cc/input/top_controls_manager.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/input/top_controls_manager.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/logging.h"
  10 #include "cc/animation/keyframed_animation_curve.h"
  11 #include "cc/animation/timing_function.h"
  12 #include "cc/input/top_controls_manager_client.h"
  13 #include "cc/output/begin_frame_args.h"
  14 #include "cc/trees/layer_tree_impl.h"
  15 #include "ui/gfx/frame_time.h"
  16 #include "ui/gfx/geometry/vector2d_f.h"
  17 #include "ui/gfx/transform.h"
  18
  19 namespace cc {
  20 namespace {
  21 // These constants were chosen empirically for their visually pleasant behavior.
  22 // Contact tedchoc@chromium.org for questions about changing these values.
  23 const int64 kShowHideMaxDurationMs = 200;
  24 }
  25
  26 // static
  27 scoped_ptr<TopControlsManager> TopControlsManager::Create(
  28     TopControlsManagerClient* client,
  29     float top_controls_show_threshold,
  30     float top_controls_hide_threshold) {
  31   return make_scoped_ptr(new TopControlsManager(client,
  32                                                 top_controls_show_threshold,
  33                                                 top_controls_hide_threshold));
  34 }
  35
  36 TopControlsManager::TopControlsManager(TopControlsManagerClient* client,
  37                                        float top_controls_show_threshold,
  38                                        float top_controls_hide_threshold)
  39     : client_(client),
  40       animation_direction_(NO_ANIMATION),
  41       permitted_state_(BOTH),
  42       accumulated_scroll_delta_(0.f),
  43       baseline_content_offset_(0.f),
  44       top_controls_show_threshold_(top_controls_hide_threshold),
  45       top_controls_hide_threshold_(top_controls_show_threshold),
  46       pinch_gesture_active_(false) {
  47   CHECK(client_);
  48 }
  49
  50 TopControlsManager::~TopControlsManager() {
  51 }
  52
  53 float TopControlsManager::ControlsTopOffset() const {
  54   return ContentTopOffset() - TopControlsHeight();
  55 }
  56
  57 float TopControlsManager::ContentTopOffset() const {
  58   return TopControlsShownRatio() * TopControlsHeight();
  59 }
  60
  61 float TopControlsManager::TopControlsShownRatio() const {
  62   return client_->CurrentTopControlsShownRatio();
  63 }
  64
  65 float TopControlsManager::TopControlsHeight() const {
  66   return client_->TopControlsHeight();
  67 }
  68
  69 void TopControlsManager::UpdateTopControlsState(TopControlsState constraints,
  70                                                 TopControlsState current,
  71                                                 bool animate) {
  72   DCHECK(!(constraints == SHOWN && current == HIDDEN));
  73   DCHECK(!(constraints == HIDDEN && current == SHOWN));
  74
  75   permitted_state_ = constraints;
  76
  77   // Don't do anything if it doesn't matter which state the controls are in.
  78   if (constraints == BOTH && current == BOTH)
  79     return;
  80
  81   // Don't do anything if there is no change in offset.
  82   float final_shown_ratio = 1.f;
  83   if (constraints == HIDDEN || current == HIDDEN)
  84     final_shown_ratio = 0.f;
  85   if (final_shown_ratio == TopControlsShownRatio())
  86     return;
  87
  88   if (animate) {
  89     SetupAnimation(final_shown_ratio ? SHOWING_CONTROLS : HIDING_CONTROLS);
  90   } else {
  91     ResetAnimations();
  92     client_->SetCurrentTopControlsShownRatio(final_shown_ratio);
  93   }
  94 }
  95
  96 void TopControlsManager::ScrollBegin() {
  97   DCHECK(!pinch_gesture_active_);
  98   ResetAnimations();
  99   ResetBaseline();
 100 }
 101
 102 gfx::Vector2dF TopControlsManager::ScrollBy(
 103     const gfx::Vector2dF& pending_delta) {
 104   if (pinch_gesture_active_)
 105     return pending_delta;
 106
 107   if (permitted_state_ == SHOWN && pending_delta.y() > 0)
 108     return pending_delta;
 109   else if (permitted_state_ == HIDDEN && pending_delta.y() < 0)
 110     return pending_delta;
 111
 112   accumulated_scroll_delta_ += pending_delta.y();
 113
 114   float old_offset = ContentTopOffset();
 115   client_->SetCurrentTopControlsShownRatio(
 116       (baseline_content_offset_ - accumulated_scroll_delta_) /
 117       TopControlsHeight());
 118
 119   // If the controls are fully visible, treat the current position as the
 120   // new baseline even if the gesture didn't end.
