day51: QTday4，绘制事件、QT连接TCP网络通信

一、绘制时钟

widget.h:

#ifndef WIDGET_H
#define WIDGET_H

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

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

    void paintEvent(QPaintEvent *event) override;
//    void timerEvent(QTimerEvent *e) override;

public slots:
    void timer_slot();

private:
    Ui::Widget *ui;

//    int timer_id;        //定义一个定时器id

    QTimer * timer;
    int hour;
    int minute;
    int second;

    QLabel *label;
};
#endif // WIDGET_H

widget.cpp:

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

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);

    timer = new QTimer(this);
    timer->start(1000);
    connect(timer,&QTimer::timeout,this,&Widget::timer_slot);


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


void Widget::paintEvent(QPaintEvent *event)
{
    //QRectF rectangle(this->width()/2-200,this->height()/2-200,400,400);
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    //painter.drawEllipse(rectangle);

    QPen pen;
    pen.setStyle(Qt::SolidLine);
    pen.setColor(QColor("Black"));
    pen.setWidth(5);

    painter.setPen(pen);
    painter.translate(this->width()/2,this->height()/2);
    painter.drawEllipse(QPoint(0,0),250,250);

    int i=12;
    while(i--)
    {
        painter.rotate(30);
        painter.drawLine(0,220,0,250);
    }

    int j=60;
    while(j--)
    {
        painter.rotate(6);
        painter.drawLine(0,240,0,250);
    }
    painter.rotate(180);

    painter.save();
    pen.setWidth(8);
    pen.setColor(QColor("red"));
    painter.setPen(pen);
    painter.rotate(30*hour+0.5*minute+0.5/60*second);
    painter.drawLine(0,0,0,50);
    painter.restore();

    painter.save();
    pen.setWidth(5);
    pen.setColor(QColor("blue"));
    painter.setPen(pen);
    painter.rotate(6*minute+0.1*second);
    painter.drawLine(0,0,0,90);
    painter.restore();

    painter.save();
    pen.setWidth(1);
    pen.setColor(QColor("green"));
    painter.setPen(pen);
    painter.rotate(6*second);
    painter.drawLine(0,0,0,150);
    painter.restore();

}

void Widget::timer_slot()
{
    /*
    this->label->resize(200,100);
    this->label->move(this->width()-100,this->height()+150);
    */
    QTime sys_t = QTime::currentTime();     //获得系统时间
    this->hour=sys_t.hour();
    this->minute=sys_t.minute();
    this->second=sys_t.second();
    update();
    /*
    //将QTime类对象转换为字符串
    QString t1 = sys_t.toString("hh:mm:ss");

    //展示
    this->label->setText(t1);
    */
}

main.cpp:

#include "widget.h"

#include 

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();
    return a.exec();
}