Called whenever the object needs to paint. The given Canvas has its
coordinate space configured such that the origin is at the top left of the
box. The area of the box is the size of the size argument. [...]
Called whenever a new instance of the custom painter delegate class is
provided to the RenderCustomPaint object, or any time that a new
CustomPaint object is created with a new instance of the custom painter
delegate class (which amounts to the same thing, because the latter is
implemented in terms of the former). [...]
Called whenever a new instance of the custom painter delegate class is
provided to the RenderCustomPaint object, or any time that a new
CustomPaint object is created with a new instance of the custom painter
delegate class (which amounts to the same thing, because the latter is
implemented in terms of the former). [...]