RepaintBoundary、RelayoutBoundary

RepaintBoundary

• RepaintBoundary子树repaint的时候，父widget和RepaintBoundary子树会被repaint，但是与RepaintBoundary子树同级的其他子树不会被repaint
• 如果父widget repaint，则RepaintBoundary子树也会repaint
• 如果非RepaintBoundary子树repaint，则也会引起浮widget repaint，导致RepaintBoundary子树也repaint

RelayoutBoundary

renderObject在layout阶段做了Relayout boundary的优化，当子树进行relayout时，满足下面三种中的一种

• parentUsesSize == false
• sizedByParent == true
• constraints.isTight
  那么该renderObject设置为Relayout boundary，也就是该renderObject的重新layout不触发parent的layout，一般情况下开发人员不需要关心Relayout boundary，除非是使用CustomMultiChildLayout