined(DEBUG_ENABLED)
  65
  66 const unsigned long MAXIMUM_TIME_WITH_VALID_LAST_VELOCITY( 50u );
  67
  68 /**
  69  * Functor which checks whether the specified actor is attached to the gesture detector.
  70  * If the actor is attached, it also checks whether the number of touches of the current pan event
  71  * are within the range of that expected by the detector.
  72  * It returns true if it is no longer attached or the touches are out of range.
  73  * This can be used in remove_if functions.
  74  */
  75 struct IsNotAttachedAndOutsideTouchesRangeFunctor
  76 {
  77   /**
  78    * Constructor
  79    * @param[in]  actor                 The actor to check whether it is attached.
  80    * @param[in]  touches               The number of touches in the current pan event.
  81    * @param[in]  outsideRangeEmitters  Reference to container where emitters outside of the touches range should be added.
  82    */
  83   IsNotAttachedAndOutsideTouchesRangeFunctor(Actor* actor, unsigned int touches, GestureDetectorContainer& outsideRangeEmitters)
  84   : actorToCheck(actor),
  85     numberOfTouches(touches),
  86     outsideTouchesRangeEmitters(outsideRangeEmitters)
  87   {
  88   }
  89
  90   /**
  91    * Returns true if not attached, false if it is still attached.
  92    * Additionally, checks if the number of touches has changed and stops sending the pan to a particular
  93    * detector if it exceeds the range of that detector.
  94    * @param[in]  detector  The detector to check.
  95    * @return true, if not attached, false otherwise.
  96    */
  97   bool operator()(GestureDetector* detector) const
  98   {
  99     bool remove(!detector->IsAttached(*actorToCheck));
 100
 101     if (!remove)
 102     {
 103       PanGestureDetector* panDetector( static_cast< PanGestureDetector* >( detector ) );
 104
 105       // Ensure number of touch points is within the range of our emitter. If it isn't then remove
 106       // this emitter and add it to the outsideTouchesRangeEmitters container
 107       if ( (numberOfTouches < panDetector->GetMinimumTouchesRequired()) ||
 108            (numberOfTouches > panDetector->GetMaximumTouchesRequired()) )
 109       {
 110         remove = true;
 111         outsideTouchesRangeEmitters.push_back(detector);
 112       }
 113     }
 114
 115     return remove;
 116   }
 117
 118   Actor* actorToCheck; ///< The actor to check whether it is attached or not.
 119   unsigned int numberOfTouches; ///< The number of touches in the pan event.
 120   GestureDetectorContainer& outsideTouchesRangeEmitters; ///< Emitters that are outside of the range of current pan.
 121 };
 122
 123 } // unnamed namespace
 124
 125 PanGestureProcessor::PanGestureProcessor( SceneGraph::UpdateManager& updateManager )
 126 : GestureProcessor( Gesture::Pan ),
 127   mPanGestureDetectors(),
 128   mCurrentPanEmitters(),
 129   mCurrentRenderTask(),
 130   mPossiblePanPosition(),
 131   mMinTouchesRequired( 1 ),
 132   mMaxTouchesRequired( 1 ),
 133   mCurrentPanEvent( nullptr ),
 134   mSceneObject( SceneGraph::PanGesture::New() ) // Create scene object to store pan information.
