jadomican.a4thyearproject.camera

Class CameraSource

java.lang.Object

jadomican.a4thyearproject.camera.CameraSource

public class CameraSource
extends java.lang.Object

Classes to manage the camera in conjunction with an underlying Mobile Vision detector. The camera source used attempts to balance processing as many preview frames as possible while also minimising lag. Some frames may be dropped to maintain a lag-free user experience, depending on the capabilities of the device's camera. Adapted from Google Mobile Vision tutorials available at: https://codelabs.developers.google.com/codelabs/mobile-vision-ocr/

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CameraSource.AutoFocusCallback Callback interface used to notify on completion of camera auto focus.
static interface	CameraSource.AutoFocusMoveCallback Callback interface used to notify on auto focus start and stop.
static class	CameraSource.Builder Builder class for configuring and creating an associated camera source.
static interface	CameraSource.PictureCallback Callback interface used to supply image data from a photo capture.
static interface	CameraSource.ShutterCallback Callback interface used to signal the moment of actual image capture.

Field Summary

Fields

Modifier and Type	Field and Description
static int	CAMERA_FACING_BACK
static int	CAMERA_FACING_FRONT

Method Summary

Modifier and Type	Method and Description
void	autoFocus(CameraSource.AutoFocusCallback cb) Starts camera auto-focus and registers a callback function to run when the camera is focused.
void	cancelAutoFocus() Cancels any auto-focus function in progress.
int	doZoom(float scale)
int	getCameraFacing() Returns the selected camera; one of CAMERA_FACING_BACK or CAMERA_FACING_FRONT.
java.lang.String	getFlashMode() Gets the current flash mode setting.
java.lang.String	getFocusMode() Gets the current focus mode setting.
com.google.android.gms.common.images.Size	getPreviewSize() Returns the preview size that is currently in use by the underlying camera.
void	release() Stops the camera and releases the resources of the camera and underlying detector.
boolean	setAutoFocusMoveCallback(CameraSource.AutoFocusMoveCallback cb) Sets camera auto-focus move callback.
boolean	setFlashMode(java.lang.String mode) Sets the flash mode.
boolean	setFocusMode(java.lang.String mode) Sets the focus mode.
CameraSource	start() Opens the camera and starts sending preview frames to the underlying detector.
CameraSource	start(android.view.SurfaceHolder surfaceHolder) Opens the camera and starts sending preview frames to the underlying detector.
void	stop() Closes the camera and stops sending frames to the underlying frame detector.
void	takePicture(CameraSource.ShutterCallback shutter, CameraSource.PictureCallback jpeg) Initiates taking a picture, which happens asynchronously.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CAMERA_FACING_BACK

public static final int CAMERA_FACING_BACK

See Also:

Constant Field Values

CAMERA_FACING_FRONT

public static final int CAMERA_FACING_FRONT

See Also:

Constant Field Values

Method Detail

release

public void release()

Stops the camera and releases the resources of the camera and underlying detector.

start

public CameraSource start()
                   throws java.io.IOException,
                          java.lang.SecurityException

Opens the camera and starts sending preview frames to the underlying detector. The preview frames are not displayed.

Throws:

java.io.IOException - if the camera's preview texture or display could not be initialized

java.lang.SecurityException

start

public CameraSource start(android.view.SurfaceHolder surfaceHolder)
                   throws java.io.IOException,
                          java.lang.SecurityException

Opens the camera and starts sending preview frames to the underlying detector. The surface holder utilises a SurfaceView, which is similar to a regular View object, but can be rendered on a separate GUI thread, allowing for faster processing. Used in this project for the camera preview which must be updated rapidly as a user scans text.

Throws:

java.io.IOException - if the supplied surface holder could not be used as the preview display

java.lang.SecurityException

stop

public void stop()

Closes the camera and stops sending frames to the underlying frame detector.

This camera source may be restarted again by calling start() or start(SurfaceHolder).

Call release() instead to completely shut down this camera source and release the resources of the underlying detector.

getPreviewSize

public com.google.android.gms.common.images.Size getPreviewSize()

Returns the preview size that is currently in use by the underlying camera.

getCameraFacing

public int getCameraFacing()

Returns the selected camera; one of CAMERA_FACING_BACK or CAMERA_FACING_FRONT.

doZoom

public int doZoom(float scale)

takePicture

public void takePicture(CameraSource.ShutterCallback shutter,
                        CameraSource.PictureCallback jpeg)

Initiates taking a picture, which happens asynchronously. The camera source should have been activated previously with start() or start(SurfaceHolder). The camera preview is suspended while the picture is being taken, but will resume once picture taking is done.

Parameters:

shutter - the callback for image capture moment, or null

jpeg - the callback for JPEG image data, or null

getFocusMode

@Nullable
public java.lang.String getFocusMode()

Gets the current focus mode setting.

Returns:

current focus mode. This value is null if the camera is not yet created. Applications should call autoFocus(AutoFocusCallback) to start the focus if focus mode is FOCUS_MODE_AUTO or FOCUS_MODE_MACRO.

See Also:

Camera.Parameters#FOCUS_MODE_AUTO, Camera.Parameters#FOCUS_MODE_INFINITY, Camera.Parameters#FOCUS_MODE_MACRO, Camera.Parameters#FOCUS_MODE_FIXED, Camera.Parameters#FOCUS_MODE_EDOF, Camera.Parameters#FOCUS_MODE_CONTINUOUS_VIDEO, Camera.Parameters#FOCUS_MODE_CONTINUOUS_PICTURE

setFocusMode

public boolean setFocusMode(java.lang.String mode)

Sets the focus mode.

Parameters:

mode - the focus mode

Returns:

true if the focus mode is set, false otherwise

See Also:

getFocusMode()

getFlashMode

@Nullable
public java.lang.String getFlashMode()

Gets the current flash mode setting.

Returns:

current flash mode. null if flash mode setting is not supported or the camera is not yet created.

See Also:

Camera.Parameters#FLASH_MODE_OFF, Camera.Parameters#FLASH_MODE_AUTO, Camera.Parameters#FLASH_MODE_ON, Camera.Parameters#FLASH_MODE_RED_EYE, Camera.Parameters#FLASH_MODE_TORCH

setFlashMode

public boolean setFlashMode(java.lang.String mode)

Sets the flash mode.

Parameters:

mode - flash mode.

Returns:

true if the flash mode is set, false otherwise

See Also:

getFlashMode()

autoFocus

public void autoFocus(@Nullable
                      CameraSource.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 start() or start(SurfaceHolder) and before stop() or release()).

Callers should check getFocusMode() to determine if this method should be called. If the camera does not support auto-focus, it is a no-op and CameraSource.AutoFocusCallback.onAutoFocus(boolean) callback will be called immediately.

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.

Parameters:

cb - the callback to run

See Also:

cancelAutoFocus()

cancelAutoFocus

public 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.

See Also:

autoFocus(AutoFocusCallback)

setAutoFocusMoveCallback

public boolean setAutoFocusMoveCallback(@Nullable
                                        CameraSource.AutoFocusMoveCallback cb)

Sets camera auto-focus move callback.

Parameters:

cb - the callback to run

Returns:

true if the operation is supported (i.e. from Jelly Bean), false otherwise