Qt由入门到放弃-QCustomPlot之QCPAxisTicker坐标轴类(一)

今天药忘吃喽~ 2022-05-15 01:13 3237阅读 0赞

[Qt由入门到放弃-QCustomPlot绘制天气曲线图并动态显示曲线坐标值(二)][Qt_-QCustomPlot]

由于项目需要，实现天气预报的曲线绘制功能，进而学习了QCustomPlot的第三方控件，这里浅尝辄止的分享一下自己对QCPAxisTicker坐标轴类的使用，先上图看QCPAxisTicker的几种用法：

![70][]

## 一、QCPAxisTicker基类 ##

QCPAxisTicker是坐标轴的基类，它的属性和方法如下，其中有刻度轴步长显示策略TickStepStrategy的枚举类型，可参考此篇文章[QCustomplot使用分享(六) 坐标轴和网格线][QCustomplot_]：

class QCPAxisTicker
    {
      
    public:
      /*!
        定义选择坐标轴步长策略
      */
      enum TickStepStrategy
      {
        tssReadability    //具有更好可读性的（由系统分配）刻度步长匹配优先于自定义分配刻度数目匹配
        ,tssMeetTickCount //使用setTickCount()函数设置用户自定义的刻度数目
      };
      // getters:
      TickStepStrategy tickStepStrategy() const { return mTickStepStrategy; }//获得刻度匹配策略
      int tickCount() const { return mTickCount; }//返回刻度数
      double tickOrigin() const { return mTickOrigin; }//获得起点坐标偏移量
      // setters:
      void setTickStepStrategy(TickStepStrategy strategy);//设置刻度匹配策略
      void setTickCount(int count);//设置刻度数目
      void setTickOrigin(double origin);//设置起点坐标偏移量
      // introduced virtual methods:虚函数自定义生成坐标刻度
      virtua void generate(const QCPRange &range, const QLocale &locale, QChar formatChar, 
      int precision, QVector<double> &ticks, QVector<double> *subTicks, QVector<QString> *tickLabels);
      
    protected:
      // property members:
      TickStepStrategy mTickStepStrategy;
      int mTickCount;
      double mTickOrigin;
    
      // introduced virtual methods:
      virtual double getTickStep(const QCPRange &range);//获得轴范围内刻度间距
      virtual int getSubTickCount(double tickStep);//一个大刻度间距中子刻度的数目
      virtual QString getTickLabel(double tick, const QLocale &locale, QChar formatChar, int precision);//获得刻度向量
      virtual QVector<double> createTickVector(double tickStep, const QCPRange &range);//生成刻度向量
      virtual QVector<double> createSubTickVector(int subTickCount, const QVector<double> &ticks);//生成子刻度向量
      //生成刻度标签向量
      virtual QVector<QString> createLabelVector(const QVector<double> &ticks,
      const QLocale &locale, QChar formatChar, int precision);
      
      // non-virtual methods:
      //trimTicks()从指定范围之外的刻中移除刻度坐标，如果keepOneOutlier==true，则在保留的刻度范围两边保留刻度标记
      void trimTicks(const QCPRange &range, QVector<double> &ticks, bool keepOneOutlier) const;
      //pickClosest()返回包含在与所提供的目标最接近的候选坐标,此方法假定候选者不是空的，按升序排序
      double pickClosest(double target, const QVector<double> &candidates) const;
      //getMantissa()返回输入的十进制尾数,例如142.6的输入将返回尾数1.426和100的大小。
      double getMantissa(double input, double *magnitude=0) const;
      //cleanMantissa()返回一个接近输入的数字，它有一个更简单的人类可读尾数
      double cleanMantissa(double input) const;
    };

## 二、 QCPAxisTickerDateTime ##

### 1.QCPAxisTickerDateTime类是日期时间坐标轴 ###

关于日期时间可看我前一篇[Qt由入门到放弃-QDate、QTime、QDateTime的相关函数][Qt_-QDate_QTime_QDateTime]，具体方法如下所示：

class  QCPAxisTickerDateTime : public QCPAxisTicker
    {
    public:
     
      // getters:
      QString dateTimeFormat();//获得日期显示格式
      Qt::TimeSpec dateTimeSpec();//获得时区
      
      // setters:
      void setDateTimeFormat(const QString &format);//设置时间显示格式
      void setDateTimeSpec(Qt::TimeSpec spec);//设置时区
      void setTickOrigin(double origin); 
      void setTickOrigin(const QDateTime &origin);
      