 135 {
 136   // Pass ownership to scene-graph; scene object lives for the lifecycle of UpdateManager
 137   updateManager.SetPanGestureProcessor( mSceneObject );
 138 }
 139
 140 PanGestureProcessor::~PanGestureProcessor()
 141 {
 142   mSceneObject = nullptr; // mSceneObject is owned and destroyed by update manager (there is only one of these for now)
 143 }
 144
 145 void PanGestureProcessor::Process( Scene& scene, const PanGestureEvent& panEvent )
 146 {
 147 #if defined(DEBUG_ENABLED)
 148   DALI_LOG_TRACE_METHOD( gLogFilter );
 149
 150   DALI_LOG_INFO( gLogFilter, Debug::General, "    Pan Event\n");
 151   DALI_LOG_INFO( gLogFilter, Debug::General, "      State: %s  Touches: %d  Time: %d  TimeDelta: %d\n",
 152                                              GESTURE_STATES[panEvent.state], panEvent.numberOfTouches, panEvent.time, panEvent.timeDelta);
 153   DALI_LOG_INFO( gLogFilter, Debug::General, "      Positions: Current: (%.0f, %.0f), Previous: (%.0f, %.0f)\n",
 154                                              panEvent.currentPosition.x, panEvent.currentPosition.y, panEvent.previousPosition.x, panEvent.previousPosition.y);
 155 #endif
 156
 157   switch( panEvent.state )
 158   {
 159     case Gesture::Possible:
 160     {
 161       mCurrentPanEmitters.clear();
 162       ResetActor();
 163
 164       HitTestAlgorithm::Results hitTestResults;
 165       if( HitTest( scene, panEvent.currentPosition, hitTestResults ) )
 166       {
 167         SetActor( &GetImplementation( hitTestResults.actor ) );
 168         mPossiblePanPosition = panEvent.currentPosition;
 169       }
 170       break;
 171     }
 172
 173     case Gesture::Started:
 174     {
 175       // Requires a core update
 176       mNeedsUpdate = true;
 177
 178       // The pan gesture should only be sent to the gesture detector which first received it so that
 179       // it can be told when the gesture ends as well.
 180
 181       HitTestAlgorithm::Results hitTestResults;
 182       HitTest( scene, panEvent.previousPosition, hitTestResults ); // Hit Test previous position
 183
 184       if ( hitTestResults.actor )
 185       {
 186         // If the current hit actor is different from the one we touched down on then set accordingly & update initial pan position
 187         if( &GetImplementation( hitTestResults.actor ) != GetCurrentGesturedActor() )
 188         {
 189           mPossiblePanPosition = panEvent.previousPosition;
 190           SetActor( &GetImplementation( hitTestResults.actor ) );
 191         }
 192
 193         // Record the current render-task for Screen->Actor coordinate conversions
 194         mCurrentRenderTask = hitTestResults.renderTask;
 195
 196         // Set mCurrentPanEvent to use inside overridden methods called in ProcessAndEmit()
 197         mCurrentPanEvent = &panEvent;
 198         ProcessAndEmit( hitTestResults );
 199         mCurrentPanEvent = nullptr;
 200       }
 201       else
 202       {
 203         ResetActor();
 204         mCurrentPanEmitters.clear();
 205       }
 206       break;
 207     }
 208
 209     case Gesture::Continuing:
 210     {
 211       // Requires a core update
 212       mNeedsUpdate = true;
 213     }
 214     // No break, Fallthrough
 215     case Gesture::Finished:
 216     case Gesture::Cancelled:
 217     {
 218       // Only send subsequent pan gesture signals if we processed the pan gesture when it started.
 219       // Check if actor is still touchable.
 220
 221       Actor* currentGesturedActor = GetCurrentGesturedActor();
 222       if ( currentGesturedActor )
 223       {
 224         if ( currentGesturedActor->IsHittable() && !mCurrentPanEmitters.empty() && mCurrentRenderTask )
 225         {
 226           GestureDetectorContainer outsideTouchesRangeEmitters;
 227
 228           // Removes emitters that no longer have the actor attached
 229           // Also remove emitters whose touches are outside the range of the current pan event and add them to outsideTouchesRangeEmitters
 230           GestureDetectorContainer::iterator endIter = std::remove_if( mCurrentPanEmitters.begin(), mCurrentPanEmitters.end(),
 231                                                                        IsNotAttachedAndOutsideTouchesRangeFunctor(currentGesturedActor, panEvent.numberOfTouches, outsideTouchesRangeEmitters) );
 232           mCurrentPanEmitters.erase( endIter, mCurrentPanEmitters.end() );
 233
 234           Vector2 actorCoords;
 235
 236           if ( !outsideTouchesRangeEmitters.empty() || !mCurrentPanEmitters.empty() )
 237           {
 238             currentGesturedActor->ScreenToLocal( *mCurrentRenderTask.Get(), actorCoords.x, actorCoords.y, panEvent.currentPosition.x, panEvent.currentPosition.y );
 239
 240             // EmitPanSignal checks whether we have a valid actor and whether the container we are passing in has emitters before it emits the pan.
