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javax.imageio.metadata
Interface IIOMetadataController

public interface IIOMetadataController

An interface to be implemented by objects that can determine the settings of an IIOMetadata object, either by putting up a GUI to obtain values from a user, or by other means. This interface merely specifies a generic activate method that invokes the controller, without regard for how the controller obtains values (i.e., whether the controller puts up a GUI or merely computes a set of values is irrelevant to this interface).

Within the activate method, a controller obtains initial values by querying the IIOMetadata object's settings, either using the XML DOM tree or a plug-in specific interface, modifies values by whatever means, then modifies the IIOMetadata object's settings, using either the setFromTree or mergeTree methods, or a plug-in specific interface. In general, applications may expect that when the activate method returns true, the IIOMetadata object is ready for use in a write operation.

Vendors may choose to provide GUIs for the IIOMetadata subclasses they define for a particular plug-in. These can be set up as default controllers in the corresponding IIOMetadata subclasses.

Alternatively, an algorithmic process such as a database lookup or the parsing of a command line could be used as a controller, in which case the activate method would simply look up or compute the settings, call methods on IIOMetadata to set its state, and return true.

See Also:

IIOMetadata.setController(javax.imageio.metadata.IIOMetadataController), IIOMetadata.getController(), IIOMetadata.getDefaultController(), IIOMetadata.hasController(), IIOMetadata.activateController()

Method Summary

Modifier and Type	Method and Description
boolean	activate(IIOMetadata metadata) Activates the controller.

Method Detail

activate

boolean activate(IIOMetadata metadata)

Activates the controller. If true is returned, all settings in the IIOMetadata object should be ready for use in a write operation. If false is returned, no settings in the IIOMetadata object will be disturbed (i.e., the user canceled the operation).

Parameters:

metadata - the IIOMetadata object to be modified.

Returns:

true if the IIOMetadata has been modified, false otherwise.

Throws:

IllegalArgumentException - if metadata is null or is not an instance of the correct class.