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

   1 /*
   2  * Copyright (c) 2020 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       DALI_FALLTHROUGH;
 215     }
 216
 217     case Gesture::Finished:
 218     case Gesture::Cancelled:
 219     {
 220       // Only send subsequent pan gesture signals if we processed the pan gesture when it started.
 221       // Check if actor is still touchable.
 222
 223       Actor* currentGesturedActor = GetCurrentGesturedActor();
 224       if ( currentGesturedActor )
 225       {
 226         if ( currentGesturedActor->IsHittable() && !mCurrentPanEmitters.empty() && mCurrentRenderTask )
 227         {
 228           GestureDetectorContainer outsideTouchesRangeEmitters;
 229
 230           // Removes emitters that no longer have the actor attached
 231           // Also remove emitters whose touches are outside the range of the current pan event and add them to outsideTouchesRangeEmitters
 232           GestureDetectorContainer::iterator endIter = std::remove_if( mCurrentPanEmitters.begin(), mCurrentPanEmitters.end(),
 233                                                                        IsNotAttachedAndOutsideTouchesRangeFunctor(currentGesturedActor, panEvent.numberOfTouches, outsideTouchesRangeEmitters) );
 234           mCurrentPanEmitters.erase( endIter, mCurrentPanEmitters.end() );
 235
 236           Vector2 actorCoords;
 237
 238           if ( !outsideTouchesRangeEmitters.empty() || !mCurrentPanEmitters.empty() )
 239           {
 240             currentGesturedActor->ScreenToLocal( *mCurrentRenderTask.Get(), actorCoords.x, actorCoords.y, panEvent.currentPosition.x, panEvent.currentPosition.y );
 241
 242             // EmitPanSignal checks whether we have a valid actor and whether the container we are passing in has emitters before it emits the pan.
 243             EmitPanSignal( currentGesturedActor, outsideTouchesRangeEmitters, panEvent, actorCoords, Gesture::Finished, mCurrentRenderTask);
 244             EmitPanSignal( currentGesturedActor, mCurrentPanEmitters, panEvent, actorCoords, panEvent.state, mCurrentRenderTask);
 245           }
 246
 247           if ( mCurrentPanEmitters.empty() )
 248           {
 249             // If we have no emitters attached then clear pan actor as well.
 250             ResetActor();
 251           }
 252
 253           // Clear current gesture detectors if pan gesture has ended or been cancelled.
 254           if ( ( panEvent.state == Gesture::Finished ) || ( panEvent.state == Gesture::Cancelled ) )
 255           {
 256             mCurrentPanEmitters.clear();
 257             ResetActor();
 258           }
 259         }
 260         else
 261         {
 262           mCurrentPanEmitters.clear();
 263           ResetActor();
 264         }
 265       }
 266       break;
 267     }
 268
 269     case Gesture::Clear:
 270     {
 271       DALI_ABORT( "Incorrect state received from Integration layer: Clear\n" );
 272       break;
 273     }
 274   }
 275 }
 276
 277 void PanGestureProcessor::AddGestureDetector( PanGestureDetector* gestureDetector, Scene& scene, int32_t minDistance, int32_t minPanEvents )
 278 {
 279   bool firstRegistration(mPanGestureDetectors.empty());
 280
 281   mPanGestureDetectors.push_back(gestureDetector);
 282
 283   if (firstRegistration)
 284   {
 285     mMinTouchesRequired = gestureDetector->GetMinimumTouchesRequired();
 286     mMaxTouchesRequired = gestureDetector->GetMaximumTouchesRequired();
 287
 288     PanGestureRequest request;
 289     request.minTouches = mMinTouchesRequired;
 290     request.maxTouches = mMaxTouchesRequired;
 291
 292     Size size = scene.GetSize();
 293     mGestureRecognizer = new PanGestureRecognizer(*this, Vector2(size.width, size.height), static_cast<const PanGestureRequest&>(request), minDistance, minPanEvents);
 294   }
 295   else
 296   {
 297     UpdateDetection();
 298   }
 299 }
 300
 301 void PanGestureProcessor::RemoveGestureDetector( PanGestureDetector* gestureDetector )
 302 {
 303   if (!mCurrentPanEmitters.empty())
 304   {
 305     // Check if the removed detector was one that is currently being panned and remove it from emitters.
 306     GestureDetectorContainer::iterator endIter = std::remove( mCurrentPanEmitters.begin(), mCurrentPanEmitters.end(), gestureDetector );
 307     mCurrentPanEmitters.erase( endIter, mCurrentPanEmitters.end() );
 308
 309     // If we no longer have any emitters, then we should clear mCurrentGesturedActor as well
 310     if ( mCurrentPanEmitters.empty() )
 311     {
 312       ResetActor();
 313     }
 314   }
 315
 316   // Find the detector...