      // static methods:
      static QDateTime keyToDateTime(double key);//时间戳转成日期
      static double dateTimeToKey(const QDateTime dateTime);//日期转成时间戳秒
      static double dateTimeToKey(const QDate date);//日期转成时间戳秒
      
    protected:
      // property members:
      QString mDateTimeFormat;//格式化时间
      Qt::TimeSpec mDateTimeSpec;//时区
      
      // non-property members:
      enum DateStrategy //设置刻度策略
      {
    	dsNone   //刻度不设置间距，默认大于等于一秒
    	, dsUniformTimeInDay  //刻度间距大于等于一天
    	, dsUniformDayInMonth  //刻度间距大于等于一月
      } mDateStrategy;
      
      // reimplemented virtual methods:
      virtual double getTickStep(const QCPRange &range);
      virtual int getSubTickCount(double tickStep) ;
      virtual QString getTickLabel(double tick, const QLocale &locale, QChar formatChar, int precision) ;
      virtual QVector<double> createTickVector(double tickStep, const QCPRange &range) ;
    };

### 2.据此实现了一个小例子： ###

void setupTestQCPAxisTickerDateTime()
    {
        customPlot->setInteraction(QCP::iRangeDrag, true);
        customPlot->setInteraction(QCP::iRangeZoom, true);
        QDateTime dateTime = QDateTime::currentDateTime();
        double  now = dateTime.toTime_t();//当前时间转化为秒
        //生成时间刻度对象
        QSharedPointer<QCPAxisTickerDateTime> dateTimeTicker(new QCPAxisTickerDateTime);
        customPlot->xAxis->setTicker(dateTimeTicker);
        //dateTimeTicker->setDateTimeSpec(Qt::UTC);//设施世界时间，即不加上时区的时间
        dateTimeTicker->setTickCount(12);
        dateTimeTicker->setTickStepStrategy(QCPAxisTicker::tssMeetTickCount);
        customPlot->xAxis->setSubTicks(false);
        customPlot->xAxis->setRange(now, now+3600*24);//x轴范围，从当前时间起往后推24小时
        QVector<double> yData, xData;//生成数据
        for (int i = 0; i <= 24; i++)
        {
            xData.push_back(now + i * 3600.0);
            yData.push_back(pow(double(i), 2) + 550.0*sin(double(i)/4.0));
        }
        dateTimeTicker->setDateTimeFormat("yyyy-M-d h:m");//设置x轴刻度显示格式
        customPlot->xAxis->setTickLabelRotation(30);//设置刻度标签顺时针旋转30度
        customPlot->yAxis->setRange(-1000,10000);
        customPlot->addGraph();
        customPlot->graph(0)->setData(xData, yData);//显示数据
    }

### 3.运行结果图： ###

![70 1][]

### 4.分析 ###

QCPAxisTickerDateTime坐标轴默认是从时间戳起点即1970-1-1 0:0:0开始，以秒为单位进行刻度划分， 以下前两行代码为核心，获取当前秒数，通过第三行代码来设置时间范围。

QDateTime dateTime = QDateTime::currentDateTime();
    double  now = dateTime.toTime_t();//当前时间转化为秒
    customPlot->xAxis->setRange(now, now+3600*24);//x轴范围，从当前时间起往后推24小时

## 三、QCPAxisTickerTime ##

### 1.QCPAxisTickerTime是时间轴刻度类 ###

class  QCPAxisTickerTime : public QCPAxisTicker
    {
    
    public:
      
      enum TimeUnit { tuMilliseconds ///< 毫秒(%z 在setTimeFormat中设置)
                      ,tuSeconds     ///< 秒 (%s)
                      ,tuMinutes     ///< 分钟 (%m)
                      ,tuHours       ///< 小时 (%h)
                      ,tuDays        ///< 天 (%d)
                    };
      // getters:
      QString timeFormat();//获得时间显示格式
      int fieldWidth(TimeUnit unit) const { return mFieldWidth.value(unit); }
      
      // setters:
      void setTimeFormat(const QString &format);
      void setFieldWidth(TimeUnit unit, int width);//设置刻度间距宽度
      
    protected:
      // property members:
      QString mTimeFormat;//时间格式化字符串
      QHash<TimeUnit, int> mFieldWidth;//时间宽度格式
      
