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ProcessCameraProvider

public final class ProcessCameraProvider
extends Object

java.lang.Object
   ↳ androidx.camera.lifecycle.ProcessCameraProvider


A singleton which can be used to bind the lifecycle of cameras to any LifecycleOwner within an application's process.

Only a single process camera provider can exist within a process, and it can be retrieved with getInstance(Context).

Heavyweight resources, such as open and running camera devices, will be scoped to the lifecycle provided to bindToLifecycle(LifecycleOwner, CameraSelector, UseCase). Other lightweight resources, such as static camera characteristics, may be retrieved and cached upon first retrieval of this provider with getInstance(Context), and will persist for the lifetime of the process.

This is the standard provider for applications to use.

Summary

Public methods

Camera bindToLifecycle(LifecycleOwner lifecycleOwner, CameraSelector cameraSelector, UseCase... useCases)

Binds the collection of UseCase to a LifecycleOwner.

Camera bindToLifecycle(LifecycleOwner lifecycleOwner, CameraSelector cameraSelector, UseCaseGroup useCaseGroup)

Binds a UseCaseGroup to a LifecycleOwner.

static void configureInstance(CameraXConfig cameraXConfig)

Perform one-time configuration of the ProcessCameraProvider singleton with the given CameraXConfig.

static ListenableFuture<ProcessCameraProvider> getInstance(Context context)

Retrieves the ProcessCameraProvider associated with the current process.

boolean hasCamera(CameraSelector cameraSelector)
boolean isBound(UseCase useCase)

Returns true if the UseCase is bound to a lifecycle.

void unbind(UseCase... useCases)

Unbinds all specified use cases from the lifecycle.

void unbindAll()

Unbinds all use cases from the lifecycle and removes them from CameraX.

Inherited methods

Public methods

bindToLifecycle

public Camera bindToLifecycle (LifecycleOwner lifecycleOwner, 
                CameraSelector cameraSelector, 
                UseCase... useCases)

Binds the collection of UseCase to a LifecycleOwner.

The state of the lifecycle will determine when the cameras are open, started, stopped and closed. When started, the use cases receive camera data.

Binding to a lifecycleOwner in state currently in Lifecycle.State.STARTED or greater will also initialize and start data capture. If the camera was already running this may cause a new initialization to occur temporarily stopping data from the camera before restarting it.

Multiple use cases can be bound via adding them all to a single bindToLifecycle call, or by using multiple bindToLifecycle calls. Using a single call that includes all the use cases helps to set up a camera session correctly for all uses cases, such as by allowing determination of resolutions depending on all the use cases bound being bound. If the use cases are bound separately, it will find the supported resolution with the priority depending on the binding sequence. If the use cases are bound with a single call, it will find the supported resolution with the priority in sequence of ImageCapture, Preview and then ImageAnalysis. The resolutions that can be supported depends on the camera device hardware level that there are some default guaranteed resolutions listed in CameraDevice.createCaptureSession(List, android.hardware.camera2.CameraCaptureSession.StateCallback, Handler).

Currently up to 3 use cases may be bound to a Lifecycle at any time. Exceeding capability of target camera device will throw an IllegalArgumentException.

A UseCase should only be bound to a single lifecycle and camera selector a time. Attempting to bind a use case to a lifecycle when it is already bound to another lifecycle is an error, and the use case binding will not change. Attempting to bind the same use case to multiple camera selectors is also an error and will not change the binding.

If different use cases are bound to different camera selectors that resolve to distinct cameras, but the same lifecycle, only one of the cameras will operate at a time. The non-operating camera will not become active until it is the only camera with use cases bound.

The Camera returned is determined by the given camera selector, plus other internal requirements, possibly from use case configurations. The camera returned from bindToLifecycle may differ from the camera determined solely by a camera selector. If the camera selector can't resolve a camera under the requirements, an IllegalArgumentException will be thrown.

Only UseCase bound to latest active Lifecycle can keep alive. UseCase bound to other Lifecycle will be stopped.

Parameters
lifecycleOwner LifecycleOwner: The lifecycleOwner which controls the lifecycle transitions of the use cases.

cameraSelector CameraSelector: The camera selector which determines the camera to use for set of use cases.

useCases UseCase: The use cases to bind to a lifecycle.

Returns
Camera The Camera instance which is determined by the camera selector and internal requirements.

Throws
IllegalStateException If the use case has already been bound to another lifecycle or method is not called on main thread.
IllegalArgumentException If the provided camera selector is unable to resolve a camera to be used for the given use cases.

bindToLifecycle

public Camera bindToLifecycle (LifecycleOwner lifecycleOwner, 
                CameraSelector cameraSelector, 
                UseCaseGroup useCaseGroup)

Binds a UseCaseGroup to a LifecycleOwner.

