使用 Qt 创建自定义消息/事件

发布于 2024-11-08 00:15:38 字数 446 浏览 0 评论 0原文

我有一个 RPC 线程正在从该线程回调我。我需要以某种方式通知 Qt 它需要从主线程进行函数调用。在直接 Windows 中，我可以通过使用自定义消息然后将该消息发布到消息队列来完成此操作，例如，我可以创建一个 WM_CALLFUNCTION 消息并通过 wParam 传递函数指针> 和通过lParam 的参数（类指针）。

有谁知道我如何用 Qt 做到这一点？我遇到过 QCustomEvent 但我不知道如何使用它或如何处理它。任何帮助将不胜感激！

编辑：

最后我选择了 QMetaObject::invokeMethod工作完美。

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坠似风落 2024-11-15 00:15:38

使用自定义事件通常涉及创建您自己的 QEvent 子类、重写将接收事件的 QObject 类（通常是主窗口类）中的 customEvent() 以及将事件从线程“发布”到接收器的一些代码。

我喜欢将事件发布代码实现为接收器类的方法。这样，调用者只需了解接收者对象，而不需要了解任何“Qt”细节。调用者将调用此方法，然后该方法将向其自身发送一条消息。希望下面的代码能让它更清楚。

// MainWindow.h
...
// Define your custom event identifier
const QEvent::Type MY_CUSTOM_EVENT = static_cast<QEvent::Type>(QEvent::User + 1);

// Define your custom event subclass
class MyCustomEvent : public QEvent
{
    public:
        MyCustomEvent(const int customData1, const int customData2):
            QEvent(MY_CUSTOM_EVENT),
            m_customData1(customData1),
            m_customData2(customData2)
        {
        }

        int getCustomData1() const
        {
            return m_customData1;
        }

        int getCustomData2() const
        {
            return m_customData2;
        }

    private:
        int m_customData1;
        int m_customData2;
};

public:
void postMyCustomEvent(const int customData1, const int customData2);
....
protected:
void customEvent(QEvent *event); // This overrides QObject::customEvent()
...
private:
void handleMyCustomEvent(const MyCustomEvent *event);

customData1 和 customData2 用于演示如何在事件中传递一些数据。它们不必是int。

// MainWindow.cpp
...
void MainWindow::postMyCustomEvent(const int customData1, const int customData2)
{   
    // This method (postMyCustomEvent) can be called from any thread

    QApplication::postEvent(this, new MyCustomEvent(customData1, customData2));   
}

void MainWindow::customEvent(QEvent * event)
{
    // When we get here, we've crossed the thread boundary and are now
    // executing in the Qt object's thread

    if(event->type() == MY_CUSTOM_EVENT)
    {
        handleMyCustomEvent(static_cast<MyCustomEvent *>(event));
    }

    // use more else ifs to handle other custom events
}

void MainWindow::handleMyCustomEvent(const MyCustomEvent *event)
{
    // Now you can safely do something with your Qt objects.
    // Access your custom data using event->getCustomData1() etc.
}

我希望我没有遗漏任何东西。有了这个，其他线程中的代码只需要获取指向 MainWindow 对象的指针（我们称之为 mainWindow）并调用

mainWindow->postMyCustomEvent(1,2);

where，仅对于我们的示例来说，< code>1 和 2 可以是任何整数数据。

Using custom events generally involves creating your own QEvent subclass, overriding customEvent() in the QObject class that will receive the event (often the main window class) and some code that "posts" the event from your thread to the receiver.

I like to implement the event posting code as a method of the receiver class. That way, the caller only has to know about the recevier object and not any of the "Qt" specifics. The caller will invoke this method which will then essentially post a message to itself. Hopefully the code below will make it clearer.

// MainWindow.h
...
// Define your custom event identifier
const QEvent::Type MY_CUSTOM_EVENT = static_cast<QEvent::Type>(QEvent::User + 1);

// Define your custom event subclass
class MyCustomEvent : public QEvent
{
    public:
        MyCustomEvent(const int customData1, const int customData2):
            QEvent(MY_CUSTOM_EVENT),
            m_customData1(customData1),
            m_customData2(customData2)
        {
        }

        int getCustomData1() const
        {
            return m_customData1;
        }

        int getCustomData2() const
        {
            return m_customData2;
        }

    private:
        int m_customData1;
        int m_customData2;
};

public:
void postMyCustomEvent(const int customData1, const int customData2);
....
protected:
void customEvent(QEvent *event); // This overrides QObject::customEvent()
...
private:
void handleMyCustomEvent(const MyCustomEvent *event);

The customData1 and customData2 are there to demonstrate how you might pass some data along in your event. They don't have to be ints.

// MainWindow.cpp
...
void MainWindow::postMyCustomEvent(const int customData1, const int customData2)
{   
    // This method (postMyCustomEvent) can be called from any thread

    QApplication::postEvent(this, new MyCustomEvent(customData1, customData2));   
}

void MainWindow::customEvent(QEvent * event)
{
    // When we get here, we've crossed the thread boundary and are now
    // executing in the Qt object's thread

    if(event->type() == MY_CUSTOM_EVENT)
    {
        handleMyCustomEvent(static_cast<MyCustomEvent *>(event));
    }

    // use more else ifs to handle other custom events
}

void MainWindow::handleMyCustomEvent(const MyCustomEvent *event)
{
    // Now you can safely do something with your Qt objects.
    // Access your custom data using event->getCustomData1() etc.
}

I hope I didn't leave anything out. With this in place, code in some other thread just needs to get a pointer to a MainWindow object (let's call it mainWindow) and call

mainWindow->postMyCustomEvent(1,2);

where, just for our example, 1 and 2 can be any integer data.

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风苍溪 2024-11-15 00:15:38

在Qt 3中，通常的通信方式
与来自非 GUI 的 GUI 线程
线程是通过发布自定义事件
到 GUI 线程中的 QObject。在Qt中
4、这仍然有效并且可以
推广到以下情况：
线程需要与任何
具有事件循环的其他线程。
为了简化编程，Qt 4 还允许
你建立signal--slot
跨线程的连接。后面的
场景，这些连接是
使用事件实现。如果
信号有任何参数，这些是
也存储在事件中。喜欢
之前，如果发送者和接收者
住在同一个线程中，Qt 做了一个
直接函数调用。