META-INF.modules.java.desktop.classes.javax.imageio.IIOParamController Maven / Gradle / Ivy
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package javax.imageio;
/**
* An interface to be implemented by objects that can determine the
* settings of an {@code IIOParam} object, either by putting up a
* GUI to obtain values from a user, or by other means. This
* interface merely specifies a generic {@code 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 {@code activate} method, a controller obtains
* initial values by querying the {@code IIOParam} object's
* {@code get} methods, modifies values by whatever means, then
* invokes the {@code IIOParam} object's {@code set} methods
* to modify the appropriate settings. Normally, these
* {@code set} methods will be invoked all at once at a final
* commit in order that a cancel operation not disturb existing
* values. In general, applications may expect that when the
* {@code activate} method returns {@code true}, the
* {@code IIOParam} object is ready for use in a read or write
* operation.
*
*
Vendors may choose to provide GUIs for the
* {@code IIOParam} subclasses they define for a particular
* plug-in. These can be set up as default controllers in the
* corresponding {@code IIOParam} subclasses.
*
*
Applications may override any default GUIs and provide their
* own controllers embedded in their own framework. All that is
* required is that the {@code activate} method behave modally
* (not returning until either cancelled or committed), though it need
* not put up an explicitly modal dialog. Such a non-modal GUI
* component would be coded roughly as follows:
*
*
*
* class MyGUI extends SomeComponent implements IIOParamController {
*
* public MyGUI() {
* // ...
* setEnabled(false);
* }
*
* public boolean activate(IIOParam param) {
* // disable other components if desired
* setEnabled(true);
* // go to sleep until either cancelled or committed
* boolean ret = false;
* if (!cancelled) {
* // set values on param
* ret = true;
* }
* setEnabled(false);
* // enable any components disabled above
* return ret;
* }
*
*
* 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 {@code activate} method would simply look up or
* compute the settings, call the {@code IIOParam.setXXX}
* methods, and return {@code true}.
*
* @see IIOParam#setController
* @see IIOParam#getController
* @see IIOParam#getDefaultController
* @see IIOParam#hasController
* @see IIOParam#activateController
*
*/
public interface IIOParamController {
/**
* Activates the controller. If {@code true} is returned,
* all settings in the {@code IIOParam} object should be
* ready for use in a read or write operation. If
* {@code false} is returned, no settings in the
* {@code IIOParam} object will be disturbed (i.e.,
* the user canceled the operation).
*
* @param param the {@code IIOParam} object to be modified.
*
* @return {@code true} if the {@code IIOParam} has been
* modified, {@code false} otherwise.
*
* @throws IllegalArgumentException if {@code param} is
* {@code null} or is not an instance of the correct class.
*/
boolean activate(IIOParam param);
}