Similar to bindToLifecycle(LifecycleOwner, CameraSelector, UseCase[]), with the addition that the bound collection of UseCase share parameters defined by UseCaseGroup such as consistent camera sensor rect across all UseCases.

If one UseCase is in multiple UseCaseGroups, it will be linked to the UseCaseGroup in the latest bindToLifecycle(LifecycleOwner, CameraSelector, UseCaseGroup) call.

Parameters
lifecycleOwner LifecycleOwner

cameraSelector CameraSelector

useCaseGroup UseCaseGroup

Returns
Camera

configureInstance

public static void configureInstance (CameraXConfig cameraXConfig)

Perform one-time configuration of the ProcessCameraProvider singleton with the given CameraXConfig.

This method allows configuration of the camera provider via CameraXConfig. All initialization tasks, such as communicating with the camera service, will be executed on the Executor set by CameraXConfig.Builder.setCameraExecutor(Executor), or by an internally defined executor if none is provided.

Once this method is called, the instance can be retrieved with getInstance(Context) without the need for implementing CameraXConfig.Provider in Application.

Configuration can only occur once. Once the ProcessCameraProvider has been configured with configureInstance() or getInstance(Context), this method will throw an IllegalStateException.

Parameters
cameraXConfig CameraXConfig: configuration options for the singleton process camera provider instance.

Throws
IllegalStateException if the camera provider has already been configured by a previous call to configureInstance() or getInstance(Context).

getInstance

public static ListenableFuture<ProcessCameraProvider> getInstance (Context context)

Retrieves the ProcessCameraProvider associated with the current process.

The instance returned here can be used to bind use cases to any LifecycleOwner with bindToLifecycle(LifecycleOwner, CameraSelector, UseCase).

The instance's configuration may be customized by subclassing the application's Application class and implementing CameraXConfig.Provider. For example, the following will initialize this process camera provider with a Camera2 implementation from androidx.camera.camera2, and with a custom executor.

 public class MyApplication extends Application implements CameraXConfig.Provider {
     @Override
     public CameraXConfig getCameraXConfig() {
         return CameraXConfig.Builder.fromConfig(Camera2Config.defaultConfig())
                    .setCameraExecutor(myExecutor)
                    .setSchedulerHandler(mySchedulerHandler)
                    .build();
     }

     . . .
 }
 

If it isn't possible to subclass the Application class, such as in library code, then the singleton can be configured via configureInstance(CameraXConfig) before the first invocation of getInstance(context), as in the following example.

class MyCustomizedCameraProvider {

     private static boolean configured = false;

     static ListenableFuture<ProcessCameraProvider> getInstance(Context context) {
         synchronized(MyCustomizedCameraProvider.class) {
             if (!configured) {
                 configured = true;
                 ProcessCameraProvider.configureInstance(
                     CameraXConfig.Builder.fromConfig(Camera2Config.defaultConfig())
                           .setCameraExecutor(myExecutor)
                           .setSchedulerHandler(mySchedulerHandler)
                           .build());
             }
         }
         return ProcessCameraProvider.getInstance(context);
     }
 }
 

If no CameraXConfig.Provider is implemented by Application, or if the singleton has not been configured via configureInstance(CameraXConfig) a default configuration will be used.

Parameters
context Context

Returns
ListenableFuture<ProcessCameraProvider> A future which will contain the ProcessCameraProvider. Cancellation of this future is a no-op. This future may fail with an InitializationException and associated cause that can be retrieved by {@link Throwable#getCause()). The cause will be a {@link androidx.camera.core.CameraUnavailableException} if it fails to access any camera during initialization.

Throws
IllegalStateException if CameraX fails to initialize via a default provider or a CameraXConfig.Provider.

hasCamera

public boolean hasCamera (CameraSelector cameraSelector)

Parameters
cameraSelector CameraSelector

Returns
boolean

Throws
CameraInfoUnavailableException

isBound

public boolean isBound (UseCase useCase)

Returns true if the UseCase is bound to a lifecycle. Otherwise returns false.

After binding a use case with bindToLifecycle(LifecycleOwner, CameraSelector, UseCase...), use cases remain bound until the lifecycle reaches a Lifecycle.State.DESTROYED state or if is unbound by calls to unbind(UseCase) or unbindAll().

Parameters
useCase UseCase

Returns
boolean

unbind

public void unbind (UseCase... useCases)

Unbinds all specified use cases from the lifecycle.

This will initiate a close of every open camera which has zero UseCase associated with it at the end of this call.

If a use case in the argument list is not bound, then it is simply ignored.

After unbinding a UseCase, the UseCase can be and bound to another Lifecycle however listeners and settings should be reset by the application.

Parameters
useCases UseCase: The collection of use cases to remove.

Throws
IllegalStateException If not called on main thread.

unbindAll

public void unbindAll ()

Unbinds all use cases from the lifecycle and removes them from CameraX.

This will initiate a close of every currently open camera.

Throws
IllegalStateException If not called on main thread.