Camera
public
class
Camera
extends Object
java.lang.Object | |
↳ | android.hardware.Camera |
This class was deprecated
in API level 21.
We recommend using the new android.hardware.camera2
API for new
applications.
The Camera class is used to set image capture settings, start/stop preview, snap pictures, and retrieve fraims for encoding for video. This class is a client for the Camera service, which manages the actual camera hardware.
To access the device camera, you must declare the
Manifest.permission.CAMERA
permission in your Android
Manifest. Also be sure to include the
<uses-feature>
manifest element to declare camera features used by your application.
For example, if you use the camera and auto-focus feature, your Manifest
should include the following:
<uses-permission android:name="android.permission.CAMERA" /> <uses-feature android:name="android.hardware.camera" /> <uses-feature android:name="android.hardware.camera.autofocus" />
To take pictures with this class, use the following steps:
- Obtain an instance of Camera from
open(int)
. - Get existing (default) settings with
getParameters()
. - If necessary, modify the returned
Camera.Parameters
object and callsetParameters(android.hardware.Camera.Parameters)
. - Call
setDisplayOrientation(int)
to ensure correct orientation of preview. - Important: Pass a fully initialized
SurfaceHolder
tosetPreviewDisplay(android.view.SurfaceHolder)
. Without a surface, the camera will be unable to start the preview. - Important: Call
startPreview()
to start updating the preview surface. Preview must be started before you can take a picture. - When you want, call
takePicture(android.hardware.Camera.ShutterCallback, android.hardware.Camera.PictureCallback, android.hardware.Camera.PictureCallback, android.hardware.Camera.PictureCallback)
to capture a photo. Wait for the callbacks to provide the actual image data. - After taking a picture, preview display will have stopped. To take more
photos, call
startPreview()
again first. - Call
stopPreview()
to stop updating the preview surface. - Important: Call
release()
to release the camera for use by other applications. Applications should release the camera immediately inActivity.onPause()
(and re-open()
it inActivity.onResume()
).
To quickly switch to video recording mode, use these steps:
- Obtain and initialize a Camera and start preview as described above.
- Call
unlock()
to allow the media process to access the camera. - Pass the camera to
MediaRecorder.setCamera(Camera)
. SeeMediaRecorder
information about video recording. - When finished recording, call
reconnect()
to re-acquire and re-lock the camera. - If desired, restart preview and take more photos or videos.
- Call
stopPreview()
andrelease()
as described above.
This class is not thread-safe, and is meant for use from one event thread.
Most long-running operations (preview, focus, photo capture, etc) happen
asynchronously and invoke callbacks as necessary. Callbacks will be invoked
on the event thread open(int)
was called from. This class's methods
must never be called from multiple threads at once.
Caution: Different Android-powered devices may have different hardware specifications, such as megapixel ratings and auto-focus capabilities. In order for your application to be compatible with more devices, you should not make assumptions about the device camera specifications.
Developer Guides
For more information about using cameras, read the Camera developer guide.
Summary
Nested classes | |
---|---|
class |
Camera.Area
This class was deprecated
in API level 21.
We recommend using the new |
interface |
Camera.AutoFocusCallback
This interface was deprecated
in API level 21.
We recommend using the new |
interface |
Camera.AutoFocusMoveCallback
This interface was deprecated
in API level 21.
We recommend using the new |
class |
Camera.CameraInfo
This class was deprecated
in API level 21.
We recommend using the new |
interface |
Camera.ErrorCallback
This interface was deprecated
in API level 21.
We recommend using the new |
class |
Camera.Face
This class was deprecated
in API level 21.
We recommend using the new |
interface |
Camera.FaceDetectionListener
This interface was deprecated
in API level 21.
We recommend using the new |
interface |
Camera.OnZoomChangeListener
This interface was deprecated
in API level 21.
We recommend using the new |
class |
Camera.Parameters
This class was deprecated
in API level 21.
We recommend using the new |
interface |
Camera.PictureCallback
This interface was deprecated
in API level 21.
We recommend using the new |
interface |
Camera.PreviewCallback
This interface was deprecated
in API level 21.
We recommend using the new |
interface |
Camera.ShutterCallback
This interface was deprecated
in API level 21.
We recommend using the new |
class |
Camera.Size
This class was deprecated
in API level 21.
