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       // It's only possible on touch-down, which is the position we want to hit-test against when the pan actually starts
 165       mPossiblePanPosition = panEvent.currentPosition;
 166       break;
 167     }
 168
 169     case Gesture::Started:
 170     {
 171       // Requires a core update
 172       mNeedsUpdate = true;
 173
 174       if ( GetCurrentGesturedActor() )
 175       {
 176         // The pan gesture should only be sent to the gesture detector which first received it so that
 177         // it can be told when the gesture ends as well.
 178
 179         HitTestAlgorithm::Results hitTestResults;
 180         HitTest( scene, mPossiblePanPosition, hitTestResults ); // Hit test original possible position...
 181
 182         if ( hitTestResults.actor )
 183         {
 184           // Record the current render-task for Screen->Actor coordinate conversions
 185           mCurrentRenderTask = hitTestResults.renderTask;
 186
 187           // Set mCurrentPanEvent to use inside overridden methods called in ProcessAndEmit()
 188           mCurrentPanEvent = &panEvent;
 189           ProcessAndEmit( hitTestResults );
 190           mCurrentPanEvent = nullptr;
 191         }
 192         else
 193         {
 194           ResetActor();
 195           mCurrentPanEmitters.clear();
 196         }
 197       }
 198       break;
 199     }
 200
 201     case Gesture::Continuing:
 202     {
 203       // Requires a core update
 204       mNeedsUpdate = true;
 205     }
 206     // No break, Fallthrough
 207     case Gesture::Finished:
 208     case Gesture::Cancelled:
 209     {
 210       // Only send subsequent pan gesture signals if we processed the pan gesture when it started.
 211       // Check if actor is still touchable.
 212
 213       Actor* currentGesturedActor = GetCurrentGesturedActor();
 214       if ( currentGesturedActor )
 215       {
 216         if ( currentGesturedActor->IsHittable() && !mCurrentPanEmitters.empty() && mCurrentRenderTask )
 217         {
 218           GestureDetectorContainer outsideTouchesRangeEmitters;
 219
 220           // Removes emitters that no longer have the actor attached
 221           // Also remove emitters whose touches are outside the range of the current pan event and add them to outsideTouchesRangeEmitters
 222           GestureDetectorContainer::iterator endIter = std::remove_if( mCurrentPanEmitters.begin(), mCurrentPanEmitters.end(),
 223                                                                        IsNotAttachedAndOutsideTouchesRangeFunctor(currentGesturedActor, panEvent.numberOfTouches, outsideTouchesRangeEmitters) );
 224           mCurrentPanEmitters.erase( endIter, mCurrentPanEmitters.end() );
 225
 226           Vector2 actorCoords;
 227
 228           if ( !outsideTouchesRangeEmitters.empty() || !mCurrentPanEmitters.empty() )
 229           {
 230             currentGesturedActor->ScreenToLocal( *mCurrentRenderTask.Get(), actorCoords.x, actorCoords.y, panEvent.currentPosition.x, panEvent.currentPosition.y );
 231
 232             // EmitPanSignal checks whether we have a valid actor and whether the container we are passing in has emitters before it emits the pan.
 233             EmitPanSignal( currentGesturedActor, outsideTouchesRangeEmitters, panEvent, actorCoords, Gesture::Finished, mCurrentRenderTask);
 234             EmitPanSignal( currentGesturedActor, mCurrentPanEmitters, panEvent, actorCoords, panEvent.state, mCurrentRenderTask);
 235           }
 236
 237           if ( mCurrentPanEmitters.empty() )
 238           {
 239             // If we have no emitters attached then clear pan actor as well.
 240             ResetActor();
 241           }
 242
 243           // Clear current gesture detectors if pan gesture has ended or been cancelled.
