ImageCapture

@RequiresApi(value = 21)
public final class ImageCapture extends UseCase


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 types

public final class ImageCapture.Builder implements ExtendableBuilder

Builder for an ImageCapture.

public final class ImageCapture.Metadata

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

Callback for image capture events.

Listener containing callbacks for image file I/O events.

Options for saving newly captured image.

Builder class for OutputFileOptions.

Info about the saved image file.

public interface ImageCapture.ScreenFlash

Interface to do the application changes required for screen flash operations.

Callback listener for discovering when the application has completed its changes for a screen flash image capture.

Constants

static final int

Optimizes capture pipeline to prioritize image quality over latency.

static final int

Optimizes capture pipeline to prioritize latency over image quality.

static final int

Optimizes capture pipeline to have better latency while keeping good image quality.

static final int

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

static final int

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

static final int

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

static final int

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

static final int

An unknown error occurred.

static final int

Auto flash.

static final int

No flash.

static final int

Always flash.

static final int

Screen flash.

Public methods

int

Returns the set capture mode.

int

Get the flash mode.

static @NonNull ImageCaptureCapabilities

Returns ImageCaptureCapabilities to query ImageCapture capability of the given CameraInfo.

@IntRange(from = 1, to = 100) int

Returns the JPEG quality setting.

@Nullable ResolutionSelector

Returns the ResolutionSelector used to select the postview size.

@NonNull ImageCaptureLatencyEstimate

Returns an estimate of the capture and processing sequence duration based on the current camera configuration and scene conditions.

@Nullable ResolutionInfo

Gets selected resolution information of the ImageCapture.

@Nullable ResolutionSelector

Returns the resolution selector setting.

@Nullable ImageCapture.ScreenFlash

Returns the ScreenFlash instance currently set, null if none.

int

Returns the desired rotation of the output image.

boolean

Returns if postview is enabled or not.

void

Sets target cropping aspect ratio for output image.

void
setFlashMode(int flashMode)

Set the flash mode.

void

Sets ScreenFlash for subsequent photo capture requests.

void
setTargetRotation(int rotation)

Sets the desired rotation of the output image.

void

Captures a new still image for in memory access.

void
takePicture(
    @NonNull ImageCapture.OutputFileOptions outputFileOptions,
    @NonNull Executor executor,
    @NonNull ImageCapture.OnImageSavedCallback imageSavedCallback
)

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

@NonNull String

Inherited methods

From androidx.camera.core.UseCase
static int
snapToSurfaceRotation(@IntRange(from = 0, to = 359) int orientation)

A utility function that can convert the orientation degrees of OrientationEventListener to the nearest Surface rotation.

Constants

CAPTURE_MODE_MAXIMIZE_QUALITY

Added in 1.0.0
public static final int CAPTURE_MODE_MAXIMIZE_QUALITY = 0

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

CAPTURE_MODE_MINIMIZE_LATENCY

Added in 1.0.0
public static final int CAPTURE_MODE_MINIMIZE_LATENCY = 1

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.

CAPTURE_MODE_ZERO_SHUTTER_LAG

Added in 1.2.0
@ExperimentalZeroShutterLag
public static final int CAPTURE_MODE_ZERO_SHUTTER_LAG = 2

Optimizes capture pipeline to have better latency while keeping good image quality. When the capture mode is set to ZERO_SHUTTER_LAG, the latency between the shutter button is clicked and the picture is taken is expected to be minimized, compared with other capture modes.

ZERO_SHUTTER_LAG mode is aiming to provide the minimum latency for instant capture. It caches intermediate results and deliver the one with the closest timestamp when takePicture is invoked.

isZslSupported can be used to query the device capability to support this mode or not. However, this mode also depends on use cases configuration and flash mode settings. If VideoCapture is bound or flash mode is not OFF or OEM Extension is ON, this mode will be disabled automatically.

