Qt 5.7 | Qt Charts | Zoom Line Example | chartview.cpp Example File

Qt 5.7.1 Reference Documentation

# chartview.cpp Example File

zoomlinechart/chartview.cpp

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      **
      ** Copyright (C) 2016 The Qt Company Ltd.
      ** Contact: https://www.qt.io/licensing/
      **
      ** This file is part of the Qt Charts module of the Qt Toolkit.
      **
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      #include "chartview.h"
      #include <QtGui/QMouseEvent>

      ChartView::ChartView(QChart *chart, QWidget *parent) :
          QChartView(chart, parent),
          m_isTouching(false)
      {
          setRubberBand(QChartView::RectangleRubberBand);
      }

      bool ChartView::viewportEvent(QEvent *event)
      {
          if (event->type() == QEvent::TouchBegin) {
              // By default touch events are converted to mouse events. So
              // after this event we will get a mouse event also but we want
              // to handle touch events as gestures only. So we need this safeguard
              // to block mouse events that are actually generated from touch.
              m_isTouching = true;

              // Turn off animations when handling gestures they
              // will only slow us down.
              chart()->setAnimationOptions(QChart::NoAnimation);
          }
          return QChartView::viewportEvent(event);
      }

      void ChartView::mousePressEvent(QMouseEvent *event)
      {
          if (m_isTouching)
              return;
          QChartView::mousePressEvent(event);
      }

      void ChartView::mouseMoveEvent(QMouseEvent *event)
      {
          if (m_isTouching)
              return;
          QChartView::mouseMoveEvent(event);
      }

      void ChartView::mouseReleaseEvent(QMouseEvent *event)
      {
          if (m_isTouching)
              m_isTouching = false;

          // Because we disabled animations when touch event was detected
          // we must put them back on.
          chart()->setAnimationOptions(QChart::SeriesAnimations);

          QChartView::mouseReleaseEvent(event);
      }

      void ChartView::keyPressEvent(QKeyEvent *event)
      {
          switch (event->key()) {
          case Qt::Key_Plus:
              chart()->zoomIn();
              break;
          case Qt::Key_Minus:
              chart()->zoomOut();
              break;
          case Qt::Key_Left:
              chart()->scroll(-10, 0);
              break;
          case Qt::Key_Right:
              chart()->scroll(10, 0);
              break;
          case Qt::Key_Up:
              chart()->scroll(0, 10);
              break;
          case Qt::Key_Down:
              chart()->scroll(0, -10);
              break;
          default:
              QGraphicsView::keyPressEvent(event);
              break;
          }
      }