 317   PanGestureDetectorContainer::iterator endIter = std::remove( mPanGestureDetectors.begin(), mPanGestureDetectors.end(), gestureDetector );
 318   DALI_ASSERT_DEBUG( endIter != mPanGestureDetectors.end() );
 319
 320   // ...and remove it
 321   mPanGestureDetectors.erase(endIter, mPanGestureDetectors.end());
 322
 323   if (mPanGestureDetectors.empty())
 324   {
 325     mGestureRecognizer = nullptr;
 326   }
 327   else
 328   {
 329     UpdateDetection();
 330   }
 331 }
 332
 333 void PanGestureProcessor::GestureDetectorUpdated( PanGestureDetector* gestureDetector )
 334 {
 335   DALI_ASSERT_DEBUG(find(mPanGestureDetectors.begin(), mPanGestureDetectors.end(), gestureDetector) != mPanGestureDetectors.end());
 336
 337   UpdateDetection();
 338 }
 339
 340 bool PanGestureProcessor::SetPanGestureProperties( const PanGesture& pan )
 341 {
 342   // If we are currently processing a pan gesture then just ignore
 343   if ( mCurrentPanEmitters.empty() && mSceneObject )
 344   {
 345     // We update the scene object directly rather than sending a message.
 346     // Sending a message could cause unnecessary delays, the scene object ensure thread safe behaviour.
 347     mSceneObject->AddGesture( pan );
 348
 349     if( Gesture::Started == pan.state || Gesture::Continuing == pan.state )
 350     {
 351       mNeedsUpdate = true;
 352     }
 353   }
 354
 355   return mNeedsUpdate;
 356 }
 357
 358 void PanGestureProcessor::EnableProfiling()
 359 {
 360   mSceneObject->EnableProfiling();
 361 }
 362
 363 void PanGestureProcessor::SetPredictionMode(int mode)
 364 {
 365   if( (mode < 0)
 366       || (mode >= SceneGraph::PanGesture::NUM_PREDICTION_MODES) )
 367   {
 368     mode = SceneGraph::PanGesture::DEFAULT_PREDICTION_MODE;
 369   }
 370   SceneGraph::PanGesture::PredictionMode modeEnum = static_cast<SceneGraph::PanGesture::PredictionMode>(mode);
 371   mSceneObject->SetPredictionMode(modeEnum);
 372 }
 373
 374 void PanGestureProcessor::SetPredictionAmount(unsigned int amount)
 375 {
 376   mSceneObject->SetPredictionAmount(amount);
 377 }
 378
 379 void PanGestureProcessor::SetMaximumPredictionAmount(unsigned int amount)
 380 {
 381   mSceneObject->SetMaximumPredictionAmount(amount);
 382 }
 383
 384 void PanGestureProcessor::SetMinimumPredictionAmount(unsigned int amount)
 385 {
 386   mSceneObject->SetMinimumPredictionAmount(amount);
 387 }
 388
 389 void PanGestureProcessor::SetPredictionAmountAdjustment(unsigned int amount)
 390 {
 391   mSceneObject->SetPredictionAmountAdjustment(amount);
 392 }
 393
 394 void PanGestureProcessor::SetSmoothingMode(int mode)
 395 {
 396   if( (mode < 0)
 397       || (mode >= SceneGraph::PanGesture::NUM_SMOOTHING_MODES) )
 398   {
 399     mode = SceneGraph::PanGesture::DEFAULT_SMOOTHING_MODE;
 400   }
 401   SceneGraph::PanGesture::SmoothingMode modeEnum = static_cast<SceneGraph::PanGesture::SmoothingMode>(mode);
 402   mSceneObject->SetSmoothingMode(modeEnum);
 403 }
 404
 405 void PanGestureProcessor::SetSmoothingAmount(float amount)
 406 {
 407   mSceneObject->SetSmoothingAmount(amount);
 408 }
 409
 410 void PanGestureProcessor::SetUseActualTimes( bool value )
 411 {
 412   mSceneObject->SetUseActualTimes( value );
 413 }
 414
 415 void PanGestureProcessor::SetInterpolationTimeRange( int value )
 416 {
 417   mSceneObject->SetInterpolationTimeRange( value );
 418 }
 419
 420 void PanGestureProcessor::SetScalarOnlyPredictionEnabled( bool value )
 421 {
 422   mSceneObject->SetScalarOnlyPredictionEnabled( value );
 423 }
 424
 425 void PanGestureProcessor::SetTwoPointPredictionEnabled( bool value )
 426 {
 427   mSceneObject->SetTwoPointPredictionEnabled( value );
 428 }
 429
 430 void PanGestureProcessor::SetTwoPointInterpolatePastTime( int value )
 431 {
 432   mSceneObject->SetTwoPointInterpolatePastTime( value );
 433 }
 434
 435 void PanGestureProcessor::SetTwoPointVelocityBias( float value )
 436 {
 437   mSceneObject->SetTwoPointVelocityBias( value );
 438 }
 439
