OverlayViewProvider

Interface for injecting custom overlay views on top of the MSDK MapView in the Android Auto surface.

The SDK's SurfaceCallback renders the MapView inside a FrameLayout. This interface allows clients to add app-specific UI elements on top of the map (speed limit display, ADAS info, compass, custom speed view, etc.).

Lifecycle

1. createOverlayView — called once during MapView creation. Return your View or null.

2. getLayoutParams — called once to position the overlay in the FrameLayout.

3. onScreenStateChanged — called when the AA screen state changes (NAVIGATION, MAP_VIEW, etc.). Use this to show/hide the overlay based on context.

4. onVisibleAreaChanged — called when the visible (unobscured) area changes. Use this to reposition the overlay so it doesn't get hidden behind template chrome.

5. onGuidanceStateChanged — called on each guidance state update during NAVIGATION. Use this to update overlay content (speed limit value, alert state, etc.).

Usage

class SpeedLimitOverlayProvider : OverlayViewProvider {
    private var overlayView: SpeedLimitView? = null

    override fun createOverlayView(context: Context): View {
        return SpeedLimitView(context).also { overlayView = it }
    }

    override fun getLayoutParams(context: Context): FrameLayout.LayoutParams {
        val size = (60 * context.resources.displayMetrics.density).toInt()
        return FrameLayout.LayoutParams(size, size).apply {
            gravity = android.view.Gravity.BOTTOM or android.view.Gravity.START
            marginStart = (16 * context.resources.displayMetrics.density).toInt()
            bottomMargin = (16 * context.resources.displayMetrics.density).toInt()
        }
    }

    override fun onGuidanceStateChanged(guidanceState: AAGuidanceState) {
        overlayView?.update(guidanceState.currentSpeedLimit)
    }
}

See also