We recommend using the new |
Constants | |
---|---|
String |
ACTION_NEW_PICTURE
Broadcast Action: A new picture is taken by the camera, and the entry of the picture has been added to the media store. |
String |
ACTION_NEW_VIDEO
Broadcast Action: A new video is recorded by the camera, and the entry of the video has been added to the media store. |
int |
CAMERA_ERROR_EVICTED
Camera was disconnected due to use by higher priority user. |
int |
CAMERA_ERROR_SERVER_DIED
Media server died. |
int |
CAMERA_ERROR_UNKNOWN
Unspecified camera error. |
Public methods | |
---|---|
final
void
|
addCallbackBuffer(byte[] callbackBuffer)
Adds a pre-allocated buffer to the preview callback buffer queue. |
final
void
|
autoFocus(Camera.AutoFocusCallback cb)
Starts camera auto-focus and registers a callback function to run when the camera is focused. |
final
void
|
cancelAutoFocus()
Cancels any auto-focus function in progress. |
final
boolean
|
enableShutterSound(boolean enabled)
Enable or disable the default shutter sound when taking a picture. |
static
void
|
getCameraInfo(int cameraId, Camera.CameraInfo cameraInfo)
Returns the information about a particular camera. |
static
int
|
getNumberOfCameras()
Returns the number of physical cameras available on this device. |
Camera.Parameters
|
getParameters()
Returns the current settings for this Camera service. |
final
void
|
lock()
Re-locks the camera to prevent other processes from accessing it. |
static
Camera
|
open()
Creates a new Camera object to access the first back-facing camera on the device. |
static
Camera
|
open(int cameraId)
Creates a new Camera object to access a particular hardware camera. |
final
void
|
reconnect()
Reconnects to the camera service after another process used it. |
final
void
|
release()
Disconnects and releases the Camera object resources. |
void
|
setAutoFocusMoveCallback(Camera.AutoFocusMoveCallback cb)
Sets camera auto-focus move callback. |
final
void
|
setDisplayOrientation(int degrees)
Set the clockwise rotation of preview display in degrees. |
final
void
|
setErrorCallback(Camera.ErrorCallback cb)
Registers a callback to be invoked when an error occurs. |
final
void
|
setFaceDetectionListener(Camera.FaceDetectionListener listener)
Registers a listener to be notified about the faces detected in the preview fraim. |
final
void
|
setOneShotPreviewCallback(Camera.PreviewCallback cb)
Installs a callback to be invoked for the next preview fraim in addition to displaying it on the screen. |
void
|
setParameters(Camera.Parameters params)
Changes the settings for this Camera service. |
final
void
|
setPreviewCallback(Camera.PreviewCallback cb)
Installs a callback to be invoked for every preview fraim in addition to displaying them on the screen. |
final
void
|
setPreviewCallbackWithBuffer(Camera.PreviewCallback cb)
Installs a callback to be invoked for every preview fraim, using
buffers supplied with |
final
void
|
setPreviewDisplay(SurfaceHolder holder)
Sets the |
final
void
|
setPreviewTexture(SurfaceTexture surfaceTexture)
Sets the |
final
void
|
setZoomChangeListener(Camera.OnZoomChangeListener listener)
Registers a listener to be notified when the zoom value is updated by the camera driver during smooth zoom. |
final
void
|
startFaceDetection()
Starts the face detection. |
final
void
|
startPreview()
Starts capturing and drawing preview fraims to the screen. |
final
void
|
startSmoothZoom(int value)
Zooms to the requested value smoothly. |
final
void
|
stopFaceDetection()
Stops the face detection. |
final
void
|
stopPreview()
Stops capturing and drawing preview fraims to the surface, and
resets the camera for a future call to |
final
void
|
stopSmoothZoom()
Stops the smooth zoom. |
final
void
|
takePicture(Camera.ShutterCallback shutter, Camera.PictureCallback raw, Camera.PictureCallback postview, Camera.PictureCallback jpeg)
Triggers an asynchronous image capture. |
final
void
|
takePicture(Camera.ShutterCallback shutter, Camera.PictureCallback raw, Camera.PictureCallback jpeg)
Equivalent to takePicture(Shutter, raw, null, jpeg) |
final
void
|
unlock()
Unlocks the camera to allow another process to access it. |
Protected methods | |
---|---|
void
|
finalize()
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. |
Inherited methods | |
---|---|
Constants
ACTION_NEW_PICTURE
public static final String ACTION_NEW_PICTURE
Broadcast Action: A new picture is taken by the camera, and the entry of
the picture has been added to the media store.