ERROR_CAMERA_CLOSED

Added in 1.0.0
public static final int ERROR_CAMERA_CLOSED = 3

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

ERROR_CAPTURE_FAILED

Added in 1.0.0
public static final int ERROR_CAPTURE_FAILED = 2

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

ERROR_FILE_IO

Added in 1.0.0
public static final int ERROR_FILE_IO = 1

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

ERROR_INVALID_CAMERA

Added in 1.0.0
public static final int ERROR_INVALID_CAMERA = 4

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

ERROR_UNKNOWN

Added in 1.0.0
public static final int ERROR_UNKNOWN = 0

An unknown error occurred.

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

FLASH_MODE_AUTO

Added in 1.0.0
public static final int FLASH_MODE_AUTO = 0

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

FLASH_MODE_OFF

Added in 1.0.0
public static final int FLASH_MODE_OFF = 2

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

FLASH_MODE_ON

Added in 1.0.0
public static final int FLASH_MODE_ON = 1

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

FLASH_MODE_SCREEN

Added in 1.4.0-alpha04
public static final int FLASH_MODE_SCREEN = 3

Screen flash. Display screen brightness will be used as alternative to flash when taking a picture with front camera.

This flash mode can be set via setFlashMode after setting a non-null ScreenFlash instance with setScreenFlash. This mode will always invoke all the necessary operations for a screen flash image capture, i.e. it is similar to FLASH_MODE_ON, not FLASH_MODE_AUTO.

The following code snippet shows an example implementation of how this flash mode can be set to an ImageCapture instance.

imageCapture.setScreenFlash(new ImageCapture.ScreenFlash() {
    
    public void apply(long expirationTimeMillis,
            ScreenFlashListener screenFlashListener) {
        whiteColorOverlayView.setVisibility(View.VISIBLE);
        maximizeScreenBrightness();
        screenFlashListener.onCompleted();
    }

    
    public void clear() {
        restoreScreenBrightness();
        whiteColorOverlayView.setVisibility(View.INVISIBLE);
    }
});

imageCapture.setFlashMode(ImageCapture.FLASH_MODE_SCREEN);
See also
setFlashMode

Public methods

getCaptureMode

Added in 1.0.0
public int getCaptureMode()

Returns the set capture mode.

This is set when constructing an ImageCapture using setCaptureMode. This is static for an instance of ImageCapture.

getFlashMode

Added in 1.0.0
public int getFlashMode()

Get the flash mode.

Returns
int

the flashMode. Value is FLASH_MODE_AUTO, FLASH_MODE_ON, FLASH_MODE_SCREEN, or FLASH_MODE_OFF.

getImageCaptureCapabilities

Added in 1.4.0-alpha04
public static @NonNull ImageCaptureCapabilities getImageCaptureCapabilities(@NonNull CameraInfo cameraInfo)

Returns ImageCaptureCapabilities to query ImageCapture capability of the given CameraInfo.

Some capabilities are only exposed on Extensions-enabled cameras. To get the correct capabilities when Extensions are enabled, you need to pass the CameraInfo from the Extensions-enabled Camera instance. To do this, use the CameraSelector instance retrieved from getExtensionEnabledCameraSelector to invoke bindToLifecycle where you can skip use cases arguments if you'd like to query it before opening the camera. Then, use the returned Camera to get the CameraInfo instance.

>The following code snippet demonstrates how to enable postview:

          
CameraSelector extensionCameraSelector =
    extensionsManager.getExtensionEnabledCameraSelector(cameraSelector, ExtensionMode.NIGHT);
Camera camera = cameraProvider.bindToLifecycle(activity, extensionCameraSelector);
ImageCaptureCapabilities capabilities =
    ImageCapture.getImageCaptureCapabilities(camera.getCameraInfo());
ImageCapture imageCapture = new ImageCapture.Builder()
    .setPostviewEnabled(capabilities.isPostviewSupported())
    .build();
}

getJpegQuality

Added in 1.1.0
public @IntRange(from = 1, to = 100) int getJpegQuality()

Returns the JPEG quality setting.

