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
 171       break;
 172     }
 173
 174     case Gesture::Started:
 175     {
 176       // Requires a core update
 177       mNeedsUpdate = true;
 178
 179       if ( GetCurrentGesturedActor() )
 180       {
 181         // The pan gesture should only be sent to the gesture detector which first received it so that
 182         // it can be told when the gesture ends as well.
 183
 184         HitTestAlgorithm::Results hitTestResults;
 185         HitTest( scene, mPossiblePanPosition, hitTestResults ); // Hit test original possible position...
 186
 187         if ( hitTestResults.actor && ( GetCurrentGesturedActor() == &GetImplementation( hitTestResults.actor ) ) )
 188         {
 189           // Record the current render-task for Screen->Actor coordinate conversions
 190           mCurrentRenderTask = hitTestResults.renderTask;
 191
 192           // Set mCurrentPanEvent to use inside overridden methods called in ProcessAndEmit()
 193           mCurrentPanEvent = &panEvent;
 194           ProcessAndEmit( hitTestResults );
 195           mCurrentPanEvent = nullptr;
 196         }
 197         else
 198         {
 199           ResetActor();
 200           mCurrentPanEmitters.clear();
 201         }
 202       }
 203       break;
 204     }
 205
 206     case Gesture::Continuing:
 207     {
 208       // Requires a core update
 209       mNeedsUpdate = true;
 210     }
 211     // No break, Fallthrough
 212     case Gesture::Finished:
 213     case Gesture::Cancelled:
 214     {
 215       // Only send subsequent pan gesture signals if we processed the pan gesture when it started.
 216       // Check if actor is still touchable.
 217
 218       Actor* currentGesturedActor = GetCurrentGesturedActor();
 219       if ( currentGesturedActor )
 220       {
 221         if ( currentGesturedActor->IsHittable() && !mCurrentPanEmitters.empty() && mCurrentRenderTask )
 222         {
 223           GestureDetectorContainer outsideTouchesRangeEmitters;
 224
 225           // Removes emitters that no longer have the actor attached
 226           // Also remove emitters whose touches are outside the range of the current pan event and add them to outsideTouchesRangeEmitters
 227           GestureDetectorContainer::iterator endIter = std::remove_if( mCurrentPanEmitters.begin(), mCurrentPanEmitters.end(),
 228                                                                        IsNotAttachedAndOutsideTouchesRangeFunctor(currentGesturedActor, panEvent.numberOfTouches, outsideTouchesRangeEmitters) );
 229           mCurrentPanEmitters.erase( endIter, mCurrentPanEmitters.end() );
 230
 231           Vector2 actorCoords;
 232
 233           if ( !outsideTouchesRangeEmitters.empty() || !mCurrentPanEmitters.empty() )
 234           {
 235             currentGesturedActor->ScreenToLocal( *mCurrentRenderTask.Get(), actorCoords.x, actorCoords.y, panEvent.currentPosition.x, panEvent.currentPosition.y );
 236
 237             // EmitPanSignal checks whether we have a valid actor and whether the container we are passing in has emitters before it emits the pan.
 238             EmitPanSignal( currentGesturedActor, outsideTouchesRangeEmitters, panEvent, actorCoords, Gesture::Finished, mCurrentRenderTask);
 239             EmitPanSignal( currentGesturedActor, mCurrentPanEmitters, panEvent, actorCoords, panEvent.state, mCurrentRenderTask);
 240           }
 241
 242           if ( mCurrentPanEmitters.empty() )
 243           {
 244             // If we have no emitters attached then clear pan actor as well.
 245             ResetActor();
 246           }
 247
 248           // Clear current gesture detectors if pan gesture has ended or been cancelled.
