Qt动图效果，蝴蝶飞，星星移动

#include "butterfly.h" #include <QtGui> #include <QDebug> #include <QtWidgets/QGraphicsScene> #include <math.h> static const double PI = 3.14159265358979323846264338327950288419717; Butterfly::Butterfly() { setFlag(QGraphicsItem::ItemIsMovable); pix_up.load(":/images/butterfly1.PNG"); pix_down.load(":/images/butterfly2.PNG"); up = true; startTimer(100); } QRectF Butterfly::boundingRect() const { // boundingRect函数的作用是必须要重新实现的，因为他用来指定当前图形对象 // 每次重绘时需要刷新的区域，如果指定的的区域不正确，就会出现图片有些区 // 域没刷新的问题 qreal adjust = 8; return QRectF(-pix_up.width()/2-adjust,-pix_up.height()/2-adjust, pix_up.width()+adjust*2,pix_up.height()+2*adjust); } void Butterfly::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) { // paint函数也必须要重新实现，顾名思义是用来绘制对象的具体内容的，每当update()被调用一次时， // paint函数也会被调用一次 // 交替绘制两张蝴蝶照片，形成扇动翅膀的飞舞效果 if(up) { painter->drawPixmap(boundingRect().topLeft(),pix_up); up = !up; } else { painter->drawPixmap(boundingRect().topLeft(),pix_down); up = !up; } // 绘制一个圆 //painter->setPen(Qt::NoPen); //painter->setBrush(Qt::darkGray); //painter->drawEllipse(-7,-7,40,40); // //painter->setPen(QPen(Qt::black,0)); //painter->setBrush(Qt::red); //painter->drawEllipse(-10,-10,40,40); } void Butterfly::timerEvent(QTimerEvent *) { // edge controll qreal edgex = scene()->sceneRect().right()+boundingRect().width()/2; qreal edgetop = scene()->sceneRect().top()+boundingRect().height()/2; qreal edgebottom = scene()->sceneRect().bottom()+boundingRect().height()/2; if (pos().x() >= edgex) setPos(scene()->sceneRect().left(),pos().y()); if (pos().y() <= edgetop) setPos(pos().x(),scene()->sceneRect().bottom()); if (pos().y() >= edgebottom) setPos(pos().x(),scene()->sceneRect().top()); angle += (qrand()%10)/20.0; qreal dx = fabs(sin(angle*PI)*10.0); qreal dy = (qrand()%20)-10.0; setPos(mapToParent(dx,dy)); update(); //qDebug() << scene()->itemsBoundingRect(); 输出到控制台 }