This is set when constructing an ImageCapture using setJpegQuality. If not set, a default value will be set according to the capture mode setting. JPEG compression quality 95 is set for CAPTURE_MODE_MINIMIZE_LATENCY and 100 is set for CAPTURE_MODE_MAXIMIZE_QUALITY. This is static for an instance of ImageCapture.

getPostviewResolutionSelector

Added in 1.4.0-alpha04
public @Nullable ResolutionSelector getPostviewResolutionSelector()

Returns the ResolutionSelector used to select the postview size.

getRealtimeCaptureLatencyEstimate

Added in 1.4.0-alpha04
public @NonNull ImageCaptureLatencyEstimate getRealtimeCaptureLatencyEstimate()

Returns an estimate of the capture and processing sequence duration based on the current camera configuration and scene conditions. The value will vary as the scene and/or camera configuration change.

The processing estimate can vary based on device processing load.

getResolutionInfo

Added in 1.1.0
public @Nullable ResolutionInfo getResolutionInfo()

Gets selected resolution information of the ImageCapture.

The returned ResolutionInfo will be expressed in the coordinates of the camera sensor. Note that the resolution might not be the same as the resolution of the received image by calling takePicture because the received image might have been rotated to the upright orientation using the target rotation setting by the device.

The resolution information might change if the use case is unbound and then rebound, setTargetRotation is called to change the target rotation setting, or setCropAspectRatio is called to change the crop aspect ratio setting. The application needs to call getResolutionInfo() again to get the latest ResolutionInfo for the changes.

Returns
@Nullable ResolutionInfo

the resolution information if the use case has been bound by the bindToLifecycle API, or null if the use case is not bound yet.

getResolutionSelector

Added in 1.3.0
public @Nullable ResolutionSelector getResolutionSelector()

Returns the resolution selector setting.

This setting is set when constructing an ImageCapture using setResolutionSelector.

getScreenFlash

Added in 1.4.0-alpha04
public @Nullable ImageCapture.ScreenFlash getScreenFlash()

Returns the ScreenFlash instance currently set, null if none.

getTargetRotation

Added in 1.0.0
public int getTargetRotation()

Returns the desired rotation of the output image.

The rotation can be set prior to constructing an ImageCapture using setTargetRotation or dynamically by calling setTargetRotation. The rotation of an image taken is determined by the rotation value set at the time image capture is initiated, such as when calling takePicture.

If no target rotation is set by the application, it is set to the value of getRotation of the default display at the time the use case is created. The use case is fully created once it has been attached to a camera.

Returns
int

The rotation of the intended target.

isPostviewEnabled

Added in 1.4.0-alpha04
public boolean isPostviewEnabled()

Returns if postview is enabled or not.

setCropAspectRatio

Added in 1.0.0
public void setCropAspectRatio(@NonNull Rational aspectRatio)

Sets target cropping aspect ratio for output image.

This aspect ratio is orientation-dependent. It should be expressed in the coordinate frame after rotating the image by the target rotation.

This sets the cropping rectangle returned by getCropRect returned from takePicture.

For example, assume the aspectRatio of 3x4. If an image has a resolution of 480x640 after applying the target rotation, then the output ImageProxy of takePicture would have a cropping rectangle of 480x640 after applying the rotation degrees. However, if an image has a resolution of 640x480 after applying the target rotation, then the cropping rectangle of the output ImageProxy would be 360x480 after applying the rotation degrees.

This crops the saved image when calling takePicture. Note that the cropping will introduce an additional latency.

Cropping occurs around the center of the image and as though it were in the target rotation. For example, assume the aspectRatio of 3x4. If an image has a resolution of 480x640 after applying the target rotation, then the saved output image would be 480x640 after applying the EXIF orientation value. However, if an image has a resolution of 640x480 after applying the target rotation, then the saved output image would be 360x480 after applying the EXIF orientation value.

This setting value will be automatically updated to match the new target rotation value when setTargetRotation is called.

Parameters
@NonNull Rational aspectRatio

New target aspect ratio.

setFlashMode

Added in 1.0.0
public void setFlashMode(int flashMode)

Set the flash mode.

The flash control for the subsequent photo capture requests. Applications can check if there is a flash unit via hasFlashUnit and update UI component if necessary. If there is no flash unit and flashMode is not FLASH_MODE_SCREEN, 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 enableTorch, 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).

