如何从QEvent获取人类可读的事件类型？

I want to debug event handling code and would like to convert QEvent::Type enum's value to a human-readable string. QEvent has a Q_GADGET macro, so presumably there's a way of pulling that off?

我想调试事件处理代码，并希望将QEvent :: Type枚举值转换为人类可读的字符串。 QEvent有一个Q_GADGET宏，所以可能有一种方法可以解决这个问题吗？

2 个解决方案

#1

Recent versions of Qt do the right thing when outputting events to the debug stream, so the below isn't neccessary. If you get an error similar to warning C4273: 'operator <<' : inconsistent dll linkage, it means that your version of Qt already supports this without need for the code below.

最新版本的Qt在将事件输出到调试流时做了正确的事情，因此下面不是必需的。如果你得到类似于警告C4273的错误：'operator <<'：不一致的dll链接，这意味着你的Qt版本已经支持这个，而不需要下面的代码。

The Q_GADGET macro adds a QMetaObject staticMetaObject member to the class. The static metaobject's definition is generated by moc, and it - in the case of QEvent - contains the enumeration information.

Q_GADGET宏将QMetaObject staticMetaObject成员添加到类中。静态元对象的定义由moc生成，而在QEvent的情况下，它包含枚举信息。

Below is an example of how to leverage that to give a more reasonable QDebug output of events.

下面是如何利用它来提供更合理的QDebug事件输出的示例。

#include <QEvent>
#include <QMetaEnum>
#include <QDebug>   

/// Gives human-readable event type information.
QDebug operator<<(QDebug str, const QEvent * ev) {
   static int eventEnumIndex = QEvent::staticMetaObject
         .indexOfEnumerator("Type");
   str << "QEvent";
   if (ev) {
      QString name = QEvent::staticMetaObject
            .enumerator(eventEnumIndex).valueToKey(ev->type());
      if (!name.isEmpty()) str << name; else str << ev->type();
   } else {
      str << (void*)ev;
   }
   return str.maybeSpace();
}

Use example:

使用示例：

void MyObject::event(QEvent* ev) {
  qDebug() << "handling an event" << ev;
}

#2

Q_GADGET and Q_ENUM can be combined to get the following template:

可以组合Q_GADGET和Q_ENUM来获取以下模板：

template<typename EnumType>
QString ToString(const EnumType& enumValue)
{
    const char* enumName = qt_getEnumName(enumValue);
    const QMetaObject* metaObject = qt_getEnumMetaObject(enumValue);
    if (metaObject)
    {
        const int enumIndex = metaObject->indexOfEnumerator(enumName);
        return QString("%1::%2::%3").arg(metaObject->className(), enumName, metaObject->enumerator(enumIndex).valueToKey(enumValue));
    }

    return QString("%1::%2").arg(enumName).arg(static_cast<int>(enumValue));
}

Example:

例：

void MyObject::event(QEvent* ev) 
{
    qDebug() << ToString(ev->type());
}

#1