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      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/transform.h"
     17 #include "ui/gfx/vector2d_f.h"
     18 
     19 namespace cc {
     20 namespace {
     21 // These constants were chosen empirically for their visually pleasant behavior.
     22 // Contact tedchoc (at) 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_height,
     30     float top_controls_show_threshold,
     31     float top_controls_hide_threshold) {
     32   return make_scoped_ptr(new TopControlsManager(client,
     33                                                 top_controls_height,
     34                                                 top_controls_show_threshold,
     35                                                 top_controls_hide_threshold));
     36 }
     37 
     38 TopControlsManager::TopControlsManager(TopControlsManagerClient* client,
     39                                        float top_controls_height,
     40                                        float top_controls_show_threshold,
     41                                        float top_controls_hide_threshold)
     42     : client_(client),
     43       animation_direction_(NO_ANIMATION),
     44       permitted_state_(BOTH),
     45       controls_top_offset_(0.f),
     46       top_controls_height_(top_controls_height),
     47       current_scroll_delta_(0.f),
     48       controls_scroll_begin_offset_(0.f),
     49       top_controls_show_height_(
     50           top_controls_height * top_controls_hide_threshold),
     51       top_controls_hide_height_(
     52           top_controls_height * (1.f - top_controls_show_threshold)),
     53       pinch_gesture_active_(false) {
     54   CHECK(client_);
     55 }
     56 
     57 TopControlsManager::~TopControlsManager() {
     58 }
     59 
     60 void TopControlsManager::UpdateTopControlsState(TopControlsState constraints,
     61                                                 TopControlsState current,
     62                                                 bool animate) {
     63   DCHECK(!(constraints == SHOWN && current == HIDDEN));
     64   DCHECK(!(constraints == HIDDEN && current == SHOWN));
     65 
     66   permitted_state_ = constraints;
     67 
     68   // Don't do anything if it doesn't matter which state the controls are in.
     69   if (constraints == BOTH && current == BOTH)
     70     return;
     71 
     72   // Don't do anything if there is no change in offset.
     73   float final_controls_position = 0.f;
     74   if (constraints == HIDDEN || current == HIDDEN) {
     75     final_controls_position = -top_controls_height_;
     76   }
     77   if (final_controls_position == controls_top_offset_) {
     78     return;
     79   }
     80 
     81   AnimationDirection animation_direction = SHOWING_CONTROLS;
     82   if (constraints == HIDDEN || current == HIDDEN)
     83     animation_direction = HIDING_CONTROLS;
     84   ResetAnimations();
     85   if (animate) {
     86     SetupAnimation(animation_direction);
     87   } else {
     88     controls_top_offset_ = final_controls_position;
     89   }
     90   client_->DidChangeTopControlsPosition();
     91 }
     92 
     93 void TopControlsManager::ScrollBegin() {
     94   DCHECK(!pinch_gesture_active_);
     95   ResetAnimations();
     96   current_scroll_delta_ = 0.f;
     97   controls_scroll_begin_offset_ = controls_top_offset_;
     98 }
     99 
    100 gfx::Vector2dF TopControlsManager::ScrollBy(
    101     const gfx::Vector2dF pending_delta) {
    102   if (pinch_gesture_active_)
    103     return pending_delta;
    104 
    105   if (permitted_state_ == SHOWN && pending_delta.y() > 0)
    106     return pending_delta;
    107   else if (permitted_state_ == HIDDEN && pending_delta.y() < 0)
    108     return pending_delta;
    109 
    110   current_scroll_delta_ += pending_delta.y();
    111 
    112   float old_offset = controls_top_offset_;
    113   SetControlsTopOffset(controls_scroll_begin_offset_ - current_scroll_delta_);
    114 
    115   // If the controls are fully visible, treat the current position as the
    116   // new baseline even if the gesture didn't end.
