2024-05-08发表2025-03-15更新QT

3 QT类库概述.md

元对象系统

属性系统、信号与槽

目的是在元对象中通过MetaObject来访问
1、必须有一个是read函数，用来读取属性值。使用Const限定
2、可选Write函数返回值必须为void，必须有一个参数
3、reset函数是将property设置为默认状态，返回值void，不带参数
4、NOTIFY信号，值改变会触发
5、STODE 一直存在
6、DESIGNABLE 属性表明在GUI builder中一直可见
7、USER 用户是否可修改
8、CONST 是否可修改，不能跟WRITE和NOTIFY同时出现
9、FINAL属性不会再派生类重写

在槽函数中，应该是知道sender对象的

案例

//QPerson.h
#define QPERSON_H

#include <QObject>

class QPerson : public QObject
{
    Q_OBJECT
    Q_CLASSINFO("author","QS")
    Q_CLASSINFO("company","LXS")
    Q_CLASSINFO("Version","1.0.0")

    Q_PROPERTY(unsigned age READ age WRITE setAge NOTIFY ageChanged)
    Q_PROPERTY(QString name MEMBER _name)
    Q_PROPERTY(int score MEMBER _score)//添加属性，元数据可以访问
private:
    unsigned _age = 10;
    QString _name ;
    int _score=79;
public:
    explicit QPerson(QString name,QObject *parent = nullptr);
    unsigned age();
    void setAge(unsigned value);
    void incAge();
signals:
     ageChanged(unsigned value);
public slots:
};

#endif // QPERSON_H

//QPerson.cpp
#include "qperson.h"

QPerson::QPerson(QString name ,QObject *parent) : QObject(parent)
{
    this->_name = name;
}

unsigned QPerson::age()
{
    return _age;
}

void QPerson::setAge(unsigned value)
{
    _age = value;
    emit(ageChanged(value));
}

void QPerson::incAge()
{
    _age++;
    emit(ageChanged(_age));
}

//widget.h
#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include "qperson.h"
namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

private:
    Ui::Widget *ui;
    QPerson * boy;
    QPerson * girl;
private slots:
    void on_btnBoyInc_clicked();
    void on_btnGirlInc_clicked();
    void on_btnMetaInfo_clicked();
    void onspin_valueChanged(int value);
    void onageChanged(unsigned value);
};

#endif // WIDGET_H

//widget.cpp
#include "widget.h"
#include "ui_widget.h"
#include <QMetaProperty>
#include <QMetaClassInfo>
Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    ui->spinBoxBoy->setProperty("isBoy",true);
    ui->spinBoxGirl->setProperty("isBoy",false);
    boy = new QPerson("王小明");
    boy->setProperty("score",85);
    boy->setProperty("age",10);
    boy->setProperty("sex","Boy");

    girl = new QPerson("小红");
    girl->setProperty("score",85);
    girl  ->setProperty("age",10);
    girl  ->setProperty("sex","girl");
    connect(boy,&QPerson::ageChanged,this,&Widget::onageChanged);
    connect(girl,&QPerson::ageChanged,this,&Widget::onageChanged);
    connect(ui->spinBoxBoy,SIGNAL(valueChanged(int)),this,SLOT(onspin_valueChanged(int)));
    connect(ui->spinBoxGirl,SIGNAL(valueChanged(int)),this,SLOT(onspin_valueChanged(int)));
}

Widget::~Widget()
{
    delete ui;
}

void Widget::onspin_valueChanged(int value)
{
    Q_UNUSED(value);//参数用不到，但是不想让他警告
    QSpinBox* spinBox = qobject_cast<QSpinBox*>(sender());
    if(spinBox->property("isBoy").toBool())
        boy->setAge(spinBox->value());
    else
        girl->setAge(spinBox->value());

}

void Widget::onageChanged(unsigned value)
{
    Q_UNUSED(value);
    QPerson* per = qobject_cast<QPerson*>(sender());
    QString name = per->property("name").toString();
    QString sex = per->property("sex").toString();
    unsigned age = per->age();
    ui->txtEdit->appendPlainText(name+","+sex+","+QString::asprintf(",年龄=%d",age));

}

void Widget::on_btnBoyInc_clicked()
{
    boy->incAge();
}

void Widget::on_btnGirlInc_clicked()
{
    girl->incAge();
}

void Widget::on_btnMetaInfo_clicked()
{
    const QMetaObject * meta = girl->metaObject();
    ui->txtEdit->clear();
    ui->txtEdit->appendPlainText("====元信息========");
    ui->txtEdit->appendPlainText(QString("类名称：%1\n").arg(meta->className()));
    ui->txtEdit->appendPlainText(QString("property"));
    for(int i = meta->propertyOffset();i<meta->propertyCount();i++)
    {
        QMetaProperty prop=meta->property(i);
        const char* propName = prop.name();
        QString propValue = boy->property(propName).toString();
        ui->txtEdit->appendPlainText(QString("属性名称：%1,属性值:%2").arg(propName).arg(propValue));
    }
    ui->txtEdit->appendPlainText(QString(""));
    ui->txtEdit->appendPlainText(QString("classInfo"));
    for(int i=meta->classInfoOffset();i<meta->classInfoCount();i++)
    {
        QMetaClassInfo info = meta->classInfo(i);
        ui->txtEdit->appendPlainText(QString("Name=%1,value=%2").arg(info.name()).arg(info.value()));
    }
}