Re: ATk, Java and Change Notifications

[Bill Haneman <Bill Haneman Sun COM>]

>The Java class AccessibleContext has a number of constants which are used to 
>indicate that something has changed. This note identifies those constants
>and states how they are currently implemented, if at all, in ATK.
>
>There is currently no implementation in ATK for the following:
>
>ACCESSIBLE_ACTION_PROPERTY
>ACCESSIBLE_ACTIVE_DESCENDANT_PROPERTY
>ACCESSIBLE_SELECTION_PROPERTY
>ACCESSIBLE_TABLE_CAPTION_CHANGED
>ACCESSIBLE_TABLE_COLUMN_DESCRIPTION_CHANGED
>ACCESSIBLE_TABLE_COLUMN_HEADER_CHANGED
>ACCESSIBLE_TABLE_MODEL_CHANGED
>ACCESSIBLE_TABLE_ROW_DESCRIPTION_CHANGED
>ACCESSIBLE_TABLE_ROW_HEADER_CHANGED
>ACCESSIBLE_TABLE_SUMMARY_CHANGED
>ACCESSIBLE_VALUE_PROPERTY
>ACCESSIBLE_VISIBLE_DATA_PROPERTY

In those cases where we don't yet have proposals for ATK (below), I suggest that 
we look into whether we should add corresponding properties to the appropriate 
ATK object.

We have the limitation that GObject interfaces cannot have properties associuated 
with them (thought they can have signals).  We would have the choice of using 
notification signals, on for instance AtkTable, or we could add the TABLE 
properties to AtkObject (as TEXT properties are already present on AtkObject, 
though they conceptually belong to AtkText implementors and are only implemented 
on AtkObjects that implement AtkText).

My opinion is that we should expose a SELECTION property, I am not sure about 
ACTION and ACTIVE_DESCENDANT.  The TABLE property changes, though I am not sure 
how often they will occur in applications, should probably be supported somehow.

I thought we had a VALUE property?  If not, we should, I think.

-Bill

>
>Proposals for ATK implementations will follow.
>
>
>ACCESSIBLE_ACTION_PROPERTY
>
>Constant used to indicate that the supported set of actions has changed.
>
>I have not found any Java code which uses this and there is no corresponding
>implementation in ATK.
>
>
>ACCESSIBLE_ACTIVE_DESCENDANT_PROPERTY
>
>Constant used to determine when the active descendant of a component has 
>changed.
>
>In Java, this is fired when the lead selection index for a JList, the
>lead selection path for a JTree, and the last selected row and column for
>a JTable has changed.
>
>Currently we do not have an implementation for this in ATK.
>
>
>ACCESSIBLE_CARET_CHANGED
>
>Constant used to determine when the accessibleText caret has changed.
>
>In ATK we have a signal "text-caret-moved" which is emitted when the caret
>position has changed.
>
>
>ACCESSIBLE_CHILD_PROPERTY
>
>Constant used to determine when Accessible children are added/removed from 
>the object.
>
>In ATK, a property called "accessible-child" is defined and a notify signal
>is emitted for that property when a child is added or removed.
>
>
>ACCESSIBLE_DESCRIPTION_PROPERTY
>
>Constant used to determine when the accessibleDescription property has changed.
>
>In ATK, a property called "accessible-description" is defined and a notify 
>signal is emitted for that property when the desciption is changed.
>
>
>ACCESSIBLE_NAME_PROPERTY
>
>Constant used to determine when the accessibleName property has changed.
>
>In ATK, a property called "accessible-name" is defined and a notify 
>signal is emitted for that property when the name is changed.
>
>
>ACCESSIBLE_SELECTION_PROPERTY
>
>Constant used to determine when the accessibleSelection has changed.
>
>
>ACCESSIBLE_STATE_PROPERTY
>
>Constant used to determine when the accessibleStateSet property has changed.
>
>In ATK, a property called "accessible-state" is defined and a notify 
>signal is emitted for that property when the name is changed. For this
>property only, the old and new values reported by the ATK property change 
>handler are meaningful, with an old value meaning that a state has been 
>switched off and a new value meaning that a state has been switched on.
>
>
>ACCESSIBLE_TABLE_CAPTION_CHANGED
>
>Constant used to indicate that the table caption has changed The old value 
>in the PropertyChangeEvent will be an Accessible representing the previous
>table caption and the new value will be an Accessible representing the new 
>table caption.
>
>
>ACCESSIBLE_TABLE_COLUMN_DESCRIPTION_CHANGED
>
>Constant used to indicate that the column description has changed The old 
>value in the PropertyChangeEvent will be null and the new value will be an
>Integer representing the column index.
>
>
>ACCESSIBLE_TABLE_COLUMN_HEADER_CHANGED
>
>Constant used to indicate that the column header has changed The old value 
>in the PropertyChangeEvent will be null and the new value will be an
>AccessibleTableModelChange representing the header change.
>
>
>ACCESSIBLE_TABLE_MODEL_CHANGED
>
>Constant used to indicate that table data has changed.
>
>
>ACCESSIBLE_TABLE_ROW_DESCRIPTION_CHANGED
>
>Constant used to indicate that the row description has changed The old 
>value in the PropertyChangeEvent will be null and the new value will be 
>an Integer representing the row index.
>
>
>ACCESSIBLE_TABLE_ROW_HEADER_CHANGED
>
>Constant used to indicate that the row header has changed The old value 
>in the PropertyChangeEvent will be null and the new value will be an
>AccessibleTableModelChange representing the header change.
>
>
>ACCESSIBLE_TABLE_SUMMARY_CHANGED
>
>Constant used to indicate that the table summary has changed The old value 
>in the PropertyChangeEvent will be an Accessible representing the previous
>table summary and the new value will be an Accessible representing the new 
>table summary.
>
>
>ACCESSIBLE_TEXT_PROPERTY
>
>Constant used to determine when the accessibleText has changed.
>
>In ATK a signal "text-changed" is defined and this signal is emitted when the
>text has changed.
>
>
>ACCESSIBLE_VALUE_PROPERTY
>
>Constant used to determine when the accessibleValue property has changed.
>
>
>ACCESSIBLE_VISIBLE_DATA_PROPERTY
>
>Constant used to determine when the visual appearance of the object has 
>changed.
>
>
>
>Padraig
>
>
>_______________________________________________
>gnome-accessibility-list mailing list
>gnome-accessibility-list gnome org
>http://mail.gnome.org/mailman/listinfo/gnome-accessibility-list

------
Bill Haneman x19279
Gnome Accessibility / Batik SVG Toolkit
Sun Microsystems Ireland