tree 19887c9a0d1c4ee83117d3324360cf88da2c96d0
parent 1bc1b8a5b8a0c5fbcd670d1963235de27a5ccec4
author Svetoslav Ganov <svetoslavganov@google.com> 1336648493 -0700
committer Svetoslav Ganov <svetoslavganov@google.com> 1336678084 -0700

Adding scroll actions to accessibility node info.

1. Scrolling actions are crucial for enabling a gesture based
   traversal of the UI and specifically scrollable containers
   especially lists and anything backed by an adapter. Since
   accessibility focus can land only attached views, it cannot
   visit views for adapter items not shown on the screen.
   Auto scrolling the list as a result of putting access focus
   ot a list item does not work well since the user may get
   trapped in a long list. Adding an accessibility node provider
   to emit virtual views for one view before the first and one
   after the last is complex and suffers the limitation of trapping
   the user. Accessibility service need an explicit scroll actions
   which may be performed upon an explicit user action. Hence,
   the user is informed for the start/end of the visible part of
   the list and he makes a deliberate choice to scroll. This will
   benefit also people developing Braille devices since they can
   scroll the content without telling the user to stop using the
   Braille controller and take the device out of his pocket to scroll
   and go back to the Braille controller.

NOTE: Without these action large portions of the screen will be
    hard to access since users will have to touch and explore to
    find and scroll the list.

Change-Id: Iafcf54d4967893205872b3649025a4e347a299ed