DecorativeViewFactory should support wrapping Context

[zach-klippenstein]

This is about the only thing it doesn't support, but I need it for wrapping the context at the root.

[rjrjr]

Also handy just for reading things from the Context, e.g. to populate the ViewEnvironment from it.

[rjrjr]

Might be less crazy making to do this with a separate decorator. The tricky bit is that the map function, (OuterT, ViewEnvironment) -> Pair<InnerT, ViewEnvironment>, gets run twice:

• when we're building the view
• when we update the view

So we don't want to change the function to:

(OuterT, ViewEnvironment, Context) -> Triple<InnerT, ViewEnvironment, Context>

because the Context transformation is only useful at build time, it would be wasted effort when updating.

[rjrjr]

And if a separate wrapper makes sense for Context transformations, maybe ViewEnvironment swizzling should move there too. We hardly ever use it, and when we do it's pretty confusing. Gonna look at current uses…

[rjrjr]

Well poo. This actually isn't useful for seeding the ViewEnvironment with values from the Context, which is what made me dust off this issue. There isn't easy enough access to the Context on updates. Putting it back in the icebox.

[rjrjr]

This will be addressed by #606

[rjrjr]

This will be addressed by #606

Nope, that didn't work out.

[rjrjr]

Possible better solution from @helios175:

fun <T : Any> ViewFactory<T>.wrapContext(
  type: KClass<T>,
  wrapContext: (ViewEnvironment, Context) -> Context
): ViewFactory<T> {
  val original = this
  return object : ViewFactory<T> {
    override val type: KClass<in T> = type

    override fun buildView(
      initialRendering: T,
      initialViewEnvironment: ViewEnvironment,
      contextForNewView: Context,
      container: ViewGroup?
    ): View {
      val adjustedContext = wrapContext(initialViewEnvironment, contextForNewView)
      return original.buildView(initialRendering, initialViewEnvironment, adjustedContext, container)
    }
  }
}

[rjrjr]

Be nice to replace DecorativewScreenViewFactory w/a set of extensions like this. At least make it non-public API.

[rjrjr]

That snippet might be naive about the requirements for LayoutInflater, though. See https://github.com/square/mortar/blob/master/mortar/src/main/java/mortar/MortarContextWrapper.java#L32