paintsChild method Null safety
- covariant RenderObject child
override
Whether the given child would be painted if paint were called.
Some RenderObjects skip painting their children if they are configured to
not produce any visible effects. For example, a RenderOffstage with
its offstage property set to true, or a RenderOpacity with its opacity
value set to zero.
In these cases, the parent may still supply a non-zero matrix in applyPaintTransform to inform callers about where it would paint the child if the child were painted at all. Alternatively, the parent may supply a zeroed out matrix if it would not otherwise be able to determine a valid matrix for the child and thus cannot meaningfully determine where the child would paint.
Implementation
@override
bool paintsChild(RenderObject child) {
assert(child.parent == this);
return opacity.value > 0;
}