 244           if ( ( panEvent.state == Gesture::Finished ) || ( panEvent.state == Gesture::Cancelled ) )
 245           {
 246             mCurrentPanEmitters.clear();
 247             ResetActor();
 248           }
 249         }
 250         else
 251         {
 252           mCurrentPanEmitters.clear();
 253           ResetActor();
 254         }
 255       }
 256       break;
 257     }
 258
 259     case Gesture::Clear:
 260     {
 261       DALI_ABORT( "Incorrect state received from Integration layer: Clear\n" );
 262       break;
 263     }
 264   }
 265 }
 266
 267 void PanGestureProcessor::AddGestureDetector( PanGestureDetector* gestureDetector, Scene& scene, int32_t minDistance, int32_t minPanEvents )
 268 {
 269   bool firstRegistration(mPanGestureDetectors.empty());
 270
 271   mPanGestureDetectors.push_back(gestureDetector);
 272
 273   if (firstRegistration)
 274   {
 275     mMinTouchesRequired = gestureDetector->GetMinimumTouchesRequired();
 276     mMaxTouchesRequired = gestureDetector->GetMaximumTouchesRequired();
 277
 278     PanGestureRequest request;
 279     request.minTouches = mMinTouchesRequired;
 280     request.maxTouches = mMaxTouchesRequired;
 281
 282     Size size = scene.GetSize();
 283     mGestureRecognizer = new PanGestureRecognizer(*this, Vector2(size.width, size.height), static_cast<const PanGestureRequest&>(request), minDistance, minPanEvents);
 284   }
 285   else
 286   {
 287     UpdateDetection();
 288   }
 289 }
 290
 291 void PanGestureProcessor::RemoveGestureDetector( PanGestureDetector* gestureDetector )
 292 {
 293   if (!mCurrentPanEmitters.empty())
 294   {
 295     // Check if the removed detector was one that is currently being panned and remove it from emitters.
 296     GestureDetectorContainer::iterator endIter = std::remove( mCurrentPanEmitters.begin(), mCurrentPanEmitters.end(), gestureDetector );
 297     mCurrentPanEmitters.erase( endIter, mCurrentPanEmitters.end() );
 298
 299     // If we no longer have any emitters, then we should clear mCurrentGesturedActor as well
 300     if ( mCurrentPanEmitters.empty() )
 301     {
 302       ResetActor();
 303     }
 304   }
 305
 306   // Find the detector...
 307   PanGestureDetectorContainer::iterator endIter = std::remove( mPanGestureDetectors.begin(), mPanGestureDetectors.end(), gestureDetector );
 308   DALI_ASSERT_DEBUG( endIter != mPanGestureDetectors.end() );
 309
 310   // ...and remove it
 311   mPanGestureDetectors.erase(endIter, mPanGestureDetectors.end());
 312
 313   if (mPanGestureDetectors.empty())
 314   {
 315     mGestureRecognizer.Detach();
 316   }
 317   else
 318   {
 319     UpdateDetection();
 320   }
 321 }
 322
 323 void PanGestureProcessor::GestureDetectorUpdated( PanGestureDetector* gestureDetector )
 324 {
 325   DALI_ASSERT_DEBUG(find(mPanGestureDetectors.begin(), mPanGestureDetectors.end(), gestureDetector) != mPanGestureDetectors.end());
 326
 327   UpdateDetection();
 328 }
 329
 330 bool PanGestureProcessor::SetPanGestureProperties( const PanGesture& pan )
 331 {
 332   // If we are currently processing a pan gesture then just ignore
 333   if ( mCurrentPanEmitters.empty() && mSceneObject )
 334   {
 335     // We update the scene object directly rather than sending a message.
 336     // Sending a message could cause unnecessary delays, the scene object ensure thread safe behaviour.
