app_list: Touch scroll and animation improvement.

ui/app_list/pagination_model.cc

 // Copyright (c) 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 "ui/app_list/pagination_model.h"
 
 #include <algorithm>
 
 #include "ui/app_list/pagination_model_observer.h"
 #include "ui/base/animation/slide_animation.h"
@@ skipping 28 matching lines @@
     // -1 and |total_pages_| are valid target page for animation.
     DCHECK(page >= -1 && page <= total_pages_);
 
     if (!transition_animation_.get()) {
       if (page == selected_page_)
         return;
 
       // Creates an animation if there is not one.
       StartTranstionAnimation(page);
       return;
-    } else if (transition_.target_page != page) {
-      // If there is a running transition, remembers it if it's new.
-      pending_selected_page_ = page;
+    } else {
+      const bool showing = transition_animation_->IsShowing();
+      const int from_page = showing ? selected_page_ :  transition_.target_page;
+      const int to_page = showing ? transition_.target_page : selected_page_;
+
+      if (from_page == page) {
+        if (showing)
+          transition_animation_->Hide();
+        else
+          transition_animation_->Show();
+        pending_selected_page_ = -1;
+      } else if (to_page != page) {
+        pending_selected_page_ = page;
+      } else {
+        pending_selected_page_ = -1;
+      }
     }
   } else {
     DCHECK(page >= 0 && page < total_pages_);
 
     if (page == selected_page_)
       return;
 
     ResetTransitionAnimation();
 
     int old_selected = selected_page_;
@@ skipping 17 matching lines @@
     return;
 
   transition_ = transition;
   NotifyTransitionChanged();
 }
 
 void PaginationModel::SetTransitionDuration(int duration_ms) {
   transition_duration_ms_ = duration_ms;
 }
 
-void PaginationModel::ResetTransitionAnimation() {
-  transition_animation_.reset();
-  transition_.target_page = -1;
-  transition_.progress = 0;
-  pending_selected_page_ = -1;
-}
-
 void PaginationModel::StartScroll() {
   // Cancels current transition animation (if any).
   transition_animation_.reset();
 }
 
 void PaginationModel::UpdateScroll(double delta) {
   // Translates scroll delta to desired page change direction.
   int page_change_dir = delta > 0 ? -1 : 1;
 
   // Initializes a transition if there is none.
@@ skipping 11 matching lines @@
     if (is_valid_page(transition_.target_page)) {
       SelectPage(transition_.target_page, false);
       clear_transition();
     }
   } else {
     transition_.progress = progress;
     NotifyTransitionChanged();
   }
 }
 
-void PaginationModel::EndScroll() {
+void PaginationModel::EndScroll(bool cancel) {
   if (!has_transition())
     return;
 
   CreateTransitionAnimation();
   transition_animation_->Reset(transition_.progress);
 
   // Always call Show to ensure animation will run.
   transition_animation_->Show();
-  if (transition_.progress < 0.5)
+  if (cancel)
     transition_animation_->Hide();
 }
 
 void PaginationModel::AddObserver(PaginationModelObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void PaginationModel::RemoveObserver(PaginationModelObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
 void PaginationModel::NotifySelectedPageChanged(int old_selected,
                                                 int new_selected) {
   FOR_EACH_OBSERVER(PaginationModelObserver,
                     observers_,
                     SelectedPageChanged(old_selected, new_selected));
 }
 
 void PaginationModel::NotifyTransitionChanged() {
   FOR_EACH_OBSERVER(PaginationModelObserver, observers_, TransitionChanged());
 }
 
 int PaginationModel::CalculateTargetPage(int delta) const {
   DCHECK_GT(total_pages_, 0);
 
   int current_page = selected_page_;
-  if (transition_animation_.get()) {
+  if (transition_animation_.get() && transition_animation_->IsShowing()) {
     current_page = pending_selected_page_ >= 0 ?
         pending_selected_page_ : transition_.target_page;
   }
 
   const int target_page = current_page + delta;
 
   int start_page = 0;
   int end_page = total_pages_ - 1;
 
   // Use invalid page when |selected_page_| is at ends.
   if (target_page < start_page && selected_page_ == start_page)
     start_page = -1;
   else if (target_page > end_page && selected_page_ == end_page)
     end_page = total_pages_;
 
   return std::max(start_page, std::min(end_page, target_page));
 }
 
 void PaginationModel::StartTranstionAnimation(int target_page) {
   DCHECK(selected_page_ != target_page);
 
   SetTransition(Transition(target_page, 0));
   CreateTransitionAnimation();
   transition_animation_->Show();
 }
 
 void PaginationModel::CreateTransitionAnimation() {
   transition_animation_.reset(new ui::SlideAnimation(this));
+  transition_animation_->SetTweenType(ui::Tween::LINEAR);
   if (transition_duration_ms_)
     transition_animation_->SetSlideDuration(transition_duration_ms_);
 }
 
+void PaginationModel::ResetTransitionAnimation() {
+  transition_animation_.reset();
+  transition_.target_page = -1;
+  transition_.progress = 0;
+  pending_selected_page_ = -1;
+}
+
 void PaginationModel::AnimationProgressed(const ui::Animation* animation) {
   transition_.progress = transition_animation_->GetCurrentValue();
   NotifyTransitionChanged();
 }
 
 void PaginationModel::AnimationEnded(const ui::Animation* animation) {
   // Save |pending_selected_page_| because SelectPage resets it.
   int next_target = pending_selected_page_;
 
   if (transition_animation_->GetCurrentValue() == 1) {
@@ skipping 12 matching lines @@
   } else if (transition_animation_->GetCurrentValue() == 0) {
     // Hiding animation ends. No page change should happen.
     ResetTransitionAnimation();
   }
 
   if (next_target >= 0)
     SelectPage(next_target, true);
 }
 
 }  // namespace app_list