Prevent overlay scrollbars expand or hover together

cc/input/scrollbar_animation_controller_thinning.cc

 // Copyright 2013 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/input/scrollbar_animation_controller_thinning.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/time/time.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/layers/scrollbar_layer_impl_base.h"
 #include "cc/trees/layer_tree_impl.h"
 
-namespace {
-const float kIdleThicknessScale = 0.4f;
-const float kDefaultMouseMoveDistanceToTriggerAnimation = 25.f;
-}
-
 namespace cc {
 
 std::unique_ptr<ScrollbarAnimationControllerThinning>
 ScrollbarAnimationControllerThinning::Create(
     int scroll_layer_id,
     ScrollbarAnimationControllerClient* client,
     base::TimeDelta delay_before_starting,
     base::TimeDelta resize_delay_before_starting,
     base::TimeDelta fade_duration,
     base::TimeDelta thinning_duration) {
   return base::WrapUnique(new ScrollbarAnimationControllerThinning(
       scroll_layer_id, client, delay_before_starting,
       resize_delay_before_starting, fade_duration, thinning_duration));
 }
 
 ScrollbarAnimationControllerThinning::ScrollbarAnimationControllerThinning(
     int scroll_layer_id,
     ScrollbarAnimationControllerClient* client,
     base::TimeDelta delay_before_starting,
     base::TimeDelta resize_delay_before_starting,
     base::TimeDelta fade_duration,
     base::TimeDelta thinning_duration)
     : ScrollbarAnimationController(scroll_layer_id,
                                    client,
                                    delay_before_starting,
                                    resize_delay_before_starting),
       opacity_(0.0f),
-      captured_(false),
-      mouse_is_over_scrollbar_(false),
-      mouse_is_near_scrollbar_(false),
-      thickness_change_(NONE),
-      mouse_move_distance_to_trigger_animation_(
-          kDefaultMouseMoveDistanceToTriggerAnimation),
-      fade_duration_(fade_duration),
-      thinning_duration_(thinning_duration),
-      current_animating_property_(OPACITY) {
-  ApplyOpacity(0.f);
-  ApplyThumbThicknessScale(kIdleThicknessScale);
+      fade_duration_(fade_duration) {
+  vertical_controller_ = SingleScrollbarAnimationControllerThinning::Create(
+      scroll_layer_id, ScrollbarOrientation::VERTICAL, client,
+      thinning_duration);
+  horizontal_controller_ = SingleScrollbarAnimationControllerThinning::Create(
+      scroll_layer_id, ScrollbarOrientation::HORIZONTAL, client,
+      thinning_duration);
+  ApplyOpacity(0.0f);
 }
 
 ScrollbarAnimationControllerThinning::~ScrollbarAnimationControllerThinning() {}
 
+SingleScrollbarAnimationControllerThinning&
+ScrollbarAnimationControllerThinning::GetScrollbarAnimationController(
+    ScrollbarOrientation orientation) const {
+  if (orientation == ScrollbarOrientation::VERTICAL)
+    return *(vertical_controller_.get());
+  else
+    return *(horizontal_controller_.get());
+}
+
+bool ScrollbarAnimationControllerThinning::mouse_is_over_scrollbar(
+    ScrollbarOrientation orientation) const {
+  return GetScrollbarAnimationController(orientation).mouse_is_over_scrollbar();
+}
+
+bool ScrollbarAnimationControllerThinning::mouse_is_near_scrollbar(
+    ScrollbarOrientation orientation) const {
+  return GetScrollbarAnimationController(orientation).mouse_is_near_scrollbar();
+}
+
+bool ScrollbarAnimationControllerThinning::mouse_is_near_any_scrollbar() const {
+  return vertical_controller_->mouse_is_near_scrollbar() ||
+         horizontal_controller_->mouse_is_near_scrollbar();
+}
+
+bool ScrollbarAnimationControllerThinning::Captured() const {
+  return vertical_controller_->captured() || horizontal_controller_->captured();
+}
+
+bool ScrollbarAnimationControllerThinning::ScrollbarsHidden() const {
+  return opacity_ == 0.0f;
+}
+
+void ScrollbarAnimationControllerThinning::set_mouse_move_distance_for_test(
+    float distance) {
+  vertical_controller_->set_mouse_move_distance_for_test(distance);
+  horizontal_controller_->set_mouse_move_distance_for_test(distance);
+}
+
+bool ScrollbarAnimationControllerThinning::Animate(base::TimeTicks now) {
+  bool animated = ScrollbarAnimationController::Animate(now);
+  animated |= vertical_controller_->Animate(now);
+  animated |= horizontal_controller_->Animate(now);
+
+  return animated;
+}
+
 void ScrollbarAnimationControllerThinning::RunAnimationFrame(float progress) {
-  if (captured_)
+  ApplyOpacity(1.f - progress);
+  if (progress == 1.f)
+    StopAnimation();
+}
+
+const base::TimeDelta& ScrollbarAnimationControllerThinning::Duration() {
+  return fade_duration_;
+}
+
+void ScrollbarAnimationControllerThinning::DidMouseDown() {
+  if (ScrollbarsHidden())
     return;
+  vertical_controller_->DidMouseDown();
+  horizontal_controller_->DidMouseDown();
+}
 
