QGraphicsScene::removeItem
有一些奇怪的地方,当我从场景中删除两个项目时,我收到以下消息:
QGraphicsScene::removeItem: item 0x5edb28's scene (0x0) is different from this scene (0x5e7790)
QGraphicsScene::removeItem: item 0x5edc18's scene (0x0) is different from this scene (0x5e7790)
即使这两个项目在场景中。
我已经根据场景检查了项目场景,但它返回 true:
if(Player->scene() == m_scene){
m_scene->addText("Same"); // this text is added
}else{
m_scene->addText("Different");
}
m_scene
来自这个类:
class Game : public QGraphicsView
{
Q_OBJECT
public:
Game();
public slots:
void FixedUpdate();
signals:
private:
QRectF *sceneSize;
QGraphicsScene *m_scene;
QGraphicsRectItem *m_rect;
QTimer *m_timer;
Character *Player;
Character *enemy;
};
Character
类是继承自QGraphicsPolygonItem
的类:
class Character : public QObject, public QGraphicsPolygonItem
{
Q_OBJECT
public:
Character(qreal x, qreal y, qreal w, qreal h, QString tag, QGraphicsScene *scene = 0, QGraphicsItem *parent = 0);
Character(QRectF rectF, QString tag, QGraphicsScene *scene = 0, QGraphicsItem *parent = 0);
Character(QString tag, QGraphicsScene *scene = 0, QGraphicsItem *parent = 0);
void setValue(qreal x, qreal y, qreal w, qreal h);
void setVelocity(qreal vx, qreal vy);
void setVelocityX(qreal vx);
void setVelocityY(qreal vy);
void setTag(QString tag);
qreal vx() const;
qreal vy() const;
qreal w() const;
qreal h() const;
QString tag() const;
QGraphicsScene *currentScene() const;
void fixedUpdate();
void removeCharacter();
signals:
public slots:
private:
qreal m_x;
qreal m_y;
qreal m_w;
qreal m_h;
qreal m_vx;
qreal m_vy;
QString m_tag;
QGraphicsScene *m_scene;
};
这就是我调用 removeItem
void Game::FixedUpdate(){
if(Player->collidesWithItem(enemy)){
Player->setVelocityX(0);
enemy->setVelocityX(0);
//removeCharacter just call scene()->removeItem(this);
Player->removeCharacter();
enemy->removeCharacter();
}else{
Player->fixedUpdate();
enemy->fixedUpdate();
}
}
有人可以解释一下为什么我会收到这些消息吗?
编辑:
Game::Game(){
sceneSize = new QRectF(0, 0, 640, 480);
m_scene = new QGraphicsScene(*sceneSize, this);
setScene(m_scene);
Player = new Character(QRectF(0, 0, 50, 50), "player", m_scene);
Player->setVelocityX(1.5);
//m_scene->addItem(Player);
enemy = new Character(QRectF(500, 0, 20, 20), "enemy", m_scene);
enemy->setVelocityX(-0.5);
//m_scene->addItem(enemy);
//m_scene->addText(QString::number(Player->x() + Player->vx()));
if(Player->scene() == m_scene){
m_scene->addText("Same");
}else{
m_scene->addText("Different");
}
m_timer = new QTimer(this);
connect(m_timer, SIGNAL(timeout()), this, SLOT(FixedUpdate()));
m_timer->start(1000 / 60);
}
最佳答案
终于找到了。
它在 Game::FixedUpdate()
函数中,它是 Player->collidesWithItem(enemy)
是 true
即使在指针被删除之后从现场移除。所以我在检查碰撞之前进行了检查,如下所示:
void Game::FixedUpdate(){
if(Player->scene() != NULL && enemy->scene() != NULL){
if(Player->collidesWithItem(enemy)){
Player->setVelocityX(0);
enemy->setVelocityX(0);
//removeCharacter just call scene()->removeItem(this);
Player->removeCharacter();
enemy->removeCharacter();
}else{
Player->fixedUpdate();
enemy->fixedUpdate();
}
}
}
删除后不显示消息。
关于c++ - QGraphicsScene::removeItem: item场景和这个场景不一样,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/26864894/