BannerViewPager split its indicator out, and left the documentation in a wiki

The readme is five wiki links and a claim about who uses it

The whole usage section is five numbered links, each pointing at a wiki page rather than at documentation in the repository: a quick start, an API reference, the view types, the binding integration, and the custom indicator. So the readme's job is orientation rather than instruction, and a reader who downloads the artifact still has to leave the repository to learn how to use it. That arrangement is common for libraries with a long history, and it is worth remembering when a readme appears to be missing the setup instructions. Above that sits a sentence listing the applications said to use it, from a video service and two music services through two payment and retail apps to a video platform, a audio platform and a large video site. That list is a marketing claim rather than a technical one, but it does explain the design pressure: a component used by that many teams needs many page styles and a swappable indicator rather than one fixed appearance.

Three page styles, and two methods that reach the rest

The first documented feature is page style, and the table names three: multiple pages at equal size, multiple pages scaled, and multiple pages overlapping. The second section says more styles can be built using two configuration methods, one that sets the page style and one that sets a reveal width. That second method is the important one, because it means the three named styles are conveniences rather than a closed set, and the reveal width is what controls how much of the neighbouring page is visible. A sample page is linked for each, so the shapes can be seen without reading the source. The naming is also a hint about the difficulty order: the plain equal-size layout is the default case, and the other two are variations on how much of the neighbour is visible and whether the page scales down as it moves away from centre. The naming is also a hint about the difficulty order: the plain equal-size layout is the default case, and the other two are variations on how much of the neighbour is visible and whether the page scales down as it moves away.

Three indicator styles times five slide modes

The indicator documentation is a grid and the grid is the specification: three indicator styles as columns and five slide modes as rows. The modes are named and they describe how the active indicator moves or changes state, while the styles describe the mark itself, one of them a rounded rectangle. So the library offers fifteen combinations from two independent axes rather than fifteen separately implemented indicators. The readme is explicit that a custom indicator is also supported, and that it means extending one base class or implementing one interface and overriding methods, which is the smallest possible surface for a replaceable component: one base class or one interface, and everything else is drawing.

The indicator was split into its own repository

One line explains a structural change that matters for anyone upgrading. The indicator library was split out of this project, and a second repository now holds it, with a link and an invitation to look there for more information. That means a project that previously took the indicator classes from this artifact now takes them from another, and the two versions can drift independently. The readme keeps the indicator documentation here as well as pointing at the new home, That duplication is the kind that tends to outlive the migration it describes.

The build directory named git is not a mistake

The repository root contains a library directory for the component itself and an application directory for the demo, plus the standard Gradle files, a wrapper for both platforms, and two directories with no obvious purpose from their names alone. One is named for code style and one is named git. A build tool configuration that is version controlled under a directory named git is not a slip; it is how a tool that lints every commit gets its own versioned rules rather than inheriting whatever the machine happens to have. The code style directory is the same idea for the source itself, so formatting decisions are reviewable in a diff rather than being a matter of whoever ran it last.

Two languages in one repository, and a demo in both

The recorded primary language is Java, and the sample links in the readme point at files with two different extensions. One page sample is a Kotlin file and one indicator sample is a Java file, which tells you the demo module demonstrates both. That matters more than it sounds: a view-binding based component can be consumed from either language, and a demo that exercises both is the only way to keep that promise honest. The binding wiki page covers the same ground from the consumer side, covering both of the binding approaches the framework offers rather than only one.

The licence text is embedded in the readme

The final section is a licence block written out in full rather than linked, with a copyright range and the standard grant of use, modification and distribution under conditions, and a warranty disclaimer. There is no separate licence file mentioned in the readme, although the repository root does contain one. The readme also carries a thanks section naming two other banner projects as prior art and one community site, which is worth reading as an acknowledgement that the page and indicator patterns here are not original to this repository.

Editorial conclusion

BannerViewPager suits an Android project that needs a carousel with multiple visible pages and a configurable indicator, and that is willing to read a wiki rather than a manual. It does not suit a project that wants one artifact, since the indicator ships separately. Before adopting it, read the page-style and indicator pages rather than the summary, and note that the current documentation lives in wiki pages while the readme only indexes them.

Frequently asked questions

Official sources

1. Issues
2. License: Apache-2.0
3. README
4. Releases
5. zhpanvip/BannerViewPager on GitHub