Qt 5.9 | Qt Charts | Zoom Line Example | chart.cpp Example File

Qt 5.9.3 Reference Documentation

# chart.cpp Example File

zoomlinechart/chart.cpp

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      ** Contact: https://www.qt.io/licensing/
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      ** This file is part of the Qt Charts module of the Qt Toolkit.
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      #include "chart.h"
      #include <QtWidgets/QGesture>
      #include <QtWidgets/QGraphicsScene>
      #include <QtWidgets/QGraphicsView>

      Chart::Chart(QGraphicsItem *parent, Qt::WindowFlags wFlags)
          : QChart(QChart::ChartTypeCartesian, parent, wFlags)
      {
          // Seems that QGraphicsView (QChartView) does not grab gestures.
          // They can only be grabbed here in the QGraphicsWidget (QChart).
          grabGesture(Qt::PanGesture);
          grabGesture(Qt::PinchGesture);
      }

      Chart::~Chart()
      {

      }

      bool Chart::sceneEvent(QEvent *event)
      {
          if (event->type() == QEvent::Gesture)
              return gestureEvent(static_cast<QGestureEvent *>(event));
          return QChart::event(event);
      }

      bool Chart::gestureEvent(QGestureEvent *event)
      {
          if (QGesture *gesture = event->gesture(Qt::PanGesture)) {
              QPanGesture *pan = static_cast<QPanGesture *>(gesture);
              QChart::scroll(-(pan->delta().x()), pan->delta().y());
          }

          if (QGesture *gesture = event->gesture(Qt::PinchGesture)) {
              QPinchGesture *pinch = static_cast<QPinchGesture *>(gesture);
              if (pinch->changeFlags() & QPinchGesture::ScaleFactorChanged)
                  QChart::zoom(pinch->scaleFactor());
          }

          return true;
      }