Add fade to white animation when power button is pressed on Athena

athena/system/power_button_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "athena/system/power_button_controller.h"
 
+#include "athena/screen/public/screen_manager.h"
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
+#include "ui/aura/window.h"
+#include "ui/compositor/layer.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
+#include "ui/gfx/animation/tween.h"
 
 namespace athena {
 
+namespace {
+
+// Duration of the animation prior to shutdown.
+const int kPreShutdownDurationMs = 1000;
+
+// Duration of the animation when shutdown is canceled.
+const int kCancelShutdownDurationMs = 500;
+
+// Additional time (beyond kPreShutdownDurationMs) to wait after starting
+// the pre-shutdown animation before actually shutting down to give time for the
+// last frame of the animation to get painted.
+const int kShutdownRequestDelayMs = 50;
+
+}  // namespace
+
 PowerButtonController::PowerButtonController()
     : brightness_is_zero_(false),
-      shutdown_requested_(false) {
+      shutdown_requested_(false),
+      can_cancel_shutdown_(true) {
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->AddObserver(
       this);
 }
 
 PowerButtonController::~PowerButtonController() {
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->RemoveObserver(
       this);
 }
 
+void PowerButtonController::StartGrayscaleAndBrightnessAnimation(
+    float target,
+    int duration_ms,
+    gfx::Tween::Type tween_type) {
+  ui::Layer* layer =
+      ScreenManager::Get()->GetContext()->GetRootWindow()->layer();
+  ui::ScopedLayerAnimationSettings settings(layer->GetAnimator());
+  settings.SetTransitionDuration(
+      base::TimeDelta::FromMilliseconds(duration_ms));
+  settings.SetTweenType(tween_type);
+  settings.SetPreemptionStrategy(
+      ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+  settings.AddObserver(this);
+  layer->SetLayerBrightness(target);
+  layer->SetLayerGrayscale(target);

[flackr, 2014/08/07 18:23:31]

Defer to oshima, but I suspect we'll want these animations to be done by the
athena screen manager rather than doing UI things from athena/system.

[oshima, 2014/08/07 19:53:38]

I'm actually fine to implement the animation itself outside of the screen
manager, but want to hind RootWindow.

How about adding ScreenManager::CreateScreenAnimator()? Since we need similar
animation for ctrl-shift-q,
I think this should be a separate clsss/function.

+}
+
+void PowerButtonController::Shutdown() {
+  chromeos::DBusThreadManager::Get()
+      ->GetPowerManagerClient()
+      ->RequestShutdown();
+}
+
 void PowerButtonController::BrightnessChanged(int level, bool user_initiated) {
   if (brightness_is_zero_)
     zero_brightness_end_time_ = base::TimeTicks::Now();
   brightness_is_zero_ = (level == 0);
 }
 
 void PowerButtonController::PowerButtonEventReceived(
     bool down,
-    const base::TimeTicks& details) {
+    const base::TimeTicks& timestamp) {
   // Avoid requesting a shutdown if the power button is pressed while the screen
   // is off (http://crbug.com/128451)
   base::TimeDelta time_since_zero_brightness = brightness_is_zero_ ?
       base::TimeDelta() : (base::TimeTicks::Now() - zero_brightness_end_time_);
   const int kShortTimeMs = 10;
   if (time_since_zero_brightness.InMilliseconds() <= kShortTimeMs)
     return;
 
-  if (down && !shutdown_requested_) {
-    shutdown_requested_ = true;
-    chromeos::DBusThreadManager::Get()
-        ->GetPowerManagerClient()
-        ->RequestShutdown();
+  if (!can_cancel_shutdown_)

[flackr, 2014/08/07 18:23:31]

Seems a bit arbitrary to no longer allow canceling shutdown once the animation
completes. Couldn't the posted task be canceled?

[oshima, 2014/08/07 19:53:38]

can we use state enum rather than multiple booleans?

+    return;
+
+  StopObservingImplicitAnimations();
+  shutdown_requested_ = down;
+  if (shutdown_requested_) {
+    StartGrayscaleAndBrightnessAnimation(
+        1.0f, kPreShutdownDurationMs, gfx::Tween::EASE_IN);
+  } else {
+    StartGrayscaleAndBrightnessAnimation(
+        0.0f, kCancelShutdownDurationMs, gfx::Tween::EASE_IN_OUT);
   }
 }
 
+void PowerButtonController::OnImplicitAnimationsCompleted() {
+  if (shutdown_requested_) {
+    can_cancel_shutdown_ = false;
+    base::MessageLoopForUI::current()->PostDelayedTask(
+        FROM_HERE,
+        base::Bind(&PowerButtonController::Shutdown, base::Unretained(this)),
+        base::TimeDelta::FromMilliseconds(kShutdownRequestDelayMs));
+  }
+}
+
 }  // namespace athena