1. 绘制椭圆  饼状型 贝塞尔曲线

绘制图像重写方法 void paintEvent(QPaintEvent *event)即可。

void Widget::paintEvent(QPaintEvent *event)

{

    QPainter painter1(this);  //新建画笔

    painter1.setRenderHint(QPainter::Antialiasing, true);  //设置 反走样

    painter1.setPen(QPen(Qt::black, 8, Qt::DashDotLine, Qt::RoundCap));  //设置线条 颜色， 大小，线型风格，拐点风格

    painter1.setBrush(QBrush(Qt::green, Qt::SolidPattern));  //设置画刷 颜色 和 风格

    painter1.drawEllipse(10, 10, 160, 80);   //画椭圆

    QPainter painter2(this);

    painter2.setRenderHint(QPainter::Antialiasing, true);

    painter2.setPen(QPen(Qt::black, 8, Qt::DashDotLine, Qt::RoundCap));

    painter2.setBrush(QBrush(Qt::blue, Qt::DiagCrossPattern));

    painter2.drawPie(10, 150, 200, 120, 60*16, 270*16);

    QPainter painter3(this);

    painter3.setRenderHint(QPainter::Antialiasing, true);

    QPainterPath path;    //轨迹

    path.moveTo(200, 150);   //先移到这个点

    path.cubicTo(250, 80, 320, 80, 400, 150); //x1 x2 和 andpoint 确定弧形

    painter3.setPen(QPen(Qt::black, 8));

    painter3.setBrush(QBrush(Qt::green, Qt::DiagCrossPattern));

    QTransform transform;      //世界变换

    transform.translate(0, 0);  //以00为中心 选装30°

    transform.rotate(+30.0);

    painter3.setWorldTransform(transform);   //添加世界变换

    painter3.drawPath(path);

}

2. 仪表盘

oventimer.h

#ifndef OVENTIMER_H

#define OVENTIMER_H

#include <QWidget>

#include <QtGui>

class OvenTimer : public QWidget

{

    Q_OBJECT

public:

    OvenTimer(QWidget *parent = 0);

    void setDuration(int secs);

    int duration() const;

    void draw(QPainter *painter);

signals:

    void timeout();

protected:

    void paintEvent(QPaintEvent *event);

    void mousePressEvent(QMouseEvent *event);

private:

    QDateTime finishTime;

    QTimer *updateTimer;

    QTimer *finishTimer;

};

#endif // OVENTIMER_H

oventimer.cpp

#include "oventimer.h"

#include <QtGui>

#include <QtCore>

#include <math.h>

const double DegreesPerMinute = 7.0;

const double DegressPerSecond = DegreesPerMinute/60;

const int MaxMinutes = 45;

const int MaxSeconds = MaxMinutes*60;

const int UpdateInterval = 5;

OvenTimer::OvenTimer(QWidget *parent)

    : QWidget(parent)

{

    finishTime = QDateTime::currentDateTime();

    updateTimer = new QTimer(this);

    connect(updateTimer, SIGNAL(timeout()), this, SLOT(update()));

    finishTimer = new QTimer(this);

    finishTimer->setSingleShot(true);

    connect(finishTimer, SIGNAL(timeout()), this, SIGNAL(stop()));

    connect(finishTimer, SIGNAL(timeout()), updateTimer, SLOT(stop()));

    QFont font;

    font.setPointSize(8);

    setFont(font);

}

void OvenTimer::setDuration(int secs)

{

    secs = qBound(0, secs, MaxSeconds);

    finishTime = QDateTime::currentDateTime().addSecs(secs);

    if( secs > 0 )

    {

        updateTimer->start(UpdateInterval*1000);

        finishTimer->start(secs*1000);

    }

    else

    {

        updateTimer->stop();

        finishTimer->stop();

    }

    update();

}

int OvenTimer::duration() const

{

    int secs = QDateTime::currentDateTime().secsTo(finishTime);

    if( secs < 0 )

        secs = 0;

    return secs;

}

void OvenTimer::mousePressEvent(QMouseEvent *event)

{

    QPointF point = event->pos() - rect().center();

    double theta = atan2(-point.x(), -point.y())*180.0/M_PI;

    setDuration(duration() + int(theta / DegressPerSecond));

    update();

}

void OvenTimer::paintEvent(QPaintEvent *event)

{

    QPainter painter(this);

    painter.setRenderHint(QPainter::Antialiasing, true);

    int side = qMin(width(), height());

    painter.setViewport( (width()-side)/2, (height()-side)/2, side, side );

    painter.setWindow(-50, -50, 100, 100);

    draw(&painter);

}

void OvenTimer::draw(QPainter *painter)

{

    static const int triangle[3][2]={ {-2,-49}, {+2,-49}, {0,-47} };

    QPen thickPen(palette().foreground(), 1.5);

    QPen thinPen(palette().foreground(), 0.5);

    QColor niceBlue(150, 150, 200);

    painter->setPen(thinPen);

    painter->setBrush(palette().foreground());

    painter->drawPolygon( QPolygon(3, &triangle[0][0]) );

    QConicalGradient coneGradient(0,0,-90.0);

    coneGradient.setColorAt(0.0, Qt::darkGray);

    coneGradient.setColorAt(0.2, niceBlue);

    coneGradient.setColorAt(0.5, Qt::white);

    coneGradient.setColorAt(1.0, Qt::darkGray);

    painter->setBrush(coneGradient);

    painter->drawEllipse(-46, -46, 92, 92);

    QRadialGradient haloGradient(0,0,20,0,0);

    haloGradient.setColorAt(0.0, Qt::lightGray);

    haloGradient.setColorAt(0.8, Qt::darkGray);

    haloGradient.setColorAt(0.9, Qt::white);

    haloGradient.setColorAt(1.0, Qt::black);

    painter->setPen(Qt::NoPen);

    painter->setBrush(haloGradient);

    painter->drawEllipse(-20, -20, 40, 40);

    QLinearGradient knobGradient(-7, -25, 7, -25);

    knobGradient.setColorAt(0.0, Qt::black);

    knobGradient.setColorAt(0.2, niceBlue);

    knobGradient.setColorAt(0.3, Qt::lightGray);

    knobGradient.setColorAt(0.8, Qt::white);

    knobGradient.setColorAt(1.0, Qt::black);

    painter->rotate(duration() * DegressPerSecond);

    painter->setBrush(knobGradient);

    painter->setPen(thinPen);

    painter->drawRoundedRect(-7, -25, 14, 50, 99, 49);

    for( int i=0; i<=MaxMinutes; i++ )

    {

        if(i%5==0)

        {

            painter->setPen(thickPen);

            painter->drawLine(0, -41, 0, -44);

            painter->drawText(-15, -41, 30, 30,

                              Qt::AlignHCenter | Qt::AlignTop,QString::number(i));

        }

        else

        {

            painter->setPen(thinPen);

            painter->drawLine(0, -42, 0, -44);

        }

        painter->rotate(-DegreesPerMinute);

    }

}