Prioritize backdrop image for cinematic background

[brendanperry]

This is a solution for #853.

The ImageView selects the first source from the array. This change allows the caller to get the backdrop image at the front of the array so that it will be displayed if it exists.

[brendanperry]

I don't seem to have permission to label this PR. If there is a way to do it, please let me know!

[LePips]

Thank you for taking a look at this, but I don't like the idea of another flag that just propagates throughout the app for only a single view usage. While the single flag is there, but I really don't like that anymore and plan on removing it:

• https://github.com/jellyfin/Swiftfin/pull/883/files#diff-054dafd14cc397e7ff4a0edfcc55a4ec77237ef458f872c7f148b2d5016fcba1R11

I'd be fine with the following workaround in CinematicBackgroundView:

// TODO: fix once Poster image sources are changed
private func backdropImageSources(from item: Item?) -> [ImageSource] {
    (item?.landscapePosterImageSources(maxWidth: UIScreen.main.bounds.width, single: false) ?? [])
        .filter { $0.url?.absoluteString.contains("Backdrop") ?? false }
}

var body: some View {
    RotateContentView(proxy: proxy)
        .onChange(of: viewModel.currentItem) { newItem in
            proxy.update {
                ImageView(backdropImageSources(from: newItem))
                    .placeholder {
                        Color.clear
                    }
                    .failure {
                        Color.clear
                    }
            }
        }
}

Obviously it's a workaround observing the URL but at least it's contained.

[brendanperry]

I completely understand the concern with the original solution. I did consider one similar to what you proposed; however, in the case that there is no backdrop photo, then no photo will show because we removed all the other fallback images from the array.

I was hoping to not make this change an immediate liability, so I tried to dig into the app a bit more tonight. I have committed some new code that I think is much better.

It does seem best to not continue to bloat the landscape images function on Base+Poster because it really seems to be designed for the poster itself and not for the cinematic background. To me it makes sense to require of whoever conforms to Poster to define their cinematic photos separately.

With that being said, I don't know what all the logic should be on the cinematic poster function. Most specifically, I don't know if this: Defaults[.Customization.Episodes.useSeriesLandscapeBackdrop] applies to the cinematic or not, so hopefully you can help me sort that part out.

I appreciate you working with me and being patient as I try to learn the project better. Do let me know if you would rather go a different direction with this. I'll be happy to adjust as needed. Thanks!

[LePips]

in the case that there is no backdrop photo, then no photo will show

I'm actually fine with that, because we should only show backdrop images in this view.

Defaults[.Customization.Episodes.useSeriesLandscapeBackdrop] applies to the cinematic or not

It does not, that should only be used for the landscape posters for episodes, at least by description for now. I may remove this in the future and just have episodes use their backdrop image. However I still have to think about this since sometimes episode backdrops aren't the same quality as the series backdrops in my experience... I will have to see again how Apple TV does this.

[LePips]

I'm overall fine with this approach for now, as I may change how posters work overall and I think that this is good to have while I work on that as a reminder.

Since other types don't need/use the cinematic view, I would rather define the default conformance on Poster:

extension Poster {
    
    func cinematicPosterImageSources() -> [ImageSource] {
        []
    }
}

and the conformances can be removed from BaseItemPerson and ChapterInfo.FullInfo.

[brendanperry]

Thanks again for the great feedback! This all makes a lot of sense. I have updated the code to reflect your requested changes. Everything looks good in my testing.