用QCustomPlot畫x軸單位是時間且實時變化的動態圖

轉載自http://blog.chinaunix.net/uid-11829250-id-5750296.html

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QTimer>
#include "qcustomplot.h"

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    //設置qcustomplot畫圖屬性，實時
    void setupRealtimeDataDemo(QCustomPlot *customPlot);
private slots:
    //添加實時數據槽
    void realtimeDataSlot();

private:
    Ui::MainWindow *ui;
    //定時器，週期調用realtimeDataSlot()槽，實現動態數據添加到曲線
    QTimer dataTimer;


};

#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QVector>
#include <QTimer>
#include <QTime>
/*
 *瞭解x座標軸的方法，添加數據的方式
 *
*/
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    setupRealtimeDataDemo(ui->customPlot);
    ui->customPlot->replot();

    ui->checkBox_temp->setChecked(true);
    ui->checkBox_hui->setChecked(true);
}

MainWindow::~MainWindow()
{
    delete ui;
}

//畫圖初始化
void MainWindow::setupRealtimeDataDemo(QCustomPlot *customPlot)
{
  customPlot->addGraph(); // blue line
  customPlot->graph(0)->setPen(QPen(Qt::blue));
  customPlot->graph(0)->setName("temp");
  //customPlot->graph(0)->setBrush(QBrush(QColor(240, 255, 200)));
  //customPlot->graph(0)->setAntialiasedFill(false);
  customPlot->addGraph(); // red line
  customPlot->graph(1)->setPen(QPen(Qt::red));
  customPlot->graph(1)->setName("hui");
  //customPlot->graph(0)->setChannelFillGraph(customPlot->graph(1));


  customPlot->xAxis->setTickLabelType(QCPAxis::ltDateTime);
  customPlot->xAxis->setDateTimeFormat("hh:mm:ss");
  customPlot->xAxis->setAutoTickStep(false);
  customPlot->xAxis->setTickStep(2);
  customPlot->axisRect()->setupFullAxesBox();

  // make left and bottom axes transfer their ranges to right and top axes:
  //connect(customPlot->xAxis, SIGNAL(rangeChanged(QCPRange)), customPlot->xAxis2, SLOT(setRange(QCPRange)));
  //connect(customPlot->yAxis, SIGNAL(rangeChanged(QCPRange)), customPlot->yAxis2, SLOT(setRange(QCPRange)));

  // setup a timer that repeatedly calls MainWindow::realtimeDataSlot:
  connect(&dataTimer, SIGNAL(timeout()), this, SLOT(realtimeDataSlot()));
  dataTimer.start(0); // Interval 0 means to refresh as fast as possible
  customPlot->legend->setVisible(true);



}

void MainWindow::realtimeDataSlot()
{
    //key的單位是秒
    double key = QDateTime::currentDateTime().toMSecsSinceEpoch()/1000.0;
    qsrand(QTime::currentTime().msec() + QTime::currentTime().second() * 10000);
    //使用隨機數產生兩條曲線
    double value0 = qrand() % 100;
    double value1 = qrand() % 80;
    if (ui->checkBox_temp->isChecked())
        ui->customPlot->graph(0)->addData(key, value0);//添加數據1到曲線1
    if (ui->checkBox_hui->isChecked())
        ui->customPlot->graph(1)->addData(key, value1);//添加數據2到曲線2
    //刪除8秒之前的數據。這裏的8要和下面設置橫座標寬度的8配合起來
    //才能起到想要的效果，可以調整這兩個值，觀察顯示的效果。
    ui->customPlot->graph(0)->removeDataBefore(key-8);
    ui->customPlot->graph(1)->removeDataBefore(key-8);

  //自動設定graph(1)曲線y軸的範圍，如果不設定，有可能看不到圖像
//也可以用ui->customPlot->yAxis->setRange(up,low)手動設定y軸範圍

    ui->customPlot->graph(0)->rescaleValueAxis();
    ui->customPlot->graph(1)->rescaleValueAxis(true);

    //這裏的8，是指橫座標時間寬度爲8秒，如果想要橫座標顯示更多的時間
    //就把8調整爲比較大到值，比如要顯示60秒，那就改成60。
    //這時removeDataBefore(key-8)中的8也要改成60，否則曲線顯示不完整。
    ui->customPlot->xAxis->setRange(key+0.25, 8, Qt::AlignRight);//設定x軸的範圍
    ui->customPlot->replot();
}

已經說的很詳細了，留作筆記