Refactoring of the Accessibility.
1. The accessibility manager service updates its internal state
based on which settings are enabled, what accessibility services
are installed and what features are requested by the enabled
services. It was trying to do the minimal amount of work to
react to contextual changes like these which resulted in missed
cases and complex code. Now there is a single method that reads
the contextual information and single method that reacts to
contextual changes. This makes the code much easier to maintain.
2. The accessibility manager service was not updating its internal
state when requested features from accessibility services change.
It was relying on changing system settings and reacting to the
settings change. This is problematic since the internal state is
not updated atomically which leads to race condition bugs. For
example, if touch exploration is enabled and a service requests
it is disabled, the internal state will not be updated but a
request for a settings change will be made. Now while the settings
change is propagating another request form the same service
comes to enable touch exploration but the system incorrectly
thinks touch exploration is enabled. At the end the feature is
disabled even though it was requested.
3. Fixed a potential NPE if the accessibility input filter's event
handler was nullified between processing two event batches.
4. Fixed a bug where, if magnification is enabled, it does not work
on the settings screen since the magnified bounds are not pushed
from the window manager to the accessibility manager.
Change-Id: Idf629a06480e12f0d88372762df6c024fe0d7856
4 files changed