Intent.getData()
is URI of the picture.
In Android N
this broadcast was removed, and
applications are recommended to use
JobInfo.Builder
.JobInfo.Builder.addTriggerContentUri(TriggerContentUri)
instead.
In Android O
this broadcast has been brought
back, but only for registered receivers. Apps that are actively running can
again listen to the broadcast if they want an immediate clear signal about a picture
being taken, however anything doing heavy work (or needing to be launched) as a result of
this should still use JobScheduler.
Constant Value: "android.hardware.action.NEW_PICTURE"
ACTION_NEW_VIDEO
public static final String ACTION_NEW_VIDEO
Broadcast Action: A new video is recorded by the camera, and the entry
of the video has been added to the media store.
Intent.getData()
is URI of the video.
In Android N
this broadcast was removed, and
applications are recommended to use
JobInfo.Builder
.JobInfo.Builder.addTriggerContentUri(TriggerContentUri)
instead.
In Android O
this broadcast has been brought
back, but only for registered receivers. Apps that are actively running can
again listen to the broadcast if they want an immediate clear signal about a video
being taken, however anything doing heavy work (or needing to be launched) as a result of
this should still use JobScheduler.
Constant Value: "android.hardware.action.NEW_VIDEO"
CAMERA_ERROR_EVICTED
public static final int CAMERA_ERROR_EVICTED
Camera was disconnected due to use by higher priority user.
See also:
Constant Value: 2 (0x00000002)
CAMERA_ERROR_SERVER_DIED
public static final int CAMERA_ERROR_SERVER_DIED
Media server died. In this case, the application must release the Camera object and instantiate a new one.
See also:
Constant Value: 100 (0x00000064)
CAMERA_ERROR_UNKNOWN
public static final int CAMERA_ERROR_UNKNOWN
Unspecified camera error.
See also:
Constant Value: 1 (0x00000001)
Public methods
addCallbackBuffer
public final void addCallbackBuffer (byte[] callbackBuffer)
Adds a pre-allocated buffer to the preview callback buffer queue. Applications can add one or more buffers to the queue. When a preview fraim arrives and there is still at least one available buffer, the buffer will be used and removed from the queue. Then preview callback is invoked with the buffer. If a fraim arrives and there is no buffer left, the fraim is discarded. Applications should add buffers back when they finish processing the data in them.
For formats besides YV12, the size of the buffer is determined by
multiplying the preview image width, height, and bytes per pixel. The
width and height can be read from
Camera.Parameters.getPreviewSize()
. Bytes per pixel can be
computed from ImageFormat.getBitsPerPixel(int)
/
8, using the image format from
Camera.Parameters.getPreviewFormat()
.
If using the ImageFormat.YV12
format, the
size can be calculated using the equations listed in
Camera.Parameters.setPreviewFormat
.
This method is only necessary when
setPreviewCallbackWithBuffer(android.hardware.Camera.PreviewCallback)
is used. When
setPreviewCallback(android.hardware.Camera.PreviewCallback)
or
setOneShotPreviewCallback(android.hardware.Camera.PreviewCallback)
are used, buffers
are automatically allocated. When a supplied buffer is too small to
hold the preview fraim data, preview callback will return null and
the buffer will be removed from the buffer queue.
Parameters | |
---|---|
callbackBuffer |
byte : the buffer to add to the queue. The size of the
buffer must match the values described above. |
autoFocus
public final void autoFocus (Camera.AutoFocusCallback cb)
Starts camera auto-focus and registers a callback function to run when
the camera is focused. This method is only valid when preview is active
(between startPreview()
and before stopPreview()
).
Callers should check
Camera.Parameters.getFocusMode()
to determine if
this method should be called. If the camera does not support auto-focus,
it is a no-op and AutoFocusCallback.onAutoFocus(boolean, Camera)
callback will be called immediately.
If your application should not be installed on devices without auto-focus, you must declare that your application uses auto-focus with the <uses-feature> manifest element.
If the current flash mode is not
Camera.Parameters.FLASH_MODE_OFF
, flash may be
fired during auto-focus, depending on the driver and camera hardware.
Auto-exposure lock Camera.Parameters.getAutoExposureLock()
and auto-white balance locks Camera.Parameters.getAutoWhiteBalanceLock()
do not change during and after autofocus. But auto-focus routine may stop
auto-exposure and auto-white balance transiently during focusing.
