how can I let parent know the measure size of a child? I set a width when measure child composable, but in parent when I try to get the width of that placeable of that child ’s width , always return the constraints’s maxWidth

SubcomposeLayout perhaps?

SubcomposeLayout

is only needed for lazy layouts. You can get the measure of a child from its father using a custom layout with Alignment lines. This talk explains it pretty neatly