qt框架为什么不会占用很高的cpu

Question

qt框架是如何做到低cpu占用的，时刻绘制桌面图像不应该占用很多cpu吗

Answer 1

并没有时刻进行绘制，画图的paintEvent不会重复触发，只有某些情况触发，如调用update，或者切换窗口等才会触发，参考QT手册如下

[virtual protected] void QWidget::paintEvent(QPaintEvent *event)
This event handler can be reimplemented in a subclass to receive paint events passed in event.
A paint event is a request to repaint all or part of a widget. It can happen for one of the following reasons:
repaint() or update() was invoked,
the widget was obscured and has now been uncovered, or
many other reasons.

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