Android Camera Focus Mode

Question

I am trying to make a custom camera application I want to let the users can choose the focus mode in this application.

The focus mode is auto and touch-to-focus

If we want to use touch-to-focus in the camera , how can be start with?

Answer 1

The feature is software/hardware/manufacture dependent, my suggestion is that you first find a phone like Galaxy Nexus flashed with Android 4.x, then try the android.hardware.Camera.Parameters.getMaxNumFocusAreas() on it, if the return value is greater than zero then you are lucky, and can then use the setFocusAreas() to implement your "touch to focus" feature.

Why:

In old Android versions there is no public API to set the focus areas. Although many manufacturers managed to create their own API and implementation, they won't share.

Android introduced the focus areas API in API level 14, however the phone manufacturers may choose not to implement it (i.e. choose to stick to their own solutions). To check if the API is supported you can call getMaxNumFocusAreasa() first, if it returns a positive integer that means the phone does implement the API and you can go on enabling the "touch focus" feature in your camera app. (The API is also one of the enablers of the "face detection" feature, when faces are recognized the camera app uses the API to let the camera do auto focus on the them.)

You may refer to the vanilla Android Camera app source code for how to use the API properly.

References:

1. Android Camera API

getMaxNumFocusAreas()

setFocusAreas()

1. Android 4.0 Camera app source code

mInitialParams.getMaxNumFocusAreas()

mParameters.setFocusAreas()

Regards

Ziteng Chen