ptolemy.actor.lib.jjs.modules.cameras

Class CameraHelper

java.lang.Object

ptolemy.actor.lib.jjs.HelperBase

ptolemy.actor.lib.jjs.modules.cameras.CameraHelper

All Implemented Interfaces:

com.github.sarxos.webcam.WebcamListener

public class CameraHelper
extends HelperBase
implements com.github.sarxos.webcam.WebcamListener

Helper for the cameras JavaScript module. This is based on the webcam-capture package by Bartosz Firyn (SarXos), available from: https://github.com/sarxos/webcam-capture.

Note that you can use the Ptolemy II ImageDisplay actor to display image sequences captured using this module, but this does not work well when executed within Eclipse. In Eclipse, the Swing event thread blocks "waiting for: OGLRenderQueue$QueueFluher", and spends most of its time blocked rather than rendering. Hence, we do not get smooth video. Perhaps this is an Eclipse bug?

See the documentation for the JavaScript cameras module to see how to use this.

If invoking the constructor generates a message like:

  Caused by: java.lang.RuntimeException: Library 'OpenIMAJGrabber' was not loaded successfully from file '/tmp/BridJExtractedLibraries5717506824090765864/OpenIMAJGrabber.so'
  

Then under Red Hat Linux, install lib4l for 64-bit JVMs, run:

  sudo yum install libstdc++.x86_64
  

The way to diagnose these problems under Linux is to unjar the webcam-capture jar and run ldd:

  cd /tmp
  jar -xf $PTII/lib/webcam-capture-0.3.12.jar
  ldd ./com/github/sarxos/webcam/ds/buildin/lib/linux_x64/OpenIMAJGrabber.so
  

Note that the webcam-capture jar contains both 32-bit and 64-bit shared libraries, be sure to run the ldd command on the version appropriate for your JVM.

Then look for libraries that are listed as "not found", then as root use yum search xxx to find them and then install them.

For example, if libv4l2.so.0 is not found, then run yum search v4l2 and if v4l2 is not installed, then yum install libv4l.x86_64.

Since:

Ptolemy II 11.0

Version:

$Id$

Author:

Edward A. Lee, Contributor: Christopher Brooks

Pt.AcceptedRating:

Red (cxh)

Pt.ProposedRating:

Yellow (eal)

Nested Class Summary

Nested classes/interfaces inherited from class ptolemy.actor.lib.jjs.HelperBase

HelperBase.DATA_TYPE

Field Summary

Fields inherited from class ptolemy.actor.lib.jjs.HelperBase

_actor, _currentObj

Constructor Summary

Constructors

Constructor and Description
CameraHelper(java.lang.Object actor, jdk.nashorn.api.scripting.ScriptObjectMirror currentObj) Create the system default camera.
CameraHelper(java.lang.Object actor, jdk.nashorn.api.scripting.ScriptObjectMirror currentObj, java.lang.String name) Create a camera with the specified name.

Method Summary

Modifier and Type	Method and Description
static java.lang.String[]	cameras() Return an array of camera names that are available on this host.
void	close() Close the camera.
static java.lang.String	defaultCamera() Return the system default camera name.
java.lang.String	getViewSize() Return the current view size for this camera, given as a JSON formatted string with fields "width" and "height", for example '{"width":176, "height":144}'.
void	open() Open the camera.
void	setViewSize(java.util.Map spec) Set the current view size for this camera, representing the desired size as a Map with integer valued fields "width" and "height".
AWTImageToken	snapshot() Return the most recent image obtained by the camera, or null if no image has been obtained.
java.lang.String[]	viewSizes() Return an array of view sizes supported by this camera, each given as a string of the form "width=176,height=144", for example.
void	webcamClosed(com.github.sarxos.webcam.WebcamEvent event) Notify this object that its camera has been closed.
void	webcamDisposed(com.github.sarxos.webcam.WebcamEvent event) Notify this object that its camera has been disposed.
void	webcamImageObtained(com.github.sarxos.webcam.WebcamEvent event) Notify this object that a new image has been obtained.
void	webcamOpen(com.github.sarxos.webcam.WebcamEvent event) Notify this object that its camera has been opened.

