CameraView

Kotlin |Java

class CameraView : FrameLayout

kotlin.Any
↳	android.view.View
	↳	android.view.ViewGroup
		↳	android.widget.FrameLayout
			↳	androidx.camera.view.CameraView

A View that displays a preview of the camera with methods , takePicture(ImageCapture.OutputFileOptions, Executor, OnImageSavedCallback), startRecording(File , Executor , OnVideoSavedCallback callback) and stopRecording().

Because the Camera is a limited resource and consumes a high amount of power, CameraView must be opened/closed. CameraView will handle opening/closing automatically through use of a . Use bindToLifecycle(LifecycleOwner) to start the camera.

Summary

Nested classes
	CaptureMode The capture mode used by CameraView.

Public constructors
<init>(@NonNull context: Context)
<init>(@NonNull context: Context, @Nullable attrs: AttributeSet?)
<init>(@NonNull context: Context, @Nullable attrs: AttributeSet?, defStyle: Int)
<init>(@NonNull context: Context, @Nullable attrs: AttributeSet?, defStyleAttr: Int, defStyleRes: Int)

Public methods
Unit	bindToLifecycle(@NonNull lifecycleOwner: LifecycleOwner) Binds control of the camera used by this view to the given lifecycle.
Unit	enableTorch(torch: Boolean) Turns on/off torch.
Int?	getCameraLensFacing() Returns the currently selected lensFacing.
CameraView.CaptureMode	getCaptureMode() Returns the scale type used to scale the preview.
Int	getFlash() Gets the active flash strategy.
Float	getMaxZoomRatio() Returns the maximum zoom ratio.
Float	getMinZoomRatio() Returns the minimum zoom ratio.
LiveData<PreviewView.StreamState!>	getPreviewStreamState() Gets the LiveData of the underlying PreviewView's PreviewView.StreamState.
PreviewView.ScaleType	getScaleType() Returns the scale type used to scale the preview.
Float	getZoomRatio() Returns the current zoom ratio.
Boolean	hasCameraWithLensFacing(lensFacing: Int) Queries whether the current device has a camera with the specified direction.
Boolean	isPinchToZoomEnabled() Returns whether the view allows pinch-to-zoom.
Boolean	isRecording()
Boolean	isTorchOn() Returns current torch status.
Boolean	isZoomSupported() Returns whether the bound camera supports zooming.
Boolean	onTouchEvent(@NonNull event: MotionEvent)
Boolean	performClick() Focus the position of the touch event, or focus the center of the preview for accessibility events
Unit	setCameraLensFacing(@Nullable lensFacing: Int?) Sets the desired camera by specifying desired lensFacing.
Unit	setCaptureMode(@NonNull captureMode: CameraView.CaptureMode) Sets the CameraView capture mode
Unit	setFlash(flashMode: Int) Sets the active flash strategy.
Unit	setPinchToZoomEnabled(enabled: Boolean) Sets whether the view should allow pinch-to-zoom.
Unit	setScaleType(@NonNull scaleType: PreviewView.ScaleType) Sets the view finder scale type.
Unit	setZoomRatio(zoomRatio: Float) Sets the current zoom ratio.
Unit	startRecording(@NonNull file: File, @NonNull executor: Executor, @NonNull callback: OnVideoSavedCallback) Takes a video and calls the OnVideoSavedCallback when done.
Unit	stopRecording() Stops an in progress video.
Unit	takePicture(@NonNull executor: Executor, @NonNull callback: ImageCapture.OnImageCapturedCallback) Takes a picture, and calls OnImageCapturedCallback#onCaptureSuccess(ImageProxy) once when done.
Unit	takePicture(@NonNull outputFileOptions: ImageCapture.OutputFileOptions, @NonNull executor: Executor, @NonNull callback: ImageCapture.OnImageSavedCallback) Takes a picture and calls OnImageSavedCallback#onImageSaved(ImageCapture.OutputFileResults) when done.
Unit	toggleCamera() Toggles between the primary front facing camera and the primary back facing camera.

Protected methods
LayoutParams	generateDefaultLayoutParams()
Unit	onAttachedToWindow()
Unit	onDetachedFromWindow()
Unit	onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int)
Unit	onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int)
Unit	onRestoreInstanceState(@Nullable savedState: Parcelable?)
Parcelable	onSaveInstanceState()

Public constructors

<init>

CameraView(@NonNull context: Context)

<init>

CameraView(
    @NonNull context: Context, 
    @Nullable attrs: AttributeSet?)

