Make `StaticResource` and `DynamicResource` automatically convert `Color`s to `ImmutableSolidColorBrush`es and add a `ColorToBrushConverter` for use by bindings.
To do this I made `GetResourceObservable` accept an optional conversion function.
Split resource nodes into two types:
- `IResourceHost` represents controls and `Application`
- `IResourceProvider` represents resource dictionaries and styles, these are owned by `IResourceHost`s
Dynamic resources are now always resolved from an `IResourceHost`: if an `IResourceProvider` doesn't have a host then a dynamic resource in the resource provider will not be resolved. Resource providers no longer have a `ResourcesChanged` event, instead they notify their `IResourceHost` owner of a resource change by calling the `NotifyHostedResourcesChanged` method.
This requires that a `<Transitions>` element is used to contain the transitions in XAML and a `new Transitions()` is used when assigning transitions from code.
- Pass information for all property changes to `OnPropertyChangedCore`; whether they result in an effective value change or not
- Added `GetBaseValue` to get a value with a specified priority
- Change the signature of `OnPropertyChanged` again to take an `AvaloniaPropertyChangedEventArgs<T>`
- Don't use Rx in the styling system. Instead introduces `IStyleActivator` which is like an `IObservable<bool>`-lite in order to cut down on allocations.
- #nullable enable on touched files
And implement the functionality in the content controls themselves. `ContentControlMixin` was too complex and even with its complexity had bugs (such as in #2821). By moving the functionality to the content controls there is some repeated code but it's much more straightforward.
Steven Kirk
Dan Walmsley
Andrey Kunchev
José Pedro
Luis von der Eltz
Luis v.d.Eltz
Nikita Tsukanov