Wear OS watches may have different hardware button configurations.
On the watch face or stream: OS- and user-configurable
In apps: App-configurable (optional)
Press & hold
Multifunction button mapping
Multifunction button actions are optional
Multifunction buttons can be assigned to actions if it fits your app's use case. Apps are not required to assign actions to multifunction buttons.
Only use multifunction buttons in your app if:
Your app has an obvious, binary action (such as, play/pause)
Your app is primarily used without the user looking at the screen
Binary actions, or actions that allow only one of two choices, help users understand what will happen each time they press a button. For example, buttons on stopwatches usually only perform a “start” or “stop” action. Give multifunction buttons to binary actions like start/stop or play/pause.
Additional multifunction buttons can be assigned to an obvious secondary action or left unassigned.
Some watches will have 2 multifunction buttons organized in a mirrored fashion, or equidistant from the center of the watch on opposite sides. This arrangement may lend itself to paired actions, such as volume up and down.
When considering paired actions, check that the watch has 2 multifunction buttons organized in a mirrored fashion. If they are not mirrored, disable the paired actions to avoid confusion.
Use multifunction buttons for shortcuts
Multifunction button actions should also be accessible as on-screen UI elements, as some watches don’t have multifunction buttons.
Focus on simplicity and immediacy
Pressing a multifunction button immediately conducts its assigned action. To prevent users from needing to look at the screen, use actions that can be completed with a single press.
Button actions should be reversible and not put users into a state where they will lose data.
Avoid mapping to UI navigation
Button actions should not replace UI navigation like swiping, paging, or scrolling. Multifunction buttons may appear in all sorts of configurations that could be counterintuitive to on-screen input.
Button education isn’t required. If you find a need to provide some guidance around the multifunction button options, here is some guidance.
Hardware button guidance should be minimal, non-blocking, and temporary.