 249           if ( ( panEvent.state == Gesture::Finished ) || ( panEvent.state == Gesture::Cancelled ) )
 250           {
 251             mCurrentPanEmitters.clear();
 252             ResetActor();
 253           }
 254         }
 255         else
 256         {
 257           mCurrentPanEmitters.clear();
 258           ResetActor();
 259         }
 260       }
 261       break;
 262     }
 263
 264     case Gesture::Clear:
 265     {
 266       DALI_ABORT( "Incorrect state received from Integration layer: Clear\n" );
 267       break;
 268     }
 269   }
 270 }
 271
 272 void PanGestureProcessor::AddGestureDetector( PanGestureDetector* gestureDetector, Scene& scene, int32_t minDistance, int32_t minPanEvents )
 273 {
 274   bool firstRegistration(mPanGestureDetectors.empty());
 275
 276   mPanGestureDetectors.push_back(gestureDetector);
 277
 278   if (firstRegistration)
 279   {
 280     mMinTouchesRequired = gestureDetector->GetMinimumTouchesRequired();
 281     mMaxTouchesRequired = gestureDetector->GetMaximumTouchesRequired();
 282
 283     PanGestureRequest request;
 284     request.minTouches = mMinTouchesRequired;
 285     request.maxTouches = mMaxTouchesRequired;
 286
 287     Size size = scene.GetSize();
 288     mGestureRecognizer = new PanGestureRecognizer(*this, Vector2(size.width, size.height), static_cast<const PanGestureRequest&>(request), minDistance, minPanEvents);
 289   }
 290   else
 291   {
 292     UpdateDetection();
 293   }
 294 }
 295
 296 void PanGestureProcessor::RemoveGestureDetector( PanGestureDetector* gestureDetector )
 297 {
 298   if (!mCurrentPanEmitters.empty())
 299   {
 300     // Check if the removed detector was one that is currently being panned and remove it from emitters.
 301     GestureDetectorContainer::iterator endIter = std::remove( mCurrentPanEmitters.begin(), mCurrentPanEmitters.end(), gestureDetector );
 302     mCurrentPanEmitters.erase( endIter, mCurrentPanEmitters.end() );
 303
 304     // If we no longer have any emitters, then we should clear mCurrentGesturedActor as well
 305     if ( mCurrentPanEmitters.empty() )
 306     {
 307       ResetActor();
 308     }
 309   }
 310
 311   // Find the detector...
 312   PanGestureDetectorContainer::iterator endIter = std::remove( mPanGestureDetectors.begin(), mPanGestureDetectors.end(), gestureDetector );
 313   DALI_ASSERT_DEBUG( endIter != mPanGestureDetectors.end() );
 314
 315   // ...and remove it
 316   mPanGestureDetectors.erase(endIter, mPanGestureDetectors.end());
 317
 318   if (mPanGestureDetectors.empty())
 319   {
 320     mGestureRecognizer.Detach();
 321   }
 322   else
 323   {
 324     UpdateDetection();
 325   }
 326 }
 327
 328 void PanGestureProcessor::GestureDetectorUpdated( PanGestureDetector* gestureDetector )
 329 {
 330   DALI_ASSERT_DEBUG(find(mPanGestureDetectors.begin(), mPanGestureDetectors.end(), gestureDetector) != mPanGestureDetectors.end());
 331
 332   UpdateDetection();
 333 }
 334
 335 bool PanGestureProcessor::SetPanGestureProperties( const PanGesture& pan )
 336 {
 337   // If we are currently processing a pan gesture then just ignore
 338   if ( mCurrentPanEmitters.empty() && mSceneObject )
 339   {
 340     // We update the scene object directly rather than sending a message.
 341     // Sending a message could cause unnecessary delays, the scene object ensure thread safe behaviour.