 440 void PanGestureProcessor::SetTwoPointAccelerationBias( float value )
 441 {
 442   mSceneObject->SetTwoPointAccelerationBias( value );
 443 }
 444
 445 void PanGestureProcessor::SetMultitapSmoothingRange( int value )
 446 {
 447   mSceneObject->SetMultitapSmoothingRange( value );
 448 }
 449
 450 const SceneGraph::PanGesture& PanGestureProcessor::GetSceneObject() const
 451 {
 452   return *mSceneObject;
 453 }
 454
 455 void PanGestureProcessor::UpdateDetection()
 456 {
 457   DALI_ASSERT_DEBUG(!mPanGestureDetectors.empty());
 458
 459   unsigned int minimumRequired = UINT_MAX;
 460   unsigned int maximumRequired = 0;
 461
 462   for ( PanGestureDetectorContainer::iterator iter = mPanGestureDetectors.begin(), endIter = mPanGestureDetectors.end(); iter != endIter; ++iter )
 463   {
 464     PanGestureDetector* detector(*iter);
 465
 466     if( detector )
 467     {
 468       unsigned int minimum = detector->GetMinimumTouchesRequired();
 469       if (minimum < minimumRequired)
 470       {
 471         minimumRequired = minimum;
 472       }
 473
 474       unsigned int maximum = detector->GetMaximumTouchesRequired();
 475       if (maximum > maximumRequired)
 476       {
 477         maximumRequired = maximum;
 478       }
 479     }
 480   }
 481
 482   if ( (minimumRequired != mMinTouchesRequired)||(maximumRequired != mMaxTouchesRequired) )
 483   {
 484     mMinTouchesRequired = minimumRequired;
 485     mMaxTouchesRequired = maximumRequired;
 486
 487     PanGestureRequest request;
 488     request.minTouches = mMinTouchesRequired;
 489     request.maxTouches = mMaxTouchesRequired;
 490     mGestureRecognizer->Update(request);
 491   }
 492 }
 493
 494 void PanGestureProcessor::EmitPanSignal( Actor* actor,
 495                                          const GestureDetectorContainer& gestureDetectors,
 496                                          const PanGestureEvent& panEvent,
 497                                          Vector2 localCurrent,
 498                                          Gesture::State state,
 499                                          RenderTaskPtr renderTask )
 500 {
 501   if ( actor && !gestureDetectors.empty() )
 502   {
 503     PanGesture pan(state);
 504     pan.time = panEvent.time;
 505
 506     pan.numberOfTouches = panEvent.numberOfTouches;
 507     pan.screenPosition = panEvent.currentPosition;
 508     pan.position = localCurrent;
 509
 510     RenderTask& renderTaskImpl( *renderTask.Get() );
 511
 512     Vector2 localPrevious;
 513     actor->ScreenToLocal( renderTaskImpl, localPrevious.x, localPrevious.y, panEvent.previousPosition.x, panEvent.previousPosition.y );
 514
 515     pan.displacement = localCurrent - localPrevious;
 516     Vector2 previousPos( panEvent.previousPosition );
 517     if ( state == Gesture::Started )
 518     {
 519       previousPos = mPossiblePanPosition;
 520     }
 521
 522     pan.screenDisplacement = panEvent.currentPosition - previousPos;
 523
 524     // Avoid dividing by 0
 525     if ( panEvent.timeDelta > 0 )
 526     {
 527       pan.velocity.x = pan.displacement.x / static_cast<float>( panEvent.timeDelta );
 528       pan.velocity.y = pan.displacement.y / static_cast<float>( panEvent.timeDelta );
 529
 530       pan.screenVelocity.x = pan.screenDisplacement.x / static_cast<float>( panEvent.timeDelta );
 531       pan.screenVelocity.y = pan.screenDisplacement.y / static_cast<float>( panEvent.timeDelta );
 532     }
 533
 534     // When the gesture ends, we may incorrectly get a ZERO velocity (as we have lifted our finger without any movement)
 535     // so we should use the last recorded velocity instead in this scenario.
 536     if ( ( state == Gesture::Finished ) && ( pan.screenVelocity == Vector2::ZERO ) &&
 537          ( panEvent.timeDelta < MAXIMUM_TIME_WITH_VALID_LAST_VELOCITY ) )
 538     {
 539       pan.velocity = mLastVelocity;
 540       pan.screenVelocity = mLastScreenVelocity;
 541     }
 542     else
 543     {
 544       // Store the current velocity for future iterations.
