Qt图形图像开发曲线图表模块QChart库缩放/平移详细方法与实例

#ifndef QTCHARTDEMOZOOM_H_38020FA5_FC74_4395_A807_61BF924D2F06
#define QTCHARTDEMOZOOM_H_38020FA5_FC74_4395_A807_61BF924D2F06
#include <QtCharts/QChartView>
using namespace QtCharts;
class QtChartDemoZoom : public QChartView
{
 Q_OBJECT
public:
 QtChartDemoZoom(QWidget* pParent = nullptr);
 ~QtChartDemoZoom();
protected:
 virtual void mouseMoveEvent(QMouseEvent *pEvent) override;
 virtual void mousePressEvent(QMouseEvent *pEvent) override;
 virtual void mouseReleaseEvent(QMouseEvent *pEvent) override;
 virtual void wheelEvent(QWheelEvent *pEvent) override;
private:
 bool m_bMiddleButtonPressed;
 QPoint m_oPrePos;
};
#endif //QTCHARTDEMOZOOM_H_38020FA5_FC74_4395_A807_61BF924D2F06

#include <QLineSeries>
QtChartDemoZoom::QtChartDemoZoom(QWidget* pParent /*= nullptr*/)
 : QChartView(pParent)
 , m_bMiddleButtonPressed(false)
 , m_oPrePos(0, 0)
{
 QLineSeries *pLineServies = new QLineSeries();
 for (int i = 0; i < 100; ++i)
 {
 pLineServies->append(i, qrand() % 10);
 }
 this->chart()->addSeries(pLineServies);
 this->chart()->createDefaultAxes();
}
 QtChartDemoZoom::~QtChartDemoZoom()
{
}
void QtChartDemoZoom::mouseMoveEvent(QMouseEvent *pEvent)
{
 if (m_bMiddleButtonPressed)
 {
 QPoint oDeltaPos = pEvent->pos() - m_oPrePos;
 this->chart()->scroll(-oDeltaPos.x(), oDeltaPos.y());
 m_oPrePos = pEvent->pos();
 }
 __super::mouseMoveEvent(pEvent);
}
void QtChartDemoZoom::mousePressEvent(QMouseEvent *pEvent)
{
 if (pEvent->button() == Qt::MiddleButton)
 {
 m_bMiddleButtonPressed = true;
 m_oPrePos = pEvent->pos();
 this->setCursor(Qt::OpenHandCursor);
 }
 __super::mousePressEvent(pEvent);
}
void QtChartDemoZoom::mouseReleaseEvent(QMouseEvent *pEvent)
{
 if (pEvent->button() == Qt::MiddleButton)
 {
 m_bMiddleButtonPressed = false;
 this->setCursor(Qt::ArrowCursor);
 }
 __super::mouseReleaseEvent(pEvent);
}
void QtChartDemoZoom::wheelEvent(QWheelEvent *pEvent)
{
 qreal rVal = std::pow(0.999, pEvent->delta()); // 设置比例
 // 1. 读取视图基本信息
 QRectF oPlotAreaRect = this->chart()->plotArea();
 QPointF oCenterPoint = oPlotAreaRect.center();
 // 2. 水平调整
 oPlotAreaRect.setWidth(oPlotAreaRect.width() * rVal);
 // 3. 竖直调整
 oPlotAreaRect.setHeight(oPlotAreaRect.height() * rVal);
 // 4.1 计算视点，视点不变，围绕中心缩放
 //QPointF oNewCenterPoint(oCenterPoint);
 // 4.2 计算视点，让鼠标点击的位置移动到窗口中心
 //QPointF oNewCenterPoint(pEvent->pos());
 // 4.3 计算视点，让鼠标点击的位置尽量保持不动(等比换算，存在一点误差)
 QPointF oNewCenterPoint(2 * oCenterPoint - pEvent->pos() - (oCenterPoint - pEvent->pos()) / rVal);
 // 5. 设置视点
 oPlotAreaRect.moveCenter(oNewCenterPoint);
 // 6. 提交缩放调整
 this->chart()->zoomIn(oPlotAreaRect);
 __super::wheelEvent(pEvent);
}