4.自定义信号槽

//!!! Qt5
#include <QObject>
 
////////// newspaper.h
class Newspaper : public QObject
{
    Q_OBJECT
public:
    Newspaper(const QString & name) :
        m_name(name)
    {
    }
 
    void send()
    {
        emit newPaper(m_name);
    }
 
signals:
    void newPaper(const QString &name);
 
private:
    QString m_name;
};
 
////////// reader.h
#include <QObject>
#include <QDebug>
 
class Reader : public QObject
{
    Q_OBJECT
public:
    Reader() {}
 
    void receiveNewspaper(const QString & name)
    {
        qDebug() << "Receives Newspaper: " << name;
    }
};
 
////////// main.cpp
#include <QCoreApplication>
 
#include "newspaper.h"
#include "reader.h"
 
int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);
 
    Newspaper newspaper("Newspaper A");
    Reader reader;
    QObject::connect(&newspaper, &Newspaper::newPaper,
                     &reader,    &Reader::receiveNewspaper);
    newspaper.send();
 
    return app.exec();
}

//!!! Qt5

#include <QObject>

////////// newspaper.h

class Newspaper : public QObject

{

    Q_OBJECT

public:

    Newspaper(const QString & name) :

        m_name(name)

    {

    }

    void send()

    {

        emit newPaper(m_name);

    }

signals:

    void newPaper(const QString &name);

private:

    QString m_name;

};

////////// reader.h

#include <QObject>

#include <QDebug>

class Reader : public QObject

{

    Q_OBJECT

public:

    Reader() {}

    void receiveNewspaper(const QString & name)

    {

        qDebug() << "Receives Newspaper: " << name;

    }

};

////////// main.cpp

#include <QCoreApplication>

#include "newspaper.h"

#include "reader.h"

int main(int argc, char *argv[])

{

    QCoreApplication app(argc, argv);

    Newspaper newspaper("Newspaper A");

    Reader reader;

    QObject::connect(&newspaper, &Newspaper::newPaper,

                     &reader,    &Reader::receiveNewspaper);

    newspaper.send();

    return app.exec();

}

自定义信号槽需要注意的事项：

• 发送者和接收者都需要是QObject的子类（当然，槽函数是全局函数、Lambda 表达式等无需接收者的时候除外）；
• 使用 signals 标记信号函数，信号是一个函数声明，返回 void，不需要实现函数代码；
• 槽函数是普通的成员函数，作为成员函数，会受到 public、private、protected 的影响；
• 使用 emit 在恰当的位置发送信号；
• 使用QObject::connect()函数连接信号和槽。


来源： https://www.devbean.net/2012/08/qt-study-road-2-custom-signal-slot/

附件列表

• 自定义信号槽.jpg