Renderer

@UiThread
open fun getMainClockElementBounds(): Rect

This method is used for accessibility support to describe the portion of the screen containing the main clock element. By default we assume this is contained in the central half of the watch face. Watch faces should override this to return the correct bounds for the main clock element.

@UiThread
fun invalidate(): Unit

Schedules a call to either CanvasRenderer.render or GlesRenderer.render to draw the next frame.

@UiThread
open fun onDestroy(): Unit

Called when the Renderer is destroyed.

@UiThread
abstract fun onDump(writer: PrintWriter): Unit

Called when adb shell dumpsys is invoked for the WatchFaceService, allowing the renderer to optionally record state for debugging purposes.

fun postInvalidate(): Unit

Posts a message to schedule a call to either CanvasRenderer.render or GlesRenderer.render to draw the next frame. Unlike invalidate, this method is thread-safe and may be called on any thread.

fun sendPreviewImageNeedsUpdateRequest(): Unit

Sends a request to the system asking it to update the preview image. This is useful for watch faces with configuration outside of the UserStyleSchema E.g. a watchface with a selectable background.

The system may choose to rate limit this method for performance reasons and the system is free to schedule when the update occurs.

Requires a compatible system to work (if the system is incompatible this does nothing). This can be called from any thread.

@UiThread
open fun shouldAnimate(): Boolean

The system periodically (at least once per minute) calls onTimeTick() to trigger a display update. If the watch face needs to animate with an interactive frame rate, calls to invalidate must be scheduled. This method controls whether or not we should do that and if shouldAnimate returns true we inhibit entering DrawMode.AMBIENT.

By default we remain at an interactive frame rate when the watch face is visible and we're not in ambient mode. Watch faces with animated transitions for entering ambient mode may need to override this to ensure they play smoothly.

@UiThread
protected open fun onRenderParametersChanged(renderParameters: RenderParameters): Unit

Called when the RenderParameters has been updated. Will always be called before the first call to CanvasRenderer.render or GlesRenderer.render.

var additionalContentDescriptionLabels: Collection<Pair<Int, ContentDescriptionLabel>>

Accessibility ContentDescriptionLabel for any rendered watch face elements other than the time and ComplicationSlots which are generated automatically.

The Int in the Pair<Int, ContentDescriptionLabel> is used to sort the ContentDescriptionLabels. Note the time piece has an accessibility traversal index of -1 and each ComplicationSlot's index is defined by its ComplicationSlot.accessibilityTraversalIndex.

val centerX: @Px Float

The center x coordinate of the SurfaceHolder this Renderer renders into.

val centerY: @Px Float

The center y coordinate of the SurfaceHolder this Renderer renders into.

var interactiveDrawModeUpdateDelayMillis: Long

The interval in milliseconds between frames in interactive DrawModes. To render at 60hz set to 16. Note when battery is low, the frame rate will be clamped to 10fps. Watch faces are recommended to use lower frame rates if possible for better battery life. Variable frame rates can also help preserve battery life, e.g. if a watch face has a short animation once per second it can adjust the frame rate inorder to sleep when not animating. In ambient mode the watch face will be rendered once per minute.

val renderParameters: RenderParameters

The current RenderParameters. Updated before every onDraw call.

val screenBounds: Rect

The bounds of the SurfaceHolder this Renderer renders into. Depending on the shape of the device's screen not all of these pixels may be visible to the user (see Configuration.isScreenRound). Note also that API level 27+ devices draw indicators in the top and bottom 24dp of the screen, avoid rendering anything important there.

var surfaceHolder: SurfaceHolder

The SurfaceHolder that renderInternal will draw into.

@WatchFaceExperimental
var watchfaceColors: WatchFaceColors?

Representative WatchFaceColors which are made available to system clients via androidx.wear.watchface.client.InteractiveWatchFaceClient.OnWatchFaceColorsListener.

Initially this value is null signifying that the colors are unknown. When possible the watchFace should assign non null WatchFaceColors and keep this updated when the colors change (e.g. due to a style change).