-  if (current_animating_property_ == OPACITY)
-    ApplyOpacity(1.f - progress);
-  else
-    ApplyThumbThicknessScale(ThumbThicknessScaleAt(progress));
+void ScrollbarAnimationControllerThinning::DidMouseUp() {
+  vertical_controller_->DidMouseUp();
+  horizontal_controller_->DidMouseUp();
+}
 
-  client_->SetNeedsRedrawForScrollbarAnimation();
-  if (progress == 1.f) {
+void ScrollbarAnimationControllerThinning::DidMouseLeave() {
+  vertical_controller_->DidMouseLeave();
+  horizontal_controller_->DidMouseLeave();
+}
+
+void ScrollbarAnimationControllerThinning::DidMouseMoveNear(
+    ScrollbarOrientation orientation,
+    float distance) {
+  GetScrollbarAnimationController(orientation).DidMouseMoveNear(distance);
+
+  if (mouse_is_near_any_scrollbar() && !ScrollbarsHidden()) {
+    ApplyOpacity(1);
     StopAnimation();
-    if (current_animating_property_ == THICKNESS) {
-      thickness_change_ = NONE;
-      SetCurrentAnimatingProperty(OPACITY);
-      if (!mouse_is_near_scrollbar_)
-        PostDelayedAnimationTask(false);
-    }
+  } else if (!animating_fade() && !currently_scrolling()) {

[bokan, 2016/12/21 23:06:09]

I don't think you need !currently_scrolling, it's used to distinguish a
continuous scroll like a touch scroll from wheel like discrete scrolls. If we're
touch scrolling (so that currently_scrolling == true) we can't be moving the
mouse. Instead, I would check that the scrollbars aren't hidden (actually just
return early if ScrollbarsHidden() above) in this branch as well since we don't
want to be spamming animation tasks when the scrollbars are already hidden.

+    PostDelayedAnimationTask(false);
   }
 }
 
-const base::TimeDelta& ScrollbarAnimationControllerThinning::Duration() {
-  if (current_animating_property_ == OPACITY)
-    return fade_duration_;
-  else
-    return thinning_duration_;
-}
-
-void ScrollbarAnimationControllerThinning::DidMouseDown() {
-  if (!mouse_is_over_scrollbar_ || opacity_ == 0.0f)
-    return;
-
-  StopAnimation();
-  captured_ = true;
-  ApplyOpacity(1.f);
-  ApplyThumbThicknessScale(1.f);
-}
-
-void ScrollbarAnimationControllerThinning::DidMouseUp() {
-  if (!captured_ || opacity_ == 0.0f)
-    return;
-
-  captured_ = false;
-  StopAnimation();
-
-  if (!mouse_is_near_scrollbar_) {
-    SetCurrentAnimatingProperty(THICKNESS);
-    thickness_change_ = DECREASE;
-    StartAnimation();
-  } else {
-    SetCurrentAnimatingProperty(OPACITY);
-  }
-}
-
-void ScrollbarAnimationControllerThinning::DidMouseLeave() {
-  if (!mouse_is_over_scrollbar_ && !mouse_is_near_scrollbar_)
-    return;
-
-  mouse_is_over_scrollbar_ = false;
-  mouse_is_near_scrollbar_ = false;
-
-  if (captured_ || opacity_ == 0.0f)
-    return;
-
-  thickness_change_ = DECREASE;
-  SetCurrentAnimatingProperty(THICKNESS);
-  StartAnimation();
-}
-
 void ScrollbarAnimationControllerThinning::DidScrollUpdate(bool on_resize) {
-  if (captured_)
+  if (Captured())
     return;
 
   ScrollbarAnimationController::DidScrollUpdate(on_resize);
-  ApplyOpacity(1.f);
-  ApplyThumbThicknessScale(mouse_is_near_scrollbar_ ? 1.f
-                                                    : kIdleThicknessScale);
-  SetCurrentAnimatingProperty(OPACITY);
 