 342     mSceneObject->AddGesture( pan );
 343
 344     if( Gesture::Started == pan.state || Gesture::Continuing == pan.state )
 345     {
 346       mNeedsUpdate = true;
 347     }
 348   }
 349
 350   return mNeedsUpdate;
 351 }
 352
 353 void PanGestureProcessor::EnableProfiling()
 354 {
 355   mSceneObject->EnableProfiling();
 356 }
 357
 358 void PanGestureProcessor::SetPredictionMode(int mode)
 359 {
 360   if( (mode < 0)
 361       || (mode >= SceneGraph::PanGesture::NUM_PREDICTION_MODES) )
 362   {
 363     mode = SceneGraph::PanGesture::DEFAULT_PREDICTION_MODE;
 364   }
 365   SceneGraph::PanGesture::PredictionMode modeEnum = static_cast<SceneGraph::PanGesture::PredictionMode>(mode);
 366   mSceneObject->SetPredictionMode(modeEnum);
 367 }
 368
 369 void PanGestureProcessor::SetPredictionAmount(unsigned int amount)
 370 {
 371   mSceneObject->SetPredictionAmount(amount);
 372 }
 373
 374 void PanGestureProcessor::SetMaximumPredictionAmount(unsigned int amount)
 375 {
 376   mSceneObject->SetMaximumPredictionAmount(amount);
 377 }
 378
 379 void PanGestureProcessor::SetMinimumPredictionAmount(unsigned int amount)
 380 {
 381   mSceneObject->SetMinimumPredictionAmount(amount);
 382 }
 383
 384 void PanGestureProcessor::SetPredictionAmountAdjustment(unsigned int amount)
 385 {
 386   mSceneObject->SetPredictionAmountAdjustment(amount);
 387 }
 388
 389 void PanGestureProcessor::SetSmoothingMode(int mode)
 390 {
 391   if( (mode < 0)
 392       || (mode >= SceneGraph::PanGesture::NUM_SMOOTHING_MODES) )
 393   {
 394     mode = SceneGraph::PanGesture::DEFAULT_SMOOTHING_MODE;
 395   }
 396   SceneGraph::PanGesture::SmoothingMode modeEnum = static_cast<SceneGraph::PanGesture::SmoothingMode>(mode);
 397   mSceneObject->SetSmoothingMode(modeEnum);
 398 }
 399
 400 void PanGestureProcessor::SetSmoothingAmount(float amount)
 401 {
 402   mSceneObject->SetSmoothingAmount(amount);
 403 }
 404
 405 void PanGestureProcessor::SetUseActualTimes( bool value )
 406 {
 407   mSceneObject->SetUseActualTimes( value );
 408 }
 409
 410 void PanGestureProcessor::SetInterpolationTimeRange( int value )
 411 {
 412   mSceneObject->SetInterpolationTimeRange( value );
 413 }
 414
 415 void PanGestureProcessor::SetScalarOnlyPredictionEnabled( bool value )
 416 {
 417   mSceneObject->SetScalarOnlyPredictionEnabled( value );
 418 }
 419
 420 void PanGestureProcessor::SetTwoPointPredictionEnabled( bool value )
 421 {
 422   mSceneObject->SetTwoPointPredictionEnabled( value );
 423 }
 424
 425 void PanGestureProcessor::SetTwoPointInterpolatePastTime( int value )
 426 {
 427   mSceneObject->SetTwoPointInterpolatePastTime( value );
 428 }
 429
 430 void PanGestureProcessor::SetTwoPointVelocityBias( float value )
 431 {
 432   mSceneObject->SetTwoPointVelocityBias( value );
 433 }
 434
 435 void PanGestureProcessor::SetTwoPointAccelerationBias( float value )
 436 {
 437   mSceneObject->SetTwoPointAccelerationBias( value );
 438 }
 439
 440 void PanGestureProcessor::SetMultitapSmoothingRange( int value )
 441 {
 442   mSceneObject->SetMultitapSmoothingRange( value );
 443 }
 444
 445 const SceneGraph::PanGesture& PanGestureProcessor::GetSceneObject() const
 446 {
 447   return *mSceneObject;
 448 }
 449
 450 void PanGestureProcessor::UpdateDetection()
 451 {
 452   DALI_ASSERT_DEBUG(!mPanGestureDetectors.empty());
 453
 454   unsigned int minimumRequired = UINT_MAX;
 455   unsigned int maximumRequired = 0;
 456
 457   for ( PanGestureDetectorContainer::iterator iter = mPanGestureDetectors.begin(), endIter = mPanGestureDetectors.end(); iter != endIter; ++iter )
