VibeCoding/.agents/skills/camerax/references/wear-os.md

Developing camera features for Wear OS is rarely about the watch's own lens, if it even has one. It's almost always about creating a Remote Viewfinder to control the phone's camera.

The Wear OS remote mindset

Feature	Phone camera app	Wear OS remote app
Screen	Rectangular (Large)	Circular and less than 2 inches in size
Connectivity	Local Hardware	Bluetooth or Wi-Fi data layer API
Latency	Direct and less than 20 ms	Networked, 100 ms to 500 ms
Interaction	Multi-touch gestures	Rotary input or single taps

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Follow the implementation guide

The circular UI challenge

Wear OS devices are often round. Standard rectangular layouts clip corner buttons.

Follow these blueprint recommendations:

• Use Horologist or Wear Compose libraries.
• Use ScalingLazyColumn for lists so that items stay within the "safe zone" of the circular display.
• Preview scaling: Crop the center of the rectangular phone viewfinder to fit the circular watch screen.

Stream the viewfinder

You can't send a raw 60 fps stream over Bluetooth. compress and throttle.

// Example: Sending a viewfinder frame to the watch
val bitmap = previewView.bitmap // Capture current frame
if (bitmap != null) {
    val compressed = compressToJpeg(bitmap, quality = 50)
    val request = PutDataMapRequest.create("/camera/preview").apply {
        dataMap.putAsset("image", Asset.createFromBytes(compressed))
    }
    Wearable.getDataClient(context).putDataItem(request.asPutDataRequest())
}

Optimization : Cap the watch preview at 10-15 fps to preserve battery and bandwidth.

Remote triggers and syncing

Use the MessageClient for low-latency commands like "Take Photo" or "Switch Camera."

// Watch sends a trigger to the phone
Wearable.getMessageClient(context).sendMessage(nodeId, "/camera/capture", null)

Rotary input support

On devices that support it, use the physical crown, Rotary Input, to control Zoom or Exposure.

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Wear OS pitfalls

• Corner clipping : Placing a Close button in the top-right corner of a square layout makes it impossible to tap the button on a round watch display.
• Battery drain: Sustained Bluetooth data transfer, viewfinder sync, drains watch battery. Proactively close the remote app if the phone screen is turned off.
• Node discovery : The phone is possibly connected to multiple "Nodes" (watches, earbuds, or tablets). Ensure your CapabilityClient filters for the specific camera_remote_host capability.
• Disconnect handling: If the watch disconnects, the phone camera must stop its high-power preview to save energy.