<init>

CameraView(
    @NonNull context: Context, 
    @Nullable attrs: AttributeSet?, 
    defStyle: Int)

<init>

CameraView(
    @NonNull context: Context, 
    @Nullable attrs: AttributeSet?, 
    defStyleAttr: Int, 
    defStyleRes: Int)

Public methods

bindToLifecycle

@RequiresPermission("android.permission.CAMERA") fun bindToLifecycle(@NonNull lifecycleOwner: LifecycleOwner): Unit

Binds control of the camera used by this view to the given lifecycle.

This links opening/closing the camera to the given lifecycle. The camera will not operate unless this method is called with a valid LifecycleOwner that is not in the state. Call this method only once camera permissions have been obtained.

Once the provided lifecycle has transitioned to a state, CameraView must be bound to a new lifecycle through this method in order to operate the camera.

Parameters
lifecycleOwner	LifecycleOwner: The lifecycle that will control this view's camera

Exceptions
IllegalArgumentException	if provided lifecycle is in a state.
IllegalStateException	if camera permissions are not granted.

enableTorch

fun enableTorch(torch: Boolean): Unit

Turns on/off torch.

Parameters
torch	Boolean: True to turn on torch, false to turn off torch.

getCameraLensFacing

@Nullable fun getCameraLensFacing(): Int?

Returns the currently selected lensFacing.

getCaptureMode

@NonNull fun getCaptureMode(): CameraView.CaptureMode

Returns the scale type used to scale the preview.

Return
CameraView.CaptureMode	The current CaptureMode.

getFlash

fun getFlash(): Int

Gets the active flash strategy.

getMaxZoomRatio

fun getMaxZoomRatio(): Float

Returns the maximum zoom ratio.

The zoom ratio corresponds to the ratio between both the widths and heights of a non-zoomed image and a maximally zoomed image for the selected camera.

Return
Float	The maximum zoom ratio.

getMinZoomRatio

fun getMinZoomRatio(): Float

Returns the minimum zoom ratio.

For most cameras this should return a zoom ratio of 1. A zoom ratio of 1 corresponds to a non-zoomed image.

Return
Float	The minimum zoom ratio.

getPreviewStreamState

@NonNull fun getPreviewStreamState(): LiveData<PreviewView.StreamState!>

Gets the LiveData of the underlying PreviewView's PreviewView.StreamState.

Return
LiveData<PreviewView.StreamState!>	A LiveData containing the PreviewView.StreamState. Apps can either get current value by LiveData#getValue() or register a observer by LiveData#observe.

See Also

• PreviewView#getPreviewStreamState()

getScaleType

@NonNull fun getScaleType(): PreviewView.ScaleType

Returns the scale type used to scale the preview.

Return
PreviewView.ScaleType	The current PreviewView.ScaleType.

getZoomRatio

fun getZoomRatio(): Float

Returns the current zoom ratio.

Return
Float	The current zoom ratio.

hasCameraWithLensFacing

@RequiresPermission("android.permission.CAMERA") fun hasCameraWithLensFacing(lensFacing: Int): Boolean

Queries whether the current device has a camera with the specified direction.

Return
Boolean	True if the device supports the direction.

Exceptions
IllegalStateException	if the CAMERA permission is not currently granted.

isPinchToZoomEnabled

fun isPinchToZoomEnabled(): Boolean

Returns whether the view allows pinch-to-zoom.

Return
Boolean	True if pinch to zoom is enabled.

isRecording

fun isRecording(): Boolean

Return
Boolean	True if currently recording.

isTorchOn

fun isTorchOn(): Boolean

Returns current torch status.

Return
Boolean	true if torch is on , otherwise false

isZoomSupported

fun isZoomSupported(): Boolean

Returns whether the bound camera supports zooming.

Return
Boolean	True if the camera supports zooming.

onTouchEvent

fun onTouchEvent(@NonNull event: MotionEvent): Boolean

performClick

fun performClick(): Boolean

Focus the position of the touch event, or focus the center of the preview for accessibility events

setCameraLensFacing

fun setCameraLensFacing(@Nullable lensFacing: Int?): Unit

Sets the desired camera by specifying desired lensFacing.

