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Class com.ibm.imageprocessing.EdgeDetectionFilter

java.lang.Object
   |
   +----com.ibm.imageprocessing.ImageProcessing
           |
           +----com.ibm.imageprocessing.EdgeDetectionFilter

public class EdgeDetectionFilter
extends ImageProcessing
This class is a concrete implementation of an ImageProcessing abstract class and provides the EdgeDetection Filtering facility. The Edge Detection filter detects discontinuities in gray level (intensity of a pixel) of an image thus producing the outline.

This class provides the concrete implementation of the startProcessing method in its base class. In this method, the edge detection filtering of the original image is done and processing events are fired to indicate the status of the processing the image.

This class uses one extended java.awt.image.ImageFilter class for filtering operation. This extended filter is available by the getImageFilter method, which can be used in the context of producer/filter/consumer paradigm and java.awt.image.FilteredImageSource can be used to take the advantage of it. For example:

      java.awt.Canvas c = new java.awt.Canvas();
      EdgeDetectionFilter edf = new EdgeDetectionFilter();
      java.awt.ImageFilter filter = edf.getImageFilter();
      java.awt.Image image = Toolkit.getDefaultToolkit().
                                          getImage("c:\\apple.gif");
      .....
      // use java.awt.MediaTracker or any other technique to load the image
      ....
      FilteredImageSource producer =new FilteredImageSource(image.getSource()
                                                                   , filter);
      java.awt.Image processedImage = c.createImage(producer);
 
There is one more way to do the filtering operation. This will be particularly useful if this class is used as a bean in an IDE and is wired to other beans to do the filtering.
      EdgeDetectionFilter edf = new EdgeDetectionFilter();
      // if FetchArgumentsEvent is used for setting the input image
      // or any control property, autoAction property should be set to false. 
      // otherwise there can be an infinite loop.  
      edf.triggerAction();
      // since the triggerAction method fires FetchArgumentsEvent, 
      // on receiving this event the input image for this bean is set using 
      // setInputImage method of this bean. When the processing
      // is over,the processed image can be retrieved using getResult
      // method.
      java.awt.Image processedImage = edf.getResult();
 

See Also:
ImageFilter, ImageProcessing, ProcessingEvent, ProcessingListener, ProcessingErrorEvent, ProcessingErrorListener, ImageProcessedEvent, ImageProcessedListener

Variable Index

 o NOTIFY_USER
Variable to be used for either notifying the user about the error messages or not

Constructor Index

 o EdgeDetectionFilter()
The default constructor.

Method Index

 o addImageProcessedListener(ImageProcessedListener)
Adds an ImageProcessedListener to the listener list.
 o addProcessingErrorListener(ProcessingErrorListener)
Adds a ProcessingErrorListener to the listener list.
 o addProcessingListener(ProcessingListener)
Adds a ProcessingListener to the listener list.
 o getImageFilter()
Returns the filter used by this class.
 o getResult()
Returns a processed image.
 o removeImageProcessedListener(ImageProcessedListener)
Removes an ImageProcessedListener from the listener list.
 o removeProcessingErrorListener(ProcessingErrorListener)
Removes a ProcessingErrorListener from the listener list.
 o removeProcessingListener(ProcessingListener)
Removes a ProcessingListener from the listener list.
 o setInputImage(Image)
Sets an inputImage to be processed by this class.
 o startProcessing()
Processes an input image and various events are fired to indicate the status of processing of the image.

Variables

 o NOTIFY_USER
 public boolean NOTIFY_USER
Variable to be used for either notifying the user about the error messages or not

Constructors

 o EdgeDetectionFilter
 public EdgeDetectionFilter()
The default constructor.

Methods

 o getResult
 public Image getResult()
Returns a processed image.

Returns:
the processed image
 o setInputImage
 public void setInputImage(Image inputImage)
Sets an inputImage to be processed by this class. If the processing flag is true , this method returns without setting the input image. If the processing flag is false, this method sets the input image and calls evaluate if autoAction is set to true. If the input argument is null and the debug flag is true, IllegalArgumentException will be thrown, else the null value will be set as the input argument and no exception will be thrown.

Parameters:
inputImage - The inputImage to be processed
Throws: IllegalArgumentException
if the passed value is null
See Also:
Image, processing, evaluate
 o getImageFilter
 public ImageFilter getImageFilter()
Returns the filter used by this class. This filter extends from java.awt.image.ImageFilter and can be used as the second argument of the constructor of the java.awt.image.FilteredImageSource class. This method is provided so that this class can be used in the context of producer/filter/consumer paradigm also . This method also facilitates the use of beans as simple classes ( instead of wiring them in IDEs).

Returns:
the image filter used by this class to do the filtering
See Also:
ImageFilter
 o addImageProcessedListener
 public synchronized void addImageProcessedListener(ImageProcessedListener listener)
Adds an ImageProcessedListener to the listener list.

Parameters:
listener - ImageProcessedListener to be added
Throws: IllegalArgumentException
if the passed value is null
See Also:
ImageProcessedListener, removeImageProcessedListener
 o removeImageProcessedListener
 public synchronized void removeImageProcessedListener(ImageProcessedListener listener)
Removes an ImageProcessedListener from the listener list.

Parameters:
listener - ImageProcessedListener to be removed
Throws: IllegalArgumentException
if the passed value is null
See Also:
ImageProcessedListener, addImageProcessedListener
 o addProcessingListener
 public synchronized void addProcessingListener(ProcessingListener listener)
Adds a ProcessingListener to the listener list.

Parameters:
listener - ProcessingListener to be added
Throws: IllegalArgumentException
if the passed value is null
See Also:
ProcessingListener, removeProcessingListener
 o removeProcessingListener
 public synchronized void removeProcessingListener(ProcessingListener listener)
Removes a ProcessingListener from the listener list.

Parameters:
listener - ProcessingListener to be removed
Throws: IllegalArgumentException
if the passed value is null
See Also:
ProcessingListener, addProcessingListener
 o addProcessingErrorListener
 public synchronized void addProcessingErrorListener(ProcessingErrorListener listener)
Adds a ProcessingErrorListener to the listener list.

Parameters:
listener - ProcessingErrorListener to be added
Throws: IllegalArgumentException
if the passed value is null
See Also:
ProcessingErrorListener, removeProcessingErrorListener
 o removeProcessingErrorListener
 public synchronized void removeProcessingErrorListener(ProcessingErrorListener listener)
Removes a ProcessingErrorListener from the listener list.

Parameters:
listener - ProcessingErrorListener to be removed
Throws: IllegalArgumentException
if the passed value is null
See Also:
ProcessingErrorListener, addProcessingErrorListener
 o startProcessing
 protected void startProcessing()
Processes an input image and various events are fired to indicate the status of processing of the image. It fires processingStarted event initially.Then it waits for an image to be loaded. If the image has been successfully loaded ( meaning that no ProcessingErrorEvent event is fired), the image is filtered and the processed image is stored as a result. If there is any error in processing ( which includes grabbing pixels for result image) it fires the ProcessingErrorEvent event and returns. If the processing is successfully completed it fires the processingOver and ImageProcessedEvent events. The old result is also stored. It then compares the new result with the old result. If they are different, the PropertyChangeEvent event is fired. If the debug flag is true and inputImage is null, NullPointerException will be thrown. If the debug flag is false and inputImage is null, the result will be set to null and all the required events will be thrown.

Throws: NullPointerException
if input image is null
Overrides:
startProcessing in class ImageProcessing
See Also:
processingStarted, processingOver, ProcessingErrorEvent, ImageProcessedEvent, PropertyChangeEvent

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