canvas_click_filter.cpp

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#include <QMouseEvent>
#include <QLineF>
#include <QDateTime>
#include "mapviz_plugins/canvas_click_filter.h"

namespace mapviz_plugins
{
  CanvasClickFilter::CanvasClickFilter() :
    is_mouse_down_(false),
    max_ms_(Q_INT64_C(500)),
    max_distance_(2.0)
  { }

  void CanvasClickFilter::setMaxClickTime(qint64 max_ms)
  {
    max_ms_ = max_ms;
  }

  void CanvasClickFilter::setMaxClickMovement(qreal max_distance)
  {
    max_distance_ = max_distance;
  }

  bool CanvasClickFilter::eventFilter(QObject* object, QEvent* event)
  {
    if (event->type() == QEvent::MouseButtonPress)
    {
      is_mouse_down_ = true;
      QMouseEvent* me = static_cast<QMouseEvent*>(event);
      mouse_down_pos_ = me->posF();
      mouse_down_time_ = QDateTime::currentMSecsSinceEpoch();
    }
    else if (event->type() == QEvent::MouseButtonRelease)
    {
      if (is_mouse_down_)
      {
        QMouseEvent* me = static_cast<QMouseEvent*>(event);

        qreal distance = QLineF(mouse_down_pos_, me->posF()).length();
        qint64 msecsDiff = QDateTime::currentMSecsSinceEpoch() - mouse_down_time_;

        // Only fire the event if the mouse has moved less than the maximum distance
        // and was held for shorter than the maximum time..  This prevents click
        // events from being fired if the user is dragging the mouse across the map
        // or just holding the cursor in place.
        if (msecsDiff < max_ms_ && distance <= max_distance_)
        {
          Q_EMIT pointClicked(me->posF());
        }
      }
      is_mouse_down_ = false;
    }
    return false;
  }
}