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Class com.ibm.imageprocessing.TransparentFilter

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

public class TransparentFilter
extends ImageProcessing
This class is a concrete implementation of an ImageProcessing abstract class and provides transparency options for an image. TransparentFilter makes specified colors in the image to appear transparent by setting the transparency coefficients of those pixels to zero.

This class provides the concrete implementation of the startProcessing method in its base class. In this method, the filtering of the original image is done and processing events are fired to indicate the status of 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 the produces/filter/consumer paradigm, and java.awt.image.FilteredImageSource can be used to take advantage of it. For example:

      java.awt.Canvas c = new java.awt.Canvas();
      TransparentFilter tf = new TransparentFilter();
      java.awt.ImageFilter filter = tf.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.
      TransparentFilter tf = new TransparentFilter();
      // 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.  
      tf.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 = tf.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 TransparentFilter()
The default constructor.

Method Index

 o addColor(Color)
Adds a transparent color to the list of transparent colors.
 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 getColorList()
Returns the list of transparent colors for an image.
 o getImageFilter()
Returns the filter used by this class.
 o getResult()
Returns a processed image.
 o removeColor(Color)
Removes a color from the list of transparent colors.
 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 setColorList(ColorList)
Sets the list of transparent colors for an image.
 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 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 TransparentFilter
 public TransparentFilter()
The default constructor.

Methods

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

Returns:
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 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 - inputImage to be processed
Throws: IllegalArgumentException
if the passed value is null
See Also:
Image, processing, evaluate
 o addColor
 public void addColor(Color color)
Adds a transparent color to the list of transparent colors. Calls the addColor method of ColorList. Also the property change event is fired if the old size of color list is not equal to the new size of the color list. If autoAction is set to true, the evaluate method is called. If the processing flag is true, the color is not added and returns without doing anything.

Parameters:
color - Color
Throws: IllegalArgumentException
if the passed value is null
See Also:
addColor, evaluate, processing
 o removeColor
 public void removeColor(Color color)
Removes a color from the list of transparent colors. Calls the removeColor method of ColorList. Also the property change event is fired if the old size of a color list is not equal to the new size of the color list. If autoAction is set to true, the evaluate method is called. If the processing flag is true, the color is not removed and returns without doing anything.

Parameters:
color - java.awt.Color
Throws: IllegalArgumentException
if the passed value is null
See Also:
removeColor, evaluate, processing
 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 also be used in the context of the producer/filter/consumer paradigm. This method also facilitates the use of beans as simple classes (instead of wiring them in IDEs).

Returns:
image filter used by this class to do the filtering
See Also:
ImageFilter
 o setColorList
 public void setColorList(ColorList colors)
Sets the list of transparent colors for an image. The property change event is also fired if the old value is not equal to the new value. If autoAction is set to true, the evaluate method is called. If the processing flag is true, the color list is not set and returns without doing anything.

Parameters:
colors - com.ibm.imageprocessing.ColorList
Throws: IllegalArgumentException
if the passed value is null
See Also:
getColorList, evaluate, processing
 o getColorList
 public ColorList getColorList()
Returns the list of transparent colors for an image.

Returns:
list of transparent colors for an image.
See Also:
setColorList
 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 the image. It fires the processingStarted event initially. Then it waits for the 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 an input image is null
Overrides:
startProcessing in class ImageProcessing
See Also:
processingStarted, processingOver, ProcessingErrorEvent, ImageProcessedEvent, PropertyChangeEvent

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