On some LEGACY devices like Samsung A3, taking pictures with FLASH_MODE_AUTO mode could cause a crash. To workaround this CameraX will disable the auto flash behavior internally on devices that have this issue.

If FLASH_MODE_SCREEN is set, a ScreenFlash implementation must be set via setScreenFlash before calling this API. Trying to use FLASH_MODE_SCREEN without a ScreenFlash instance set or with a non-front camera will result in an IllegalArgumentException. It is the application's responsibility to change flashMode while switching the camera in case it leads to a non-supported case (e.g. switching to rear camera while FLASH_MODE_SCREEN is still on).

Parameters
int flashMode

the flash mode. Value is FLASH_MODE_AUTO, FLASH_MODE_ON, FLASH_MODE_SCREEN or FLASH_MODE_OFF.

Throws
java.lang.IllegalArgumentException

If flash mode is invalid or FLASH_MODE_SCREEN is used without a ScreenFlash instance or front camera.

setScreenFlash

Added in 1.4.0-alpha04
public void setScreenFlash(@Nullable ImageCapture.ScreenFlash screenFlash)

Sets ScreenFlash for subsequent photo capture requests.

The calling of this API will take effect for FLASH_MODE_SCREEN only and the screenFlash instance will be ignored for other flash modes.

If the implementation provided by the user is no longer valid (e.g. due to any android.app.Activity or android.view.View reference used in the implementation becoming invalid), user needs to re-set a new valid ScreenFlash or clear the previous one with setScreenFlash(null), whichever appropriate.

Parameters
@Nullable ImageCapture.ScreenFlash screenFlash

A ScreenFlash implementation that is used to notify API users when app side changes need to be done. This will replace the previous ScreenFlash instance set with this method.

setTargetRotation

Added in 1.0.0
public void setTargetRotation(int rotation)

Sets the desired rotation of the output image.

This will affect the EXIF rotation metadata in images saved by takePicture calls and the 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 setTargetRotation, using 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, set target rotation dynamically according to the android.view.OrientationEventListener, without re-creating the use case. snapToSurfaceRotation is a helper function to convert the orientation of the android.view.OrientationEventListener to a rotation value. See snapToSurfaceRotation for more information and sample code.

When this function is called, value set by setTargetResolution will be updated automatically to make sure the suitable resolution can be selected when the use case is bound. Value set by setCropAspectRatio will also be updated automatically to make sure the output image is cropped into expected aspect ratio.

If no target rotation is set by the application, it is set to the value of getRotation of the default display at the time the use case is bound. To return to the default value, set the value to

context.getSystemService(WindowManager.class).getDefaultDisplay().getRotation();

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

Parameters
int rotation

Target rotation of the output image, expressed as one of ROTATION_0, ROTATION_90, ROTATION_180, or ROTATION_270.

takePicture

Added in 1.0.0
public void takePicture(
    @NonNull Executor executor,
    @NonNull ImageCapture.OnImageCapturedCallback callback
)

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 close on the returned image.

Parameters
@NonNull Executor executor

The executor in which the callback methods will be run.

@NonNull ImageCapture.OnImageCapturedCallback callback

Callback to be invoked for the newly captured image

Throws
java.lang.IllegalArgumentException

If FLASH_MODE_SCREEN is used without a non-null ScreenFlash instance set.

takePicture

Added in 1.0.0
public void takePicture(
    @NonNull ImageCapture.OutputFileOptions outputFileOptions,
    @NonNull Executor executor,
    @NonNull ImageCapture.OnImageSavedCallback imageSavedCallback
)

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.

If the ImageCapture is in a UseCaseGroup where ViewPort is set, or setCropAspectRatio is used, the image may be cropped before saving to disk which causes an additional latency.

Parameters
@NonNull ImageCapture.OutputFileOptions outputFileOptions

Options to store the newly captured image.

@NonNull Executor executor

The executor in which the callback methods will be run.

@NonNull ImageCapture.OnImageSavedCallback imageSavedCallback

Callback to be called for the newly captured image.

Throws
java.lang.IllegalArgumentException

If FLASH_MODE_SCREEN is used without a a non-null ScreenFlash instance set.

See also
ViewPort

toString

public @NonNull String toString()