field_of_view

A Flutter plugin to get the camera's field of view (FOV) on iOS and Android.

Features

Get horizontal and vertical field of view angles from the back camera
No camera permissions required
Strongly-typed API using Pigeon
Supports iOS and Android

Installation

Add this to your package's pubspec.yaml file:

dependencies:
  field_of_view: ^0.0.1

Usage

import 'package:field_of_view/field_of_view.dart';

final fov = FieldOfView();

try {
  final response = await fov.getFieldOfView();
  print('Horizontal FOV: ${response.horizontalFov}°');
  print('Vertical FOV: ${response.verticalFov}°');
} on PlatformException catch (e) {
  print('Error: ${e.message}');
}

Response

The FieldOfViewResponse contains:

Property	Type	Description
`horizontalFov`	`double`	Horizontal field of view in degrees
`verticalFov`	`double`	Vertical field of view in degrees

Note: The FOV values represent the camera sensor's native orientation (landscape), so horizontal FOV will typically be larger than vertical FOV, regardless of device orientation.

Error handling

The plugin throws PlatformException with the following error codes:

Code	Description
`CAMERA_UNAVAILABLE`	No back camera found on the device
`SENSOR_UNAVAILABLE`	Could not retrieve sensor size information
`FOCAL_LENGTH_UNAVAILABLE`	Could not retrieve focal length information

How it works

iOS: Uses AVCaptureDevice.Format.geometricDistortionCorrectedVideoFieldOfView for horizontal FOV (corrected for lens distortion) and calculates vertical FOV from the aspect ratio. Requires iOS 13.0+.
Android: Uses Camera2 API to read SENSOR_INFO_PHYSICAL_SIZE and LENS_INFO_AVAILABLE_FOCAL_LENGTHS from CameraCharacteristics, then calculates FOV using the pinhole camera model:

FOV = 2 × atan(sensorSize / (2 × focalLength))