 241             EmitPanSignal( currentGesturedActor, outsideTouchesRangeEmitters, panEvent, actorCoords, Gesture::Finished, mCurrentRenderTask);
 242             EmitPanSignal( currentGesturedActor, mCurrentPanEmitters, panEvent, actorCoords, panEvent.state, mCurrentRenderTask);
 243           }
 244
 245           if ( mCurrentPanEmitters.empty() )
 246           {
 247             // If we have no emitters attached then clear pan actor as well.
 248             ResetActor();
 249           }
 250
 251           // Clear current gesture detectors if pan gesture has ended or been cancelled.
 252           if ( ( panEvent.state == Gesture::Finished ) || ( panEvent.state == Gesture::Cancelled ) )
 253           {
 254             mCurrentPanEmitters.clear();
 255             ResetActor();
 256           }
 257         }
 258         else
 259         {
 260           mCurrentPanEmitters.clear();
 261           ResetActor();
 262         }
 263       }
 264       break;
 265     }
 266
 267     case Gesture::Clear:
 268     {
 269       DALI_ABORT( "Incorrect state received from Integration layer: Clear\n" );
 270       break;
 271     }
 272   }
 273 }
 274
 275 void PanGestureProcessor::AddGestureDetector( PanGestureDetector* gestureDetector, Scene& scene, int32_t minDistance, int32_t minPanEvents )
 276 {
 277   bool firstRegistration(mPanGestureDetectors.empty());
 278
 279   mPanGestureDetectors.push_back(gestureDetector);
 280
 281   if (firstRegistration)
 282   {
 283     mMinTouchesRequired = gestureDetector->GetMinimumTouchesRequired();
 284     mMaxTouchesRequired = gestureDetector->GetMaximumTouchesRequired();
 285
 286     PanGestureRequest request;
 287     request.minTouches = mMinTouchesRequired;
 288     request.maxTouches = mMaxTouchesRequired;
 289
 290     Size size = scene.GetSize();
 291     mGestureRecognizer = new PanGestureRecognizer(*this, Vector2(size.width, size.height), static_cast<const PanGestureRequest&>(request), minDistance, minPanEvents);
 292   }
 293   else
 294   {
 295     UpdateDetection();
 296   }
 297 }
 298
 299 void PanGestureProcessor::RemoveGestureDetector( PanGestureDetector* gestureDetector )
 300 {
 301   if (!mCurrentPanEmitters.empty())
 302   {
 303     // Check if the removed detector was one that is currently being panned and remove it from emitters.
 304     GestureDetectorContainer::iterator endIter = std::remove( mCurrentPanEmitters.begin(), mCurrentPanEmitters.end(), gestureDetector );
 305     mCurrentPanEmitters.erase( endIter, mCurrentPanEmitters.end() );
 306
 307     // If we no longer have any emitters, then we should clear mCurrentGesturedActor as well
 308     if ( mCurrentPanEmitters.empty() )
 309     {
 310       ResetActor();
 311     }
 312   }
 313
 314   // Find the detector...
 315   PanGestureDetectorContainer::iterator endIter = std::remove( mPanGestureDetectors.begin(), mPanGestureDetectors.end(), gestureDetector );
 316   DALI_ASSERT_DEBUG( endIter != mPanGestureDetectors.end() );
 317
 318   // ...and remove it
 319   mPanGestureDetectors.erase(endIter, mPanGestureDetectors.end());
 320
 321   if (mPanGestureDetectors.empty())
 322   {
 323     mGestureRecognizer.Detach();
 324   }
 325   else
 326   {
 327     UpdateDetection();
 328   }
 329 }
 330
 331 void PanGestureProcessor::GestureDetectorUpdated( PanGestureDetector* gestureDetector )
 332 {
 333   DALI_ASSERT_DEBUG(find(mPanGestureDetectors.begin(), mPanGestureDetectors.end(), gestureDetector) != mPanGestureDetectors.end());
 334
 335   UpdateDetection();
 336 }
 337
 338 bool PanGestureProcessor::SetPanGestureProperties( const PanGesture& pan )
 339 {
 340   // If we are currently processing a pan gesture then just ignore
 341   if ( mCurrentPanEmitters.empty() && mSceneObject )
 342   {
 343     // We update the scene object directly rather than sending a message.
 344     // Sending a message could cause unnecessary delays, the scene object ensure thread safe behaviour.