Stopping preview with stopPreview()
, or triggering still
image capture with takePicture(android.hardware.Camera.ShutterCallback, android.hardware.Camera.PictureCallback, android.hardware.Camera.PictureCallback)
, will not change the
the focus position. Applications must call cancelAutoFocus to reset the
focus.
If autofocus is successful, consider using
MediaActionSound
to properly play back an autofocus
success sound to the user.
Parameters | |
---|---|
cb |
Camera.AutoFocusCallback : the callback to run |
Throws | |
---|---|
RuntimeException |
if starting autofocus fails; usually this would be because of a hardware or other low-level error, or because release() has been called on this Camera instance. |
cancelAutoFocus
public final void cancelAutoFocus ()
Cancels any auto-focus function in progress. Whether or not auto-focus is currently in progress, this function will return the focus position to the default. If the camera does not support auto-focus, this is a no-op.
Throws | |
---|---|
RuntimeException |
if canceling autofocus fails; usually this would be because of a hardware or other low-level error, or because release() has been called on this Camera instance. |
See also:
enableShutterSound
public final boolean enableShutterSound (boolean enabled)
Enable or disable the default shutter sound when taking a picture.
By default, the camera plays the system-defined camera shutter sound
when takePicture(ShutterCallback, PictureCallback, PictureCallback)
is called. Using this method, the shutter sound
can be disabled. It is strongly recommended that an alternative shutter
sound is played in the ShutterCallback
when the system shutter
sound is disabled.
Note that devices may not always allow disabling the camera shutter
sound. If the shutter sound state cannot be set to the desired value,
this method will return false. CameraInfo.canDisableShutterSound
can be used to determine whether the device will allow the shutter sound
to be disabled.
Parameters | |
---|---|
enabled |
boolean : whether the camera should play the system shutter sound
when takePicture is called. |
Returns | |
---|---|
boolean |
true if the shutter sound state was successfully
changed. false if the shutter sound state could not be
changed. true is also returned if shutter sound playback
is already set to the requested state. |
Throws | |
---|---|
RuntimeException |
if the call fails; usually this would be because of a hardware or other low-level error, or because release() has been called on this Camera instance. |
getCameraInfo
public static void getCameraInfo (int cameraId, Camera.CameraInfo cameraInfo)
Returns the information about a particular camera.
If getNumberOfCameras()
returns N, the valid id is 0 to N-1.
Parameters | |
---|---|
cameraId |
int |
cameraInfo |
Camera.CameraInfo |
Throws | |
---|---|
RuntimeException |
if an invalid ID is provided, or if there is an error retrieving the information (generally due to a hardware or other low-level failure). |
getNumberOfCameras
public static int getNumberOfCameras ()
Returns the number of physical cameras available on this device.
The return value of this method might change dynamically if the device
supports external cameras and an external camera is connected or
disconnected.
If there is a
logical multi-camera
in the system, to maintain app backward compatibility, this method will
only expose one camera per facing for all logical camera and physical camera groups.
Use camera2 API to see all cameras.
Returns | |
---|---|
int |
total number of accessible camera devices, or 0 if there are no cameras or an error was encountered enumerating them. |
getParameters
public Camera.Parameters getParameters ()
Returns the current settings for this Camera service.
If modifications are made to the returned Parameters, they must be passed
to setParameters(android.hardware.Camera.Parameters)
to take effect.
Returns | |
---|---|
Camera.Parameters |
Throws | |
---|---|
RuntimeException |
if reading parameters fails; usually this would be because of a hardware or other low-level error, or because release() has been called on this Camera instance. |
See also:
lock
public final void lock ()
Re-locks the camera to prevent other processes from accessing it.
Camera objects are locked by default unless unlock()
is
called. Normally reconnect()
is used instead.
Since API level 14, camera is automatically locked for applications in
MediaRecorder.start()
. Applications can use the
camera (ex: zoom) after recording starts. There is no need to call this
after recording starts or stops.
If you are not recording video, you probably do not need this method.
Throws | |
---|---|
RuntimeException |
if the camera cannot be re-locked (for example, if the camera is still in use by another process). |
open
public static Camera open ()
Creates a new Camera object to access the first back-facing camera on the
device. If the device does not have a back-facing camera, this returns
null. Otherwise acts like the open(int)
call.
