Neutral zoom?

[stevengoldberg]

Prerequisites

• I have searched existing issues for a similar request.

What problem are you trying to solve?

This isn't a feature request, but it didn't fit the bug template. Not sure whether this is a bug, a docs issue, or user error.

On an iOS device with an ultra-wide-angle camera:

const device = useCameraDevice('back', { physicalDevices: ['ultra-wide-angle', 'wide-angle', 'telephoto'] })
console.log(device.minZoom)
console.log(device.zoomLensSwitchFactors)

Proposed API / solution

The docs on zooming say:

If a virtual Camera contains an 'ultra-wide-angle' Camera (the "0.5x Camera"), the user may zoom out to less than 1 (here 0.5) instead.

minZoom <= 1 (e.g. 0.5x)
natural zoom = 1
maxZoom >= 1 (e.g. 3x)

And the section on zoomLensSwitchFactors says:

const camera = ... // Triple-Camera (0.5x, 1x, 3x)
camera.zoomLensSwitchFactors // [1, 3]

But the actual output is:

console.log(device.minZoom) // 1
console.log(device.zoomLensSwitchFactors) // [2, 8]

Is this the expected output?

In vision camera v4, there was a neutralZoom property, but that doesn't exist in v5. If minZoom is correctly returned as 1, how is the application meant to determine that neutralZoom should be 2?

Alternatives considered

No response

Platforms this should target

iOS

Would you be willing to contribute this?

No, I'm requesting only.

Additional context

No response

Submission

• I described the problem, not just the solution.
• I wrote this request in my own words. I did not paste AI-generated proposals.

[stevengoldberg]

I suppose that the application can recreate the logic v4 used to calculate neutralZoom, since virtualDeviceSwitchOverVideoZoomFactors is now exposed by the library. But imo it would make sense for the library to continue exposing neutralZoom rather than leaving that to the application.

I believe that displayVideoZoomFactorMultiplier ought to be exposed by the library, however. The purpose of this value is to translate from the internal zoom value to a UI-displayable one.

E.g. on iOS when using the rear triple camera, displayVideoZoomFactorMultiplier will be 0.5, so a zoom value of 2 (which is neutral) gets displayed as 1. But when using e.g. the front camera, displayVideoZoomFactorMultiplier is 1.