 345     mSceneObject->AddGesture( pan );
 346
 347     if( Gesture::Started == pan.state || Gesture::Continuing == pan.state )
 348     {
 349       mNeedsUpdate = true;
 350     }
 351   }
 352
 353   return mNeedsUpdate;
 354 }
 355
 356 void PanGestureProcessor::EnableProfiling()
 357 {
 358   mSceneObject->EnableProfiling();
 359 }
 360
 361 void PanGestureProcessor::SetPredictionMode(int mode)
 362 {
 363   if( (mode < 0)
 364       || (mode >= SceneGraph::PanGesture::NUM_PREDICTION_MODES) )
 365   {
 366     mode = SceneGraph::PanGesture::DEFAULT_PREDICTION_MODE;
 367   }
 368   SceneGraph::PanGesture::PredictionMode modeEnum = static_cast<SceneGraph::PanGesture::PredictionMode>(mode);
 369   mSceneObject->SetPredictionMode(modeEnum);
 370 }
 371
 372 void PanGestureProcessor::SetPredictionAmount(unsigned int amount)
 373 {
 374   mSceneObject->SetPredictionAmount(amount);
 375 }
 376
 377 void PanGestureProcessor::SetMaximumPredictionAmount(unsigned int amount)
 378 {
 379   mSceneObject->SetMaximumPredictionAmount(amount);
 380 }
 381
 382 void PanGestureProcessor::SetMinimumPredictionAmount(unsigned int amount)
 383 {
 384   mSceneObject->SetMinimumPredictionAmount(amount);
 385 }
 386
 387 void PanGestureProcessor::SetPredictionAmountAdjustment(unsigned int amount)
 388 {
 389   mSceneObject->SetPredictionAmountAdjustment(amount);
 390 }
 391
 392 void PanGestureProcessor::SetSmoothingMode(int mode)
 393 {
 394   if( (mode < 0)
 395       || (mode >= SceneGraph::PanGesture::NUM_SMOOTHING_MODES) )
 396   {
 397     mode = SceneGraph::PanGesture::DEFAULT_SMOOTHING_MODE;
 398   }
 399   SceneGraph::PanGesture::SmoothingMode modeEnum = static_cast<SceneGraph::PanGesture::SmoothingMode>(mode);
 400   mSceneObject->SetSmoothingMode(modeEnum);
 401 }
 402
 403 void PanGestureProcessor::SetSmoothingAmount(float amount)
 404 {
 405   mSceneObject->SetSmoothingAmount(amount);
 406 }
 407
 408 void PanGestureProcessor::SetUseActualTimes( bool value )
 409 {
 410   mSceneObject->SetUseActualTimes( value );
 411 }
 412
 413 void PanGestureProcessor::SetInterpolationTimeRange( int value )
 414 {
 415   mSceneObject->SetInterpolationTimeRange( value );
 416 }
 417
 418 void PanGestureProcessor::SetScalarOnlyPredictionEnabled( bool value )
 419 {
 420   mSceneObject->SetScalarOnlyPredictionEnabled( value );
 421 }
 422
 423 void PanGestureProcessor::SetTwoPointPredictionEnabled( bool value )
 424 {
 425   mSceneObject->SetTwoPointPredictionEnabled( value );
 426 }
 427
 428 void PanGestureProcessor::SetTwoPointInterpolatePastTime( int value )
 429 {
 430   mSceneObject->SetTwoPointInterpolatePastTime( value );
 431 }
 432
 433 void PanGestureProcessor::SetTwoPointVelocityBias( float value )
 434 {
 435   mSceneObject->SetTwoPointVelocityBias( value );
 436 }
 437
 438 void PanGestureProcessor::SetTwoPointAccelerationBias( float value )
 439 {
 440   mSceneObject->SetTwoPointAccelerationBias( value );
 441 }
 442
 443 void PanGestureProcessor::SetMultitapSmoothingRange( int value )
 444 {
 445   mSceneObject->SetMultitapSmoothingRange( value );
 446 }
 447
 448 const SceneGraph::PanGesture& PanGestureProcessor::GetSceneObject() const
 449 {
 450   return *mSceneObject;
 451 }
 452
 453 void PanGestureProcessor::UpdateDetection()
 454 {
 455   DALI_ASSERT_DEBUG(!mPanGestureDetectors.empty());
 456
 457   unsigned int minimumRequired = UINT_MAX;
 458   unsigned int maximumRequired = 0;
 459
 460   for ( PanGestureDetectorContainer::iterator iter = mPanGestureDetectors.begin(), endIter = mPanGestureDetectors.end(); iter != endIter; ++iter )