 458   {
 459     PanGestureDetector* detector(*iter);
 460
 461     if( detector )
 462     {
 463       unsigned int minimum = detector->GetMinimumTouchesRequired();
 464       if (minimum < minimumRequired)
 465       {
 466         minimumRequired = minimum;
 467       }
 468
 469       unsigned int maximum = detector->GetMaximumTouchesRequired();
 470       if (maximum > maximumRequired)
 471       {
 472         maximumRequired = maximum;
 473       }
 474     }
 475   }
 476
 477   if ( (minimumRequired != mMinTouchesRequired)||(maximumRequired != mMaxTouchesRequired) )
 478   {
 479     mMinTouchesRequired = minimumRequired;
 480     mMaxTouchesRequired = maximumRequired;
 481
 482     PanGestureRequest request;
 483     request.minTouches = mMinTouchesRequired;
 484     request.maxTouches = mMaxTouchesRequired;
 485     mGestureRecognizer->Update(request);
 486   }
 487 }
 488
 489 void PanGestureProcessor::EmitPanSignal( Actor* actor,
 490                                          const GestureDetectorContainer& gestureDetectors,
 491                                          const PanGestureEvent& panEvent,
 492                                          Vector2 localCurrent,
 493                                          Gesture::State state,
 494                                          RenderTaskPtr renderTask )
 495 {
 496   if ( actor && !gestureDetectors.empty() )
 497   {
 498     PanGesture pan(state);
 499     pan.time = panEvent.time;
 500
 501     pan.numberOfTouches = panEvent.numberOfTouches;
 502     pan.screenPosition = panEvent.currentPosition;
 503     pan.position = localCurrent;
 504
 505     RenderTask& renderTaskImpl( *renderTask.Get() );
 506
 507     Vector2 localPrevious;
 508     actor->ScreenToLocal( renderTaskImpl, localPrevious.x, localPrevious.y, panEvent.previousPosition.x, panEvent.previousPosition.y );
 509
 510     pan.displacement = localCurrent - localPrevious;
 511     Vector2 previousPos( panEvent.previousPosition );
 512     if ( state == Gesture::Started )
 513     {
 514       previousPos = mPossiblePanPosition;
 515     }
 516
 517     pan.screenDisplacement = panEvent.currentPosition - previousPos;
 518
 519     // Avoid dividing by 0
 520     if ( panEvent.timeDelta > 0 )
 521     {
 522       pan.velocity.x = pan.displacement.x / static_cast<float>( panEvent.timeDelta );
 523       pan.velocity.y = pan.displacement.y / static_cast<float>( panEvent.timeDelta );
 524
 525       pan.screenVelocity.x = pan.screenDisplacement.x / static_cast<float>( panEvent.timeDelta );
 526       pan.screenVelocity.y = pan.screenDisplacement.y / static_cast<float>( panEvent.timeDelta );
 527     }
 528
 529     // When the gesture ends, we may incorrectly get a ZERO velocity (as we have lifted our finger without any movement)
 530     // so we should use the last recorded velocity instead in this scenario.
 531     if ( ( state == Gesture::Finished ) && ( pan.screenVelocity == Vector2::ZERO ) &&
 532          ( panEvent.timeDelta < MAXIMUM_TIME_WITH_VALID_LAST_VELOCITY ) )
 533     {
 534       pan.velocity = mLastVelocity;
 535       pan.screenVelocity = mLastScreenVelocity;
 536     }
 537     else
 538     {
 539       // Store the current velocity for future iterations.
 540       mLastVelocity = pan.velocity;
 541       mLastScreenVelocity = pan.screenVelocity;
 542     }
 543
 544     if ( mSceneObject )
 545     {
 546       // We update the scene object directly rather than sending a message.
 547       // Sending a message could cause unnecessary delays, the scene object ensure thread safe behaviour.
