#pragma once

#include <QtWidgets/QMainWindow>
#include "ui_QtClock.h"

class QtClock : public QMainWindow
{
	Q_OBJECT

public:
	QtClock(QWidget *parent = Q_NULLPTR);

	QRectF textRectF(double radius, int pointSize, double angle);

	void paintEvent(QPaintEvent *event);

private:
	Ui::QtClockClass ui;
};

#include "QtClock.h"

#include <QTimer>
#include <QtMath>
#include <QTime>
#include <QPainter>

QtClock::QtClock(QWidget *parent)
	: QMainWindow(parent)
{
	ui.setupUi(this);

	// 构造定时器，设置超时为 1 秒
	QTimer *timer = new QTimer(this);
	connect(timer, SIGNAL(timeout()), this, SLOT(update()));
	timer->start(1000);

}

QRectF QtClock::textRectF(double radius, int pointSize, double angle)
{
	QRectF rectF;
	rectF.setX(radius*qCos(angle*M_PI / 180.0) - pointSize * 2);
	rectF.setY(radius*qSin(angle*M_PI / 180.0) - pointSize / 2.0);
	rectF.setWidth(pointSize * 4);
	rectF.setHeight(pointSize);
	return rectF;
}

void QtClock::paintEvent(QPaintEvent *event)
{
	Q_UNUSED(event);

	// 时针、分针、秒针位置 - 多边形
	static const QPoint hourHand[3] = {
		QPoint(7, 8),
		QPoint(-7, 8),
		QPoint(0, -30)
	};
	static const QPoint minuteHand[3] = {
		QPoint(7, 8),
		QPoint(-7, 8),
		QPoint(0, -65)
	};

	static const QPoint secondHand[3] = {
		QPoint(7, 8),
		QPoint(-7, 8),
		QPoint(0, -80)
	};

	// 时针、分针、秒针颜色
	QColor hourColor(200, 100, 0, 200);
	QColor minuteColor(0, 127, 127, 150);
	QColor secondColor(0, 160, 230, 150);

	int side = qMin(width(), height());
	QTime time = QTime::currentTime();

	QPainter painter(this);
	painter.setRenderHint(QPainter::Antialiasing);
	// 平移坐标系原点至中心点
	painter.translate(width() / 2, height() / 2);
	// 缩放
	painter.scale(side / 200.0, side / 200.0);

	// 绘制时针
	painter.setPen(Qt::NoPen);
	painter.setBrush(hourColor);

	painter.save();
	// 每圈360° = 12h 即：旋转角度 = 小时数 * 30°
	painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
	painter.drawConvexPolygon(hourHand, 3);
	painter.restore();

	painter.setPen(hourColor);

	// 绘制小时线 （360度 / 12 = 30度）
	for (int i = 0; i < 12; ++i) {
		painter.drawLine(88, 0, 96, 0);
		painter.rotate(30.0);
	}

	int radius = 100;
	QFont font = painter.font();
	font.setBold(true);
	painter.setFont(font);
	int pointSize = font.pointSize();

	// 绘制小时文本
	int nHour = 0;
	for (int i = 0; i < 12; ++i) {
		nHour = i + 3;
		if (nHour > 12)
			nHour -= 12;
		painter.drawText(textRectF(radius*0.8, pointSize, i * 30), Qt::AlignCenter, QString::number(nHour));
	}

	// 绘制分针
	painter.setPen(Qt::NoPen);
	painter.setBrush(minuteColor);

	painter.save();
	// 每圈360° = 60m 即：旋转角度 = 分钟数 * 6°
	painter.rotate(6.0 * (time.minute() + time.second() / 60.0));
	painter.drawConvexPolygon(minuteHand, 3);
	painter.restore();

	painter.setPen(minuteColor);

	// 绘制分钟线 （360度 / 60 = 6度）
	for (int j = 0; j < 60; ++j) {
		if ((j % 5) != 0)
			painter.drawLine(92, 0, 96, 0);
		painter.rotate(6.0);
	}

	// 绘制秒针
	painter.setPen(Qt::NoPen);
	painter.setBrush(secondColor);

	painter.save();
	// 每圈360° = 60s 即：旋转角度 = 秒数 * 6°
	painter.rotate(6.0 * time.second());
	painter.drawConvexPolygon(secondHand, 3);
	painter.restore();
}

运行效果如下