 461   {
 462     PanGestureDetector* detector(*iter);
 463
 464     if( detector )
 465     {
 466       unsigned int minimum = detector->GetMinimumTouchesRequired();
 467       if (minimum < minimumRequired)
 468       {
 469         minimumRequired = minimum;
 470       }
 471
 472       unsigned int maximum = detector->GetMaximumTouchesRequired();
 473       if (maximum > maximumRequired)
 474       {
 475         maximumRequired = maximum;
 476       }
 477     }
 478   }
 479
 480   if ( (minimumRequired != mMinTouchesRequired)||(maximumRequired != mMaxTouchesRequired) )
 481   {
 482     mMinTouchesRequired = minimumRequired;
 483     mMaxTouchesRequired = maximumRequired;
 484
 485     PanGestureRequest request;
 486     request.minTouches = mMinTouchesRequired;
 487     request.maxTouches = mMaxTouchesRequired;
 488     mGestureRecognizer->Update(request);
 489   }
 490 }
 491
 492 void PanGestureProcessor::EmitPanSignal( Actor* actor,
 493                                          const GestureDetectorContainer& gestureDetectors,
 494                                          const PanGestureEvent& panEvent,
 495                                          Vector2 localCurrent,
 496                                          Gesture::State state,
 497                                          RenderTaskPtr renderTask )
 498 {
 499   if ( actor && !gestureDetectors.empty() )
 500   {
 501     PanGesture pan(state);
 502     pan.time = panEvent.time;
 503
 504     pan.numberOfTouches = panEvent.numberOfTouches;
 505     pan.screenPosition = panEvent.currentPosition;
 506     pan.position = localCurrent;
 507
 508     RenderTask& renderTaskImpl( *renderTask.Get() );
 509
 510     Vector2 localPrevious;
 511     actor->ScreenToLocal( renderTaskImpl, localPrevious.x, localPrevious.y, panEvent.previousPosition.x, panEvent.previousPosition.y );
 512
 513     pan.displacement = localCurrent - localPrevious;
 514     Vector2 previousPos( panEvent.previousPosition );
 515     if ( state == Gesture::Started )
 516     {
 517       previousPos = mPossiblePanPosition;
 518     }
 519
 520     pan.screenDisplacement = panEvent.currentPosition - previousPos;
 521
 522     // Avoid dividing by 0
 523     if ( panEvent.timeDelta > 0 )
 524     {
 525       pan.velocity.x = pan.displacement.x / static_cast<float>( panEvent.timeDelta );
 526       pan.velocity.y = pan.displacement.y / static_cast<float>( panEvent.timeDelta );
 527
 528       pan.screenVelocity.x = pan.screenDisplacement.x / static_cast<float>( panEvent.timeDelta );
 529       pan.screenVelocity.y = pan.screenDisplacement.y / static_cast<float>( panEvent.timeDelta );
 530     }
 531
 532     // When the gesture ends, we may incorrectly get a ZERO velocity (as we have lifted our finger without any movement)
 533     // so we should use the last recorded velocity instead in this scenario.
 534     if ( ( state == Gesture::Finished ) && ( pan.screenVelocity == Vector2::ZERO ) &&
 535          ( panEvent.timeDelta < MAXIMUM_TIME_WITH_VALID_LAST_VELOCITY ) )
 536     {
 537       pan.velocity = mLastVelocity;
 538       pan.screenVelocity = mLastScreenVelocity;
 539     }
 540     else
 541     {
 542       // Store the current velocity for future iterations.
 543       mLastVelocity = pan.velocity;
 544       mLastScreenVelocity = pan.screenVelocity;
 545     }
 546
 547     if ( mSceneObject )
 548     {
 549       // We update the scene object directly rather than sending a message.
 550       // Sending a message could cause unnecessary delays, the scene object ensure thread safe behaviour.
