QStyle platform style

Introduction

Qt actually uses the QStyle class to implement various platform-specific behaviors.The main job of QStyle is to give a suitable system appearance; to determine the size and shape of components.

Easy to use

Generic components: Don't try to display with images, use the icons predefined in style().

style()->drawPrimitive(QStyle::PE_IndicatorBranch, &opt, painer, this);

Custom style

Rewrite widget's paintEvent() function

inherits the QStyle class: QProxyStyle

https://blog.51cto.com/devbean/471941