MultiResolutionImageReader

See also:

• ImageReader
• CameraCharacteristics.SCALER_MULTI_RESOLUTION_STREAM_CONFIGURATION_MAP

MultiResolutionImageReader

public MultiResolutionImageReader (Collection<MultiResolutionStreamInfo> streams, 
                int format, 
                int maxImages)

Create a new multi-resolution reader based on a group of camera stream properties returned by a camera device.

The valid size and formats depend on the camera characteristics. MultiResolutionImageReader for an image format is supported by the camera device if the format is in the supported multi-resolution output stream formats returned by MultiResolutionStreamConfigurationMap.getOutputFormats(). If the image format is supported, the MultiResolutionImageReader object can be created with the streams objects returned by MultiResolutionStreamConfigurationMap.getOutputInfo(int).

The maxImages parameter determines the maximum number of Image objects that can be acquired from each of the ImageReader within the MultiResolutionImageReader. However, requesting more buffers will use up more memory, so it is important to use only the minimum number necessary. The application is strongly recommended to acquire no more than maxImages images from all of the internal ImageReader objects combined. By keeping track of the number of acquired images for the MultiResolutionImageReader, the application doesn't need to do the bookkeeping for each internal ImageReader returned from onImageAvailable callback.

Unlike the normal ImageReader, the MultiResolutionImageReader has a more complex configuration sequence. Instead of passing the same surface to OutputConfiguration and CaptureRequest, the OutputConfiguration.createInstancesForMultiResolutionOutput(MultiResolutionImageReader) call needs to be used to create the OutputConfigurations for session creation, and then getSurface() is used to get CaptureRequest.

close

public void close ()

Closes this resource, relinquishing any underlying resources. This method is invoked automatically on objects managed by the try-with-resources statement.

flush

public void flush ()

Flush pending images from all internal ImageReaders

Acquire and close pending images from all internal ImageReaders. This has the same effect as calling acquireLatestImage() on all internal ImageReaders, and closing all latest images.

getStreamInfoForImageReader

public MultiResolutionStreamInfo getStreamInfoForImageReader (ImageReader reader)

Get the MultiResolutionStreamInfo describing the ImageReader an image originates from

An image from a MultiResolutionImageReader is produced from one of the underlying ImageReaders. This function returns the MultiResolutionStreamInfo to describe the property for that ImageReader, such as width, height, and physical camera Id.

getSurface

public Surface getSurface ()

Get the surface that is used as a target for CaptureRequest

The application must use the surface returned by this function as a target for CaptureRequest. The camera device makes the decision on which internal ImageReader will receive the output image.

Please note that holding on to the Surface objects returned by this method is not enough to keep their parent MultiResolutionImageReaders from being reclaimed. In that sense, a Surface acts like a weak reference to the MultiResolutionImageReader that provides it.

setOnImageAvailableListener

public void setOnImageAvailableListener (ImageReader.OnImageAvailableListener listener, 
                Executor executor)

Set onImageAvailableListener callback.

This function sets the onImageAvailableListener for all the internal ImageReader objects.

For a multi-resolution ImageReader, the timestamps of images acquired in onImageAvailable callback from different internal ImageReaders may become out-of-order due to the asynchronous callbacks between the different resolution image queues.

finalize

protected void finalize ()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.

The general contract of finalize is that it is invoked if and when the Java virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.

The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.

The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.

The finalize method is never invoked more than once by a Java virtual machine for any given object.

Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.