 337     mSceneObject->AddGesture( pan );
 338
 339     if( Gesture::Started == pan.state || Gesture::Continuing == pan.state )
 340     {
 341       mNeedsUpdate = true;
 342     }
 343   }
 344
 345   return mNeedsUpdate;
 346 }
 347
 348 void PanGestureProcessor::EnableProfiling()
 349 {
 350   mSceneObject->EnableProfiling();
 351 }
 352
 353 void PanGestureProcessor::SetPredictionMode(int mode)
 354 {
 355   if( (mode < 0)
 356       || (mode >= SceneGraph::PanGesture::NUM_PREDICTION_MODES) )
 357   {
 358     mode = SceneGraph::PanGesture::DEFAULT_PREDICTION_MODE;
 359   }
 360   SceneGraph::PanGesture::PredictionMode modeEnum = static_cast<SceneGraph::PanGesture::PredictionMode>(mode);
 361   mSceneObject->SetPredictionMode(modeEnum);
 362 }
 363
 364 void PanGestureProcessor::SetPredictionAmount(unsigned int amount)
 365 {
 366   mSceneObject->SetPredictionAmount(amount);
 367 }
 368
 369 void PanGestureProcessor::SetMaximumPredictionAmount(unsigned int amount)
 370 {
 371   mSceneObject->SetMaximumPredictionAmount(amount);
 372 }
 373
 374 void PanGestureProcessor::SetMinimumPredictionAmount(unsigned int amount)
 375 {
 376   mSceneObject->SetMinimumPredictionAmount(amount);
 377 }
 378
 379 void PanGestureProcessor::SetPredictionAmountAdjustment(unsigned int amount)
 380 {
 381   mSceneObject->SetPredictionAmountAdjustment(amount);
 382 }
 383
 384 void PanGestureProcessor::SetSmoothingMode(int mode)
 385 {
 386   if( (mode < 0)
 387       || (mode >= SceneGraph::PanGesture::NUM_SMOOTHING_MODES) )
 388   {
 389     mode = SceneGraph::PanGesture::DEFAULT_SMOOTHING_MODE;
 390   }
 391   SceneGraph::PanGesture::SmoothingMode modeEnum = static_cast<SceneGraph::PanGesture::SmoothingMode>(mode);
 392   mSceneObject->SetSmoothingMode(modeEnum);
 393 }
 394
 395 void PanGestureProcessor::SetSmoothingAmount(float amount)
 396 {
 397   mSceneObject->SetSmoothingAmount(amount);
 398 }
 399
 400 void PanGestureProcessor::SetUseActualTimes( bool value )
 401 {
 402   mSceneObject->SetUseActualTimes( value );
 403 }
 404
 405 void PanGestureProcessor::SetInterpolationTimeRange( int value )
 406 {
 407   mSceneObject->SetInterpolationTimeRange( value );
 408 }
 409
 410 void PanGestureProcessor::SetScalarOnlyPredictionEnabled( bool value )
 411 {
 412   mSceneObject->SetScalarOnlyPredictionEnabled( value );
 413 }
 414
 415 void PanGestureProcessor::SetTwoPointPredictionEnabled( bool value )
 416 {
 417   mSceneObject->SetTwoPointPredictionEnabled( value );
 418 }
 419
 420 void PanGestureProcessor::SetTwoPointInterpolatePastTime( int value )
 421 {
 422   mSceneObject->SetTwoPointInterpolatePastTime( value );
 423 }
 424
 425 void PanGestureProcessor::SetTwoPointVelocityBias( float value )
 426 {
 427   mSceneObject->SetTwoPointVelocityBias( value );
 428 }
 429
 430 void PanGestureProcessor::SetTwoPointAccelerationBias( float value )
 431 {
 432   mSceneObject->SetTwoPointAccelerationBias( value );
 433 }
 434
 435 void PanGestureProcessor::SetMultitapSmoothingRange( int value )
 436 {
 437   mSceneObject->SetMultitapSmoothingRange( value );
 438 }
 439
 440 const SceneGraph::PanGesture& PanGestureProcessor::GetSceneObject() const
 441 {
 442   return *mSceneObject;
 443 }
 444
 445 void PanGestureProcessor::UpdateDetection()
 446 {
 447   DALI_ASSERT_DEBUG(!mPanGestureDetectors.empty());
 448
 449   unsigned int minimumRequired = UINT_MAX;
 450   unsigned int maximumRequired = 0;
 451
 452   for ( PanGestureDetectorContainer::iterator iter = mPanGestureDetectors.begin(), endIter = mPanGestureDetectors.end(); iter != endIter; ++iter )
