How apps work
UI toolkits
Views, Compose, and the machinery between your state and the screen.
7 pages77 min7 interactive10200 words
- 01The View systemA View is a rectangle that measures itself, lays out its children and records drawing commands. The whole UI of Android before Compose is that one idea, applied recursively.beginner11 mininteractive
- 02Custom viewsWriting a View is the smallest useful unit of Android UI work: measure, draw, handle input, save state. It is also the best way to learn what the framework does for you everywhere else.intermediate11 mininteractive
- 03Why ComposeThe View system made you the maintainer of a mutable tree. Compose replaced that with a function from state to UI — and in exchange, took away your control over when things run.intermediate11 mininteractive
- 04How Compose worksCompose is a compiler plugin, a positional memory table and a snapshot system. Once you can see those three, recomposition stops being magic and becomes predictable.nerd11 mininteractive
- 05Compose vs Views, measuredNeither toolkit is unconditionally faster. The honest answer depends on what the screen does, what it costs to build the first frame, and whether you measured or guessed.nerd11 mininteractive
- 06Design languagesFive visual languages in eighteen years: pre-Holo, Holo, Material, Material You and Material 3 Expressive. Each one was an answer to a specific failure of the last.intermediate11 mininteractive
- 07AccessibilityAccessibility is not a feature you add at the end. It is the set of semantics your UI publishes so that a screen reader, a switch or a keyboard can operate it — and Compose changes how you publish them.intermediate11 mininteractive
Test yourself
Test yourself: UI toolkits
Which of these make a composable non-skippable? (Select all that apply.)