Before you start, please note that the ability to use following technologies is **required** and that existing contributors will not actively teach them to you.
The quickest way to get started is to copy an existing extension's folder structure and renaming it as needed. We also recommend reading through a few existing extensions' code before you start.
Each extension should reside in `src/<lang>/<mysourcename>`. Use `all` as `<lang>` if your target source supports multiple languages or if it could support multiple sources.
A minimal [Android manifest file](https://developer.android.com/guide/topics/manifest/manifest-intro) is needed for Android to recognize a extension when it's compiled into an APK file. You can also add intent filters inside this file (see [URL intent filter](#url-intent-filter) for more information).
| `pkgNameSuffix` | A unique suffix added to `eu.kanade.tachiyomi.extension`. The language and the site name should be enough. Remember your extension code implementation must be placed in this package. |
| `extClass` | Points to the class that implements `Source`. You can use a relative path starting with a dot (the package name is the base path). This is used to find and instantiate the source(s). |
| `extVersionCode` | The extension version code. This must be a positive integer and incremented with any change to the code. |
| `libVersion` | The version of the [extensions library](https://github.com/tachiyomiorg/extensions-lib) used. |
The extension's version name is generated automatically by concatenating `libVersion` and `extVersionCode`. With the example used above, the version would be `1.2.1`.
Extensions rely on [extensions-lib](https://github.com/tachiyomiorg/extensions-lib), which provides some interfaces and stubs from the [app](https://github.com/tachiyomiorg/tachiyomi) for compilation purposes. The actual implementations can be found [here](https://github.com/tachiyomiorg/tachiyomi/tree/dev/app/src/main/java/eu/kanade/tachiyomi/source). Referencing the actual implementation will help with understanding extensions' call flow.
[`duktape-stub`](https://github.com/tachiyomiorg/tachiyomi-extensions/tree/master/lib/duktape-stub) provides stubs for using Duktape functionality without pulling in the full library. Functionality is bundled into the main Tachiyomi app.
[`lib-ratelimit`](https://github.com/tachiyomiorg/tachiyomi-extensions/tree/master/lib/ratelimit) is a library for adding rate limiting functionality as an [OkHttp interceptor](https://square.github.io/okhttp/interceptors/).
[`lib-dataimage`](https://github.com/tachiyomiorg/tachiyomi-extensions/tree/master/lib/dataimage) is a library for handling [base 64 encoded image data](https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs) using an [OkHttp interceptor](https://square.github.io/okhttp/interceptors/).
You may find yourself needing additional functionality and wanting to add more dependencies to your `build.gradle` file. Since extensions are run within the main Tachiyomi app, you can make use of [its dependencies](https://github.com/tachiyomiorg/tachiyomi/blob/master/app/build.gradle).
Notice that we're using `compileOnly` instead of `implementation`, since the app already contains it. You could use `implementation` instead for a new dependency, or you prefer not to rely on whatever the main app has at the expense of app size.
Note that using `compileOnly` restricts you to versions that must be compatible with those used in [Tachiyomi v0.8.5+](https://github.com/tachiyomiorg/tachiyomi/blob/82141cec6e612885fef4fa70092e29e99d60adbb/app/build.gradle#L104) for proper backwards compatibility.
The class which is refrenced and defined by `extClass` in `build.gradle`. This class should implement either `SourceFactory` or one of the `Source` implementations: `HttpSource` or `ParsedHttpSource`.
|`SourceFactory`| Used to expose multiple `Source`s. Use it when there's minor differences between your target sources or they are essentially mirrors to the same website. |
| `HttpSource`| For online source, where requests are made using HTTP. |
| `ParsedHttpSource`| Similar to `HttpSource`, but has methods useful for scraping pages. |
| `name` | Name displayed in the "Sources" tab in Tachiyomi. |
| `baseUrl` | Base URL of the source without any trailing slashes. |
| `lang` | An ISO 639-1 compliant language code (two letters in lower case). |
| `id` | Identifier of your source, automatically set in `HttpSource`. It should only be manually overriden if you need to copy an existing autogenerated ID. |
- The app calls `fetchPopularManga` which should return a `MangasPage` containing the first batch of found `SManga` entries.
- This method supports pagination. When user scrolls the manga list and more results must be fetched, the app calls it again with increasing `page` values(starting with `page=1`). This continues until `MangasPage.hasNextPage` is passed as `true` and `MangasPage.mangas` is not empty.
- To show the list properly, the app needs `url`, `title` and `thumbnail_url`. You must set them here. The rest of the fields could be filled later.(refer to Manga Details below)
- You should set `thumbnail_url` if is available, if not, `fetchMangaDetails` will be **immediately** called.(this will increase network calls heavily and should be avoided)
- When the user searches inside the app, `fetchSearchManga` will be called and the rest of the flow is similar to what happens with `fetchPopularManga`.
-`fetchMangaDetails` is called to update a manga's details from when it was initialized earlier.
- During a backup, only `url` and `title` are stored. To restore the rest of the manga data, the app calls `fetchMangaDetails`, so all fields should be (re)filled in if possible.
-`SManga.initialized` tells the app if it should call `fetchMangaDetails`. If you are overriding `fetchMangaDetails`, make sure to pass it as `true`.
- If `Page.imageUrl`s are available immediately, you should pass them here. Otherwise, you should set `page.url` to a page that contains them and override `imageUrlParse` to fill those `imageUrl`s.
- If you don't pass `SChapter.date_upload`, the user won't get notifications for new chapters. refer to [this issue](https://github.com/tachiyomiorg/tachiyomi/issues/2089) for more info. `System.currentTimeMillis()` works as a substitute when real data is not available.
- Sometimes you may find no use for some inherited methods. If so just override them and throw exceptions: `throw UnsupportedOperationException("Not used.")`
- By implementing `ConfigurableSource` you can add settings to your source, which is backed by [`SharedPreferences`](https://developer.android.com/reference/android/content/SharedPreferences).
Extensions can define URL intent filters by defining it inside a custom `AndroidManifest.xml` file.
For an example, refer to [the NHentai module's `AndroidManifest.xml` file](https://github.com/tachiyomiorg/tachiyomi-extensions/blob/master/src/all/nhentai/AndroidManifest.xml) and [its corresponding `NHUrlActivity` handler](https://github.com/tachiyomiorg/tachiyomi-extensions/blob/master/src/all/nhentai/src/eu/kanade/tachiyomi/extension/all/nhentai/NHUrlActivity.kt).
Directly debugging your extension (i.e stepping through the extension code) is not possible due to the way that extension code is loaded into the app. However, logs printed from extensions (via [`Logcat`](https://developer.android.com/studio/debug/am-logcat)) do work.
