C++&QT day11

绘制时钟

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include 
#include //绘制事件类
#include //信息调试类
#include //画家类
#include //定时器类
#include 
#include 

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

    //重写绘制事件处理函数
    void paintEvent(QPaintEvent *event) override;

    void drawHourHand(QPainter *painter);//时针
    void drawMinuteHand(QPainter *painter);//分针
    void drawSecondHand(QPainter *painter);//秒针
    void drawClockDial(QPainter *painter);//表盘
private:
    Ui::Widget *ui;
    QPen hourHandPen;
    QPen minuteHandPen;
    QPen font;
    static const QPoint hourHand[4];
    static const QPoint minuteHand[4];
    static const QPoint secondHand[4];

};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"

const QPoint Widget::hourHand[4] = {
    QPoint(3, 5),
    QPoint(0, 13),
    QPoint(-3, 5),
    QPoint(0, -40)
};
const QPoint Widget::minuteHand[4] = {
    QPoint(3, 5),
    QPoint(0, 16),
    QPoint(-3, 5),
    QPoint(0, -70)
};
const QPoint Widget::secondHand[4] = {
    QPoint(3, 5),
    QPoint(0, 18),
    QPoint(-3, 5),
    QPoint(0, -90)
};
Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);

    QTimer *timer = new QTimer(this);
    timer->start(1000);//一秒
    connect(timer,SIGNAL(timeout()), this, SLOT(update()));
    hourHandPen = QPen(palette().foreground(), 2.0);//调色板，2.0，1.0为颜色代码，这里是调整刻度线的颜色
    minuteHandPen = QPen(palette().foreground(), 1.0);
    setWindowTitle("The Clock");//设置对话框名称
    resize(600, 600);//重设对话框大小
}

Widget::~Widget()
{
    delete ui;
}
//绘制时针
void Widget::drawHourHand(QPainter *painter)
{


        QTime time = QTime::currentTime();//获取当前系统的时间
        painter->setBrush(QColor("pink"));//设定粉色画笔
        painter->setPen(QColor("pink"));//将时针调成粉色
        painter->save();
        painter->rotate(30.0*(time.hour()+time.minute()/60.0));
        painter->drawConvexPolygon(hourHand,4);//绘制时针
        painter->restore();//绘制图形后复位坐标系
}
//绘制分针
void Widget::drawMinuteHand(QPainter *painter)
{

        QTime time = QTime::currentTime();
        painter->setBrush(QColor("skyblue"));
        painter->setPen(QColor("skyblue"));
        painter->save();
        painter->rotate(6.0*(time.minute()+time.second()/60.0));
        painter->drawConvexPolygon(minuteHand,4);//绘制分针
        painter->restore();//绘制图形后复位坐标系
}
//绘制秒针
void Widget::drawSecondHand(QPainter *painter)
{

        QTime time = QTime::currentTime();
        painter->setBrush(QColor("yellow"));
        painter->setPen(QColor("yellow"));
        painter->save();//保存坐标系，防止坐标系跑偏了
        painter->rotate(6.0*time.second());//注意是6.0，不是6
        painter->drawConvexPolygon(secondHand,4);//绘制秒针
        painter->restore();//绘制图形后复位坐标系
}
//绘制表盘
void Widget::drawClockDial(QPainter *painter)
{
        //绘制钟表刻度盘和数字
        for (int i = 1; i <=60; ++i)
        {
            painter->save();
            painter->rotate(6*i);//坐标轴旋转6度
            if (i % 5 == 0)
            {
                painter->setPen(hourHandPen);
                painter->drawLine(0, -98, 0, -82);
                painter->drawText(-20, -82, 40, 40,
                                  Qt::AlignHCenter | Qt::AlignTop,
                                  QString::number(i/5));
            }
            else
            {
                painter->setPen(minuteHandPen);
                painter->drawLine(0, -98, 0, -88);
            }
            painter->restore();//绘制图形后复位坐标系
        }
}
void Widget::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
    QPen pen;
    pen.setColor(QColor("blue"));
    pen.setWidth(5);
    painter.setRenderHint(QPainter::Antialiasing, true);
    int side = qMin(width(), height());
    painter.setViewport((width() - side) / 2, (height() - side) / 2,
                        side, side);//让时钟的位置处于对话框的中心
    painter.setWindow(0, 0, 200, 200);
    painter.translate(100,100);//重新设定坐标原点
    //调用重绘函数
    drawClockDial(&painter);
    drawHourHand(&painter);
    drawMinuteHand(&painter);
    drawSecondHand(&painter);
     //绘制时针固定圆
    painter.setBrush(QColor("black"));
    painter.drawEllipse(QPoint(0,0),3,3);

}

思维导图：