problem description

how to redraw (dirty rectangle) in the dirty area of canvas when the data changes

the environmental background of the problems and what methods you have tried

when the data changes, you want to modify it with minimum granularity to reduce the pressure on CPU.

from the articles consulted, canvas does not have a ready-made method for redrawing dirty areas. It can only record the location of each element under scene, and then use clip to modify the elements in the corresponding position.

but in this case, I don"t know what to do with some elements that may have coincident parts.

I hope those who have studied can give me some advice