一文详解Qt中的对象树机制

class MyLabel : public QLabel;
class MyLayout : public QGridLayout;
class MyPushButton : public QPushButton;
class MyRadioButton : public QRadioButton;

//MyLabel类
MyLabel::MyLabel(QWidget *parent):QLabel(parent)
{
    qDebug()<<"MyLabel构造"<<this;
}
 
MyLabel::~MyLabel()
{
    qDebug()<<"MyLabel析构"<<this;
}
//MyLayout类
MyLayout::MyLayout(QWidget *parent):QGridLayout(parent)
{
    qDebug()<<"MyLayout构造"<<this;
}
MyLayout::~MyLayout()
{
    qDebug()<<"MyLayout析构"<<this;
}
//MyPushButton类
MyPushButton::MyPushButton(QWidget *parent):QPushButton(parent)
{
    qDebug()<<"MyPushButton构造"<<this;
}
MyPushButton::~MyPushButton()
{
    qDebug()<<"MyPushButton析构"<<this;
}
//MyRadioButton类
MyRadioButton::MyRadioButton(QWidget *parent):QRadioButton(parent)
{
    qDebug()<<"MyRadioButton构造"<<this;
}
MyRadioButton::~MyRadioButton()
{
    qDebug()<<"MyRadioButton析构"<<this;
}

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
 
    //当前窗体设为父窗体
    MyLabel *myLabel =new MyLabel(&w);
    MyPushButton*myBtn=new MyPushButton(&w);
    MyRadioButton*myRbtn=new MyRadioButton(&w);
    MyLayout*myLayout=new MyLayout(&w);
    //设置文本
    myLabel->setText("子标签");
    myBtn->setText("子按钮");
    myRbtn->setText("子单选");
    //控件添加到布局管理器中
    myLayout->addWidget(myLabel,0,0);
    myLayout->addWidget(myBtn,1,0);
    myLayout->addWidget(myRbtn,2,0);
 
    return a.exec();
 
}

const QObjectList listW=w.children();
qDebug()<<"w.children()";
foreach (QObject* obj, listW) {
    qDebug()<<obj;
}

//创建一个sun布局管理器，将标签控件设为其父窗体
MyLayout*sunLayout=new MyLayout(myLabel);
//创建三个按钮控件，这里并未指明其父窗体
MyPushButton*sunBtn1=new MyPushButton;
MyPushButton*sunBtn2=new MyPushButton;
MyPushButton*sunBtn3=new MyPushButton;
//设置文本
sunBtn1->setText("孙按钮1");
sunBtn2->setText("孙按钮2");
sunBtn3->setText("孙按钮3");
//将按钮添加到布局管理器中
sunLayout->addWidget(sunBtn1);
sunLayout->addWidget(sunBtn2);
sunLayout->addWidget(sunBtn3);
//按钮初始时未设定父类，只是将其放入sun布局管理器中。
//sun布局管理器的父窗体设定为myLabel，当myLabel指定其布局管理器为孙布局管理器时，按钮会重新将myLabel设定为其父窗体
myLabel->setLayout(sunLayout);

//查看w子类
const QObjectList listW=w.children();
qDebug()<<"w.children()";
foreach (QObject* obj, listW) {
    qDebug()<<obj;
}
 
//查看myLabel子类
const QObjectList listLabel=myLabel->children();
qDebug()<<"myLabel.children()";
foreach (QObject* obj, listLabel) {
    qDebug()<<obj;
}