Qt 利用 Qwt 绘制动态曲线

这是一个简单的总结，如果有问题，欢迎留言。

效果图：

绘制前的准备

.配置QWt   建议参考博客  http://blog.youkuaiyun.com/zhuyunfei/article/details/51008228 亲测有效

绘制函数

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QTimer>
#include <QTime>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
#include <qwt_legend.h>
#include <math.h>
#include <qwt_plot_zoomer.h>
#include <qwt_plot_panner.h>
#include <qwt_plot_magnifier.h>
#include <qwt_plot_grid.h>
#include <qwt_scale_draw.h>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void setupRealtimeDataDemo(QwtPlot *qwtplot);

private:
    Ui::MainWindow *ui;
    QVector<double> xdata;
    QVector<double> ydata;
    QTimer updateTimer;
    QString demoName;
    QwtPlotCurve *curve ;
    double getData(double inteval);

private slots:
    void updatedataSlot();
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"




MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setupRealtimeDataDemo(ui->qwtPlot);
}



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



void MainWindow::setupRealtimeDataDemo(QwtPlot *qwtplot)
{


    //初始化xdata,x对应长度为5的坐标，y初始全为0
    for(int i=1;i<5001;i++){
        xdata.append(double(i)/1000-5);
        ydata.append(0);
    }

    demoName = "Real Time Data Demo";
    qwtplot->setTitle(demoName);
    qwtplot->setCanvasBackground(Qt::gray);//背景
    qwtplot->insertLegend(new QwtLegend(),QwtPlot::RightLegend);//标签

    curve = new QwtPlotCurve();
    curve->setTitle("肌电信号");//曲线名字
    curve->setPen( Qt::yellow, 1 );//曲线的颜色 宽度;

    QTime curtime;
    curtime=curtime.currentTime();
    qwtplot->setAxisTitle(QwtPlot::xBottom, " System Uptime");
    qwtplot->setAxisTitle(QwtPlot::yLeft,"EMG");
    qwtplot->setAxisScale(QwtPlot::yLeft,-2,2,1);
    qwtplot->setAxisScale(QwtPlot::xBottom,-5,0,1);



    QwtPlotZoomer *zoomer = new QwtPlotZoomer( qwtplot->canvas() );
    zoomer->setRubberBandPen( QColor( Qt::blue ) );
    zoomer->setTrackerPen( QColor( Qt::black ) );
    zoomer->setMousePattern(QwtEventPattern::MouseSelect2,Qt::RightButton, Qt::ControlModifier );
    zoomer->setMousePattern(QwtEventPattern::MouseSelect3,Qt::RightButton );
    QwtPlotMagnifier *magnifier = new QwtPlotMagnifier( qwtplot->canvas() );                 //默认的滑轮及右键缩放功能  图形的整体缩放

    //    magnifier->setMouseButton(Qt::LeftButton);     //设置哪个按钮与滑轮为缩放画布  如果不设置(注册掉当前行)按钮默认为滑轮以及右键为缩放

    QwtPlotGrid *grid = new QwtPlotGrid();
    grid->enableX( true );//设置网格线
    grid->enableY( true );
    grid->setMajorPen( Qt::black, 0, Qt::DotLine );
    grid->attach(qwtplot);

    connect(&updateTimer,SIGNAL(timeout()),this,SLOT(updatedataSlot()));
    updateTimer.start(0);


}


/**
 * @brief getData
 * @param inteval
 * @return
 * 获取一个值  模拟串口接收到的值
 */
double MainWindow::getData(double time){

    double s = qCos( time * M_PI * 2 ) ;
    return s;
}


//用于更新ydata,实际情况就是read数据
void MainWindow::updatedataSlot(){
    static QTime dataTime(QTime::currentTime());
    long int eltime = dataTime.elapsed();
    static int lastpointtime = 0;

    int size = (eltime - lastpointtime);


    if(size>0){//有数据传入
        ydata.erase(ydata.begin(),ydata.begin()+size);//擦除多余的数据
        for(int i=1;i<size+1;i++){
            ydata.append(getData((((double)lastpointtime+i)/1000)));
        }
        lastpointtime = eltime;
    }

    curve->setSamples(xdata,ydata);
    curve->attach(ui->qwtPlot);
    ui->qwtPlot->replot();

    static double lastFpsKey;
    static int frameCount;
    ++frameCount;
    double fpstime = (double)eltime/1000.0-lastFpsKey;
    if ( fpstime> 2) // average fps over 2 seconds
    {
        ui->statusBar->showMessage(
                    QString("%1 FPS")
                    .arg(frameCount/fpstime, 0, 'f', 0)
                    , 0);
        lastFpsKey = (double)eltime/1000.0;
        frameCount = 0;
    }
}

有不明白的地方欢迎留言！