Consider different UX for OPDS feeds

[stevenzeck]

In working on #403 I found that doing the layouts for OPDS feeds was a pain. Right now it's all of this on a single screen:

1. 0 or more buttons for the feed navigation
2. A list of images in a grid layout for the feed publications
3. 0 or more lists of images in a horizontal linear layout list. Each one has a title and a "More" text/button. This is for the publications in a group
4. 0 or more buttons for the group navigation
5. Facets are placed in the toolbar menu as "FILTER"

I don't have a good design for this right now. But I think this whole experience can be improved. Maybe look to other implementations for inspiration?

[mickael-menu]

What do you think should be improved exactly? Is it the fact that we have different components on the same screen? This matches the content of mixed OPDS 2 feed.

I can't find it in the spec, but I always thought that we could have either groups OR a single pair (navigation and/or publications), which should simplify things a bit (@HadrienGardeur do you confirm?). In this case, here are the various layouts we can have for a feed:

• Navigation A list of sub-feeds
• Publications A vertically scrolled list of publications, with optionally a navigation list of sub-feeds at the top (maybe as chips?)
• Mixed A vertically scrolled list with two kinds of cells:
  • NavigationCell A list of sub-feeds, maybe as chips to make it nicer?
  • PublicationsCell A horizontally scrolled carousel with a title and a "More" button to expand it to a Publications layout

You can register to the beta test of Aldiko to check how we implemented this: https://play.google.com/apps/testing/com.aldiko.android

[stevenzeck]

It may just be the limited number of OPDS feeds I've worked with thus far, but I find it hard to navigate through them. If the feed publication list has a lot of items, I don't even know if there are group publications or navigations for a group. The navigation buttons definitely take up too much space.

I'm thinking of better ways to present them, but I feel what the testapp does right now can be vastly improved.

[mickael-menu]

Yes, I agree that the way navigation links are presented is not very appealing.