ImageCapture

open class ImageCapture : UseCase
kotlin.Any
   ↳ androidx.camera.core.UseCase
   ↳ androidx.camera.core.ImageCapture

A use case for taking a picture.

This class is designed for basic picture taking. It provides takePicture() functions to take a picture to memory or save to a file, and provides image metadata. Pictures are taken in automatic mode after focus has converged. The flash mode can additionally be set by the application.

TakePicture returns immediately and a listener is called to provide the results after the capture completes. Multiple calls to takePicture will take pictures sequentially starting after the previous picture is captured.

Note that focus and exposure metering regions can be controlled via Preview.

When capturing to memory, the captured image is made available through an ImageProxy via an ImageCapture.OnImageCapturedCallback.

Summary

Nested classes

Builder for an ImageCapture.

Holder class for metadata that will be saved with captured images.
abstract

Callback for when an image capture has completed.
abstract

Listener containing callbacks for image file I/O events.

Constants
static Int

Optimizes capture pipeline to prioritize image quality over latency.
static Int

Optimizes capture pipeline to prioritize latency over image quality.
static Int

An error indicating the request cannot be done due to camera is closed.
static Int

An error reported by camera framework indicating the capture request is failed.
static Int

An error occurred while attempting to read or write a file, such as when saving an image to a File.
static Int

An error indicating this ImageCapture is not bound to a valid camera.
static Int

An unknown error occurred.
static Int

Auto flash.
static Int

No flash.
static Int

Always flash.

Public methods
open Int

Get the flash mode.
open Unit
setFlashMode(flashMode: Int)

Set the flash mode.
open Unit
setTargetAspectRatioCustom(@NonNull aspectRatio: Rational)

Sets target aspect ratio.
open Unit

Sets the desired rotation of the output image.
open Unit
takePicture(@NonNull executor: Executor, @NonNull callback: ImageCapture.OnImageCapturedCallback)

Captures a new still image for in memory access.
open Unit
takePicture(@NonNull saveLocation: File, @NonNull executor: Executor, @NonNull imageSavedCallback: ImageCapture.OnImageSavedCallback)

Captures a new still image and saves to a file.
open Unit
takePicture(@NonNull saveLocation: File, @NonNull metadata: ImageCapture.Metadata, @NonNull executor: Executor, @NonNull imageSavedCallback: ImageCapture.OnImageSavedCallback)

Captures a new still image and saves to a file along with application specified metadata.
open String

Constants

CAPTURE_MODE_MAXIMIZE_QUALITY

static val CAPTURE_MODE_MAXIMIZE_QUALITY: Int

Optimizes capture pipeline to prioritize image quality over latency. When the capture mode is set to MAX_QUALITY, images may take longer to capture.

Value: 0

CAPTURE_MODE_MINIMIZE_LATENCY

static val CAPTURE_MODE_MINIMIZE_LATENCY: Int

Optimizes capture pipeline to prioritize latency over image quality. When the capture mode is set to MIN_LATENCY, images may capture faster but the image quality may be reduced.

Value: 1

ERROR_CAMERA_CLOSED

static val ERROR_CAMERA_CLOSED: Int

An error indicating the request cannot be done due to camera is closed.

Value: 3

ERROR_CAPTURE_FAILED

static val ERROR_CAPTURE_FAILED: Int

An error reported by camera framework indicating the capture request is failed.

Value: 2

ERROR_FILE_IO

static val ERROR_FILE_IO: Int

An error occurred while attempting to read or write a file, such as when saving an image to a File.

Value: 1

ERROR_INVALID_CAMERA

static val ERROR_INVALID_CAMERA: Int

An error indicating this ImageCapture is not bound to a valid camera.

Value: 4

ERROR_UNKNOWN

static val ERROR_UNKNOWN: Int

An unknown error occurred.

See message parameter in onError callback or log for more details.

Value: 0

FLASH_MODE_AUTO

static val FLASH_MODE_AUTO: Int

Auto flash. The flash will be used according to the camera system's determination when taking a picture.

Value: 0

FLASH_MODE_OFF

static val FLASH_MODE_OFF: Int

No flash. The flash will never be used when taking a picture.

Value: 2

FLASH_MODE_ON

static val FLASH_MODE_ON: Int

Always flash. The flash will always be used when taking a picture.

Value: 1

Public methods

getFlashMode

open fun getFlashMode(): Int

Get the flash mode.

Return
Int: the flashMode.

setFlashMode

open fun setFlashMode(flashMode: Int): Unit

Set the flash mode.

