Animate exapand arrow position during app list view state change

BUG=1026343

Change-Id: Ibb517db781ceffd26e7f4fa9e00d087d9b814af3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2004053Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Commit-Queue: Toni Baržić <tbarzic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732518}

ash/app_list/views/contents_view.cc

@@ -849,7 +849,7 @@ void ContentsView::AnimateToViewState(AppListViewState target_view_state,
   // |layer| - The layer to transform.
   // |y_offset| - The initial vertical offset - the layer's vertical offset will
   //              be animated to 0.
-  auto animate_transform = [](base::TimeDelta duration, int y_offset,
+  auto animate_transform = [](base::TimeDelta duration, float y_offset,
                               views::View* view) {
     ui::Layer* layer = view->layer();
     gfx::Transform transform;
@@ -941,6 +941,10 @@ void ContentsView::AnimateToViewState(AppListViewState target_view_state,
   // Schedule expand arrow repaint to ensure the view picks up the new target
   // state.
   expand_arrow_view()->SchedulePaint();
+  animate_transform(
+      duration,
+      expand_arrow_view()->CalculateOffsetFromCurrentAppListProgress(progress),
+      expand_arrow_view());
 }
 
 void ContentsView::SetExpandArrowViewVisibility(bool show) {

ash/app_list/views/expand_arrow_view.cc

@@ -85,6 +85,25 @@ constexpr int kFocusRingWidth = 2;
 constexpr int kTapTargetWidth = 156;
 constexpr int kTapTargetHeight = 72;
 
+float GetCircleCenterYForAppListProgress(float progress) {
+  if (progress <= 1) {
+    return gfx::Tween::FloatValueBetween(progress, kCircleCenterClosedY,
+                                         kCircleCenterPeekingY);
+  }
+  return gfx::Tween::FloatValueBetween(std::min(1.0f, progress - 1),
+                                       kCircleCenterPeekingY,
+                                       kCircleCenterFullscreenY);
+}
+
+float GetArrowYForAppListProgress(float progress) {
+  if (progress <= 1) {
+    return gfx::Tween::FloatValueBetween(progress, kArrowClosedY,
+                                         kArrowPeekingY);
+  }
+  return gfx::Tween::FloatValueBetween(std::min(1.0f, progress - 1),
+                                       kArrowPeekingY, kArrowFullscreenY);
+}
+
 }  // namespace
 
 ExpandArrowView::ExpandArrowView(ContentsView* contents_view,
@@ -122,23 +141,13 @@ void ExpandArrowView::PaintButtonContents(gfx::Canvas* canvas) {
   SkColor circle_color = kBackgroundColor;
   const float progress = app_list_view_->GetAppListTransitionProgress(
       AppListView::kProgressFlagNone);
-  if (progress <= 1) {
-    // Currently transition progress is between closed and peeking state.
-    // Change the y positions of arrow and circle.
-    circle_center.set_y(gfx::Tween::FloatValueBetween(
-        progress, kCircleCenterClosedY, kCircleCenterPeekingY));
-    arrow_origin.set_y(
-        gfx::Tween::FloatValueBetween(progress, kArrowClosedY, kArrowPeekingY));
-  } else {
+  circle_center.set_y(GetCircleCenterYForAppListProgress(progress));
+  arrow_origin.set_y(GetArrowYForAppListProgress(progress));
+  // If transition progress is between peeking and fullscreen state, change the
+  // shape of the arrow and the opacity of the circle in addition to changing
+  // the circle and arrow position.
+  if (progress > 1) {
     const float peeking_to_full_progress = progress - 1;
-    // Currently transition progress is between peeking and fullscreen state.
-    // Change the y positions of arrow and circle. Also change the shape of
-    // the arrow and the opacity of the circle.
-    circle_center.set_y(gfx::Tween::FloatValueBetween(
-        peeking_to_full_progress, kCircleCenterPeekingY,
-        kCircleCenterFullscreenY));
-    arrow_origin.set_y(gfx::Tween::FloatValueBetween(
-        peeking_to_full_progress, kArrowPeekingY, kArrowFullscreenY));
     for (size_t i = 0; i < kPointCount; ++i) {
       arrow_points[i].set_y(gfx::Tween::FloatValueBetween(
           peeking_to_full_progress, kPeekingPoints[i].y(),
@@ -374,6 +383,14 @@ void ExpandArrowView::MaybeEnableHintingAnimation(bool enabled) {
   }
 }
 
+float ExpandArrowView::CalculateOffsetFromCurrentAppListProgress(
+    double progress) const {
+  const float current_progress = app_list_view_->GetAppListTransitionProgress(
+      AppListView::kProgressFlagNone);
+  return GetCircleCenterYForAppListProgress(progress) -
+         GetCircleCenterYForAppListProgress(current_progress);
+}
+
 void ExpandArrowView::ScheduleHintingAnimation(bool is_first_time) {
   int delay_in_sec = kAnimationIntervalInSec;
   if (is_first_time)

ash/app_list/views/expand_arrow_view.h

@@ -54,6 +54,11 @@ class APP_LIST_EXPORT ExpandArrowView : public views::Button,
   std::unique_ptr<views::InkDropMask> CreateInkDropMask() const override;
   std::unique_ptr<views::InkDropRipple> CreateInkDropRipple() const override;
 
+  // Calculates vertical offset between expand arrow circle's positions with app
+  // list view drag progress |progress| and the current app list progress
+  // (calculated without taking app list animation state into account).
+  float CalculateOffsetFromCurrentAppListProgress(double progress) const;
+
   void MaybeEnableHintingAnimation(bool enabled);
 
   bool IsHintingAnimationRunningForTest() {