<Swing Dev> Please review fix for 7179482 : Component.accessibleContext and JComponent.accessibleContext refactoring

[Pete Brunet]

Some more code has been added.  A counter has been added to each of the
three files.  It is incremented when addPropertyChangeListener is called
and decremented when removePropertyChangeListener is called.  Only when
the count is zero, i.e. the first add and last remove, do specific
handlers (see below) get added/removed.

Component.java: This code has Component and Focus handlers.

Container.java: This code has a Container handler.

JComponent.java:  This code has Container and Focus handlers.

See http://cr.openjdk.java.net/~ptbrunet/7179482/webrev.01/

Pete

-------- Original Message --------
Subject: 	<Swing Dev> Please review fix for 7179482 :
Component.accessibleContext and JComponent.accessibleContext refactoring
Date: 	Fri, 09 Nov 2012 15:27:33 -0600
From: 	Pete Brunet <peter.brunet at oracle.com>
Reply-To: 	peter.brunet at oracle.com
To: 	awt-dev <awt-dev at openjdk.java.net>, swing-dev at openjdk.java.net



Please review the following fix planned for JDK8.  Part of the fix will
go into 7u12 under 7177111.

Problem:
In the process of evaluating 7177111 the following problems were noticed:
- Both Component and JComponent have field "accessibleContext".  In
Component it is package-private and accessed by other classes from
java.awt, but in JComponent it is protected and therefore this field
hides the same superclass field from any subclass.  These two fields
should be refactored to a single protected field in Component.
- Container.AccessibleAWTContainer has an addPropertyChangeListener but
not a removePropertyChangeListener.  This method is needed so stale
listeners can be removed when AT are no longer attached to a Java process.
- The JComponent.AccessibleJComponent.accessibleFocusHandler field
functionally duplicates its superclass field,
Component.AccessibleAWTComponent.accessibleAWTFocusHandler.  When this
field is used properly there are no logical issues.  However, the
existence of this field could cause confusion for a developer trying to
understand the code.  The superclass field is sufficient.

Solution:
- Change java.awt.Component.accessibleContext from package-private to
protected.  This will allow use by subclasses and the removal of the
duplicate field in javax.swing.JComponent.
- Add
java.awt.Container.AccessibleAWTContainer.removePropertyChangeListener
so stale listeners can be removed when an Assistive Technology is no
longer attached to a Java process.
- Remove the protected field javax.swing.JComponent.accessibleContext. 
Instead the protected field java.awt.Component.accessibleContext, will
be used.  With the change subclasses would now use the protected field
in the Component superclass.
- Remove public method javax.swing.JComponent.getAccessibleContext. 
Instead it superclass public method
java.awt.Component.getAccessibleContext method would be used.
- javax.swing.JComponent.AccessibleJComponent.accessibleFocusHandler
field will be deprecated.  Developers should use the
java.awt.Component.AccessibleAWTComponent.accessibleAWTFocusHandler
field instead.

Webrev:  http://cr.openjdk.java.net/~ptbrunet/7179482/webrev.00/
Bug:  http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7179482
CCC:  http://ccc.us.oracle.com/7179482




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