This change removes the modulation of the screen brightness
by the electron beam level. The screen brightness remains
constant while the electron beam animation is playing.
Previously we were multiplying the screen brightness by the
electron beam level so as to animate both at the same time.
The problem is that when the screen brightness is already dim
to begin with, it may not be possible to see the electron beam
animation because the modulated screen brightness rapidly
converges on 0. This may manifest give the appearance of
an abrupt transition or a flash as the screen turns off.
Bug: 7387800
Change-Id: I27b90f0098bbdc3de1d66fad819548d1301405cd
Reduce latency of screen on/off and improve how it is synchronized with
backlight changes. Screen state changes are no longer posted to vsync
which should save time. What's more, the state change occurs on a
separate thread so we no longer run the risk of blocking the Looper
for a long time while waiting for the screen to turn on or off.
Bug: 7382919
Bug: 7139924
Change-Id: I375950d1b07e22fcb94efb82892fd817e2f780dc
Always use the ElectronBeam now, even when we are only animating
the backlight so that we will have a black surface remaining
on the screen after the screen turns off.
When turning on the screen, keep the black surface showing until
we unblock screen on then dismiss it as usual.
This change eliminates the flashing of old display content when
the screen is turned on. It also helps to conceal some of the
latency of turning the screen on. We always turn the screen on
immediately (even when screen on has nominally been blocked) and
rely on the black surface to hide the screen contents until the
last moment. Dismissing the black surface is practically
instantaneous compared to turning the screen on.
Bug: 7299370
Bug: 7139924
Change-Id: I57d13287acd05bd0a48811095bb02dc7bc7cbeb6
Disable backlight before turning off the screen.
Enable backlight after turning on the screen.
Bug: 7016215
Change-Id: Idb763f85f7a40e852483c57e0a0d1b27eb943f08
The system depends on receiving reliable vsync signals from
surface flinger during the boot process. If it doesn't get them
because the screen is off then a hang may occur.
This isn't a problem when surface flinger manages the screen
blanking itself but it is a problem for devices that still
rely on early-suspend. When early-suspend is involved, the
screen may be off without surface flinger knowing. This is a
problem because surface flinger will only synthesize fake
vsyncs when it knows the screen is off, otherwise relying
on the hardware to generate vsync signals itself. Unfortunately,
the hardware won't generate vsync signals if the screen was
turned off by early-suspend, so we have a problem.
Bug: 6975688
Change-Id: Iaf4527f716bf4ea72cc3e6fdaf060855697b02f2
Also added an internal flag to control whether the electron beam
on animation is used. It's on for now but we might want to
turn if off if we can't get the HAL to provide the
necessary screen on synchronization on all devices.
Change-Id: Iaa3cfa0fd61de10174e68351e4db890eff2d2918
Fixes b/6996990
Ideally, the HWC HAL should turn off the backlight when the display is turned
off. This patch enforces this at the PowerManager, which can guard against
errant HWC implementations.
Change-Id: Ibb826a02871c983f8a68034d010e68abe9c5c1d5
Signed-off-by: Iliyan Malchev <malchev@google.com>
The major goal of this rewrite is to make it easier to implement
power management policies correctly. According, the new
implementation primarily uses state-based rather than event-based
triggers for applying changes to the current power state.
For example, when an application requests that the proximity
sensor be used to manage the screen state (by way of a wake lock),
the power manager makes note of the fact that the set of
wake locks changed. Then it executes a common update function
that recalculates the entire state, first looking at wake locks,
then considering user activity, and eventually determining whether
the screen should be turned on or off. At this point it may
make a request to a component called the DisplayPowerController
to asynchronously update the display's powe state. Likewise,
DisplayPowerController makes note of the updated power request
and schedules its own update function to figure out what needs
to be changed.
The big benefit of this approach is that it's easy to mutate
multiple properties of the power state simultaneously then
apply their joint effects together all at once. Transitions
between states are detected and resolved by the update in
a consistent manner.
The new power manager service has is implemented as a set of
loosely coupled components. For the most part, information
only flows one way through these components (by issuing a
request to that component) although some components support
sending a message back to indicate when the work has been
completed. For example, the DisplayPowerController posts
a callback runnable asynchronously to tell the PowerManagerService
when the display is ready. An important feature of this
approach is that each component neatly encapsulates its
state and maintains its own invariants. Moreover, we do
not need to worry about deadlocks or awkward mutual exclusion
semantics because most of the requests are asynchronous.
The benefits of this design are especially apparent in
the implementation of the screen on / off and brightness
control animations which are able to take advantage of
framework features like properties, ObjectAnimator
and Choreographer.
The screen on / off animation is now the responsibility
of the power manager (instead of surface flinger). This change
makes it much easier to ensure that the animation is properly
coordinated with other power state changes and eliminates
the cause of race conditions in the older implementation.
The because of the userActivity() function has been changed
so that it never wakes the device from sleep. This change
removes ambiguity around forcing or disabling user activity
for various purposes. To wake the device, use wakeUp().
To put it to sleep, use goToSleep(). Simple.
The power manager service interface and API has been significantly
simplified and consolidated. Also fixed some inconsistencies
related to how the minimum and maximum screen brightness setting
was presented in brightness control widgets and enforced behind
the scenes.
At present the following features are implemented:
- Wake locks.
- User activity.
- Wake up / go to sleep.
- Power state broadcasts.
- Battery stats and event log notifications.
- Dreams.
- Proximity screen off.
- Animated screen on / off transitions.
- Auto-dimming.
- Auto-brightness control for the screen backlight with
different timeouts for ramping up versus ramping down.
- Auto-on when plugged or unplugged.
- Stay on when plugged.
- Device administration maximum user activity timeout.
- Application controlled brightness via window manager.
The following features are not yet implemented:
- Reduced user activity timeout for the key guard.
- Reduced user activity timeout for the phone application.
- Coordinating screen on barriers with the window manager.
- Preventing auto-rotation during power state changes.
- Auto-brightness adjustment setting (feature was disabled
in previous version of the power manager service pending
an improved UI design so leaving it out for now).
- Interpolated brightness control (a proposed new scheme
for more compactly specifying auto-brightness levels
in config.xml).
- Button / keyboard backlight control.
- Change window manager to associated WorkSource with
KEEP_SCREEN_ON_FLAG wake lock instead of talking
directly to the battery stats service.
- Optionally support animating screen brightness when
turning on/off instead of playing electron beam animation
(config_animateScreenLights).
Change-Id: I1d7a52e98f0449f76d70bf421f6a7f245957d1d7
