Qt QThread问题使用信号/槽从工人到gui [英] Qt QThread trouble using signal/slot going from worker to gui

问题描述

我有一个QT应用程序，使用QT Creator和伴随它的GUI工具开发。我有一个主线程 TheGui 和一个工作线程，由主线程创建 WorkerThread （称为<$

I have a QT application that was developed using QT Creator and the GUI tool that accompanies it. I have a main thread, TheGui and a worker thread that is created by the main thread, WorkerThread (called thread).

我遇到的问题是，当我在GUI中创建一个插槽使用

The problem I'm having is when I create a slot in the GUI by using

public slot:
  void updateTable(string str);

和信号 void sendList（string str） ; 在工作线程的头文件中，插槽永远不会被调用。我使用

within the header file of the GUI and signal void sendList(string str); within the header file of the worker thread, the slot never gets called. I connected the two using

connect(&thread, SIGNAL(sendList(string str),
        this,    SLOT(updateTable(string str)));

类似，除了在工作线程中的槽和来自GUI的信号，它工作正常。我知道从使用调试器的信号sendList确实被调用，它是永远不会进入它。

within the constructor in the GUI cpp file. I did something similar except with the slot in the worker thread and signal from the GUI and it worked fine. I know from using the debugger that the signal sendList is indeed getting called, it is just never going into it.

任何想法？

推荐答案

1. slot在不同的线程，它们之间的连接具有 Qt :: QueuedConnection 类型。对于排队连接，Qt必须能够保存信号参数的副本，
   
   因此，要通知Qt类型是可复制的，你必须使用Qt的元对象系统注册它（参见 QMetaType ）如下：

1. Because the signal and the slot are on distinct threads, the connection between them has the Qt::QueuedConnection type. And for queued connections, Qt has to be able to save a copy of the signal parameters, to pass them later to the slot.
   So, to inform Qt that the type is copyable, you have to register it with Qt's meta-object system (see QMetaType) like this:

// This macro call should be put in one of your .h files 
Q_DECLARE_METATYPE(std::string)

// You should call this function before any (queued) 
// signal/slot connection involving the type
qRegisterMetaType<std::string>();

参数名称不应包含在 QObject： ：connect 调用，类型名称应该与传递给 Q_DECLARE_METATYPE 的类型名称完全相同：

The parameter name shouldn't be included in the QObject::connect call, and the type names should be exactly the same as the ones you passed to Q_DECLARE_METATYPE:

connect(&thread, SIGNAL(sendList(std::string), this, SLOT(updateTable(std::string)));

您也可以使用 QString 或 QByteArray ，而不是 std :: string ，因为这些函数是slot和信号，因此已经是Qt特定的。

You can also use QString or QByteArray, which are already registered, instead of std::string, since these functions are slots and signals and as such are already Qt specific.

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