Interface IIOParamController
public interface IIOParamController
An interface to be implemented by objects that can determine the settings of an IIOParam
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 IIOParam
object's get
methods, modifies values by whatever means, then invokes the IIOParam
object's set
methods to modify the appropriate settings. Normally, these 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 activate
method returns true
, the IIOParam
object is ready for use in a read or write operation.
Vendors may choose to provide GUIs for the IIOParam
subclasses they define for a particular plug-in. These can be set up as default controllers in the corresponding 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 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 activate
method would simply look up or compute the settings, call the IIOParam.setXXX
methods, and return true
.
- See Also:
-
IIOParam.setController(javax.imageio.IIOParamController)
,IIOParam.getController()
,IIOParam.getDefaultController()
,IIOParam.hasController()
,IIOParam.activateController()
Method Summary
Modifier and Type | Method | Description |
---|---|---|
boolean | activate(IIOParam param) | Activates the controller. |
Method Detail
activate
boolean activate(IIOParam param)
Activates the controller. If true
is returned, all settings in the IIOParam
object should be ready for use in a read or write operation. If false
is returned, no settings in the IIOParam
object will be disturbed (i.e., the user canceled the operation).
- Parameters:
-
param
- theIIOParam
object to be modified. - Returns:
-
true
if theIIOParam
has been modified,false
otherwise. - Throws:
-
IllegalArgumentException
- ifparam
isnull
or is not an instance of the correct class.