[ash-md] Remove the number of animators used for the Shelf animations.

ash/common/shelf/shelf_background_animator.cc

 // Copyright 2016 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 "ash/common/shelf/shelf_background_animator.h"
 
 #include <algorithm>
 
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/shelf/shelf_background_animator_observer.h"
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf.h"
+#include "ui/gfx/animation/slide_animation.h"
 
 namespace ash {
 
-namespace {
-// The total number of animators that will call BackgroundAnimationEnded().
-const int kNumAnimators = 3;
+const int ShelfBackgroundAnimator::kMaxAlpha = 255;

[James Cook, 2017/02/08 00:31:27]

Can this be initialized in header?

[bruthig, 2017/02/10 18:49:09]

Done.

 
-const int kMaxAlpha = 255;
-}  // namespace
+void ShelfBackgroundAnimator::AnimationValues::UpdateCurrentValues(double t) {
+  current_alpha_ =
+      gfx::Tween::IntValueBetween(t, initial_alpha_, target_alpha_);
+}
+
+void ShelfBackgroundAnimator::AnimationValues::SetTargetValues(
+    int target_alpha) {
+  DCHECK_LE(target_alpha, kMaxAlpha);
+  DCHECK_GE(target_alpha, 0);
+  initial_alpha_ = current_alpha_;
+  target_alpha_ = target_alpha;
+}
 
 ShelfBackgroundAnimator::ShelfBackgroundAnimator(
     ShelfBackgroundType background_type,
     WmShelf* wm_shelf)
     : wm_shelf_(wm_shelf) {
   if (wm_shelf_)
     wm_shelf_->AddObserver(this);
   // Initialize animators so that adding observers get notified with consistent
   // values.
-  AnimateBackground(background_type, BACKGROUND_CHANGE_IMMEDIATE);
+  AnimateBackground(background_type, gfx::ANIMATION_CHANGE_IMMEDIATE);
 }
 
 ShelfBackgroundAnimator::~ShelfBackgroundAnimator() {
   if (wm_shelf_)
     wm_shelf_->RemoveObserver(this);
 }
 
 void ShelfBackgroundAnimator::AddObserver(
     ShelfBackgroundAnimatorObserver* observer) {
   observers_.AddObserver(observer);
-  Initialize(observer);
+  NotifyObserver(observer);
 }
 
 void ShelfBackgroundAnimator::RemoveObserver(
     ShelfBackgroundAnimatorObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
-void ShelfBackgroundAnimator::Initialize(
-    ShelfBackgroundAnimatorObserver* observer) const {
-  observer->UpdateShelfOpaqueBackground(opaque_background_animator_->alpha());
-  observer->UpdateShelfItemBackground(item_background_animator_->alpha());
+void ShelfBackgroundAnimator::NotifyObserver(
+    ShelfBackgroundAnimatorObserver* observer) {
+  observer->UpdateShelfBackground(shelf_background_values_.current_alpha());
+  observer->UpdateShelfItemBackground(item_background_values_.current_alpha());
 }
 
 void ShelfBackgroundAnimator::PaintBackground(
     ShelfBackgroundType background_type,
-    BackgroundAnimatorChangeType change_type) {
+    gfx::AnimationChangeType change_type) {
   if (target_background_type_ == background_type &&
-      change_type == BACKGROUND_CHANGE_ANIMATE) {
+      change_type == gfx::ANIMATION_CHANGE_ANIMATE) {
     return;
   }
 
   AnimateBackground(background_type, change_type);
 }
 
+void ShelfBackgroundAnimator::AnimationProgressed(
+    const gfx::Animation* animation) {
+  shelf_background_values_.UpdateCurrentValues(animation->GetCurrentValue());
+  item_background_values_.UpdateCurrentValues(animation->GetCurrentValue());
+  NotifyObservers();
+}
+
+void ShelfBackgroundAnimator::AnimationEnded(const gfx::Animation* animation) {
+  shelf_background_values_.UpdateCurrentValues(animation->GetCurrentValue());
+  item_background_values_.UpdateCurrentValues(animation->GetCurrentValue());
+  NotifyObservers();
+}
+
 void ShelfBackgroundAnimator::OnBackgroundTypeChanged(
     ShelfBackgroundType background_type,
-    BackgroundAnimatorChangeType change_type) {
+    gfx::AnimationChangeType change_type) {
   PaintBackground(background_type, change_type);
 }
 
-void ShelfBackgroundAnimator::UpdateBackground(BackgroundAnimator* animator,
-                                               int alpha) {
-  OnAlphaChanged(animator, alpha);
-}
-
-void ShelfBackgroundAnimator::BackgroundAnimationEnded(
-    BackgroundAnimator* animator) {
-  ++successful_animator_count_;
-  DCHECK_LE(successful_animator_count_, kNumAnimators);
-  // UpdateBackground() is only called when alpha values change, this ensures
-  // observers are always notified for every background change.
-  OnAlphaChanged(animator, animator->alpha());
-}
-
-void ShelfBackgroundAnimator::OnAlphaChanged(BackgroundAnimator* animator,
-                                             int alpha) {
-  if (animator == opaque_background_animator_.get()) {
-    for (auto& observer : observers_)
-      observer.UpdateShelfOpaqueBackground(alpha);
-  } else if (animator == item_background_animator_.get()) {
-    for (auto& observer : observers_)
-      observer.UpdateShelfItemBackground(alpha);
-  } else {
-    NOTREACHED();
-  }
+void ShelfBackgroundAnimator::NotifyObservers() {
+  for (auto& observer : observers_)
+    NotifyObserver(&observer);
 }
 
 void ShelfBackgroundAnimator::AnimateBackground(
     ShelfBackgroundType background_type,
-    BackgroundAnimatorChangeType change_type) {
-  // Ensure BackgroundAnimationEnded() has been called for all the
-  // BackgroundAnimators owned by this so that |successful_animator_count_|
-  // is stable and doesn't get updated as a side effect of destroying/animating
-  // the animators.
-  StopAnimators();
+    gfx::AnimationChangeType change_type) {
+  const bool was_animating = animator_ && animator_->is_animating();
+  StopAnimator();
 