Methods inherited from class ptolemy.actor.lib.jjs.HelperBase

_appendNumericToBuffer, _appendToBuffer, _error, _error, _error, _error, _extractFromBuffer, _issueResponse, _removeDuplicates, _sizeOfType, _toJavaBytes, _toJSArray, getHelping

Methods inherited from class java.lang.Object

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

Constructor Detail

CameraHelper

public CameraHelper(java.lang.Object actor,
                    jdk.nashorn.api.scripting.ScriptObjectMirror currentObj)
             throws java.io.IOException

Create the system default camera. If the system does not have a physical camera, then the dummy is used.

Parameters:

actor - The actor associated with this camera.

currentObj - The JavaScript object that this is helping.

Throws:

java.io.IOException - If there is no such camera.

CameraHelper

public CameraHelper(java.lang.Object actor,
                    jdk.nashorn.api.scripting.ScriptObjectMirror currentObj,
                    java.lang.String name)
             throws java.io.IOException

Create a camera with the specified name. The name is required to be one of those returned by cameras(), or else a exception will be thrown. If cameras() returns no cameras, then the dummy camera is used.

Parameters:

name - The name of the camera.

actor - The actor associated with this camera.

currentObj - The JavaScript object that this is helping.

Throws:

java.io.IOException - If the camera does not exist.

Method Detail

cameras

public static java.lang.String[] cameras()

Return an array of camera names that are available on this host. This method refreshes the list. The dummy camera is for testing machine configurations that have no camera. Note that selecting the dummy camera typically disables any other cameras that may be present. This is because the WebcamDummyDriver is loaded and set as the default camera.

Returns:

A list of camera names, or null if there none.

close

public void close()

Close the camera.

defaultCamera

public static java.lang.String defaultCamera()

Return the system default camera name.

Returns:

The system default camera, or null if there aren't any.

getViewSize

public java.lang.String getViewSize()

Return the current view size for this camera, given as a JSON formatted string with fields "width" and "height", for example '{"width":176, "height":144}'.

Returns:

A string representing the current view size.

See Also:

setViewSize(Map)

open

public void open()

Open the camera. This starts a sequence of notifications that call webcamImageObtained() and trigger emission of the "image" event for the corresponding JavaScript object.

setViewSize

public void setViewSize(java.util.Map spec)
                 throws IllegalActionException

Set the current view size for this camera, representing the desired size as a Map with integer valued fields "width" and "height".

Parameters:

spec - A map with integer valued fields "width" and "height".

Throws:

IllegalActionException - If either field is absent.

See Also:

getViewSize()

snapshot

public AWTImageToken snapshot()

Return the most recent image obtained by the camera, or null if no image has been obtained.

Returns:

A Ptolemy II token containing the image, or null if there is no image to return.

viewSizes

public java.lang.String[] viewSizes()

Return an array of view sizes supported by this camera, each given as a string of the form "width=176,height=144", for example.

Returns:

An array of strings representing available view sizes.

webcamClosed

public void webcamClosed(com.github.sarxos.webcam.WebcamEvent event)

Notify this object that its camera has been closed.

Specified by:

webcamClosed in interface com.github.sarxos.webcam.WebcamListener

Parameters:

event - The event that closed the camera.

webcamDisposed

public void webcamDisposed(com.github.sarxos.webcam.WebcamEvent event)

Notify this object that its camera has been disposed.

Specified by:

webcamDisposed in interface com.github.sarxos.webcam.WebcamListener

Parameters:

event - The event that disposed the camera.

webcamImageObtained

public void webcamImageObtained(com.github.sarxos.webcam.WebcamEvent event)

Notify this object that a new image has been obtained. This causes the associated JavaScript Camera object to emit an "image" event with the image as an argument.

Specified by:

webcamImageObtained in interface com.github.sarxos.webcam.WebcamListener

Parameters:

event - The event of obtaining the image.

webcamOpen

public void webcamOpen(com.github.sarxos.webcam.WebcamEvent event)

Notify this object that its camera has been opened.

Specified by:

webcamOpen in interface com.github.sarxos.webcam.WebcamListener

Parameters:

event - The event that opened the camera.