ImageResolver typedef
ImageResolver =
ImageProvider<Object> ? Function(String src)
Turns a node's src into something Flutter can draw.
A stored address is untrusted input, which is why this is a hook rather than a switch inside the widget: an application knows which hosts it trusts, whether it has an image cache, and what an offline placeholder looks like. defaultImageResolver handles the ordinary cases.
Implementation
typedef ImageResolver = ImageProvider<Object>? Function(String src);