-  bool show_background = true;
-  if (can_reuse_animators_ && previous_background_type_ == background_type) {
-    DCHECK_EQ(opaque_background_animator_->paints_background(),
-              item_background_animator_->paints_background());
+  const bool change_immediately =
+      change_type == gfx::ANIMATION_CHANGE_IMMEDIATE;
+  if (can_reuse_animator_ && previous_background_type_ == background_type) {
+    if (animator_->IsShowing()) {

[James Cook, 2017/02/08 00:31:27]

You're checking for null animator_ on line 103. Can animator_ ever be null here?
If not, a comment somewhere would be nice.

[bruthig, 2017/02/10 18:49:09]

Comment added, WDYT?

+      if (change_immediately)
+        animator_->HideImmediately();
+      else
+        animator_->Hide();
+    } else {
+      if (change_immediately)
+        animator_->ShowImmediately();
+      else
+        animator_->Show();
+    }
+  } else {
+    // If the previous animator completed successfully and the animation was
+    // between 2 distinct states, then the last values are valid end state
+    // values.
+    can_reuse_animator_ =
+        target_background_type_ != background_type && !was_animating;
 
-    show_background = !opaque_background_animator_->paints_background();
-  } else {
-    CreateAnimators(background_type, change_type);
+    CreateAnimator(background_type);
 
-    // If all the previous animators completed successfully and the animation
-    // was between 2 distinct states, then the last alpha values are valid
-    // end state values.
-    can_reuse_animators_ = target_background_type_ != background_type &&
-                           successful_animator_count_ == kNumAnimators;
+    if (change_immediately)
+      animator_->ShowImmediately();
+    else
+      animator_->Show();
   }
 
-  successful_animator_count_ = 0;
-
-  opaque_background_animator_->SetPaintsBackground(show_background,
-                                                   change_type);
-  item_background_animator_->SetPaintsBackground(show_background, change_type);
-
   if (target_background_type_ != background_type) {
     previous_background_type_ = target_background_type_;
     target_background_type_ = background_type;
   }
 }
 
-void ShelfBackgroundAnimator::CreateAnimators(
-    ShelfBackgroundType background_type,
-    BackgroundAnimatorChangeType change_type) {
-  const int opaque_background_alpha =
-      opaque_background_animator_ ? opaque_background_animator_->alpha() : 0;
-  const int item_background_alpha =
-      item_background_animator_ ? item_background_animator_->alpha() : 0;
-
-  const bool is_material = MaterialDesignController::IsShelfMaterial();
+void ShelfBackgroundAnimator::CreateAnimator(
+    ShelfBackgroundType background_type) {
   int duration_ms = 0;
+  int target_shelf_background = 0;
+  int target_shelf_item_background = 0;
 
   switch (background_type) {
     case SHELF_BACKGROUND_DEFAULT:
-      duration_ms = is_material ? 500 : 1000;
-      opaque_background_animator_.reset(
-          new BackgroundAnimator(this, opaque_background_alpha, 0));
-      item_background_animator_.reset(
-          new BackgroundAnimator(this, item_background_alpha,
-                                 GetShelfConstant(SHELF_BACKGROUND_ALPHA)));
+      duration_ms = 500;
+      target_shelf_background = 0;
+      target_shelf_item_background = kShelfTranslucentAlpha;
       break;
     case SHELF_BACKGROUND_OVERLAP:
-      duration_ms = is_material ? 500 : 1000;
-      opaque_background_animator_.reset(new BackgroundAnimator(
-          this, opaque_background_alpha,
-          is_material ? GetShelfConstant(SHELF_BACKGROUND_ALPHA) : 0));
-      item_background_animator_.reset(new BackgroundAnimator(
-          this, item_background_alpha,
-          is_material ? 0 : GetShelfConstant(SHELF_BACKGROUND_ALPHA)));
+      duration_ms = 500;
+      target_shelf_background = kShelfTranslucentAlpha;
+      target_shelf_item_background = 0;
       break;
     case SHELF_BACKGROUND_MAXIMIZED:
-      duration_ms = is_material ? 250 : 1000;
-      opaque_background_animator_.reset(
-          new BackgroundAnimator(this, opaque_background_alpha, kMaxAlpha));
-      item_background_animator_.reset(new BackgroundAnimator(
-          this, item_background_alpha, is_material ? 0 : kMaxAlpha));
+      duration_ms = 250;
+      target_shelf_background = kMaxAlpha;
+      target_shelf_item_background = 0;
       break;
   }
 
-  opaque_background_animator_->SetDuration(duration_ms);
-  item_background_animator_->SetDuration(duration_ms);
+  animator_.reset(new gfx::SlideAnimation(this));
+  animator_->SetSlideDuration(duration_ms);
+  shelf_background_values_.SetTargetValues(target_shelf_background);
+  item_background_values_.SetTargetValues(target_shelf_item_background);
 }
 
-void ShelfBackgroundAnimator::StopAnimators() {
-  if (opaque_background_animator_)
-    opaque_background_animator_->Stop();
-  if (item_background_animator_)
-    item_background_animator_->Stop();
+void ShelfBackgroundAnimator::StopAnimator() {
+  if (animator_)
+    animator_->Stop();
 }
 
 }  // namespace ash