javax.media.jai.operator
Class NullDescriptor

java.lang.Object
  |
  +--javax.media.jai.OperationDescriptorImpl
        |
        +--javax.media.jai.operator.NullDescriptor

All Implemented Interfaces:

OperationDescriptor, RegistryElementDescriptor, Serializable

public class NullDescriptor

extends OperationDescriptorImpl

An OperationDescriptor describing the "Null" operation.

The "Null" operation performs no processing. It merely propagates its first source along the operation chain unmodified. There may be an arbitrary number of sources but only the first one is passed along so it must have the appropriate class type for the operation mode.

This operation may be useful as a placeholder in operation chains and in creating nodes to which PropertyGenerators may be attached. This would enable non-image data nodes to be present in chains without requiring that specific OperationDescriptors be implemented for these operations. The PropertyGenerators required would in this case be added locally to the nodes using the addPropertyGenerator() method of the node.

Resource List

Name	Value
GlobalName	Null
LocalName	Null
Vendor	com.sun.media.jai
Description	An operation which does no processing.
DocURL	http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/NullDescriptor.html
Version	1.0

No parameters are needed for this operation.

Since:

JAI 1.1

See Also:

OperationDescriptor, Serialized Form

Fields inherited from class javax.media.jai.OperationDescriptorImpl

resources, sourceNames, supportedModes

Constructor Summary

NullDescriptor()
Constructor.

Method Summary

Object	getInvalidRegion(String modeName, ParameterBlock oldParamBlock, RenderingHints oldHints, ParameterBlock newParamBlock, RenderingHints newHints, OperationNode node) Calculates the region over which two distinct renderings of the "Null" operation may be expected to differ.
protected boolean	validateSources(String modeName, ParameterBlock args, StringBuffer msg) Returns true if there is at least one source and the first source is a RenderedImage or RenderableImage.

Methods inherited from class javax.media.jai.OperationDescriptorImpl

arePropertiesSupported, getDefaultSourceClass, getDestClass, getDestClass, getName, getNumParameters, getNumSources, getParamClasses, getParamDefaults, getParamDefaultValue, getParameterListDescriptor, getParamMaxValue, getParamMinValue, getParamNames, getPropertyGenerators, getPropertyGenerators, getRenderableDestClass, getRenderableSourceClasses, getResourceBundle, getResources, getSourceClasses, getSourceClasses, getSourceNames, getSupportedModes, isImmediate, isModeSupported, isRenderableSupported, isRenderedSupported, makeDefaultSourceClassList, validateArguments, validateArguments, validateParameters, validateParameters, validateRenderableArguments, validateRenderableSources, validateSources

Methods inherited from class java.lang.Object

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

Constructor Detail

NullDescriptor

public NullDescriptor()

Constructor.

Method Detail

validateSources

protected boolean validateSources(String modeName,
                                  ParameterBlock args,
                                  StringBuffer msg)

Returns true if there is at least one source and the first source is a RenderedImage or RenderableImage.

Overrides:

validateSources in class OperationDescriptorImpl

Throws:

IllegalArgumentException - if args is null.

IllegalArgumentException - if msg is null and the validation fails.

getInvalidRegion

public Object getInvalidRegion(String modeName,
                               ParameterBlock oldParamBlock,
                               RenderingHints oldHints,
                               ParameterBlock newParamBlock,
                               RenderingHints newHints,
                               OperationNode node)

Calculates the region over which two distinct renderings of the "Null" operation may be expected to differ.

The operation returns an empty Shape if the first source in each of the two ParameterBlocks are equal according to the equals() method of the old source or null for all other cases.

Overrides:

getInvalidRegion in class OperationDescriptorImpl

Parameters:

modeName - The name of the mode.

oldParamBlock - The previous sources and parameters.

oldHints - The previous hints.

newParamBlock - The current sources and parameters.

newHints - The current hints.

node - The affected node in the processing chain (ignored).

Returns:

The region over which the data of two renderings of this operation may be expected to be invalid or null if there is no common region of validity. A non-null empty region indicates that the operation would produce identical data over the bounds of the old rendering although perhaps not over the area occupied by the tiles of the old rendering.

Throws:

IllegalArgumentException - if modeName is null or if either oldParamBlock or newParamBlock is null.

IllegalArgumentException - if oldParamBlock or newParamBlock does not contain at least one source.