35.QT蝴蝶飞舞

fly.h

 1 #ifndef FLY_H
 2 #define FLY_H
 3 #include <QObject>
 4 #include <QPainter>
 5 #include <QGraphicsScene>
 6 #include <QGraphicsView>
 7 #include <QGraphicsItem>
 8 #include <QPixmap>
 9 #include <math.h>
10 #include <QTime>
11 #include <QEvent>
12 
13 //图元对象
14 class fly : public QObject,public QGraphicsItem
15 {
16     Q_OBJECT
17 public:
18     explicit fly(QObject *parent = nullptr);
19 
20     //区域
21     QRectF boundingRect() const;
22     //时间定时器
23     void timerEvent(QTimerEvent *event);
24 signals:
25 
26 public slots:
27 
28 protected:
29     //绘制
30     void paint(QPainter *painter,const QStyleOptionGraphicsItem *option,QWidget *widget);
31 
32 public:
33     bool up;
34     QPixmap pix_up;
35     QPixmap pix_down;
36 
37     qreal angle;
38 
39 };
40 
41 #endif // FLY_H

fly.cpp

 1 #include "fly.h"
 2 
 3 fly::fly(QObject *parent) : QObject(parent)
 4 {
 5     //载入
 6     up = true;
 7     pix_up.load("up.png");
 8     pix_down.load("down.png");
 9 
10     startTimer(30);
11 }
12 
13 //图元的边界区域
14 QRectF fly::boundingRect() const
15 {
16     qreal angletemp = 2;
17     return QRectF(-pix_up.width()/2-angletemp,
18                   -pix_up.height()/2-angletemp,
19                   pix_up.width()+angletemp*2,
20                   pix_up.height()+angletemp*2);
21 }
22 
23 //定时器函数
24 void fly::timerEvent(QTimerEvent *event)
25 {
26     //边界控制
27     qreal edgex = scene()->sceneRect().right()+boundingRect().width()/2;
28     qreal edgetop=scene()->sceneRect().top()+boundingRect().height()/2;
29     qreal edgebottom = scene()->sceneRect().bottom()+boundingRect().height()/2;
30 
31     if(pos().x()>=edgex)
32         setPos(scene()->sceneRect().left(),pos().y());
33     if(pos().y()<=edgetop)
34         setPos(pos().x(),scene()->sceneRect().bottom());
35     if(pos().y()>=edgebottom)
36         setPos(pos().x(),scene()->sceneRect().top());
37 
38 #define PI 3.14
39     angle += (qrand() % 10)/20.0;
40     qreal dx = fabs(sin(angle*PI)*10);
41     qreal dy = (qrand()%20)-10.0;
42 
43     //设置位置,转换坐标
44     setPos(mapToParent(dx,dy));
45 }
46 
47 void fly::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
48 {
49     if(up)
50     {
51         painter->drawPixmap(boundingRect().topLeft(),pix_up);
52         up = !up;
53     }
54     else
55     {
56         painter->drawPixmap(boundingRect().topLeft(),pix_down);
57         up = !up;
58     }
59 }

main.cpp

 1 #include "dialog.h"
 2 #include <QApplication>
 3 #include <QGraphicsScene>
 4 #include <QGraphicsView>
 5 #include "fly.h"
 6 
 7 int main(int argc, char *argv[])
 8 {
 9     QApplication a(argc, argv);
10 
11     //创建图像场景
12     QGraphicsScene *scene = new QGraphicsScene;
13     //设置区域
14     scene->setSceneRect(-300,-200,400,500);
15 
16     fly *f = new fly;
17     f->setPos(-100,0);
18     scene->addItem(f);
19 
20     QGraphicsView *view = new QGraphicsView;
21     view->setScene(scene);
22     view->resize(800,600);
23     view->show();
24 
25     return a.exec();
26 }