[camera] Return all possible cameras on Android

[martingeorgiu]

This PR is Android equivalent to #5636 which I did recently for iOS.

flutter/flutter#91247

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[martingeorgiu]

Hi everyone, I intentionally did not add any tests for now, because I want to make sure, that this PR has any chances of merging. The way I solved the issue is that the .getCameraIdList() does not return all physical cameras and .getPhysicalCameraIds() on CameraCharacteristics does not help either (it works for some devices, but it miserably fails for others).

In the Android docs, there is information that non-removable cameras ids are integers from 0 (https://developer.android.com/reference/android/hardware/camera2/CameraManager.html#getCameraIdList()).

With this fact in mind, I've created this PR, which finally returns all possible cameras on my test device "Alcatel 1s", which was the hardest nut to crack out of all my Android test phones.

I'm fully aware that this is not an ideal solution, but with the current state of Camera2 Android API, AFAIK there is sadly no better solution. We were using this change in production for some time now and sometimes there is camera id to which .getCameraCharacteristics() does not throw Exception (so it's included in the final list), but when user tries to access it, it fails. We tackle this issue with "middleware" which remembers IDs which weren't in fact working and we won't display them to the user.

[martingeorgiu]

Also, I made gradle version changes to the Android example to be able to build it with no strange problems (which I hope is not an issue in any way).

[stuartmorgan]

.getPhysicalCameraIds() on CameraCharacteristics does not help either (it works for some devices, but it miserably fails for others

Can you elaborate on "miserably fails"? What does it do?

sometimes there is camera id to which .getCameraCharacteristics() does not throw Exception (so it's included in the final list), but when user tries to access it, it fails.

Based on the explanation in https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics#getPhysicalCameraIds() it sounds like that's expected behavior, and that what you're doing here is explicitly bypassing code that's meant to prevent that situation.

It's not clear to me why returning cameras that won't work is a desirable change.

[martingeorgiu]

Hi @stuartmorgan,

I meant that the getCameraIdList() returns e.g. on "Alcatel 1s" 2 cameras. Index 0 (one camera from the back) and index 1 (one camera from the front). When I use getPhysicalCameraIds() on the one from the back, I get an empty array. But the device has 3 back cameras and when I access the index 2 and 3, I can use them with no real issue.

The problem is, that at least from what I've read and tried there is no official way to get these two additional indexes. So the final solution for me was to do a simple loop which tries to find all of them. (and the mechanism to check whether there is a camera for such index, was using the getCameraCharacteristics())

[stuartmorgan]

But the device has 3 back cameras and when I access the index 2 and 3, I can use them with no real issue.

But you also said that on other devices these extra camera indexes fail when used. Given the docs I linked to, it sounds like what you are doing here is exposing cameras that are not actually supported for individual use, and if/when they do work it's basically an accident. Am I misunderstanding?

[lucasoskorep]

@stuartmorgan @martingeorgiu https://tech.gc.com/every-camera-every-angle-on-android/ this article may be a great help explaining what is going on here. It seems that Flutter camera for now supports some physical camera setups properly, but it gets lost when using logical camera setups and some of the weirder physical camera setups.

For instance the pixel 6 has 2 physical back cameras and 1 logical back camera. The camera returned by the camera flutter plugin is logical, but the zoom instances are set incorrectly on it. The phone supports .7 to 7 zoom levels on its logical camera, but the camera plugin lists 1 as the minimum which stops the android API from swapping between the physical cameras built into the 1 logical camera returned.

Looking more into what a good solution for this would look like now without trying to open the physical cameras directly.

[lucasoskorep]

@martingeorgiu let me know if this allows you to get around your issue using the multiple physical cameras combined into a single logical camera. #6150

[martingeorgiu]

@lucasoskorep Sadly that did not help. The issues with devices where this plugin is not returning all cameras are afaik caused by an intentional restriction of the manufacturer (probably to promote their main camera app) and the cases, where this PR would help, are probably as @stuartmorgan said basically by accident.
So I'll close the PR as it is more or less a hack. If I would in the future found out about some better way, I will post a new PR:)

[lucasoskorep]

@martingeorgiu oh yeah I see that now - seems my issue is for a different bug. Thanks for clarifying :)