cc: Support animating scroll offset

cc/animation/layer_animation_controller.cc

 // Copyright 2012 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 "cc/animation/layer_animation_controller.h"
 
 #include <algorithm>
 
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_delegate.h"
 #include "cc/animation/animation_registrar.h"
 #include "cc/animation/keyframed_animation_curve.h"
 #include "cc/animation/layer_animation_value_observer.h"
+#include "cc/animation/layer_animation_value_provider.h"
+#include "cc/animation/scroll_offset_animation_curve.h"
 #include "cc/base/scoped_ptr_algorithm.h"
 #include "cc/output/filter_operations.h"
 #include "ui/gfx/box_f.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 
 LayerAnimationController::LayerAnimationController(int id)
     : registrar_(0),
       id_(id),
       is_active_(false),
       last_tick_time_(0),
+      value_provider_(NULL),
       layer_animation_delegate_(NULL) {}
 
 LayerAnimationController::~LayerAnimationController() {
   if (registrar_)
     registrar_->UnregisterAnimationController(this);
 }
 
 scoped_refptr<LayerAnimationController> LayerAnimationController::Create(
     int id) {
   return make_scoped_refptr(new LayerAnimationController(id));
@@ skipping 140 matching lines @@
                              monotonic_time);
         event.filters = animation->curve()->ToFilterAnimationCurve()->GetValue(
             monotonic_time);
         event.is_impl_only = true;
         events->push_back(event);
         break;
       }
 
       case Animation::BackgroundColor: { break; }
 
+      case Animation::ScrollOffset: {
+        // Impl-side changes to scroll offset are already sent back to the
+        // main thread (e.g. for user-driven scrolling), so a PropertyUpdate
+        // isn't needed.
+        break;
+      }
+
       case Animation::TargetPropertyEnumSize:
         NOTREACHED();
     }
   }
 }
 
 void LayerAnimationController::UpdateState(bool start_ready_animations,
                                            AnimationEventsVector* events) {
   if (!HasActiveValueObserver())
     return;
@@ skipping 207 matching lines @@
 
     // If the animation is not running on the impl thread, it does not
     // necessarily mean that it needs to be copied over and started; it may
     // have already finished. In this case, the impl thread animation will
     // have already notified that it has started and the main thread animation
     // will no longer need
     // a synchronized start time.
     if (!active_animations_[i]->needs_synchronized_start_time())
       continue;
 
+    // Scroll animations always start at the current scroll offset.
+    if (active_animations_[i]->target_property() == Animation::ScrollOffset) {
+      gfx::Vector2dF current_scroll_offset;
+      if (controller_impl->value_provider_) {
+        current_scroll_offset =
+            controller_impl->value_provider_->ScrollOffsetForAnimation();
+      } else {
+        // The owning layer isn't yet in the active tree, so the main thread
+        // scroll offset will be up-to-date.
+        current_scroll_offset = value_provider_->ScrollOffsetForAnimation();
+      }
+      active_animations_[i]->curve()->ToScrollOffsetAnimationCurve()
+          ->SetInitialValue(current_scroll_offset);
+    }
+
     // The new animation should be set to run as soon as possible.
     Animation::RunState initial_run_state =
         Animation::WaitingForTargetAvailability;
     double start_time = 0;
     scoped_ptr<Animation> to_add(active_animations_[i]->CloneAndInitialize(
         initial_run_state, start_time));
     DCHECK(!to_add->needs_synchronized_start_time());
     controller_impl->AddAnimation(to_add.Pass());
   }
 }
@@ skipping 247 matching lines @@
               filter_animation_curve->GetValue(trimmed);
           NotifyObserversFilterAnimated(filter);
           break;
         }
 
         case Animation::BackgroundColor: {
           // Not yet implemented.
           break;
         }
 
+        case Animation::ScrollOffset: {
+          const ScrollOffsetAnimationCurve* scroll_offset_animation_curve =
+              active_animations_[i]->curve()->ToScrollOffsetAnimationCurve();
+          const gfx::Vector2dF scroll_offset =
+              scroll_offset_animation_curve->GetValue(trimmed);
+          NotifyObserversScrollOffsetAnimated(scroll_offset);
+          break;
+        }
+
         // Do nothing for sentinel value.
         case Animation::TargetPropertyEnumSize:
           NOTREACHED();
       }
     }
   }
 }
 
 void LayerAnimationController::UpdateActivation(UpdateActivationType type) {
   bool force = type == ForceActivation;
@@ skipping 27 matching lines @@
                     OnTransformAnimated(transform));
 }
 
 void LayerAnimationController::NotifyObserversFilterAnimated(
     const FilterOperations& filters) {
   FOR_EACH_OBSERVER(LayerAnimationValueObserver,
                     value_observers_,
                     OnFilterAnimated(filters));
 }
 
+void LayerAnimationController::NotifyObserversScrollOffsetAnimated(
+    gfx::Vector2dF scroll_offset) {
+  FOR_EACH_OBSERVER(LayerAnimationValueObserver,
+                    value_observers_,
+                    OnScrollOffsetAnimated(scroll_offset));
+}
+
 void LayerAnimationController::NotifyObserversAnimationWaitingForDeletion() {
   FOR_EACH_OBSERVER(LayerAnimationValueObserver,
                     value_observers_,
                     OnAnimationWaitingForDeletion());
 }
 
 bool LayerAnimationController::HasValueObserver() {
   if (value_observers_.might_have_observers()) {
     ObserverListBase<LayerAnimationValueObserver>::Iterator it(
         value_observers_);
     return it.GetNext() != NULL;
   }
   return false;
 }
 
 bool LayerAnimationController::HasActiveValueObserver() {
   if (value_observers_.might_have_observers()) {
     ObserverListBase<LayerAnimationValueObserver>::Iterator it(
         value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != NULL)
       if (obs->IsActive())
         return true;
   }
   return false;
 }
 
 }  // namespace cc