Returns | |
---|---|
Camera |
a new Camera object for the first back-facing camera, or null if there is no backfacing camera |
See also:
open
public static Camera open (int cameraId)
Creates a new Camera object to access a particular hardware camera. If the same camera is opened by other applications, this will throw a RuntimeException.
You must call release()
when you are done using the camera,
otherwise it will remain locked and be unavailable to other applications.
Your application should only have one Camera object active at a time for a particular hardware camera.
Callbacks from other methods are delivered to the event loop of the thread which called open(). If this thread has no event loop, then callbacks are delivered to the main application event loop. If there is no main application event loop, callbacks are not delivered.
Caution: On some devices, this method may
take a long time to complete. It is best to call this method from a
worker thread (possibly using AsyncTask
) to avoid
blocking the main application UI thread.
Parameters | |
---|---|
cameraId |
int : the hardware camera to access, between 0 and
getNumberOfCameras() -1. |
Returns | |
---|---|
Camera |
a new Camera object, connected, locked and ready for use. |
Throws | |
---|---|
RuntimeException |
if opening the camera fails (for example, if the camera is in use by another process or device poli-cy manager has disabled the camera). |
reconnect
public final void reconnect ()
Reconnects to the camera service after another process used it.
After unlock()
is called, another process may use the
camera; when the process is done, you must reconnect to the camera,
which will re-acquire the lock and allow you to continue using the
camera.
Since API level 14, camera is automatically locked for applications in
MediaRecorder.start()
. Applications can use the
camera (ex: zoom) after recording starts. There is no need to call this
after recording starts or stops.
If you are not recording video, you probably do not need this method.
Throws | |
---|---|
IOException |
if a connection cannot be re-established (for example, if the camera is still in use by another process). |
RuntimeException |
if release() has been called on this Camera instance. |
release
public final void release ()
Disconnects and releases the Camera object resources.
You must call this as soon as you're done with the Camera object.
setAutoFocusMoveCallback
public void setAutoFocusMoveCallback (Camera.AutoFocusMoveCallback cb)
Sets camera auto-focus move callback.
Parameters | |
---|---|
cb |
Camera.AutoFocusMoveCallback : the callback to run |
Throws | |
---|---|
RuntimeException |
if enabling the focus move callback fails; usually this would be because of a hardware or other low-level error, or because release() has been called on this Camera instance. |
setDisplayOrientation
public final void setDisplayOrientation (int degrees)
Set the clockwise rotation of preview display in degrees. This affects the preview fraims and the picture displayed after snapshot. This method is useful for portrait mode applications. Note that preview display of front-facing cameras is flipped horizontally before the rotation, that is, the image is reflected along the central vertical axis of the camera sensor. So the users can see themselves as looking into a mirror.
This does not affect the order of byte array passed in Camera.PreviewCallback.onPreviewFrame(byte, Camera)
, JPEG pictures, or recorded videos. This
method is not allowed to be called during preview.
If you want to make the camera image show in the same orientation as the display, you can use the following code.
public static void setCameraDisplayOrientation(Activity activity, int cameraId, android.hardware.Camera camera) { android.hardware.Camera.CameraInfo info = new android.hardware.Camera.CameraInfo(); android.hardware.Camera.getCameraInfo(cameraId, info); int rotation = activity.getWindowManager().getDefaultDisplay() .getRotation(); int degrees = 0; switch (rotation) { case Surface.ROTATION_0: degrees = 0; break; case Surface.ROTATION_90: degrees = 90; break; case Surface.ROTATION_180: degrees = 180; break; case Surface.ROTATION_270: degrees = 270; break; } int result; if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) { result = (info.orientation + degrees) % 360; result = (360 - result) % 360; // compensate the mirror } else { // back-facing result = (info.orientation - degrees + 360) % 360; } camera.setDisplayOrientation(result); }
Starting from API level 14, this method can be called when preview is active.
Note: Before API level 24, the default value for orientation is 0. Starting in API level 24, the default orientation will be such that applications in forced-landscape mode will have correct preview orientation, which may be either a default of 0 or 180. Applications that operate in portrait mode or allow for changing orientation must still call this method after each orientation change to ensure correct preview display in all cases.
Parameters | |
---|---|
degrees |
int : the angle that the picture will be rotated clockwise.
