goldendict-ng/src/gestures.cc

/* This file is (c) 2014 Abs62
 * Part of GoldenDict. Licensed under GPLv3 or later, see the LICENSE file */

#include <QTouchEvent>
#include <QSwipeGesture>
#include <QVariant>
#include <math.h>
#include "ui/articleview.hh"
#include "gestures.hh"

namespace Gestures {

Qt::GestureType GDPinchGestureType;
Qt::GestureType GDSwipeGestureType;
static bool fewTouchPointsPresented;

bool isFewTouchPointsPresented()
{
  return fewTouchPointsPresented;
}

QSwipeGesture::SwipeDirection getHorizontalDirection( qreal angle )
{
  if ( ( 0 <= angle && angle <= 45 ) || ( 315 <= angle && angle <= 360 ) )
    return QSwipeGesture::Right;

  if ( 135 <= angle && angle <= 225 )
    return QSwipeGesture::Left;

  return QSwipeGesture::NoDirection;
}

QSwipeGesture::SwipeDirection getVerticalDirection( qreal angle )
{
  if ( 45 < angle && angle < 135 )
    return QSwipeGesture::Up;

  if ( 225 < angle && angle < 315 )
    return QSwipeGesture::Down;

  return QSwipeGesture::NoDirection;
}

GDPinchGesture::GDPinchGesture( QObject * parent ):
  QGesture( parent ),
  isNewSequence( true )
{
}

QGesture * GDPinchGestureRecognizer::create( QObject * pTarget )
{
  if ( pTarget && pTarget->isWidgetType() ) {
    static_cast< QWidget * >( pTarget )->setAttribute( Qt::WA_AcceptTouchEvents );
  }
  QGesture * pGesture = new GDPinchGesture( pTarget );
  return pGesture;
}

void GDPinchGestureRecognizer::reset( QGesture * pGesture )
{
  QGestureRecognizer::reset( pGesture );
}

QGestureRecognizer::Result GDPinchGestureRecognizer::recognize( QGesture * state, QObject *, QEvent * event )
{
  QGestureRecognizer::Result result = QGestureRecognizer::Ignore;
  GDPinchGesture * gest             = static_cast< GDPinchGesture * >( state );

  switch ( event->type() ) {
    case QEvent::TouchBegin: {
      result              = QGestureRecognizer::MayBeGesture;
      gest->isNewSequence = true;
      break;
    }
    case QEvent::TouchCancel:
    case QEvent::TouchEnd: {
      result                  = QGestureRecognizer::CancelGesture;
      fewTouchPointsPresented = false;
      break;
    }
    case QEvent::TouchUpdate: {
      gest->scaleChanged           = false;
      const QTouchEvent * const ev = static_cast< const QTouchEvent * >( event );
      fewTouchPointsPresented      = ( ev->touchPoints().size() > 1 );
      if ( ev->touchPoints().size() == 2 ) {
        QTouchEvent::TouchPoint p1 = ev->touchPoints().at( 0 );
        QTouchEvent::TouchPoint p2 = ev->touchPoints().at( 1 );

        QPointF centerPoint = ( p1.screenPos() + p2.screenPos() ) / 2.0;
        gest->setHotSpot( centerPoint );
        if ( gest->isNewSequence ) {
          gest->startPosition[ 0 ] = p1.screenPos();
          gest->startPosition[ 1 ] = p2.screenPos();
          gest->lastCenterPoint    = centerPoint;
        }
        else {
          gest->lastCenterPoint = gest->centerPoint;
        }
        gest->centerPoint = centerPoint;

        if ( gest->isNewSequence ) {
          gest->scaleFactor      = 1.0;
          gest->lastScaleFactor  = 1.0;
          gest->totalScaleFactor = 1.0;
        }
        else {
          gest->lastScaleFactor = gest->scaleFactor;
          QLineF line( p1.screenPos(), p2.screenPos() );
          QLineF lastLine( p1.lastScreenPos(), p2.lastScreenPos() );
          gest->scaleFactor = line.length() / lastLine.length();
        }

        gest->totalScaleFactor = gest->totalScaleFactor * gest->scaleFactor;
        gest->scaleChanged     = true;

        gest->isNewSequence = false;
        if ( gest->totalScaleFactor <= OUT_SCALE_LIMIT || gest->totalScaleFactor >= IN_SCALE_LIMIT ) {
          result              = QGestureRecognizer::TriggerGesture;
          gest->isNewSequence = true;
        }
        else
          result = QGestureRecognizer::MayBeGesture;
      }
      else {
        gest->isNewSequence = true;
        if ( gest->state() == Qt::NoGesture )
          result = QGestureRecognizer::Ignore;
        else
          result = QGestureRecognizer::FinishGesture;
      }
      break;
    }
    case QEvent::MouseButtonPress:
    case QEvent::MouseMove:
    case QEvent::MouseButtonRelease:
      result = QGestureRecognizer::Ignore;
      break;
    default:
      result = QGestureRecognizer::Ignore;
      break;
  }
  return result;
}