-  // Don't fade out the scrollbar when mouse is near.
-  if (mouse_is_near_scrollbar_)
+  ApplyOpacity(1);
+  vertical_controller_->UpdateThumbThicknessScale();
+  horizontal_controller_->UpdateThumbThicknessScale();
+
+  if (mouse_is_near_any_scrollbar())
     StopAnimation();
 }
 
 void ScrollbarAnimationControllerThinning::DidScrollEnd() {
   ScrollbarAnimationController::DidScrollEnd();
 
   // Don't fade out the scrollbar when mouse is near.
-  if (mouse_is_near_scrollbar_)
+  if (mouse_is_near_any_scrollbar())
     StopAnimation();
 }
 
-void ScrollbarAnimationControllerThinning::DidMouseMoveNear(float distance) {
-  bool mouse_is_over_scrollbar = distance == 0.0f;
-  bool mouse_is_near_scrollbar =
-      distance < mouse_move_distance_to_trigger_animation_;
-
-  if (captured_ || opacity_ == 0.0f) {
-    mouse_is_near_scrollbar_ = mouse_is_near_scrollbar;
-    mouse_is_over_scrollbar_ = mouse_is_over_scrollbar;
-    return;
-  }
-
-  if (mouse_is_over_scrollbar == mouse_is_over_scrollbar_ &&
-      mouse_is_near_scrollbar == mouse_is_near_scrollbar_)
-    return;
-
-  if (mouse_is_over_scrollbar_ != mouse_is_over_scrollbar)
-    mouse_is_over_scrollbar_ = mouse_is_over_scrollbar;
-
-  if (mouse_is_near_scrollbar_ != mouse_is_near_scrollbar) {
-    mouse_is_near_scrollbar_ = mouse_is_near_scrollbar;
-    thickness_change_ = mouse_is_near_scrollbar_ ? INCREASE : DECREASE;
-  }
-
-  SetCurrentAnimatingProperty(THICKNESS);
-  StartAnimation();
-}
-
-bool ScrollbarAnimationControllerThinning::ScrollbarsHidden() const {
-  return opacity_ == 0.0f;
-}
-
-float ScrollbarAnimationControllerThinning::ThumbThicknessScaleAt(
-    float progress) {
-  if (thickness_change_ == NONE)
-    return mouse_is_near_scrollbar_ ? 1.f : kIdleThicknessScale;
-  float factor = thickness_change_ == INCREASE ? progress : (1.f - progress);
-  return ((1.f - kIdleThicknessScale) * factor) + kIdleThicknessScale;
-}
-
-float ScrollbarAnimationControllerThinning::AdjustScale(
-    float new_value,
-    float current_value,
-    AnimationChange animation_change,
-    float min_value,
-    float max_value) {
-  float result;
-  if (animation_change == INCREASE && current_value > new_value)
-    result = current_value;
-  else if (animation_change == DECREASE && current_value < new_value)
-    result = current_value;
-  else
-    result = new_value;
-  if (result > max_value)
-    return max_value;
-  if (result < min_value)
-    return min_value;
-  return result;
-}
-
 void ScrollbarAnimationControllerThinning::ApplyOpacity(float opacity) {
   for (ScrollbarLayerImplBase* scrollbar : Scrollbars()) {
     if (!scrollbar->is_overlay_scrollbar())
       continue;
     float effective_opacity = scrollbar->CanScrollOrientation() ? opacity : 0;
     PropertyTrees* property_trees =
         scrollbar->layer_tree_impl()->property_trees();
     // If this method is called during LayerImpl::PushPropertiesTo, we may not
     // yet have valid effect_id_to_index_map entries as property trees are
     // pushed after layers during activation. We can skip updating opacity in
@@ skipping 10 matching lines @@
 
   bool previouslyVisible = opacity_ > 0.0f;
   bool currentlyVisible = opacity > 0.0f;
 
   opacity_ = opacity;
 
   if (previouslyVisible != currentlyVisible)
     client_->DidChangeScrollbarVisibility();
 }
 
-void ScrollbarAnimationControllerThinning::ApplyThumbThicknessScale(
-    float thumb_thickness_scale) {
-  for (ScrollbarLayerImplBase* scrollbar : Scrollbars()) {
-    if (!scrollbar->is_overlay_scrollbar())
-      continue;
-
-    scrollbar->SetThumbThicknessScaleFactor(AdjustScale(
-        thumb_thickness_scale, scrollbar->thumb_thickness_scale_factor(),
-        thickness_change_, kIdleThicknessScale, 1));
-  }
-}
-
-void ScrollbarAnimationControllerThinning::SetCurrentAnimatingProperty(
-    AnimatingProperty property) {
-  if (current_animating_property_ == property)
-    return;
-
-  StopAnimation();
-  current_animating_property_ = property;
-  if (current_animating_property_ == THICKNESS)
-    ApplyOpacity(1.f);
-}
-
 }  // namespace cc