Qt绘制实时曲线图形简单例程 - Qt实时绘图

       使用Qt绘制图形，首先需要了解Qt的窗口与视口的概念，理解Qt的坐标变换，然后学会掌握Qpainter这个类的使用就能实现基本的绘图功能了。下面一个实时绘制曲线图形的例子（坐标用应该直接使用一个Qpoint模板的列表表示比较好）。这里，实时数据只是由使用creatData函数产生，在实际工程中将数据改为读取实时数据即可。

头文件

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTimer>
#include <QList>

class Widget : public QWidget
{
    Q_OBJECT

protected:
    void paintEvent(QPaintEvent *);
public:
    int m_count;
    float x;
    QTimer* m_Timer;
    QList<float> xList;
    QList<float> yList;

    Widget(QWidget *parent = 0);
    ~Widget();

public slots:
    void creatData();

};

#endif // WIDGET_H

源文件

#include "Widget.h"
#include <QPainter>
#include <QPointF>
#include <QPen>
#include <qmath.h>
Widget::Widget(QWidget *parent) : QWidget(parent)
{
    x = -10;
    m_count = 0;
    m_Timer = new QTimer(this);
    m_Timer->start(10);
    connect(m_Timer,SIGNAL(timeout()),this,SLOT(creatData()));
}
void Widget::creatData()
{
    x += 0.2;
    m_count += 1;
    if(m_count%2)
    {
        xList.append(x);
        yList.append(qSin(x));
    }
    else
    {
        xList.append(x);
        yList.append(qSin(x));
        update();
    }
    if(m_count == 100)
    {
        xList.clear();
        yList.clear();
        m_count = 0;
        x = -10;
    }
}
void Widget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    QPen pen;
    pen.setColor(Qt::green);
    pen.setStyle(Qt::SolidLine);
    pen.setWidthF(0.05);
    painter.setPen(pen);
    painter.setViewport(50, 50, width()-100, height()-100);
    painter.setWindow(-10, 2, 20, -4); // (-10, 2)    (10, -2)
    painter.fillRect(-10, 2, 20, -4, Qt::white);
    painter.drawLine(QPointF(-10, 0), QPointF(10, 0));   // x
    painter.drawLine(QPointF(0, 2), QPointF(0, -2));     // y
    for(int i = 0; i < yList.count(); i++)
    {
        if(i == 0)
            painter.drawPoint(QPointF(xList[i], yList[i]));
        else
            painter.drawLine(QPointF(xList[i-1], yList[i-1]), QPointF(xList[i], yList[i]));
    }
}
Widget::~Widget()
{
    
}

主函数

#include <QApplication>
#include "Widget.h"
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();
    
    return a.exec();
}