 545       mLastVelocity = pan.velocity;
 546       mLastScreenVelocity = pan.screenVelocity;
 547     }
 548
 549     if ( mSceneObject )
 550     {
 551       // We update the scene object directly rather than sending a message.
 552       // Sending a message could cause unnecessary delays, the scene object ensure thread safe behaviour.
 553       mSceneObject->AddGesture( pan );
 554     }
 555
 556     Dali::Actor actorHandle( actor );
 557
 558     const GestureDetectorContainer::const_iterator endIter = gestureDetectors.end();
 559     for ( GestureDetectorContainer::const_iterator iter = gestureDetectors.begin(); iter != endIter; ++iter )
 560     {
 561       static_cast< PanGestureDetector* >( *iter )->EmitPanGestureSignal( actorHandle, pan );
 562     }
 563   }
 564 }
 565
 566 void PanGestureProcessor::OnGesturedActorStageDisconnection()
 567 {
 568   mCurrentPanEmitters.clear();
 569 }
 570
 571 bool PanGestureProcessor::CheckGestureDetector( GestureDetector* detector, Actor* actor )
 572 {
 573   DALI_ASSERT_DEBUG( mCurrentPanEvent );
 574
 575   bool retVal( false );
 576   PanGestureDetector* panDetector( static_cast< PanGestureDetector* >( detector ) );
 577
 578   if ( ( mCurrentPanEvent->numberOfTouches >= panDetector->GetMinimumTouchesRequired() ) &&
 579        ( mCurrentPanEvent->numberOfTouches <= panDetector->GetMaximumTouchesRequired() ) )
 580   {
 581     // Check if the detector requires directional panning.
 582     if ( panDetector->RequiresDirectionalPan() && mCurrentRenderTask )
 583     {
 584       // It does, calculate the angle of the pan in local actor coordinates and ensures it fits
 585       // the detector's criteria.
 586       RenderTask& renderTaskImpl = *mCurrentRenderTask.Get();
 587
 588       Vector2 startPosition, currentPosition;
 589       actor->ScreenToLocal( renderTaskImpl, startPosition.x,   startPosition.y,   mPossiblePanPosition.x,              mPossiblePanPosition.y );
 590       actor->ScreenToLocal( renderTaskImpl, currentPosition.x, currentPosition.y, mCurrentPanEvent->currentPosition.x, mCurrentPanEvent->currentPosition.y );
 591       Vector2 displacement( currentPosition - startPosition );
 592
 593       Radian angle( atanf( displacement.y / displacement.x ) );
 594
 595       /////////////////////////////
 596       //            |            //
 597       //            |            //
 598       //   Q3 (-,-) | Q4 (+,-)   //
 599       //            |            //
 600       //    ----------------- +x //
 601       //            |            //
 602       //   Q2 (-,+) | Q1 (+,+)   //
 603       //            |            //
 604       //            |            //
 605       //           +y            //
 606       /////////////////////////////
 607       // Quadrant 1: As is
 608       // Quadrant 2: 180 degrees + angle
 609       // Quadrant 3: angle - 180 degrees
 610       // Quadrant 4: As is
 611       /////////////////////////////
 612
 613       if ( displacement.x < 0.0f )
 614       {
 615         if ( displacement.y >= 0.0f )
 616         {
 617           // Quadrant 2
 618           angle.radian += Math::PI;
 619         }
 620         else
 621         {
 622           // Quadrant 3
 623           angle.radian -= Math::PI;
 624         }
 625       }
 626
 627       if ( panDetector->CheckAngleAllowed( angle ) )
 628       {
 629         retVal = true;
 630       }
 631     }
 632     else
 633     {
 634       // Directional panning not required so we can use this actor and gesture detector.
 635       retVal = true;
 636     }
 637   }
 638   return retVal;
 639 }
 640
 641 void PanGestureProcessor::EmitGestureSignal( Actor* actor, const GestureDetectorContainer& gestureDetectors, Vector2 actorCoordinates )
 642 {
 643   DALI_ASSERT_DEBUG ( mCurrentPanEvent );
 644
 645   mCurrentPanEmitters.clear();
 646   ResetActor();
 647
 648   actor->ScreenToLocal( *mCurrentRenderTask.Get(), actorCoordinates.x, actorCoordinates.y, mCurrentPanEvent->currentPosition.x, mCurrentPanEvent->currentPosition.y );
 649
 650   EmitPanSignal( actor, gestureDetectors, *mCurrentPanEvent, actorCoordinates, mCurrentPanEvent->state, mCurrentRenderTask );
 651
 652   if ( actor->OnStage() )
 653   {
 654     mCurrentPanEmitters = gestureDetectors;
 655     SetActor( actor );
 656   }
 657 }
 658
 659 } // namespace Internal
 660
 661 } // namespace Dali