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); }