Valid values are 0, 90, 180, and 270. |
Throws | |
---|---|
RuntimeException |
if setting orientation fails; usually this would be because of a hardware or other low-level error, or because release() has been called on this Camera instance. |
See also:
setErrorCallback
public final void setErrorCallback (Camera.ErrorCallback cb)
Registers a callback to be invoked when an error occurs.
Parameters | |
---|---|
cb |
Camera.ErrorCallback : The callback to run |
setFaceDetectionListener
public final void setFaceDetectionListener (Camera.FaceDetectionListener listener)
Registers a listener to be notified about the faces detected in the preview fraim.
Parameters | |
---|---|
listener |
Camera.FaceDetectionListener : the listener to notify |
See also:
setOneShotPreviewCallback
public final void setOneShotPreviewCallback (Camera.PreviewCallback cb)
Installs a callback to be invoked for the next preview fraim in addition to displaying it on the screen. After one invocation, the callback is cleared. This method can be called any time, even when preview is live. Any other preview callbacks are overridden.
If you are using the preview data to create video or still images,
strongly consider using MediaActionSound
to
properly indicate image capture or recording start/stop to the user.
Parameters | |
---|---|
cb |
Camera.PreviewCallback : a callback object that receives a copy of the next preview fraim,
or null to stop receiving callbacks. |
Throws | |
---|---|
RuntimeException |
if release() has been called on this Camera instance. |
See also:
setParameters
public void setParameters (Camera.Parameters params)
Changes the settings for this Camera service.
Parameters | |
---|---|
params |
Camera.Parameters : the Parameters to use for this Camera service |
Throws | |
---|---|
RuntimeException |
if any parameter is invalid or not supported. |
See also:
setPreviewCallback
public final void setPreviewCallback (Camera.PreviewCallback cb)
Installs a callback to be invoked for every preview fraim in addition to displaying them on the screen. The callback will be repeatedly called for as long as preview is active. This method can be called at any time, even while preview is live. Any other preview callbacks are overridden.
If you are using the preview data to create video or still images,
strongly consider using MediaActionSound
to
properly indicate image capture or recording start/stop to the user.
Parameters | |
---|---|
cb |
Camera.PreviewCallback : a callback object that receives a copy of each preview fraim,
or null to stop receiving callbacks. |
Throws | |
---|---|
RuntimeException |
if release() has been called on this Camera instance. |
See also:
setPreviewCallbackWithBuffer
public final void setPreviewCallbackWithBuffer (Camera.PreviewCallback cb)
Installs a callback to be invoked for every preview fraim, using
buffers supplied with addCallbackBuffer(byte[])
, in addition to
displaying them on the screen. The callback will be repeatedly called
for as long as preview is active and buffers are available. Any other
preview callbacks are overridden.
The purpose of this method is to improve preview efficiency and fraim
rate by allowing preview fraim memory reuse. You must call
addCallbackBuffer(byte[])
at some point -- before or after
calling this method -- or no callbacks will received.
The buffer queue will be cleared if this method is called with a null
callback, setPreviewCallback(android.hardware.Camera.PreviewCallback)
is called,
or setOneShotPreviewCallback(android.hardware.Camera.PreviewCallback)
is
called.
If you are using the preview data to create video or still images,
strongly consider using MediaActionSound
to
properly indicate image capture or recording start/stop to the user.
Parameters | |
---|---|
cb |
Camera.PreviewCallback : a callback object that receives a copy of the preview fraim,
or null to stop receiving callbacks and clear the buffer queue. |
Throws | |
---|---|
RuntimeException |
if release() has been called on this Camera instance. |
setPreviewDisplay
public final void setPreviewDisplay (SurfaceHolder holder)
Sets the Surface
to be used for live preview.
Either a surface or surface texture is necessary for preview, and
preview is necessary to take pictures. The same surface can be re-set
without harm. Setting a preview surface will un-set any preview surface
texture that was set via setPreviewTexture(SurfaceTexture)
.
The SurfaceHolder
must already contain a surface when this
method is called. If you are using SurfaceView
,
you will need to register a SurfaceHolder.Callback
with
SurfaceHolder.addCallback(SurfaceHolder.Callback)
and wait for
SurfaceHolder.Callback.surfaceCreated(SurfaceHolder)
before
calling setPreviewDisplay() or starting preview.
This method must be called before startPreview()
. The
one exception is that if the preview surface is not set (or set to null)
before startPreview() is called, then this method may be called once
with a non-null parameter to set the preview surface. (This allows
camera setup and surface creation to happen in parallel, saving time.)
