指向要调用的回调函数的指针(对于一种或多种事件类型)——为每种特定的事件注册一个回调函数，然后将在事件发生时调用这些函数。

Pointer to the callback function to be invoked (for one or more event Types) — for each specific event, register a callback function, and then these functions are called when the event occurs.

youdao

指向要调用的回调函数的指针(对于一种或多种事件类型)——为每种特定的事件注册一个回调函数，然后将在事件发生时调用这些函数。

Pointer to the callback function to be invoked (for one or more event Types) — for each specific event, register a callback function, and then these functions are called when the event occurs.

youdao