 453   {
 454     PanGestureDetector* detector(*iter);
 455
 456     if( detector )
 457     {
 458       unsigned int minimum = detector->GetMinimumTouchesRequired();
 459       if (minimum < minimumRequired)
 460       {
 461         minimumRequired = minimum;
 462       }
 463
 464       unsigned int maximum = detector->GetMaximumTouchesRequired();
 465       if (maximum > maximumRequired)
 466       {
 467         maximumRequired = maximum;
 468       }
 469     }
 470   }
 471
 472   if ( (minimumRequired != mMinTouchesRequired)||(maximumRequired != mMaxTouchesRequired) )
 473   {
 474     mMinTouchesRequired = minimumRequired;
 475     mMaxTouchesRequired = maximumRequired;
 476
 477     PanGestureRequest request;
 478     request.minTouches = mMinTouchesRequired;
 479     request.maxTouches = mMaxTouchesRequired;
 480     mGestureRecognizer->Update(request);
 481   }
 482 }
 483
 484 void PanGestureProcessor::EmitPanSignal( Actor* actor,
 485                                          const GestureDetectorContainer& gestureDetectors,
 486                                          const PanGestureEvent& panEvent,
 487                                          Vector2 localCurrent,
 488                                          Gesture::State state,
 489                                          RenderTaskPtr renderTask )
 490 {
 491   if ( actor && !gestureDetectors.empty() )
 492   {
 493     PanGesture pan(state);
 494     pan.time = panEvent.time;
 495
 496     pan.numberOfTouches = panEvent.numberOfTouches;
 497     pan.screenPosition = panEvent.currentPosition;
 498     pan.position = localCurrent;
 499
 500     RenderTask& renderTaskImpl( *renderTask.Get() );
 501
 502     Vector2 localPrevious;
 503     actor->ScreenToLocal( renderTaskImpl, localPrevious.x, localPrevious.y, panEvent.previousPosition.x, panEvent.previousPosition.y );
 504
 505     pan.displacement = localCurrent - localPrevious;
 506     Vector2 previousPos( panEvent.previousPosition );
 507     if ( state == Gesture::Started )
 508     {
 509       previousPos = mPossiblePanPosition;
 510     }
 511
 512     pan.screenDisplacement = panEvent.currentPosition - previousPos;
 513
 514     // Avoid dividing by 0
 515     if ( panEvent.timeDelta > 0 )
 516     {
 517       pan.velocity.x = pan.displacement.x / static_cast<float>( panEvent.timeDelta );
 518       pan.velocity.y = pan.displacement.y / static_cast<float>( panEvent.timeDelta );
 519
 520       pan.screenVelocity.x = pan.screenDisplacement.x / static_cast<float>( panEvent.timeDelta );
 521       pan.screenVelocity.y = pan.screenDisplacement.y / static_cast<float>( panEvent.timeDelta );
 522     }
 523
 524     // When the gesture ends, we may incorrectly get a ZERO velocity (as we have lifted our finger without any movement)
 525     // so we should use the last recorded velocity instead in this scenario.
 526     if ( ( state == Gesture::Finished ) && ( pan.screenVelocity == Vector2::ZERO ) &&
 527          ( panEvent.timeDelta < MAXIMUM_TIME_WITH_VALID_LAST_VELOCITY ) )
 528     {
 529       pan.velocity = mLastVelocity;
 530       pan.screenVelocity = mLastScreenVelocity;
 531     }
 532     else
 533     {
 534       // Store the current velocity for future iterations.
 535       mLastVelocity = pan.velocity;
 536       mLastScreenVelocity = pan.screenVelocity;
 537     }
 538
 539     if ( mSceneObject )
 540     {
 541       // We update the scene object directly rather than sending a message.
 542       // Sending a message could cause unnecessary delays, the scene object ensure thread safe behaviour.