GDSwipeGesture::GDSwipeGesture( QObject * parent ):
  QGesture( parent ),
  vertDirection( QSwipeGesture::NoDirection ),
  horizDirection( QSwipeGesture::NoDirection ),
  started( false )
{
}

QGesture * GDSwipeGestureRecognizer::create( QObject * pTarget )
{
  if ( pTarget && pTarget->isWidgetType() ) {
    static_cast< QWidget * >( pTarget )->setAttribute( Qt::WA_AcceptTouchEvents );
  }
  QGesture * pGesture = new GDSwipeGesture( pTarget );
  return pGesture;
}

void GDSwipeGestureRecognizer::reset( QGesture * pGesture )
{
  GDSwipeGesture * gest    = static_cast< GDSwipeGesture * >( pGesture );
  gest->vertDirection      = QSwipeGesture::NoDirection;
  gest->horizDirection     = QSwipeGesture::NoDirection;
  gest->lastPositions[ 0 ] = QPoint();
  gest->lastPositions[ 1 ] = QPoint();

  QGestureRecognizer::reset( pGesture );
}

qreal GDSwipeGestureRecognizer::computeAngle( int dx, int dy )
{
  double PI = 3.14159265;

  // Need to convert from screen coordinates direction
  // into classical coordinates direction.
  dy = -dy;

  double result = atan2( (double)dy, (double)dx );
  result        = ( result * 180 ) / PI;

  // Always return positive angle.
  if ( result < 0 )
    result += 360;

  return result;
}

QGestureRecognizer::Result GDSwipeGestureRecognizer::recognize( QGesture * state, QObject *, QEvent * event )
{
  GDSwipeGesture * swipe            = static_cast< GDSwipeGesture * >( state );
  QGestureRecognizer::Result result = QGestureRecognizer::Ignore;

  switch ( event->type() ) {
    case QEvent::TouchBegin: {
      swipe->unsetHotSpot();
      swipe->lastPositions[ 0 ] = QPoint();
      swipe->started            = true;
      result                    = QGestureRecognizer::MayBeGesture;
      break;
    }
    case QEvent::TouchCancel:
    case QEvent::TouchEnd: {
      fewTouchPointsPresented = false;
      result                  = QGestureRecognizer::CancelGesture;
      break;
    }
    case QEvent::TouchUpdate: {
      const QTouchEvent * const ev = static_cast< const QTouchEvent * >( event );
      fewTouchPointsPresented      = ( ev->touchPoints().size() > 1 );
      if ( !swipe->started )
        result = QGestureRecognizer::CancelGesture;
      else if ( ev->touchPoints().size() == 2 ) {
        //2-point gesture

        QTouchEvent::TouchPoint p1 = ev->touchPoints().at( 0 );
        QTouchEvent::TouchPoint p2 = ev->touchPoints().at( 1 );

        if ( swipe->lastPositions[ 0 ].isNull() ) {
          swipe->lastPositions[ 0 ] = p1.startScreenPos().toPoint();
          swipe->lastPositions[ 1 ] = p2.startScreenPos().toPoint();
        }

        if ( !swipe->hasHotSpot() ) {
          swipe->setHotSpot( ( p1.startScreenPos() + p2.startScreenPos() ) / 2 );
        }

        int dx1 = p1.screenPos().toPoint().x() - swipe->lastPositions[ 0 ].x();
        int dx2 = p2.screenPos().toPoint().x() - swipe->lastPositions[ 1 ].x();
        int dy1 = p1.screenPos().toPoint().y() - swipe->lastPositions[ 0 ].y();
        int dy2 = p2.screenPos().toPoint().y() - swipe->lastPositions[ 1 ].y();