 121   if (TopControlsShownRatio() == 1.f)
 122     ResetBaseline();
 123
 124   ResetAnimations();
 125
 126   gfx::Vector2dF applied_delta(0.f, old_offset - ContentTopOffset());
 127   return pending_delta - applied_delta;
 128 }
 129
 130 void TopControlsManager::ScrollEnd() {
 131   DCHECK(!pinch_gesture_active_);
 132   StartAnimationIfNecessary();
 133 }
 134
 135 void TopControlsManager::PinchBegin() {
 136   DCHECK(!pinch_gesture_active_);
 137   pinch_gesture_active_ = true;
 138   StartAnimationIfNecessary();
 139 }
 140
 141 void TopControlsManager::PinchEnd() {
 142   DCHECK(pinch_gesture_active_);
 143   // Pinch{Begin,End} will always occur within the scope of Scroll{Begin,End},
 144   // so return to a state expected by the remaining scroll sequence.
 145   pinch_gesture_active_ = false;
 146   ScrollBegin();
 147 }
 148
 149 void TopControlsManager::MainThreadHasStoppedFlinging() {
 150   StartAnimationIfNecessary();
 151 }
 152
 153 gfx::Vector2dF TopControlsManager::Animate(base::TimeTicks monotonic_time) {
 154   if (!top_controls_animation_ || !client_->HaveRootScrollLayer())
 155     return gfx::Vector2dF();
 156
 157   base::TimeDelta time = monotonic_time - base::TimeTicks();
 158
 159   float old_offset = ContentTopOffset();
 160   client_->SetCurrentTopControlsShownRatio(
 161       top_controls_animation_->GetValue(time));
 162
 163   if (IsAnimationCompleteAtTime(monotonic_time))
 164     ResetAnimations();
 165
 166   gfx::Vector2dF scroll_delta(0.f, ContentTopOffset() - old_offset);
 167   return scroll_delta;
 168 }
 169
 170 void TopControlsManager::ResetAnimations() {
 171   top_controls_animation_ = nullptr;
 172   animation_direction_ = NO_ANIMATION;
 173 }
 174
 175 void TopControlsManager::SetupAnimation(AnimationDirection direction) {
 176   DCHECK_NE(NO_ANIMATION, direction);
 177   DCHECK_IMPLIES(direction == HIDING_CONTROLS, TopControlsShownRatio() > 0.f);
 178   DCHECK_IMPLIES(direction == SHOWING_CONTROLS, TopControlsShownRatio() < 1.f);
 179
 180   if (top_controls_animation_ && animation_direction_ == direction)
 181     return;
 182
 183   top_controls_animation_ = KeyframedFloatAnimationCurve::Create();
 184   base::TimeDelta start_time = gfx::FrameTime::Now() - base::TimeTicks();
 185   top_controls_animation_->AddKeyframe(
 186       FloatKeyframe::Create(start_time, TopControlsShownRatio(), nullptr));
 187   float max_ending_ratio = (direction == SHOWING_CONTROLS ? 1 : -1);
 188   top_controls_animation_->AddKeyframe(FloatKeyframe::Create(
 189       start_time + base::TimeDelta::FromMilliseconds(kShowHideMaxDurationMs),
 190       TopControlsShownRatio() + max_ending_ratio,
 191       EaseTimingFunction::Create()));
 192   animation_direction_ = direction;
 193   client_->DidChangeTopControlsPosition();
 194 }
 195
 196 void TopControlsManager::StartAnimationIfNecessary() {
 197   if (TopControlsShownRatio() == 0.f || TopControlsShownRatio() == 1.f)
 198     return;
 199
 200   if (TopControlsShownRatio() >= 1.f - top_controls_hide_threshold_) {
 201     // If we're showing so much that the hide threshold won't trigger, show.
 202     SetupAnimation(SHOWING_CONTROLS);
 203   } else if (TopControlsShownRatio() <= top_controls_show_threshold_) {
 204     // If we're showing so little that the show threshold won't trigger, hide.
 205     SetupAnimation(HIDING_CONTROLS);
 206   } else {
 207     // If we could be either showing or hiding, we determine which one to
 208     // do based on whether or not the total scroll delta was moving up or
 209     // down.
 210     SetupAnimation(accumulated_scroll_delta_ <= 0.f ? SHOWING_CONTROLS
 211                                                     : HIDING_CONTROLS);
 212   }
 213 }
 214
 215 bool TopControlsManager::IsAnimationCompleteAtTime(base::TimeTicks time) {
 216   if (!top_controls_animation_)
 217     return true;
 218
 219   base::TimeDelta animation_time = time - base::TimeTicks();
 220   float new_ratio = top_controls_animation_->GetValue(animation_time);
 221
 222   if ((animation_direction_ == SHOWING_CONTROLS && new_ratio >= 1.f) ||
 223       (animation_direction_ == HIDING_CONTROLS && new_ratio <= 0.f)) {
 224     return true;
 225   }
 226   return false;
 227 }
 228
 229 void TopControlsManager::ResetBaseline() {
 230   accumulated_scroll_delta_ = 0.f;
 231   baseline_content_offset_ = ContentTopOffset();
 232 }
 233
 234 }  // namespace cc