qt使用qwt 跟随鼠标显示坐标

头文件

#include <qwt_plot_canvas.h>
#include <qwt_plot_layout.h>
#include <qwt_plot_picker.h>
#include <qwt_picker_machine.h>
#include <qwt_painter.h>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_marker.h>
#include <qwt_plot_grid.h>
#include <qwt_plot_magnifier.h>
#include <qwt_plot_panner.h>
#include <qwt_legend.h>
#include <qwt_plot_directpainter.h>
#include <qwt_series_data.h>
#include <qwt_symbol.h>
#include <qwt_interval.h>
#include <qwt_date_scale_draw.h>
#include <qwt_plot_zoomer.h>
#include <qwt_plot_renderer.h>//保存用

初始化时候

        picker_01 = new QwtPlotPicker(QwtPlot::xBottom, QwtPlot::yLeft,
                                                  QwtPlotPicker::CrossRubberBand, QwtPicker::AlwaysOn,ui->plot_temp->canvas());
        picker_01->setStateMachine(new QwtPickerDragPointMachine());
        picker_01->setRubberBandPen(QColor(Qt::blue));//线的颜色
        picker_01->setRubberBand(QwtPicker::CrossRubberBand);
        picker_01->setTrackerMode(QwtPicker::AlwaysOn);//被激活时候显示
        picker_01->setTrackerPen(QColor(Qt::black));//字的颜色

注意在获取selected时候我使用两种方式，一种是直接旧的connect方式，一种lambda方式，经过测试lambda方式失败

        connect(picker_01,QOverload<const QPointF & >::of(&QwtPlotPicker::selected),this,[=](const QPointF &pos){
            QString info; info.sprintf("x:%d y:%d",pos.x(),pos.y());
            myDebugMsg(info);
            //
        });//失败
        //void selected( const QPolygon &polygon )
        connect(picker_01,QOverload<const QPolygon & >::of(&QwtPicker::selected),this,[=](const QPolygon &pos){
            //QString info="test"; //info.sprintf("x:%d y:%d",pos.x(),pos.y());
            //myDebugMsg(info);
            QPoint point = ui->plot_temp->canvas()->mapFromGlobal(QCursor::pos());
            QString info =  QString("x = %1, y = %2").arg(ui->plot_temp->invTransform(QwtPlot::xBottom,point.x())).arg(ui->plot_temp ->invTransform(QwtPlot::yLeft,point.y()) );
            myDebugMsg(info);
        });//失败
        //testslot

使用旧版connect方式成功

connect( picker_01, SIGNAL( selected( const QPolygon & ) ), SLOT( testslot( const QPolygon & ) ) );
        connect( picker_01, SIGNAL( selected( const QPointF & ) ), SLOT( testslot2( const QPointF & ) ) );

    void testslot(const QPolygon &pos){
        //QPoint point = ui->plot_monitoring->canvas()->mapFromGlobal(QCursor::pos());
        //QString info =  QString("x = %1, y = %2").arg(ui->plot_monitoring->invTransform(QwtPlot::xBottom,point.x())).arg(ui->plot_monitoring ->invTransform(QwtPlot::yLeft,point.y()) );
        QString info = "test";
        myDebugMsg(info);
    }
    void testslot2(const QPointF &pos){
        QString info; info.sprintf("x:%f y:%f",pos.x(),pos.y());
        myDebugMsg(info);
    }