 551       mSceneObject->AddGesture( pan );
 552     }
 553
 554     Dali::Actor actorHandle( actor );
 555
 556     const GestureDetectorContainer::const_iterator endIter = gestureDetectors.end();
 557     for ( GestureDetectorContainer::const_iterator iter = gestureDetectors.begin(); iter != endIter; ++iter )
 558     {
 559       static_cast< PanGestureDetector* >( *iter )->EmitPanGestureSignal( actorHandle, pan );
 560     }
 561   }
 562 }
 563
 564 void PanGestureProcessor::OnGesturedActorStageDisconnection()
 565 {
 566   mCurrentPanEmitters.clear();
 567 }
 568
 569 bool PanGestureProcessor::CheckGestureDetector( GestureDetector* detector, Actor* actor )
 570 {
 571   DALI_ASSERT_DEBUG( mCurrentPanEvent );
 572
 573   bool retVal( false );
 574   PanGestureDetector* panDetector( static_cast< PanGestureDetector* >( detector ) );
 575
 576   if ( ( mCurrentPanEvent->numberOfTouches >= panDetector->GetMinimumTouchesRequired() ) &&
 577        ( mCurrentPanEvent->numberOfTouches <= panDetector->GetMaximumTouchesRequired() ) )
 578   {
 579     // Check if the detector requires directional panning.
 580     if ( panDetector->RequiresDirectionalPan() && mCurrentRenderTask )
 581     {
 582       // It does, calculate the angle of the pan in local actor coordinates and ensures it fits
 583       // the detector's criteria.
 584       RenderTask& renderTaskImpl = *mCurrentRenderTask.Get();
 585
 586       Vector2 startPosition, currentPosition;
 587       actor->ScreenToLocal( renderTaskImpl, startPosition.x,   startPosition.y,   mPossiblePanPosition.x,              mPossiblePanPosition.y );
 588       actor->ScreenToLocal( renderTaskImpl, currentPosition.x, currentPosition.y, mCurrentPanEvent->currentPosition.x, mCurrentPanEvent->currentPosition.y );
 589       Vector2 displacement( currentPosition - startPosition );
 590
 591       Radian angle( atanf( displacement.y / displacement.x ) );
 592
 593       /////////////////////////////
 594       //            |            //
 595       //            |            //
 596       //   Q3 (-,-) | Q4 (+,-)   //
 597       //            |            //
 598       //    ----------------- +x //
 599       //            |            //
 600       //   Q2 (-,+) | Q1 (+,+)   //
 601       //            |            //
 602       //            |            //
 603       //           +y            //
 604       /////////////////////////////
 605       // Quadrant 1: As is
 606       // Quadrant 2: 180 degrees + angle
 607       // Quadrant 3: angle - 180 degrees
 608       // Quadrant 4: As is
 609       /////////////////////////////
 610
 611       if ( displacement.x < 0.0f )
 612       {
 613         if ( displacement.y >= 0.0f )
 614         {
 615           // Quadrant 2
 616           angle.radian += Math::PI;
 617         }
 618         else
 619         {
 620           // Quadrant 3
 621           angle.radian -= Math::PI;
 622         }
 623       }
 624
 625       if ( panDetector->CheckAngleAllowed( angle ) )
 626       {
 627         retVal = true;
 628       }
 629     }
 630     else
 631     {
 632       // Directional panning not required so we can use this actor and gesture detector.
 633       retVal = true;
 634     }
 635   }
 636   return retVal;
 637 }
 638
 639 void PanGestureProcessor::EmitGestureSignal( Actor* actor, const GestureDetectorContainer& gestureDetectors, Vector2 actorCoordinates )
 640 {
 641   DALI_ASSERT_DEBUG ( mCurrentPanEvent );
 642
 643   mCurrentPanEmitters.clear();
 644   ResetActor();
 645
 646   actor->ScreenToLocal( *mCurrentRenderTask.Get(), actorCoordinates.x, actorCoordinates.y, mCurrentPanEvent->currentPosition.x, mCurrentPanEvent->currentPosition.y );
 647
 648   EmitPanSignal( actor, gestureDetectors, *mCurrentPanEvent, actorCoordinates, mCurrentPanEvent->state, mCurrentRenderTask );
 649
 650   if ( actor->OnStage() )
 651   {
 652     mCurrentPanEmitters = gestureDetectors;
 653     SetActor( actor );
 654   }
 655 }
 656
 657 } // namespace Internal
 658
 659 } // namespace Dali