[提问]QT中的事件机制//事件循环分发之什么意思？ [复制链接]

当一个widget第一次可见，或是被遮挡后再次变为可见，窗口系统产生一个(spontaneous) paint事件，要求程序重画widget,事件循环最终从事件队列中捡选这个事件并把它分发到那个需要重画的widget。并不是所有的paint事件都是由窗口系统产生的。当你调用QWidget::update()去强行重画widget,这个widget会post 一个paint 事件给自己。这个paint事件被放入队列，最终被事件循环分发之。

The Event System

In Qt, events are objects, derived from the abstract QEvent class, that represent things that have happened either within an application or as a result of outside activity that the application needs to know about. Events can be received and handled by any instance of a QObject subclass, but they are especially relevant to widgets. This document describes how events are delivered and handled in a typical application.

详细的可以查看qt帮助