一、效果展示
定义xBottom为带单位的刻度值
定义xBottom为分钟:秒数的刻度值
二、具体步骤
2.1、自定义坐标轴
自定义坐标轴刻度,需要继承自QwtScaleDraw
,然后重写如下虚函数:
virtual QwtText label(double v) const;
定义一个规则,然后设置坐标轴范围时,按定义的规则传入即可。
例如,定义mm:ss刻度值:
#ifndef TIMESCALEDRAW_H#define TIMESCALEDRAW_H#include <QWT/qwt_scale_draw.h>#include <QDateTime>class TimeScaleDraw : public QwtScaleDraw{public:TimeScaleDraw();virtual QwtText label(double v) const;};#endif // TIMESCALEDRAW_H
#include "timescaledraw.h"TimeScaleDraw::TimeScaleDraw(){}QwtText TimeScaleDraw::label(double v) const{QDateTime dt;dt.setTime_t((int)v);return dt.toString("mm:ss");}
传入的值是v,但是返回的是一个字符串,这个字符串是实际显示在坐标轴上的刻度值,如果需要刻度值带单位,则可以这样写:
QwtText TimeScaleDraw::label(double v) const{QString ret = "";ret = QString::number(v)+"mA";if(ret.isEmpty())return;elsereturn ret;}
2.2、使用自定义坐标轴
QWT_Area = new QWidget;QWT_Area->resize(this->width(),this->height());m_Qwt1 = new QwtPlot(QWT_Area);m_Qwt1->resize(this->width(),this->height());m_Qwt1->setAxisScale(QwtPlot::xBottom,0,10);m_Qwt1->setAxisScale(QwtPlot::yLeft,0,10);m_Qwt1->enableAxis(QwtPlot::xBottom,true);m_Qwt1->enableAxis(QwtPlot::xTop,false);m_Qwt1->enableAxis(QwtPlot::yLeft,true);m_Qwt1->enableAxis(QwtPlot::yRight,false);m_Qwt1->setAxisScaleDraw(QwtPlot::xBottom,new TimeScaleDraw());m_Qwt1->setAxisScale(QwtPlot::xBottom, QDateTime::currentDateTime().toTime_t() - 100,QDateTime::currentDateTime().toTime_t()); //标尺范围QWT_Area->show();
m_Qwt1->setAxisScaleDraw(QwtPlot::xBottom,new TimeScaleDraw());
:给xBottom设置自定义坐标轴m_Qwt1->setAxisScale(QwtPlot::xBottom, QDateTime::currentDateTime().toTime_t() - 100,QDateTime::currentDateTime().toTime_t());
:按自定义坐标轴定义的规则设置坐标轴范围
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