 548       mSceneObject->AddGesture( pan );
 549     }
 550
 551     Dali::Actor actorHandle( actor );
 552
 553     const GestureDetectorContainer::const_iterator endIter = gestureDetectors.end();
 554     for ( GestureDetectorContainer::const_iterator iter = gestureDetectors.begin(); iter != endIter; ++iter )
 555     {
 556       static_cast< PanGestureDetector* >( *iter )->EmitPanGestureSignal( actorHandle, pan );
 557     }
 558   }
 559 }
 560
 561 void PanGestureProcessor::OnGesturedActorStageDisconnection()
 562 {
 563   mCurrentPanEmitters.clear();
 564 }
 565
 566 bool PanGestureProcessor::CheckGestureDetector( GestureDetector* detector, Actor* actor )
 567 {
 568   DALI_ASSERT_DEBUG( mCurrentPanEvent );
 569
 570   bool retVal( false );
 571   PanGestureDetector* panDetector( static_cast< PanGestureDetector* >( detector ) );
 572
 573   if ( ( mCurrentPanEvent->numberOfTouches >= panDetector->GetMinimumTouchesRequired() ) &&
 574        ( mCurrentPanEvent->numberOfTouches <= panDetector->GetMaximumTouchesRequired() ) )
 575   {
 576     // Check if the detector requires directional panning.
 577     if ( panDetector->RequiresDirectionalPan() && mCurrentRenderTask )
 578     {
 579       // It does, calculate the angle of the pan in local actor coordinates and ensures it fits
 580       // the detector's criteria.
 581       RenderTask& renderTaskImpl = *mCurrentRenderTask.Get();
 582
 583       Vector2 startPosition, currentPosition;
 584       actor->ScreenToLocal( renderTaskImpl, startPosition.x,   startPosition.y,   mPossiblePanPosition.x,              mPossiblePanPosition.y );
 585       actor->ScreenToLocal( renderTaskImpl, currentPosition.x, currentPosition.y, mCurrentPanEvent->currentPosition.x, mCurrentPanEvent->currentPosition.y );
 586       Vector2 displacement( currentPosition - startPosition );
 587
 588       Radian angle( atanf( displacement.y / displacement.x ) );
 589
 590       /////////////////////////////
 591       //            |            //
 592       //            |            //
 593       //   Q3 (-,-) | Q4 (+,-)   //
 594       //            |            //
 595       //    ----------------- +x //
 596       //            |            //
 597       //   Q2 (-,+) | Q1 (+,+)   //
 598       //            |            //
 599       //            |            //
 600       //           +y            //
 601       /////////////////////////////
 602       // Quadrant 1: As is
 603       // Quadrant 2: 180 degrees + angle
 604       // Quadrant 3: angle - 180 degrees
 605       // Quadrant 4: As is
 606       /////////////////////////////
 607
 608       if ( displacement.x < 0.0f )
 609       {
 610         if ( displacement.y >= 0.0f )
 611         {
 612           // Quadrant 2
 613           angle.radian += Math::PI;
 614         }
 615         else
 616         {
 617           // Quadrant 3
 618           angle.radian -= Math::PI;
 619         }
 620       }
 621
 622       if ( panDetector->CheckAngleAllowed( angle ) )
 623       {
 624         retVal = true;
 625       }
 626     }
 627     else
 628     {
 629       // Directional panning not required so we can use this actor and gesture detector.
 630       retVal = true;
 631     }
 632   }
 633   return retVal;
 634 }
 635
 636 void PanGestureProcessor::EmitGestureSignal( Actor* actor, const GestureDetectorContainer& gestureDetectors, Vector2 actorCoordinates )
 637 {
 638   DALI_ASSERT_DEBUG ( mCurrentPanEvent );
 639
 640   mCurrentPanEmitters.clear();
 641   ResetActor();
 642
 643   actor->ScreenToLocal( *mCurrentRenderTask.Get(), actorCoordinates.x, actorCoordinates.y, mCurrentPanEvent->currentPosition.x, mCurrentPanEvent->currentPosition.y );
 644
 645   EmitPanSignal( actor, gestureDetectors, *mCurrentPanEvent, actorCoordinates, mCurrentPanEvent->state, mCurrentRenderTask );
 646
 647   if ( actor->OnStage() )
 648   {
 649     mCurrentPanEmitters = gestureDetectors;
 650     SetActor( actor );
 651   }
 652 }
 653
 654 } // namespace Internal
 655
 656 } // namespace Dali