The flash control for the subsequent photo capture requests. Applications can check if there is a flash unit via CameraInfo#hasFlashUnit() and update UI component if necessary. If there is no flash unit, then calling this API will take no effect for the subsequent photo capture requests and they will act like FLASH_MODE_OFF.

When the torch is enabled via CameraControl#enableTorch(boolean), the torch will remain enabled during photo capture regardless of flashMode setting. When the torch is disabled, flash will function as specified by setFlashMode(int).

Parameters
flashMode Int: the flash mode.

setTargetAspectRatioCustom

open fun setTargetAspectRatioCustom(@NonNull aspectRatio: Rational): Unit

Sets target aspect ratio.

This sets the cropping rectangle returned by ImageProxy#getCropRect() returned from ImageCapture#takePicture(Executor, OnImageCapturedCallback).

This crops the saved image when calling ImageCapture#takePicture(File, Executor, OnImageSavedCallback) or ImageCapture#takePicture(File, Metadata, Executor, OnImageSavedCallback).

Cropping occurs around the center of the image and as though it were in the target rotation.

Parameters
aspectRatio Rational: New target aspect ratio.

setTargetRotation

open fun setTargetRotation(rotation: Int): Unit

Sets the desired rotation of the output image.

This will affect the EXIF rotation metadata in images saved by takePicture calls and the ImageInfo#getRotationDegrees() value of the ImageProxy returned by OnImageCapturedCallback. These will be set to be the rotation, which if applied to the output image data, will make the image match target rotation specified here.

While rotation can also be set via Builder#setTargetRotation(int), using ImageCapture#setTargetRotation(int) allows the target rotation to be set dynamically.

In general, it is best to use an android.view.OrientationEventListener to set the target rotation. This way, the rotation output will indicate which way is down for a given image. This is important since display orientation may be locked by device default, user setting, or app configuration, and some devices may not transition to a reverse-portrait display orientation. In these cases, use ImageCapture#setTargetRotation to set target rotation dynamically according to the android.view.OrientationEventListener, without re-creating the use case. Note the OrientationEventListener output of degrees in the range [0..359] should be converted to a surface rotation, i.e. one of Surface#ROTATION_0, Surface#ROTATION_90, Surface#ROTATION_180, or Surface#ROTATION_270.

If no target rotation is set by the application, it is set to the value of Display#getRotation() of the default display at the time the use case is created.

takePicture uses the target rotation at the time it begins executing (which may be delayed waiting on a previous takePicture call to complete).

Parameters
rotation Int: Target rotation of the output image, expressed as one of Surface#ROTATION_0, Surface#ROTATION_90, Surface#ROTATION_180, or Surface#ROTATION_270.

takePicture

open fun takePicture(
    @NonNull executor: Executor, 
    @NonNull callback: ImageCapture.OnImageCapturedCallback
): Unit

Captures a new still image for in memory access.

The callback will be called only once for every invocation of this method. The listener is responsible for calling Image#close() on the returned image.

Parameters
executor Executor: The executor in which the callback methods will be run.
callback ImageCapture.OnImageCapturedCallback: Callback to be invoked for the newly captured image

takePicture

open fun takePicture(
    @NonNull saveLocation: File, 
    @NonNull executor: Executor, 
    @NonNull imageSavedCallback: ImageCapture.OnImageSavedCallback
): Unit

Captures a new still image and saves to a file.

The listener's callback will be called only once for every invocation of this method.

Parameters
saveLocation File: Location to store the newly captured image.
executor Executor: The executor in which the listener callback methods will be run.
imageSavedCallback ImageCapture.OnImageSavedCallback: Callback to be called for the newly captured image.

takePicture

open fun takePicture(
    @NonNull saveLocation: File, 
    @NonNull metadata: ImageCapture.Metadata, 
    @NonNull executor: Executor, 
    @NonNull imageSavedCallback: ImageCapture.OnImageSavedCallback
): Unit

Captures a new still image and saves to a file along with application specified metadata.

The callback will be called only once for every invocation of this method.

This function accepts metadata as a parameter from application code. For JPEGs, this metadata will be included in the EXIF.

Parameters
saveLocation File: Location to store the newly captured image.
metadata ImageCapture.Metadata: Metadata to be stored with the saved image. For JPEG this will be included in the EXIF.
executor Executor: The executor in which the callback methods will be run.
imageSavedCallback ImageCapture.OnImageSavedCallback: Callback to be called for the newly captured image.

toString

@NonNull open fun toString(): String