qwtplotpicker简单使用

void ReadSonicPoint::useQwtPlotPicker()
{
	auto picker = new QwtPlotPicker(ui.qwtPlot_Sonic->canvas());
	picker->setStateMachine(new QwtPickerDragPointMachine());
	picker->setRubberBandPen(QColor(Qt::darkMagenta));
	picker->setRubberBand(QwtPicker::CrossRubberBand);
	picker->setTrackerMode(QwtPicker::ActiveOnly);//被激活时候显示
	picker->setTrackerPen(QColor(Qt::black));//显示实时的坐标
}

效果：

点中图像 显示坐标值