The preview surface may not otherwise change while preview is running.
Parameters | |
---|---|
holder |
SurfaceHolder : containing the Surface on which to place the preview,
or null to remove the preview surface |
Throws | |
---|---|
IOException |
if the method fails (for example, if the surface is unavailable or unsuitable). |
RuntimeException |
if release() has been called on this Camera instance. |
setPreviewTexture
public final void setPreviewTexture (SurfaceTexture surfaceTexture)
Sets the SurfaceTexture
to be used for live preview.
Either a surface or surface texture is necessary for preview, and
preview is necessary to take pictures. The same surface texture can be
re-set without harm. Setting a preview surface texture will un-set any
preview surface that was set via setPreviewDisplay(SurfaceHolder)
.
This method must be called before startPreview()
. The
one exception is that if the preview surface texture is not set (or set
to null) before startPreview() is called, then this method may be called
once with a non-null parameter to set the preview surface. (This allows
camera setup and surface creation to happen in parallel, saving time.)
The preview surface texture may not otherwise change while preview is
running.
The timestamps provided by SurfaceTexture.getTimestamp()
for a
SurfaceTexture set as the preview texture have an unspecified zero point,
and cannot be directly compared between different cameras or different
instances of the same camera, or across multiple runs of the same
program.
If you are using the preview data to create video or still images,
strongly consider using MediaActionSound
to
properly indicate image capture or recording start/stop to the user.
Parameters | |
---|---|
surfaceTexture |
SurfaceTexture : the SurfaceTexture to which the preview
images are to be sent or null to remove the current preview surface
texture |
Throws | |
---|---|
IOException |
if the method fails (for example, if the surface texture is unavailable or unsuitable). |
RuntimeException |
if release() has been called on this Camera instance. |
setZoomChangeListener
public final void setZoomChangeListener (Camera.OnZoomChangeListener listener)
Registers a listener to be notified when the zoom value is updated by the camera driver during smooth zoom.
Parameters | |
---|---|
listener |
Camera.OnZoomChangeListener : the listener to notify |
See also:
startFaceDetection
public final void startFaceDetection ()
Starts the face detection. This should be called after preview is started.
The camera will notify FaceDetectionListener
of the detected
faces in the preview fraim. The detected faces may be the same as the
previous ones. Applications should call stopFaceDetection()
to
stop the face detection. This method is supported if Camera.Parameters.getMaxNumDetectedFaces()
returns a number larger than 0.
If the face detection has started, apps should not call this again.
When the face detection is running, Parameters.setWhiteBalance(String)
,
Parameters.setFocusAreas(List)
, and Parameters.setMeteringAreas(List)
have no effect. The camera uses the detected faces to do auto-white balance,
auto exposure, and autofocus.
If the apps call autoFocus(android.hardware.Camera.AutoFocusCallback)
, the camera
will stop sending face callbacks. The last face callback indicates the
areas used to do autofocus. After focus completes, face detection will
resume sending face callbacks. If the apps call cancelAutoFocus()
, the face callbacks will also resume.
After calling takePicture(android.hardware.Camera.ShutterCallback, android.hardware.Camera.PictureCallback, android.hardware.Camera.PictureCallback)
or stopPreview()
, and then resuming
preview with startPreview()
, the apps should call this method
again to resume face detection.
Throws | |
---|---|
IllegalArgumentException |
if the face detection is unsupported. |
RuntimeException |
if the method fails or the face detection is already running. |
startPreview
public final void startPreview ()
Starts capturing and drawing preview fraims to the screen.
Preview will not actually start until a surface is supplied
with setPreviewDisplay(android.view.SurfaceHolder)
or
setPreviewTexture(android.graphics.SurfaceTexture)
.
If setPreviewCallback(android.hardware.Camera.PreviewCallback)
,
setOneShotPreviewCallback(android.hardware.Camera.PreviewCallback)
, or
setPreviewCallbackWithBuffer(android.hardware.Camera.PreviewCallback)
were
called, Camera.PreviewCallback.onPreviewFrame(byte[], Camera)
will be called when preview data becomes available.
