paintChild abstract method
Paint the i
th child using the given transform.
The child will be painted in a coordinate system that concatenates the container's coordinate system with the given transform. The origin of the parent's coordinate system is the upper left corner of the parent, with x increasing rightward and y increasing downward.
The container will clip the children to its bounds.
Implementation
void paintChild(int i, { Matrix4 transform, double opacity = 1.0 });