QT custom class uses custom parametric signals and slots

Recently, signals have been used in custom classes to connect to MainWindow Slot function in class , The specific operation is as follows ：

Key points ： Inherit QObject

Initialize the custom class in the header file MyThread1, Here due to inherited QThread Has inherited QObject, No nested inheritance , Therefore, it is unnecessary public QObject, But still need to join Q_OBJECT To guarantee moc The compiler can connect signals and slot functions

// Location ：mainwindow.h
// An instance of a thread class , If you only use custom signals, in addition to signals Don't care about other parts 
class MyThread1 : public QThread 
{
    
    Q_OBJECT

public:
    MyThread1();
    void stop();
    QTcpSocket* position;
    bool pos_connected;
signals:
    void pos_update(QString x,QString y);
protected:
    void run();
private:
    volatile bool stopped;
};

Main points two ： Custom signals and slots

Declare signals in custom classes pos_update(QString x,QString y), But it's just a signal , No need to cpp The implementation is given in the document

stay MainWindow Add the slot function corresponding to the signal

Be careful ： Number of parameters of signal and slot 、 The type and order should be consistent （ There can be more signal parameters than slot functions , But it's not recommended either , On the contrary, it is absolutely impossible to have more slot function parameters than signal parameters ） As for using user-defined data types as signal parameters, you can refer to link
The slot function must be implemented ：

// Location ：mainwindow.cpp
// After receiving the message from another thread, display it in ui On the interface 
void MainWindow::update(QString x,QString y)
{
    
    ui->pos_x->setText(x);
    ui->pos_y->setText(y);
}

Main points three ： Connect the signal to the slot

It is best to use pointers when instantiating classes , Convenient for signal connection , In the figure below, there are two ways to express signal connection , It's all... In essence connect(const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method,
Qt::ConnectionType type = Qt::AutoConnection)
See [ link ](https://blog.csdn.net/qq_27898413/article/details/11967
7345)

// Location ：mainwindow.cpp Declared global variables 
MyThread1 *thread1 = new MyThread1();

// Location ：mainwindow.cpp in MainWinw Class 
connect(thread1,&MyThread1::pos_update,this,&MainWindow::update);

Point four ： Sending signal

Directly where the signal needs to be sent emit that will do

// Location ：mainwindow.cpp Any need to call update The place of 
emit pos_update(posx,posy);