Reenable triggering of screen rotations by sensors.

chrome/browser/ui/touch/sensors/screen_orientation_listener.cc

Index: chrome/browser/ui/touch/sensors/screen_orientation_listener.cc
diff --git a/chrome/browser/ui/touch/sensors/screen_orientation_listener.cc b/chrome/browser/ui/touch/sensors/screen_orientation_listener.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4b2aa864d400fb202b15aaa99d360959cd35abda
--- /dev/null
+++ b/chrome/browser/ui/touch/sensors/screen_orientation_listener.cc
@@ -0,0 +1,106 @@
+// Copyright (c) 2011 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 "chrome/browser/ui/touch/sensors/screen_orientation_listener.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/sensors/sensors_provider.h"
+#include "ui/gfx/compositor/layer.h"
+#include "ui/gfx/compositor/layer_animation_sequence.h"
+#include "ui/gfx/compositor/layer_animator.h"
+#include "ui/gfx/compositor/screen_rotation.h"
+#include "ui/gfx/interpolated_transform.h"
+#include "views/desktop/desktop_window_view.h"
+
+#if defined(USE_AURA)
+#include "ui/aura/desktop.h"
+#endif
+
+namespace {
+
+// Converts degrees to an angle in the range [-180, 180).
+int NormalizeAngle(int degrees) {
+  while (degrees <= -180) degrees += 360;
+  while (degrees > 180) degrees -= 360;
+  return degrees;
+}
+
+static int SymmetricRound(float x) {
+  return static_cast<int>(
+    x > 0
+      ? std::floor(x + 0.5f)
+      : std::ceil(x - 0.5f));
+}
+
+}  // namespace
+
+ScreenOrientationListener::ScreenOrientationListener() {
+  sensors::Provider::GetInstance()->AddListener(this);
+}
+
+ScreenOrientationListener::~ScreenOrientationListener() {
+  sensors::Provider::GetInstance()->RemoveListener(this);
+}
+
+void ScreenOrientationListener::OnScreenOrientationChanged(
+    const sensors::ScreenOrientation& change) {
+  ui::Layer* to_rotate = NULL;
+  ui::LayerAnimationObserver* observer = NULL;
+#if defined(USE_AURA)
+  aura::Desktop* aura_desktop = aura::Desktop::GetInstance();
+  if (aura_desktop) {
+    to_rotate = aura_desktop->layer();
+    observer = aura_desktop;
+  }
+#endif
+  if (!to_rotate) {
+    views::desktop::DesktopWindowView* views_desktop =
+        views::desktop::DesktopWindowView::desktop_window_view;
+    if (views_desktop) {
+      views_desktop->SetPaintToLayer(true);
+      to_rotate = views_desktop->layer();
+      observer = views_desktop;
+    }
+  }
+
+  if (!to_rotate || !observer)
+    return;
+
+  bool should_rotate = true;
+  int new_degrees = 0;
+  switch (change.upward) {
+    case sensors::ScreenOrientation::TOP: break;
+    case sensors::ScreenOrientation::RIGHT: new_degrees = 90; break;
+    case sensors::ScreenOrientation::LEFT: new_degrees = -90; break;
+    case sensors::ScreenOrientation::BOTTOM: new_degrees = 180; break;
+    // Ignore front and back orientations.
+    default: should_rotate = false;
+  }
+
+  if (!should_rotate)
+    return;
+
+  float rotation = 0.0f;
+  int delta = 0;
+  const ui::Transform& transform = to_rotate->GetTargetTransform();
+  if (ui::InterpolatedTransform::FactorTRS(transform,
+                                           NULL, &rotation, NULL))
+    delta = NormalizeAngle(new_degrees - SymmetricRound(rotation));
+
+  // No rotation to do.
+  if (delta == 0)
+    return;
+
+  scoped_ptr<ui::LayerAnimationSequence> screen_rotation(
+      new ui::LayerAnimationSequence(new ui::ScreenRotation(delta)));
+  screen_rotation->AddObserver(observer);
+  to_rotate->GetAnimator()->set_preemption_strategy(
+      ui::LayerAnimator::REPLACE_QUEUED_ANIMATIONS);
+  to_rotate->GetAnimator()->ScheduleAnimation(screen_rotation.release());
+}
+
+// static
+ScreenOrientationListener* ScreenOrientationListener::GetInstance() {
+  return Singleton<ScreenOrientationListener>::get();
+}