org.a11y.atspi.Cache

Description

The application should expose this interface at the /org/a11y/atspi/cache object path.

The org.a11y.atspi.Accessible interface has methods like GetChildren and GetChildAtIndex, but these only transfer an object’s DBus id. The caller has to then query the object’s properties individually. Transferring objects one by one and then their properties produces a lot of traffic in the accessibility bus.

So, this Cache interface can be used to query objects in bulk. Assistive tech should try to do a bulk query of all the objects in a new window with the GetItems method, and then update them dynamically from the AddAccessible and RemoveAccessible signals.

FIXME: Does GetItems only get called if an application implements GetApplicationBusAddress? GTK4 doesn’t implement that, but it implements GetItems - does that ever get called?

Methods

org.a11y.atspi.Cache.GetItems

GetItems (
  OUT nodes a((so)(so)(so)iiassusau)
)

bulk query an application’s accessible objects. Returns: an array with one element for each available object. Each element’s fields are like this:

(so): accessible object reference - DBus name and object path. The rest of the fields refer to this main object.
(so): application reference - DBus name and object path. This is the owner of the main object; the root path of the application that registered via the Embed method of the org.a11y.atspi.Socket interface.
(so): parent object reference - DBus name and object path.
If the main object has no parent:
- If it is a control, or a window, return the parent application.
- If the object has the application role, return a null reference. FIXME: atk-adaptor/adaptors/cache-adaptor.c:append_cache_item() returns a reference to the registry in this case (the one it obtained from the initial Socket::Embed call); GTK4 returns a null reference.
- Otherwise, return a null reference (”” for the application name name and “/org/a11y/atspi/null” for the object path).
i: index in parent, or -1 for transient widgets/menu items. Equivalent to the GetIndexInParent method of the org.a11y.atspi.Accessible interface.
i: child count of main object, or -1 for defunct/menus. Equivalent to the ChildCount property of the org.a11y.atspi.Accessible interface.
as: array of names of the interfaces that the main object supports. Equivalent to the GetInterfaces method of the org.a11y.atspi.Accessible interface.
s: human-readable, localized, short name for the main object. Equivalent to the Name property of the org.a11y.atspi.Accessible interface.
u: role. Equivalent to the GetRole method of the org.a11y.atspi.Accessible interface.
s: human-readable, localized description of the object in more detail. Equivalent to the Description property of the org.a11y.atspi.Accessible interface.
au: Set of states currently held by an object. Equivalent to the GetState method of the org.a11y.atspi.Accessible interface.

Deprecation note: The signature for the return value of this method changed in 2015, in commit b2c8c4c7. It used to be “a((so)(so)(so)a(so)assusau)”. The “a(so)” instead of “ii” is a list of references to child objects. The implementation in atspi-misc.c can handle either version, although the intention is to deprecate the code that handles the old version. Qt still uses this old signature and should be changed to the new scheme (see qspi_struct_marshallers.cpp in the Qt source code).

nodes

Signals