 543       mSceneObject->AddGesture( pan );
 544     }
 545
 546     Dali::Actor actorHandle( actor );
 547
 548     const GestureDetectorContainer::const_iterator endIter = gestureDetectors.end();
 549     for ( GestureDetectorContainer::const_iterator iter = gestureDetectors.begin(); iter != endIter; ++iter )
 550     {
 551       static_cast< PanGestureDetector* >( *iter )->EmitPanGestureSignal( actorHandle, pan );
 552     }
 553   }
 554 }
 555
 556 void PanGestureProcessor::OnGesturedActorStageDisconnection()
 557 {
 558   mCurrentPanEmitters.clear();
 559 }
 560
 561 bool PanGestureProcessor::CheckGestureDetector( GestureDetector* detector, Actor* actor )
 562 {
 563   DALI_ASSERT_DEBUG( mCurrentPanEvent );
 564
 565   bool retVal( false );
 566   PanGestureDetector* panDetector( static_cast< PanGestureDetector* >( detector ) );
 567
 568   if ( ( mCurrentPanEvent->numberOfTouches >= panDetector->GetMinimumTouchesRequired() ) &&
 569        ( mCurrentPanEvent->numberOfTouches <= panDetector->GetMaximumTouchesRequired() ) )
 570   {
 571     // Check if the detector requires directional panning.
 572     if ( panDetector->RequiresDirectionalPan() && mCurrentRenderTask )
 573     {
 574       // It does, calculate the angle of the pan in local actor coordinates and ensures it fits
 575       // the detector's criteria.
 576       RenderTask& renderTaskImpl = *mCurrentRenderTask.Get();
 577
 578       Vector2 startPosition, currentPosition;
 579       actor->ScreenToLocal( renderTaskImpl, startPosition.x,   startPosition.y,   mPossiblePanPosition.x,              mPossiblePanPosition.y );
 580       actor->ScreenToLocal( renderTaskImpl, currentPosition.x, currentPosition.y, mCurrentPanEvent->currentPosition.x, mCurrentPanEvent->currentPosition.y );
 581       Vector2 displacement( currentPosition - startPosition );
 582
 583       Radian angle( atanf( displacement.y / displacement.x ) );
 584
 585       /////////////////////////////
 586       //            |            //
 587       //            |            //
 588       //   Q3 (-,-) | Q4 (+,-)   //
 589       //            |            //
 590       //    ----------------- +x //
 591       //            |            //
 592       //   Q2 (-,+) | Q1 (+,+)   //
 593       //            |            //
 594       //            |            //
 595       //           +y            //
 596       /////////////////////////////
 597       // Quadrant 1: As is
 598       // Quadrant 2: 180 degrees + angle
 599       // Quadrant 3: angle - 180 degrees
 600       // Quadrant 4: As is
 601       /////////////////////////////
 602
 603       if ( displacement.x < 0.0f )
 604       {
 605         if ( displacement.y >= 0.0f )
 606         {
 607           // Quadrant 2
 608           angle.radian += Math::PI;
 609         }
 610         else
 611         {
 612           // Quadrant 3
 613           angle.radian -= Math::PI;
 614         }
 615       }
 616
 617       if ( panDetector->CheckAngleAllowed( angle ) )
 618       {
 619         retVal = true;
 620       }
 621     }
 622     else
 623     {
 624       // Directional panning not required so we can use this actor and gesture detector.
 625       retVal = true;
 626     }
 627   }
 628   return retVal;
 629 }
 630
 631 void PanGestureProcessor::EmitGestureSignal( Actor* actor, const GestureDetectorContainer& gestureDetectors, Vector2 actorCoordinates )
 632 {
 633   DALI_ASSERT_DEBUG ( mCurrentPanEvent );
 634
 635   mCurrentPanEmitters.clear();
 636   ResetActor();
 637
 638   actor->ScreenToLocal( *mCurrentRenderTask.Get(), actorCoordinates.x, actorCoordinates.y, mCurrentPanEvent->currentPosition.x, mCurrentPanEvent->currentPosition.y );
 639
 640   EmitPanSignal( actor, gestureDetectors, *mCurrentPanEvent, actorCoordinates, mCurrentPanEvent->state, mCurrentRenderTask );
 641
 642   if ( actor->OnStage() )
 643   {
 644     mCurrentPanEmitters = gestureDetectors;
 645     SetActor( actor );
 646   }
 647 }
 648
 649 } // namespace Internal
 650
 651 } // namespace Dali