      // non-property members:
      //最小的单位,最大的单位(如定义mSmallestUnit(tuSeconds),mBiggestUnit(tuHours))
      TimeUnit mSmallestUnit, mBiggestUnit;
      QHash<TimeUnit, QString> mFormatPattern;
      
      // reimplemented virtual methods:
      virtual double getTickStep(const QCPRange &range) ;
      virtual int getSubTickCount(double tickStep) ;
      virtual QString getTickLabel(double tick, const QLocale &locale, QChar formatChar, int precision) ;
      //对特定的值value用指定文本text替换时间单位
      void replaceUnit(QString &text, TimeUnit unit, int value) const;
    };

### 2.据此实现了一个小例子： ###

void MainWindow::setupTestQCPAxisTickerTime()
    {
    
        customPlot->setInteraction(QCP::iRangeDrag, true);
        customPlot->setInteraction(QCP::iRangeZoom, true);
        customPlot->rescaleAxes();
    
        QDateTime dateTime = QDateTime::currentDateTime();
        QString dataString = dateTime.toString("yyyy:M:dd:hh:mm:ss");
        qDebug()<<"*********"<<dataString;
        int hours = dateTime.time().hour();//获取当前的小时数
    
        QSharedPointer<QCPAxisTickerTime> timeTicker(new QCPAxisTickerTime);
        customPlot->xAxis->setTicker(timeTicker);
        timeTicker->setTickCount(6);
        //设置刻度表示策略
        timeTicker->setTickStepStrategy(QCPAxisTicker::tssMeetTickCount);
        customPlot->xAxis->setSubTicks(false);
        timeTicker->setTickOrigin(3600*3);//x轴起点坐标加3小时，即从当前hours+3开始
        customPlot->xAxis->setRange(hours*3600, hours*3600 +3600*12);
        customPlot->yAxis->setRange(-1000,1000);
        timeTicker->setTimeFormat("%dday-%hhour");
    
        QVector<double> yData, xData;
        for (int i = 0; i <= 24; i++){
            xData.push_back(hours*3600 + i * 3600);
            yData.push_back(pow(double(i), 2) + 550.0*sin(double(i)/4.0));
        }
        customPlot->addGraph();
        customPlot->graph(0)->setData(xData, yData);
    
    }

### 3.运行结果图： ###

![70 2][]

### 4.分析 ###

时间可以以毫秒、秒、分钟、小时和天显示。取决于通过setTimeFormat函数定义的最大可用单位，超过最大单位的。例如，如果格式字符串为"%M:%s"，则为坐标值7815（2小时，10分钟和15秒）被创建，得到的刻度标签将显示"130:15"（130分钟，15秒）。如果格式字符串为"%H:%M:%s"，则为"小时"。单位将被使用，标签将是“2:10:15”。

## 四、QCPAxisTickerText ##

### 1.QCPAxisTickerText是文本刻度标签 ###

/*
    设置文本刻度标签
    */
    class QCPAxisTickerText : public QCPAxisTicker
    {
    public:
     
      // getters:
      QMap<double, QString> &ticks();//获得坐标轴标签
      int subTickCount();//获得子刻度数目
      
      // setters:
      void setTicks(const QMap<double, QString> &ticks);//坐标轴标签添加坐标轴
      void setTicks(const QVector<double> &positions, const QVector<QString> labels);//坐标轴标签添加坐标轴
      void setSubTickCount(int subTicks);//设置子刻度数目
      
      // non-virtual methods:
      void clear();
      //addTick()坐标轴添加文本标签三种形式
      void addTick(double position, QString label);
      void addTicks(const QMap<double, QString> &ticks);
      void addTicks(const QVector<double> &positions, const QVector<QString> &labels);
      
    protected:
      // property members:
      QMap<double, QString> mTicks;//坐标轴标签
      int mSubTickCount;//子刻度数目
      
      // reimplemented virtual methods:
      virtual double getTickStep(const QCPRange &range) ;
      virtual int getSubTickCount(double tickStep) ;
      virtual QString getTickLabel(double tick, const QLocale &locale, QChar formatChar, int precision) ;
      virtual QVector<double> createTickVector(double tickStep, const QCPRange &range) ;
      
    };

