QtCharts图形移动和缩放

#include "ChartView.h" #include <QApplication> #include <QValueAxis> ChartView::ChartView(QChart *chart, QWidget *parent) : QChartView(chart, parent) { m_isPress = false; m_ctrlPress = false; m_alreadySaveRange = false; m_coordItem = nullptr; this->setDragMode(QGraphicsView::RubberBandDrag); this->setMouseTracking(false); setCursor(QCursor(Qt::PointingHandCursor)); //设置鼠标指针为手指形 } ChartView::~ChartView() { } void ChartView::mousePressEvent(QMouseEvent *event) { if (event->button() == Qt::LeftButton) { m_lastPoint = event->pos(); m_isPress = true; } } void ChartView::mouseMoveEvent(QMouseEvent *event) { if (!m_coordItem) { m_coordItem = new QGraphicsSimpleTextItem(this->chart()); m_coordItem->setZValue(5); m_coordItem->setPos(100, 60); m_coordItem->show(); } const QPoint curPos = event->pos(); QPointF curVal = this->chart()->mapToValue(QPointF(curPos)); QString coordStr = QString("X = %1, Y = %2").arg(curVal.x()).arg(curVal.y()); m_coordItem->setText(coordStr); if (m_isPress) { QPoint offset = curPos - m_lastPoint; m_lastPoint = curPos; if (!m_alreadySaveRange) { this->saveAxisRange(); m_alreadySaveRange = true; } this->chart()->scroll(-offset.x(), offset.y()); } } void ChartView::mouseReleaseEvent(QMouseEvent *event) { m_isPress = false; if (event->button() == Qt::RightButton) { if (m_alreadySaveRange) { this->chart()->axisX()->setRange(m_xMin, m_xMax); this->chart()->axisY()->setRange(m_yMin, m_yMax); } } } void ChartView::wheelEvent(QWheelEvent *event) { const QPoint curPos = event->pos(); QPointF curVal = this->chart()->mapToValue(QPointF(curPos)); if (!m_alreadySaveRange) { this->saveAxisRange(); m_alreadySaveRange = true; } const double factor = 1.5;//缩放比例 if (m_ctrlPress) {//Y轴 QValueAxis *axisY = dynamic_cast<QValueAxis*>(this->chart()->axisY()); const double yMin = axisY->min(); const double yMax = axisY->max(); const double yCentral = curVal.y(); double bottomOffset; double topOffset; if (event->delta() > 0) {//放大 bottomOffset = 1.0 / factor * (yCentral - yMin); topOffset = 1.0 / factor * (yMax - yCentral); } else {//缩小 bottomOffset = 1.0 * factor * (yCentral - yMin); topOffset = 1.0 * factor * (yMax - yCentral); } this->chart()->axisY()->setRange(yCentral - bottomOffset, yCentral + topOffset); } else {//X轴 QValueAxis *axisX = dynamic_cast<QValueAxis*>(this->chart()->axisX()); const double xMin = axisX->min(); const double xMax = axisX->max(); const double xCentral = curVal.x(); double leftOffset; double rightOffset; if (event->delta() > 0) {//放大 leftOffset = 1.0 / factor * (xCentral - xMin); rightOffset = 1.0 / factor * (xMax - xCentral); } else {//缩小 leftOffset = 1.0 * factor * (xCentral - xMin); rightOffset = 1.0 * factor * (xMax - xCentral); } this->chart()->axisX()->setRange(xCentral - leftOffset, xCentral + rightOffset); } } void ChartView::keyPressEvent(QKeyEvent *event) { if (event->key() == Qt::Key_Control) { m_ctrlPress = true; } } void ChartView::keyReleaseEvent(QKeyEvent *event) { if (event->key() == Qt::Key_Control) { m_ctrlPress = false; } } void ChartView::saveAxisRange() { QValueAxis *axisX = dynamic_cast<QValueAxis*>(this->chart()->axisX()); m_xMin = axisX->min(); m_xMax = axisX->max(); QValueAxis *axisY = dynamic_cast<QValueAxis*>(this->chart()->axisY()); m_yMin = axisY->min(); m_yMax = axisY->max(); }