c++ - 从非成员静态函数发出信号

Question

我第一次尝试使用 QThread，我想从非成员静态函数发出信号。

我的 DataReceiver.h 文件:

#ifndef DATARECEIVER_H
#define DATARECEIVER_H

#include <QObject>
#include "vrpn_Analog.h"

class DataReceiver : public QObject {
    Q_OBJECT

public:
    DataReceiver();

public slots:
    void check();
signals:
    void blink();
};

void VRPN_CALLBACK handle_analog( void* userData, const vrpn_ANALOGCB a );

#endif // DATARECEIVER_H

我的 DataReceiver.cpp 文件:

#include "datareceiver.h"
#include "vrpn_Analog.h"

DataReceiver::DataReceiver()
{

}

void DataReceiver::check()
{
    bool running = true;

    /* VRPN Analog object */
    vrpn_Analog_Remote* VRPNAnalog;

    /* Binding of the VRPN Analog to a callback */
    VRPNAnalog = new vrpn_Analog_Remote("openvibe_vrpn_analog@localhost");
    VRPNAnalog->register_change_handler(NULL, handle_analog);

    /* The main loop of the program, each VRPN object must be called in order to process data */
    while (running)
    {
        VRPNAnalog->mainloop();
    }
}

void VRPN_CALLBACK handle_analog( void* userData, const vrpn_ANALOGCB a )
{
    for( int i=0; i < a.num_channel; i++ )
    {
        if (a.channel[i] > 0)
        {
             emit blink();
        }
    }
}

在 handle_analog 中，我尝试发出信号，我想在另一个类中使用它。

void MainWindow::checkChannels()
{
    QThread *thread = new QThread;
    DataReceiver *dataReceiver = new DataReceiver();

    dataReceiver->moveToThread(thread);
    //connect(thread, SIGNAL(blink()), this, SLOT(nextImage()));
    thread->start();
}

但是当我尝试运行时出现错误:

error: C2352: 'DataReceiver::blink' : illegal call of non-static member function

我知道我的错误在哪里，但我不知道如何改正。

Answer 1

如果没有相应的对象来发出信号，那么发出信号是没有意义的，因为您没有任何东西可以连接到它。

因此，您想要的是将指向您的DataReceiver 的指针作为userData 传递，并实现一个发出信号的公共(public)方法。然后你可以将 userData 转换为 DataReceiver 并调用它的方法。

以下不完整的代码试图说明我的意思

void DataReceiver::emitBlink() { // Should of course also be added in header.
    emit blink();
}
...
/// Pass in "this" as userData   
VRPNAnalog->register_change_handler(this, handle_analog);

...
void VRPN_CALLBACK handle_analog( void* userData, const vrpn_ANALOGCB a )
{
...
    reinterpret_cast<DataReceiver*>(userData)->emitBlink();
...
}