What do ProGuard, Multidex, Resource Merger and Realm have in common? Answer: All of these components owe key functionality to the Android Transform API. It is a centerpiece of the Android Gradle Plugin's internal architecutre, as it is responsible for processing intermediary build artifacts, and before the introduction of D8, it was even tasked with the bytecode transformation of Java 8 code for Android as well. To third-party developers, it offers a hook into the creation of an APK through a centralized concept, the Transform, which can inspect and modify classes or resources. Little documentation and a lack of accessibility to the topic have rendered the Transform API a "hidden gem" in the Android plugin infrastructure.

This talk will explore the Transform API, and introduce the required steps to register a custom transformation for a given scope to the audience, in a live coding session.