Class FileLoadDescriptor

All Implemented Interfaces:
OperationDescriptor, RegistryElementDescriptor, Serializable

public class FileLoadDescriptor
extends OperationDescriptorImpl

An OperationDescriptor describing the "FileLoad" operation.

In the default instance the validateParameters() method checks that the named file exists and is readable. If not, it will return false, causing JAI.createNS() to throw an IllegalArgumentException. In special cases like when an image is loaded from a Remote system, the above check for existence of a file on the local system could be bypassed. This is done by setting the Boolean variable checkFileLocally to FALSE in the ParameterBlock

The allowable formats are those registered with the class.

The second parameter contains an instance of ImageDecodeParam to be used during the decoding. It may be set to null in order to perform default decoding, or equivalently may be omitted.

The classes in the package are not a committed part of the JAI API. Future releases of JAI will make use of new classes in their place. This class will change accordingly.

Resource List
Name Value
GlobalName fileload
LocalName fileload
Description Reads an image from a file.
Version 1.0
arg0Desc The path of the file to read from.
arg1Desc The ImageDecodeParam to use.
arg2Desc Boolean specifying if File existence should be checked locally.

Parameter List
Name Class Type Default Value
filename java.lang.String NO_PARAMETER_DEFAULT
param null
checkFileLocally java.lang.Boolean TRUE

See Also:
OperationDescriptor, Serialized Form

Fields inherited from class
resources, sourceNames, supportedModes
Fields inherited from interface
Constructor Summary
Method Summary
static RenderedOp create(String filename, ImageDecodeParam param, Boolean checkFileLocally, RenderingHints hints)
          Reads an image from a file.
protected  boolean validateParameters(ParameterBlock args, StringBuffer msg)
          Validates the input parameters.
Methods inherited from class
arePropertiesSupported, getDefaultSourceClass, getDestClass, getDestClass, getInvalidRegion, 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, validateRenderableArguments, validateRenderableSources, validateSources, validateSources
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public FileLoadDescriptor()
Method Detail


protected boolean validateParameters(ParameterBlock args,
                                     StringBuffer msg)
Validates the input parameters.

In addition to the standard checks performed by the superclass method, this method by default checks that the source file exists and is readable. This check may be bypassed by setting the checkFileLocally parameter to FALSE

validateParameters in class OperationDescriptorImpl
Following copied from class:
IllegalArgumentException - if args is null.
IllegalArgumentException - if msg is null and the validation fails.
See Also:
OperationDescriptorImpl.validateParameters(java.lang.String, java.awt.image.renderable.ParameterBlock, java.lang.StringBuffer)


public static RenderedOp create(String filename,
                                ImageDecodeParam param,
                                Boolean checkFileLocally,
                                RenderingHints hints)
Reads an image from a file.

Creates a ParameterBlockJAI from all supplied arguments except hints and invokes JAI.create(String,ParameterBlock,RenderingHints).

filename - The path of the file to read from.
param - The ImageDecodeParam to use. May be null.
checkFileLocally - Boolean specifying if File existence should be checked locally May be null.
hints - The RenderingHints to use. May be null.
The RenderedOp destination.
IllegalArgumentException - if filename is null.
See Also:
JAI, ParameterBlockJAI, RenderedOp