Hello World! 学习编程语言的最简单最经典的小程序,当然Qt也不例外。在学习画图时,我觉得写个时钟小程序也是个比较好的开始。在之前的《Matlab及Java小时》一文中,我也从写时钟程序作为学习画图的开始。三者之间的不同点在于,matlab是通过while循环来进行重绘,Java和Qt事件来处理。实时显示时钟,都是通过改变指针与坐标轴的相对位置来实现的。前两者都是改变指针,而Qt是旋转坐标轴。具体代码如下:
1.widget.h文件
#ifndef WIDGET_H #define WIDGET_H #include <QWidget> namespace Ui { class Widget; } class Widget : public QWidget { Q_OBJECT public: explicit Widget(QWidget *parent = 0); ~Widget(); private: Ui::Widget *ui; protected: void paintEvent(QPaintEvent *event);//添加重绘事件 }; #endif // WIDGET_H
2.main.cpp
#include <QtGui/QApplication> #include "widget.h" #include<QTextCodec> #include<QPainter> #include<QtGui> #include<QDebug> int main(int argc, char *argv[]) { QApplication a(argc, argv); QTextCodec::setCodecForTr(QTextCodec::codecForLocale()); Widget w; w.show(); return a.exec(); }
3.widget.cpp
#include "widget.h" #include "ui_widget.h" #include<QPainter> #include<QtGui> #include<QDebug> #include<QFont> Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget) { ui->setupUi(this); QTimer *timer = new QTimer(this);//创建一秒定时器 connect(timer, SIGNAL(timeout()), this, SLOT(update()));//信号与槽关联 timer->start(1000); setWindowTitle(tr("我的时钟--designed by TW")); } Widget::~Widget() { delete ui; } void Widget::paintEvent(QPaintEvent *event) { int side = qMin(width(), height());//获取窗口的较短边的值 QPainter painter(this);//指定画图设备 painter.fillRect(rect(),Qt::yellow);//设置背景色 painter.setRenderHint(QPainter::Antialiasing);//开启抗锯齿 painter.translate(width() / 2, height() / 2);//将坐标移到窗口正中心 painter.scale(side / 200.0, side / 200.0);//进行缩放 QPen pen;//设置画笔的,宽度,样式,颜色 pen.setWidth(2); pen.setStyle(Qt::SolidLine); pen.setColor(Qt::red); painter.setPen(pen); for (int i = 0; i < 12; ++i) //画表盘时针刻度 { painter.drawLine(87, 0, 95, 0); painter.rotate(30);//将坐标进行顺时针选择30度 } pen.setWidth(1); pen.setColor(Qt::black); painter.setPen(pen); for (int i = 0; i < 60; ++i) //画表盘时针刻度 { if(i%5!=0) painter.drawLine(90, 0, 95, 0); painter.rotate(6); } pen.setColor(Qt::black); painter.setPen(pen); QFont font("Century"); painter.setFont(font); //标时刻的数值 painter.drawText(-6,-75,tr("12")); painter.drawText(-3,80,tr("6")); painter.drawText(75,5,tr("3")); painter.drawText(-80,5,tr("9")); painter.drawArc(-3,-3,6,6,0,360*16);//画中心小圆环 ///////////////////////////////////// QTime time = QTime::currentTime();//获取当前系统时间 // qDebug()<<time.hour(); // qDebug()<<time.minute(); // qDebug()<<time.second(); //画时针 painter.save();//在旋转坐标系前,保存原来坐标系 painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0))); pen.setColor(Qt::green); pen.setWidth(4); painter.setPen(pen); painter.drawLine(0,0,0,-60); painter.restore();//在旋转坐标系后,恢复原来坐标系 //画分针 painter.save(); painter.rotate(6.0 * (time.minute() + time.second() / 60.0)); pen.setColor(Qt::blue); pen.setWidth(2); painter.setPen(pen); painter.drawLine(0,0,0,-80); painter.restore(); //画秒针 painter.save(); painter.rotate(6.0 *time.second() ); pen.setColor(Qt::red); pen.setWidth(1); painter.setPen(pen); //秒针形状由两条直线和一个小圆环组成 painter.drawArc(-3,-66,6,6,0,360*16); painter.drawLine(0,20,0,-60); painter.drawLine(0,-66,0,-85); painter.restore(); }
运行结果如下图:
原文:http://blog.csdn.net/tengweitw/article/details/22308627
作者:nineheadedbird