        if ( qAbs( ( dx1 + dx2 ) / 2.0 ) >= MOVE_X_TRESHOLD || qAbs( ( dy1 + dy2 ) / 2.0 ) >= MOVE_Y_TRESHOLD ) {
          qreal angle1                           = computeAngle( dx1, dy1 );
          qreal angle2                           = computeAngle( dx2, dy2 );
          QSwipeGesture::SwipeDirection vertDir  = getVerticalDirection( angle1 );
          QSwipeGesture::SwipeDirection horizDir = getHorizontalDirection( angle1 );

          if ( vertDir != getVerticalDirection( angle2 ) || horizDir != getHorizontalDirection( angle2 ) ) {
            // It seems it is no swipe gesture
            result = QGestureRecognizer::CancelGesture;
            break;
          }

          if ( ( swipe->vertDirection != QSwipeGesture::NoDirection && horizDir != QSwipeGesture::NoDirection )
               || ( swipe->horizDirection != QSwipeGesture::NoDirection && vertDir != QSwipeGesture::NoDirection ) ) {
            // Gesture direction changed
            result = QGestureRecognizer::CancelGesture;
            break;
          }

          swipe->vertDirection  = vertDir;
          swipe->horizDirection = horizDir;

          swipe->lastPositions[ 0 ] = p1.screenPos().toPoint();
          swipe->lastPositions[ 1 ] = p2.screenPos().toPoint();

          result = QGestureRecognizer::TriggerGesture;
        }
        else
          result = QGestureRecognizer::MayBeGesture;
      }
      else // No 2-point gesture
        result = QGestureRecognizer::CancelGesture;
      break;
    }
    case QEvent::MouseButtonPress:
    case QEvent::MouseMove:
    case QEvent::MouseButtonRelease:
      result = QGestureRecognizer::Ignore;
      break;
    default:
      result = QGestureRecognizer::Ignore;
      break;
  }

  return result;
}

const qreal GDPinchGestureRecognizer::OUT_SCALE_LIMIT = 0.5;
const qreal GDPinchGestureRecognizer::IN_SCALE_LIMIT  = 2;

bool handleGestureEvent( QObject * obj, QEvent * event, GestureResult & result, QPoint & point )
{
  result = NOT_HANLDED;

  if ( event->type() != QEvent::Gesture || !obj->isWidgetType() )
    return false;

  QGestureEvent * gev = static_cast< QGestureEvent * >( event );

  gev->accept( Qt::PanGesture );

  QGesture * gesture = gev->gesture( GDSwipeGestureType );
  if ( gesture ) {
    GDSwipeGesture * swipe = static_cast< GDSwipeGesture * >( gesture );
    point                  = swipe->hotSpot().toPoint();

    if ( swipe->getHorizDirection() != QSwipeGesture::NoDirection )
      result = swipe->getHorizDirection() == QSwipeGesture::Left ? SWIPE_LEFT : SWIPE_RIGHT;

    if ( swipe->getVertDirection() != QSwipeGesture::NoDirection )
      result = swipe->getVertDirection() == QSwipeGesture::Up ? SWIPE_UP : SWIPE_DOWN;

    gev->setAccepted( true );
    return true;
  }

  gesture = gev->gesture( GDPinchGestureType );
  if ( gesture ) {
    GDPinchGesture * pinch = static_cast< GDPinchGesture * >( gesture );
    point                  = pinch->getCenterPoint().toPoint();

    if ( pinch->isScaleChanged() ) {
      if ( pinch->getTotalScaleFactor() <= GDPinchGestureRecognizer::OUT_SCALE_LIMIT )
        result = ZOOM_OUT;
      if ( pinch->getTotalScaleFactor() >= GDPinchGestureRecognizer::IN_SCALE_LIMIT )
        result = ZOOM_IN;
    }
    gev->setAccepted( true );
    return true;
  }

  gesture = gev->gesture( Qt::PanGesture );
  if ( gesture ) {
    gev->setAccepted( true );
    return true;
  }
  return false;
}

void registerRecognizers()
{
  QGestureRecognizer * pRecognizer = new Gestures::GDPinchGestureRecognizer();
  GDPinchGestureType               = QGestureRecognizer::registerRecognizer( pRecognizer );

  pRecognizer        = new Gestures::GDSwipeGestureRecognizer();
  GDSwipeGestureType = QGestureRecognizer::registerRecognizer( pRecognizer );
}

void unregisterRecognizers()
{
  if ( GDPinchGestureType )
    QGestureRecognizer::unregisterRecognizer( GDPinchGestureType );

  if ( GDSwipeGestureType )
    QGestureRecognizer::unregisterRecognizer( GDSwipeGestureType );
}

} // namespace Gestures