### 2.据此实现了一个小例子： ###

void MainWindow::setupTestQCPAxisTickerText()
    {
        //画柱状图
        QCPBars *regen = new QCPBars(customPlot->xAxis, customPlot->yAxis);
        regen->setAntialiased(false); // gives more crisp, pixel aligned bar borders
        regen->setStackingGap(1);
        regen->setName("Regenerative");
        regen->setPen(QPen(QColor(0, 168, 140).lighter(130)));
        regen->setBrush(QColor(0, 168, 140));
        // stack bars on top of each other:
       // regen->moveAbove(nuclear);
        QVector<double> ticks;
        QVector<QString> labels;
        ticks << 1 << 2 << 3 << 4 << 5 << 6 << 7;
        labels << "USA" << "Japan" << "Germany" << "France" << "UK" << "Italy" << "Canada";
        QSharedPointer<QCPAxisTickerText> textTicker(new QCPAxisTickerText);
        textTicker->addTicks(ticks, labels);
        customPlot->xAxis->setTicker(textTicker);
        customPlot->xAxis->setTickLabelRotation(60);
        customPlot->xAxis->setSubTicks(false);
        customPlot->xAxis->setTickLength(0, 4);
        customPlot->xAxis->setRange(0, 8);
        customPlot->xAxis->setTickPen(QPen(Qt::white));
    
        // prepare y axis:
        customPlot->yAxis->setRange(0, 12.1);
        customPlot->yAxis->setPadding(5); // a bit more space to the left border
        customPlot->yAxis->setLabel("Power Consumption in\nKilowatts per Capita (2007)");
        //customPlot->yAxis->setBasePen(QPen(Qt::white));
        customPlot->yAxis->setTickPen(QPen(Qt::white));
        customPlot->yAxis->setSubTickPen(QPen(Qt::white));
        // Add data:
        QVector<double>  regenData;
        regenData   << 0.06*10.5 << 0.05*5.5 << 0.04*5.5 << 0.06*5.8 << 0.02*5.2 << 0.07*4.2 << 0.25*11.2;
        regen->setData(ticks, regenData);
    
    }

### 3.运行结果图： ###

![70 3][]

## 五、QCPAxisTickerPi ##

### 1.QCPAxisTickerPi设置Pi刻度标签 ###

class  QCPAxisTickerPi : public QCPAxisTicker
    {
      
    public:
    
      enum FractionStyle { fsFloatingPoint     //分数被显示为规则十进制浮点数，例如“0.25”或“0.125”
                           ,fsAsciiFractions   //分数是用ASCII字符写成的有理数，例如“1/4”或“1/8”
                           ,fsUnicodeFractions //分数使用子和上标UTF-8数字和分数符号来编写
                         };
    
      QString piSymbol() const { return mPiSymbol; }//返回代替PI的符号标志
      double piValue() const { return mPiValue; }//返回PI表示的值
      bool periodicity() const { return mPeriodicity; }//是否周期性地出现
      FractionStyle fractionStyle() const { return mFractionStyle; }//轴上数据分数显示风格
      
      void setPiSymbol(QString symbol);//设置PI符号位的用symbol代替显示
      void setPiValue(double pi);//设置PI表示的值，不指定PI表示默认值3.1415926....
      //setPeriodicity()设置轴标签是否周期性地出现
      //若要禁用周期性，将multiplesOfPi设置为0。例如将轴定义0到2PI的周期则会将multiplesOfPi设置为2
      void setPeriodicity(int multiplesOfPi);
      //设置轴的分数显示形式
      void setFractionStyle(FractionStyle style);
      
    protected:
      QString mPiSymbol;
      double mPiValue;
      int mPeriodicity;
      FractionStyle mFractionStyle;
    
      double mPiTickStep; // size of one tick step in units of mPiValue
    
      virtual double getTickStep(const QCPRange &range) ;
      virtual int getSubTickCount(double tickStep) ;
      virtual QString getTickLabel(double tick, const QLocale &locale, QChar formatChar, int precision) ;
    
      void simplifyFraction(int &numerator, int &denominator) const;//对给定的分子numerator，分母denominator化成最简真分数
      QString fractionToString(int numerator, int denominator) const;//转成字符串
      QString unicodeFraction(int numerator, int denominator) const;//转成unicode编码
      QString unicodeSuperscript(int number) const;//返回表示数字为上标的Unicode字符串
      QString unicodeSubscript(int number) const;//返回表示数字为下标的Unicode字符串
    };

