qt 自定义窗口绘制正弦曲线

circlewidget.h

#ifndef CIRCLAWIDGET_H

#define CIRCLAWIDGET_H

#include <QFrame>

#include<QVector>

#include<QMouseEvent>

class CircleWidget:public QFrame

{

    Q_OBJECT

public:

    CircleWidget(QWidget *parent);

    ~CircleWidget();

private:

    void paintEvent(QPaintEvent *event);

public:

    void Adjust(int period, int grain, int radius);

    QPoint origin();            // 坐标原点位置

    QPoint toCoord(QPoint p);   // 将GUI窗口的点(x,y)转换成坐标系统里的点

    QPoint fromCoord(QPoint p); // 将坐标系内的(x,y)转成GUI的坐标

private:

    int m_period, m_grain, m_radius;

};

#endif // CIRCLAWIDGET_H

circlewidget.cpp

# include"circlewidget.h"

#include<QPainter>

#include<QDebug>

#include<math.h>

CircleWidget::CircleWidget(QWidget *parent):QFrame(parent)

{

        m_period = ;  //周期

        m_grain = ;    //粒度

        m_radius = ; // 振幅

}

CircleWidget::~CircleWidget()

{

}

void CircleWidget::paintEvent(QPaintEvent *event)

{

    QPainter painter(this);

        int width = this->width();

        int height = this->height();

        QRect rect(,, width, height);

        // 设置背景为黑色

        painter.setBrush(QBrush(QColor(0x00,0x00, 0x00)));

        painter.drawRect(rect);

        painter.setPen(QPen(QColor(, , ))); // 设置线条为绿色

        QPoint o = origin();

        painter.drawLine(QPoint(, o.y()), QPoint(width, o.y())); // x轴

        painter.drawLine(QPoint(o.x(), ), QPoint(o.x(), height));// y轴

        // 正弦曲线: 从坐标原点，向左、向右伸展

        QPoint p1(,);

        for(int x=; x<width/; x+=m_grain)

        {

            // y=sin(x)

            double angle = (double) x / m_period *  * 3.1415926;

            double y = m_radius * sin(angle);

            QPoint p2(x, y);

            // 右侧

            painter.drawLine(fromCoord(p1), fromCoord(p2));

            // 左侧

            QPoint base(,);

            painter.drawLine(fromCoord(base-p1), fromCoord(base-p2));

            p1 = p2;

        }

}

void CircleWidget::Adjust(int period, int grain, int radius)

{

    m_period = period;

    m_grain = grain;

    m_radius = radius;

    update(); // 更新重绘

}

QPoint CircleWidget::origin()

{

    QRect r = this->rect();

    return r.center();

}

// 将GUI窗口的点(x,y)转换成数学坐标系统里的点

QPoint CircleWidget::toCoord(QPoint p)

{

    // 圆心

    QPoint o = this->origin();

    QPoint result =  p - o;

    result.setY( - result.y()); // y坐标反转

    return result;

}

// 将数学坐标系内的(x,y)转成GUI的坐标

QPoint CircleWidget::fromCoord(QPoint p)

{

    // 圆心

    QPoint o = this->origin();

    p.setY( - p.y()); // y坐标反转

    return p + o;

}

结果：