使用Qt创建模拟时钟

main.cpp

#include <QtGui/QApplication>

#include "analogclock.h"



Q_DECL_EXPORT int main(int argc, char *argv[])

{

QApplication theApp(argc, argv);



AnalogClock clock;

clock.show();



return theApp.exec();

}

analogclock.h

#ifndef ANALOGCLOCK_H

#define ANALOGCLOCK_H



#include <QWidget>



class AnalogClock : public QWidget

{

Q_OBJECT

public:

explicit AnalogClock(QWidget *parent = 0);



signals:



public slots:



protected:

void paintEvent(QPaintEvent *event);

};



#endif // ANALOGCLOCK_H void paintEvent(QPaintEvent *event);

analogclock.cpp

#include <QtGui>

#include "analogclock.h"



AnalogClock::AnalogClock(QWidget *parent) :

QWidget(parent)

{

QTimer* timer = new QTimer(this);

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

timer->start(1000);

setWindowTitle(tr("Analog Clock"));

resize(200, 200);



}



void AnalogClock::paintEvent(QPaintEvent *)

{

// 时针和分针的点坐标

//画的是三角形，所以需要三个点的坐标

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, -60)

};



static const QPoint secondHand[3] = {

QPoint(4, 8),

QPoint(-4, 8),

QPoint(0, -100)

};



/* 设置时针和分针的颜色 */

QColor hourColor(127, 0, 127);

QColor minuteColor(0, 127, 127, 191);

QColor secondColor(0, 100, 100);



/* QT自带函数，返回两个数的最小值 */

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



/* 获取当前时间 */

QTime time = QTime::currentTime();



/*

在this这个可绘画设备上创建一个绘画者

设置渲染，用反锯齿效果

用一个重载函数转换一下坐标系

缩放一下这个坐标系

*/

//The QPainter class performs low-level painting on widgets and other paint devices.

QPainter painter(this);



//Sets the given render hint on the painter if on is true; otherwise clears the render hint

//Renderhints are used to specify flags to QPainter that may or may not be respected by any given engine.

painter.setRenderHint(QPainter::Antialiasing);



//Translates the coordinate system by the given offset

painter.translate(width()/2, height()/2);



//Scales the coordinate system by (sx, sy).

painter.scale(side/200.0, side/200.0);



/* 用一个重载函数设置一下画笔的类型，NoPen就是没有线

再用一个重载函数设置一下笔刷的颜色，用默认类型

*/

//Sets the painter's pen to be the given pen.

//The pen defines how to draw lines and outlines, and it also defines the text color.

painter.setPen(Qt::NoPen);



//sets the painter's brush to the given brush.

//The painter's brush defines how shapes are filled.

painter.setBrush(hourColor);



//Saves the current painter state (pushes the state onto a stack).

//A save() must be followed by a corresponding restore(); the end() function unwinds the stack.

painter.save(); //保存当前的绘画者状态



//用给出的角度旋转坐标系

//Rotates the coordinate system the given angle clockwise.

painter.rotate(30.0*((time.hour()+time.minute()/60.0)));



//用线把点连起来

//Draws the convex polygon defined by the first pointCount points in the array points using the current pen.

//The first point is implicitly connected to the last point, and the polygon is filled with the current brush().

painter.drawConvexPolygon(hourHand, 3);



//恢复当前的绘画者状态

//Restores the current painter state (pops a saved state off the stack).

painter.restore();



painter.setPen(hourColor);



/* 画代表小时的线 */

for (int i = 0; i < 12; ++i) {

//Draws a line from (x1, y1) to (x2, y2) and sets the current pen position to (x2, y2).

painter.drawLine(88, 0, 96, 0);

painter.rotate(30.0);

}



//下面画分钟的过程是上面的重复，只是分针的颜色用到了透明度

painter.setPen(Qt::NoPen);

painter.setBrush(minuteColor);

painter.save();

painter.rotate(6.0*(time.minute()+time.second()/60.0));

painter.drawConvexPolygon(minuteHand, 3);

painter.restore();

painter.setPen(minuteColor);



/* 画代表分钟的线 */

for (int j = 0; j < 60; ++j) {

if((j % 5) != 0) {

painter.drawLine(92, 0, 96,0);

}

painter.rotate(6.0);

}



//下面画秒针的过程是上面的重复

painter.setPen(Qt::NoPen);

painter.setBrush(secondColor);

painter.save();

painter.rotate(6.0*(time.second()));

painter.drawConvexPolygon(secondHand, 3);

painter.restore();

painter.setPen(minuteColor);

}

FROM: http://www.cnblogs.com/johnpher/archive/2012/01/01/2570587.html