### 2.据此实现了一个小例子： ###

void MainWindow::setupTestQCPAxisTickerPi()
    {
        QSharedPointer<QCPAxisTickerPi> pITicker(new QCPAxisTickerPi());
        customPlot->xAxis->setTicker(pITicker);
        //pITicker->setPeriodicity(2);
        //pITicker->setPiSymbol("--");
        pITicker->setFractionStyle(QCPAxisTickerPi::fsUnicodeFractions);
        pITicker->setPiValue(3.1415*2);//设置pi表示的值
        customPlot->xAxis->setRange(0, 3.0*M_PI);
        customPlot->xAxis->setVisible(true);
        QVector<double> x2(250), y2(250);
        for (int i=0; i<250; ++i) // data for graphs 2, 3 and 4
         {
           x2[i] = i/250.0*3*M_PI;
           y2[i] = qSin(x2[i]+ M_PI) + M_PI;
         }
        customPlot->addGraph(customPlot->xAxis, customPlot->yAxis);
        customPlot->graph(0)->setData(x2, y2);
    
    }

### 3.运行结果图： ###

![70 4][]

## 六、QCPAxisTickerLog ##

### 1.QCPAxisTickerLog设置log对数刻度标签 ###

class  QCPAxisTickerLog : public QCPAxisTicker
    {
    public:
      QCPAxisTickerLog();
     
      double logBase() const { return mLogBase; }
      int subTickCount() const { return mSubTickCount; }
      
      void setLogBase(double base);//设置对数的基数值
      void setSubTickCount(int subTicks);//设置子刻度数目
      
    protected:
      double mLogBase;
      int mSubTickCount;
    
      double mLogBaseLnInv;
    
      virtual double getTickStep(const QCPRange &range) ;
      virtual int getSubTickCount(double tickStep) ;
      virtual QVector<double> createTickVector(double tickStep, const QCPRange &range) ;
    };

### 2.据此实现了一个小例子： ###

void MainWindow::setupTestQCPAxisTickerLog()
    {
        QSharedPointer<QCPAxisTickerLog> logTicker(new QCPAxisTickerLog);
        customPlot->xAxis->setTicker(logTicker);
        // don't forget to also set the scale type accordingly, otherwise you'll have
        // logarithmically spaced ticks on a linear axis:
        customPlot->xAxis->setScaleType(QCPAxis::stLogarithmic);
        customPlot->xAxis->setRange(0,250);
        logTicker->setLogBase(10);
        QVector<double> x2(250), y2(250);
        for (int i=0; i<250; ++i) // data for graphs 2, 3 and 4
         {
           x2[i] = i;
           y2[i] = log(i);
         }
        customPlot->addGraph(customPlot->xAxis, customPlot->yAxis);
        customPlot->graph(0)->setData(x2, y2);
    
    }

### 3.运行结果图： ###

![70 5][]

## 七、QCPAxisTickerFixed ##

### 1.QCPAxisTickerFixed定义轴标尺修改指定的步长控制坐标轴刻度的数目 ###

class  QCPAxisTickerFixed : public QCPAxisTicker
    {
      
    public:
      
      enum ScaleStrategy { ssNone      //固定刻度，不允许修改
                           ,ssMultiples //设置刻度间距为整数倍长度
                           ,ssPowers    //设置刻度间距为指数倍长度
                         };
    
      // getters:
      double tickStep() const { return mTickStep; }
      ScaleStrategy scaleStrategy() const { return mScaleStrategy; }
      
      // setters:
      void setTickStep(double step);
      void setScaleStrategy(ScaleStrategy strategy);
      
    protected:
      // property members:
      double mTickStep;
      ScaleStrategy mScaleStrategy;
      
      // reimplemented virtual methods:
      virtual double getTickStep(const QCPRange &range) ;
    };

## 八、完整代码下载 ##

### [点我下载][Link 1] ###

[Qt_-QCustomPlot]: https://blog.csdn.net/bwangk/article/details/82082133
[70]: /images/20220515/9aa0149c9a0f414c885d98a3112a563f.png
[QCustomplot_]: https://www.cnblogs.com/swarmbees/p/6059812.html
[Qt_-QDate_QTime_QDateTime]: https://blog.csdn.net/bwangk/article/details/80793492
[70 1]: /images/20220515/f2102d7b6d2741f5902be0c72cf9762f.png
[70 2]: /images/20220515/dc9ef241752d43fd9d8b0026c34955d4.png
[70 3]: /images/20220515/6ab769a7a79d48259a314453ed2f5d0a.png
[70 4]: /images/20220515/c8c3cfb799a94153ae9ba75d192ce9a7.png
[70 5]: /images/20220515/2a082346885145bdb4e52b6920889fdd.png
[Link 1]: https://download.csdn.net/download/bwangk/10620804