QCustomPlot实现实时动态曲线

原文地址：http://blog.chinaunix.net/uid-11829250-id-5750296.html
Qt4中，可以使用QCustompPlot来绘制曲线，QCustompPlot是一个第三方工具，可以到官网下载：http://www.qcustomplot.com/index.php/download

这里实现一个实时动态曲线图，用随机数作为实时数据，程序运行结果如下：


主机环境：fedora9，Qt4.7，Qtcreator 2.0.1
使用Qtcreator 2.0.1新建一个工程，基类模板选择QMainWindow。将解压得到的QCustompPlot文件夹里面的头文件qcustomplot.h和源文件qcustomplot.cpp复制粘贴到工程文件夹下。在Qtcreator中，对着工程名右键，添加已有文件，将头文件qcustomplot.h和源文件qcustomplot.cpp都添加到工程中来。
在界面上拖拽一个widget部件，然后升级成Qcustomplot，(参考：http://www.bubuko.com/infodetail-744744.html)部件名称改为customPlot
mainwindow.h代码如下：#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();
//设置qcustomplot画图属性，实时
void setupRealtimeDataDemo(QCustomPlot *customPlot);
private slots:
//添加实时数据槽
void realtimeDataSlot();

private:
Ui::MainWindow *ui;
//定时器，周期调用realtimeDataSlot()槽，实现动态数据添加到曲线
QTimer dataTimer;

};

#endif // MAINWINDOW_Hmainwindow.cpp代码如下：#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QVector>
#include <QTimer>
#include <QTime>

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;
}

//画图初始化
void MainWindow::setupRealtimeDataDemo(QCustomPlot *customPlot)
{
//#if QT_VERSION < QT_VERSION_CHECK(4, 7, 0)
//QMessageBox::critical(this, "", "You're using Qt < 4.7, the realtime data demo needs functions that are available with Qt 4.7 to work properly");
//#endif
//demoName = "Real Time Data Demo";

// include this section to fully disable antialiasing for higher performance:
/*
customPlot->setNotAntialiasedElements(QCP::aeAll);
QFont font;
font.setStyleStrategy(QFont::NoAntialias);
customPlot->xAxis->setTickLabelFont(font);
customPlot->yAxis->setTickLabelFont(font);
customPlot->legend->setFont(font);
*/
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的单位是秒
double key = QDateTime::currentDateTime().toMSecsSinceEpoch()/1000.0;
qsrand(QTime::currentTime().msec() + QTime::currentTime().second() * 10000);
//使用随机数产生两条曲线
double value0 = qrand() % 100;
double value1 = qrand() % 80;
if (ui->checkBox_temp->isChecked())
ui->customPlot->graph(0)->addData(key, value0);//添加数据1到曲线1
if (ui->checkBox_hui->isChecked())
ui->customPlot->graph(1)->addData(key, value1);//添加数据2到曲线2
//删除8秒之前的数据。这里的8要和下面设置横坐标宽度的8配合起来
//才能起到想要的效果，可以调整这两个值，观察显示的效果。
ui->customPlot->graph(0)->removeDataBefore(key-8);
ui->customPlot->graph(1)->removeDataBefore(key-8);

//自动设定graph(1)曲线y轴的范围，如果不设定，有可能看不到图像
//也可以用ui->customPlot->yAxis->setRange(up,low)手动设定y轴范围
ui->customPlot->graph(0)->rescaleValueAxis();
ui->customPlot->graph(1)->rescaleValueAxis(true);

//这里的8，是指横坐标时间宽度为8秒，如果想要横坐标显示更多的时间
//就把8调整为比较大到值，比如要显示60秒，那就改成60。
//这时removeDataBefore(key-8)中的8也要改成60，否则曲线显示不完整。
ui->customPlot->xAxis->setRange(key+0.25, 8, Qt::AlignRight);//设定x轴的范围
ui->customPlot->replot();
}