Native Device Orientation

This is a plugin project that allows for getting the native device orientation.

Why?

Flutter provides a couple of way to get the 'orientation', but they all amount to basically checking whether the screen is taller or wider. This could fail for a strangely shaped device, but that isn't the primary issue.

The primary issue is that this method doesn't differentiate between landscape left and landscape right (what you get from rotation an upright phone left or right).

This isn't an issue for most applications, but when I was writing a plugin which displays a camera image, it became a problem as I need to know which way the screen is rotated.

Using the plugin - built-in widget

There are two ways of using the plugin. The most basic is what is shown in the example code; this entails encapsulating your code in a NativeDeviceOrientationReader widget, and then using NativeDeviceOrientationReader.orientation(context); in a widget encapsulated within the context.

This allows you to control when the device starts listening for orientation changes (which could use a bit of energy) by deciding where the NativeDeviceOrientationReader is instantiated, while being able to access the orientation in a simple way.

Note that there could be a very slight time between when the NativeDeviceOrientationReader widget is instantiated and when the orientation is read where the widget could be built with an incorrect orientation; it uses flutter's method of size until the first message it receives back from the native code (which should be fairly immediate anyways). It assumes that landscape is right and portrait is upright during this time.

See example and source code for more details.

Using the plugin - directly

It is also possible to bypass the helper widget to access the native calls directly. This is done by using the NativeDeviceOrientationCommunicator class. It is a singleton but can be instantiated like a normal class, and handles the communication between the ios/android code and the flutter code.

This class has two interesting properties:

  1. Future<NativeDeviceOrientation> get orientation async: This can be called to get the orientation asynchronously.

  2. Stream<NativeDeviceOrientation> get onOrientationChanged: This can be called to get a stream which receives new events whenever the orientation changes. It should also get an initial value pretty much immediately.

Libraries

native_device_orientation