qt 委托 paint（） 显示数据

Subclassing

When subclassing QItemDelegate to create a delegate that displays items using a custom renderer, it is important to ensure that the delegate can render items suitably for all the required states; e.g. selected, disabled, checked. The documentation for the paint() function contains some hints to show how this can be achieved.

委托的一个作用就是：显示item。

那么paint（）函数是必须的，因为，自定义委托，必须要绘制出item的数据。也就是显示出来。