From e6705bf25d00048ee7b9cc4b6bf9699c17d53306 Mon Sep 17 00:00:00 2001
From: David Friedman
Your watch face can respond to a single-tap gesture from the user, as long as +there’s not another UI element that also responds to that gesture. Some possible use cases for +interacting with the watch face include:
+ +Only single taps are available. This restriction is important for maintaining clear and +consistent system interactions, and for making watch face interactions as simple as +possible: Neither you nor the user should think of watch faces as full-fledged apps. Figure 1 +summarizes the categories of gestures, and their uses.
+ ++ Figure 1. Available, reserved, and blocked gestures. +
+ +As a rule, watch-face interaction should be lightweight, with the user completing their desired +action within one or two touches. + +If you want to cause a simple state change on the watch face, such as a purely aesthetic +change, you can use the entire canvas of the watch face as the tap target.
+ +For a more significant change or action, such as launching an activity or sending a message to a +friend, it’s important to keep targets smaller, between 48-90 dpi, to avoid false-positive taps. +There should be a gap between targets of at least 8-16 dpi. For an optimized tappable experience, +display a maximum of 7 to 9 targets at once.
+ +You can also use different regions of the screen to trigger different changes to the watch face. +For example, tapping on the entire canvas could toggle states for the entire face. Tapping a specific target +could produce an inline display of information related to the target. Last, tapping outside the +target could restore the watch face to its default state.
+ +Provide visual feedback when the user’s finger touches down on the watch face. The tap +event does not trigger until the user lifts their finger, but visual feedback on touchdown helps +indicate that the system has received the touch, and also helps the user know where the touch +landed.
+ +Warning: Do not immediately launch a UI on touchdown. A UI that +you launch on touchdown conflicts with gestures for interacting with system UI elements including +the watch face picker, notification stream, settings shade, and app launcher.
+ +