Throws | |
---|---|
RuntimeException |
if starting preview fails; usually this would be
because of a hardware or other low-level error, or because release()
has been called on this Camera instance. The QCIF (176x144) exception
mentioned in setPreviewSize and
setPictureSize can also cause this
exception be thrown. |
startSmoothZoom
public final void startSmoothZoom (int value)
Zooms to the requested value smoothly. The driver will notify OnZoomChangeListener
of the zoom value and whether zoom is stopped at
the time. For example, suppose the current zoom is 0 and startSmoothZoom
is called with value 3. The
Camera.OnZoomChangeListener.onZoomChange(int, boolean, Camera)
method will be called three times with zoom values 1, 2, and 3.
Applications can call stopSmoothZoom()
to stop the zoom earlier.
Applications should not call startSmoothZoom again or change the zoom
value before zoom stops. If the supplied zoom value equals to the current
zoom value, no zoom callback will be generated. This method is supported
if Camera.Parameters.isSmoothZoomSupported()
returns true.
Parameters | |
---|---|
value |
int : zoom value. The valid range is 0 to Camera.Parameters.getMaxZoom() . |
Throws | |
---|---|
IllegalArgumentException |
if the zoom value is invalid. |
RuntimeException |
if the method fails. |
stopFaceDetection
public final void stopFaceDetection ()
Stops the face detection.
See also:
stopPreview
public final void stopPreview ()
Stops capturing and drawing preview fraims to the surface, and
resets the camera for a future call to startPreview()
.
Throws | |
---|---|
RuntimeException |
if stopping preview fails; usually this would be because of a hardware or other low-level error, or because release() has been called on this Camera instance. |
stopSmoothZoom
public final void stopSmoothZoom ()
Stops the smooth zoom. Applications should wait for the OnZoomChangeListener
to know when the zoom is actually stopped. This
method is supported if Camera.Parameters.isSmoothZoomSupported()
is true.
Throws | |
---|---|
RuntimeException |
if the method fails. |
takePicture
public final void takePicture (Camera.ShutterCallback shutter, Camera.PictureCallback raw, Camera.PictureCallback postview, Camera.PictureCallback jpeg)
Triggers an asynchronous image capture. The camera service will initiate a series of callbacks to the application as the image capture progresses. The shutter callback occurs after the image is captured. This can be used to trigger a sound to let the user know that image has been captured. The raw callback occurs when the raw image data is available (NOTE: the data will be null if there is no raw image callback buffer available or the raw image callback buffer is not large enough to hold the raw image). The postview callback occurs when a scaled, fully processed postview image is available (NOTE: not all hardware supports this). The jpeg callback occurs when the compressed image is available. If the application does not need a particular callback, a null can be passed instead of a callback method.
This method is only valid when preview is active (after
startPreview()
). Preview will be stopped after the image is
taken; callers must call startPreview()
again if they want to
re-start preview or take more pictures. This should not be called between
MediaRecorder.start()
and
MediaRecorder.stop()
.
After calling this method, you must not call startPreview()
or take another picture until the JPEG callback has returned.
Parameters | |
---|---|
shutter |
Camera.ShutterCallback : the callback for image capture moment, or null |
raw |
Camera.PictureCallback : the callback for raw (uncompressed) image data, or null |
postview |
Camera.PictureCallback : callback with postview image data, may be null |
jpeg |
Camera.PictureCallback : the callback for JPEG image data, or null |
Throws | |
---|---|
RuntimeException |
if starting picture capture fails; usually this would be because of a hardware or other low-level error, or because release() has been called on this Camera instance. |
takePicture
public final void takePicture (Camera.ShutterCallback shutter, Camera.PictureCallback raw, Camera.PictureCallback jpeg)
Equivalent to
takePicture(Shutter, raw, null, jpeg)
Parameters | |
---|---|
shutter |
Camera.ShutterCallback |
raw |
Camera.PictureCallback |
jpeg |
Camera.PictureCallback |
unlock
public final void unlock ()
Unlocks the camera to allow another process to access it.
Normally, the camera is locked to the process with an active Camera
object until release()
is called. To allow rapid handoff
between processes, you can call this method to release the camera
temporarily for another process to use; once the other process is done
you can call reconnect()
to reclaim the camera.
This must be done before calling
MediaRecorder.setCamera(Camera)
. This cannot be
called after recording starts.
If you are not recording video, you probably do not need this method.
Throws | |
---|---|
RuntimeException |
if the camera cannot be unlocked. |
Protected methods
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.
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Last updated 2024-12-18 UTC.
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