This will choose the primary camera with the specified camera lensFacing.

If called before bindToLifecycle(LifecycleOwner), this will set the camera to be used when first bound to the lifecycle. If the specified lensFacing is not supported by the device, as determined by hasCameraWithLensFacing(int), the first supported lensFacing will be chosen when bindToLifecycle(LifecycleOwner) is called.

If called with null AFTER binding to the lifecycle, the behavior would be equivalent to unbind the use cases without the lifecycle having to be destroyed.

Parameters
lensFacing	Int?: The desired camera lensFacing.

setCaptureMode

fun setCaptureMode(@NonNull captureMode: CameraView.CaptureMode): Unit

Sets the CameraView capture mode

This controls only image or video capture function is enabled or both are enabled.

Parameters
captureMode	CameraView.CaptureMode: The desired CaptureMode.

setFlash

fun setFlash(flashMode: Int): Unit

Sets the active flash strategy.

setPinchToZoomEnabled

fun setPinchToZoomEnabled(enabled: Boolean): Unit

Sets whether the view should allow pinch-to-zoom.

When enabled, the user can pinch the camera to zoom in/out. This only has an effect if the bound camera supports zoom.

Parameters
enabled	Boolean: True to enable pinch-to-zoom.

setScaleType

fun setScaleType(@NonNull scaleType: PreviewView.ScaleType): Unit

Sets the view finder scale type.

This controls how the view finder should be scaled and positioned within the view.

Parameters
scaleType	PreviewView.ScaleType: The desired PreviewView.ScaleType.

setZoomRatio

fun setZoomRatio(zoomRatio: Float): Unit

Sets the current zoom ratio.

Valid zoom values range from getMinZoomRatio() to getMaxZoomRatio().

Parameters
zoomRatio	Float: The requested zoom ratio.

startRecording

fun startRecording(
    @NonNull file: File, 
    @NonNull executor: Executor, 
    @NonNull callback: OnVideoSavedCallback
): Unit

Takes a video and calls the OnVideoSavedCallback when done.

Parameters
file	File: The destination.
executor	Executor: The executor in which the callback methods will be run.
callback	OnVideoSavedCallback: Callback which will receive success or failure.

stopRecording

fun stopRecording(): Unit

Stops an in progress video.

takePicture

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

Takes a picture, and calls OnImageCapturedCallback#onCaptureSuccess(ImageProxy) once when done.

Parameters
executor	Executor: The executor in which the callback methods will be run.
callback	ImageCapture.OnImageCapturedCallback: Callback which will receive success or failure callbacks.

takePicture

fun takePicture(
    @NonNull outputFileOptions: ImageCapture.OutputFileOptions, 
    @NonNull executor: Executor, 
    @NonNull callback: ImageCapture.OnImageSavedCallback
): Unit

Takes a picture and calls OnImageSavedCallback#onImageSaved(ImageCapture.OutputFileResults) when done.

The value of ImageCapture.Metadata#isReversedHorizontal() in the ImageCapture.OutputFileOptions will be overwritten based on camera direction. For front camera, it will be set to true; for back camera, it will be set to false.

Parameters
outputFileOptions	ImageCapture.OutputFileOptions: Options to store the newly captured image.
executor	Executor: The executor in which the callback methods will be run.
callback	ImageCapture.OnImageSavedCallback: Callback which will receive success or failure.

toggleCamera

fun toggleCamera(): Unit

Toggles between the primary front facing camera and the primary back facing camera.

This will have no effect if not already bound to a lifecycle via .

Protected methods

generateDefaultLayoutParams

@NonNull protected fun generateDefaultLayoutParams(): LayoutParams

onAttachedToWindow

protected fun onAttachedToWindow(): Unit

onDetachedFromWindow

protected fun onDetachedFromWindow(): Unit

onLayout

protected fun onLayout(
    changed: Boolean, 
    left: Int, 
    top: Int, 
    right: Int, 
    bottom: Int
): Unit

onMeasure

protected fun onMeasure(
    widthMeasureSpec: Int, 
    heightMeasureSpec: Int
): Unit

onRestoreInstanceState

protected fun onRestoreInstanceState(@Nullable savedState: Parcelable?): Unit

onSaveInstanceState

@NonNull protected fun onSaveInstanceState(): Parcelable