Qt学习例子14——Interactiveitem

Interactiveitem工程在上个例子的基础之上添加了鼠标事件，从而实现交互。

程序依此图而作：

 

 

程序代码如下：

 

//main.cpp

 

#include <QtGui/QApplication>

#include <QGraphicsView>

#include <QGraphicsScene>

#include "smileyitem.h"

int main(int argc, char *argv[])

{

    QApplication a(argc, argv);

    QGraphicsView w;

    QGraphicsScene scene;

    w.setScene(&scene);

    SmileyItem *item = new SmileyItem;

    scene.addItem(item);

    item->setFlag(QGraphicsItem::ItemIsMovable);

    w.setRenderHint(QPainter::Antialiasing);

    w.show();

    w.resize(600,400);

    return a.exec();

}

//smileyitem.h

 

#ifndef SMILEYITEM_H

#define SMILEYITEM_H

#include <QGraphicsItem>

class SmileyItem : public QGraphicsItem

{

public:

    SmileyItem();

    QRectF boundingRect() const;

    QPainterPath shape() const;

    void paint(QPainter * painter, const QStyleOptionGraphicsItem * option, QWidget * widget = 0);

protected:

    void paintEye(QPainter *painter, const QPointF &pt, const QPointF &focus, bool bigEye);

    void paintSmile(QPainter *painter, const QRectF &rect);

    void hoverEnterEvent(QGraphicsSceneHoverEvent *event);

    void hoverMoveEvent(QGraphicsSceneHoverEvent *event);

    void hoverLeaveEvent(QGraphicsSceneHoverEvent *event);

    void mousePressEvent(QGraphicsSceneMouseEvent *event);

    void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);

private:

    QPointF m_focus;

    bool m_bigEyes;

};

#endif // SMILEYITEM_H

 

 

//smileitem.cpp

 

#include "smileyitem.h"

#include <QPainter>

#include <QGraphicsSceneHoverEvent>

#include <cmath>

QPoint computePupil (const QPoint &center, const QPoint &focus, int eyeWidth, int eyeHeight)

{

    QPointF dPoint = focus-center;

    if (dPoint.x() == 0 && dPoint.y() == 0) {

        return center;

    } else {

        double angle = atan2 (dPoint.y(), dPoint.x());

        double cosa = cos (angle);

        double sina = sin (angle);

        double h = hypot (eyeHeight * cosa, eyeWidth * sina);

        double x = (eyeWidth * eyeHeight) * cosa / h;

        double y = (eyeWidth * eyeHeight) * sina / h;

        double dist = hypot (x*0.7, y*0.7); //?

        if (dist > hypot (dPoint.x(), dPoint.y())) {

            return dPoint.toPoint()+center;

        } else {

            return QPoint(dist*cosa+center.x(), dist*sina+center.y());

       }

    }

}

SmileyItem::SmileyItem()

{

    setAcceptHoverEvents(true);

    m_bigEyes = false;

}

QRectF SmileyItem::boundingRect() const {

    return QRectF(-50, -50, 100, 100);

}

QPainterPath SmileyItem::shape() const {

    // enter your code here

    QPainterPath path;

    path.addEllipse(boundingRect());

    return path;

    return QGraphicsItem::shape();

}

void SmileyItem::paint(QPainter * painter, const QStyleOptionGraphicsItem * option, QWidget *widget ) {

    painter->setPen(Qt::NoPen);

    painter->setBrush(Qt::yellow);

    painter->drawEllipse(boundingRect());

    paintEye(painter, QPointF(-15,-25), m_focus, m_bigEyes);

    paintEye(painter, QPointF(15, -25), m_focus, m_bigEyes);

    paintSmile(painter, QRectF(-33, -12, 66, 50));

}

void SmileyItem::paintEye(QPainter *painter, const QPointF &pt, const QPointF &focus, bool bigEye){

    QPen pen(Qt::black);

    pen.setWidthF(1.5);

    painter->setPen(pen);

    painter->setBrush(Qt::white);

    QSize eyeSize(6,12);

    if(bigEye)

        eyeSize+=QSize(2,4);

    painter->drawEllipse(pt, eyeSize.width(), eyeSize.height());

    painter->setPen(Qt::NoPen);

    painter->setBrush(Qt::black);

    QPoint pupilPoint = focus.isNull() ? pt.toPoint() : computePupil(pt.toPoint(),focus.toPoint(),

                                                                     eyeSize.width(),eyeSize.height());

    painter->drawEllipse(pupilPoint, 2, 2);

}

void SmileyItem::paintSmile(QPainter *painter, const QRectF &rect) {

    QPen pen(Qt::black);

    pen.setWidthF(1.5);

   painter->setPen(pen);

    painter->drawArc(rect, 0, -180*16);

}

void SmileyItem::hoverEnterEvent(QGraphicsSceneHoverEvent *event) {

    // enter your code here

    m_focus=event->pos();

    update();

}

void SmileyItem::hoverMoveEvent(QGraphicsSceneHoverEvent *event) {

    // enter your code here

    m_focus=event->pos();

    update();

}

void SmileyItem::hoverLeaveEvent(QGraphicsSceneHoverEvent *event) {

    // enter your code here

    m_focus=QPointF();

    update();

}

void SmileyItem::mousePressEvent(QGraphicsSceneMouseEvent *event) {

    // enter your code here

    m_bigEyes=!m_bigEyes;

    update();

    QGraphicsItem::mousePressEvent(event);

}

void SmileyItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event) {

    // enter your code here

    m_bigEyes=!m_bigEyes;

    update();

    QGraphicsItem::mouseReleaseEvent(event);

}

 

 

程序效果图如下：