    117   if (controls_top_offset_ == 0.f) {
    118     current_scroll_delta_ = 0.f;
    119     controls_scroll_begin_offset_ = 0.f;
    120   }
    121 
    122   ResetAnimations();
    123 
    124   gfx::Vector2dF applied_delta(0.f, old_offset - controls_top_offset_);
    125   return pending_delta - applied_delta;
    126 }
    127 
    128 void TopControlsManager::ScrollEnd() {
    129   DCHECK(!pinch_gesture_active_);
    130   StartAnimationIfNecessary();
    131 }
    132 
    133 void TopControlsManager::PinchBegin() {
    134   DCHECK(!pinch_gesture_active_);
    135   pinch_gesture_active_ = true;
    136   StartAnimationIfNecessary();
    137 }
    138 
    139 void TopControlsManager::PinchEnd() {
    140   DCHECK(pinch_gesture_active_);
    141   // Pinch{Begin,End} will always occur within the scope of Scroll{Begin,End},
    142   // so return to a state expected by the remaining scroll sequence.
    143   pinch_gesture_active_ = false;
    144   ScrollBegin();
    145 }
    146 
    147 void TopControlsManager::SetControlsTopOffset(float controls_top_offset) {
    148   controls_top_offset = std::max(controls_top_offset, -top_controls_height_);
    149   controls_top_offset = std::min(controls_top_offset, 0.f);
    150 
    151   if (controls_top_offset_ == controls_top_offset)
    152     return;
    153 
    154   controls_top_offset_ = controls_top_offset;
    155 
    156   client_->DidChangeTopControlsPosition();
    157 }
    158 
    159 gfx::Vector2dF TopControlsManager::Animate(base::TimeTicks monotonic_time) {
    160   if (!top_controls_animation_ || !client_->HaveRootScrollLayer())
    161     return gfx::Vector2dF();
    162 
    163   double time = (monotonic_time - base::TimeTicks()).InMillisecondsF();
    164 
    165   float old_offset = controls_top_offset_;
    166   SetControlsTopOffset(top_controls_animation_->GetValue(time));
    167 
    168   if (IsAnimationCompleteAtTime(monotonic_time))
    169     ResetAnimations();
    170 
    171   gfx::Vector2dF scroll_delta(0.f, controls_top_offset_ - old_offset);
    172   return scroll_delta;
    173 }
    174 
    175 void TopControlsManager::ResetAnimations() {
    176   if (top_controls_animation_)
    177     top_controls_animation_.reset();
    178 
    179   animation_direction_ = NO_ANIMATION;
    180 }
    181 
    182 void TopControlsManager::SetupAnimation(AnimationDirection direction) {
    183   DCHECK(direction != NO_ANIMATION);
    184 
    185   if (direction == SHOWING_CONTROLS && controls_top_offset_ == 0)
    186     return;
    187 
    188   if (direction == HIDING_CONTROLS &&
    189       controls_top_offset_ == -top_controls_height_) {
    190     return;
    191   }
    192 
    193   if (top_controls_animation_ && animation_direction_ == direction)
    194     return;
    195 
    196   top_controls_animation_ = KeyframedFloatAnimationCurve::Create();
    197   double start_time =
    198       (gfx::FrameTime::Now() - base::TimeTicks()).InMillisecondsF();
    199   top_controls_animation_->AddKeyframe(
    200       FloatKeyframe::Create(start_time, controls_top_offset_,
    201                             scoped_ptr<TimingFunction>()));
    202   float max_ending_offset =
    203       (direction == SHOWING_CONTROLS ? 1 : -1) * top_controls_height_;
    204   top_controls_animation_->AddKeyframe(
    205       FloatKeyframe::Create(start_time + kShowHideMaxDurationMs,
    206                             controls_top_offset_ + max_ending_offset,
    207                             EaseTimingFunction::Create()));
    208   animation_direction_ = direction;
    209   client_->DidChangeTopControlsPosition();
    210 }
    211 
    212 void TopControlsManager::StartAnimationIfNecessary() {
    213   if (controls_top_offset_ != 0
    214       && controls_top_offset_ != -top_controls_height_) {
    215     AnimationDirection show_controls = NO_ANIMATION;
    216 
    217     if (controls_top_offset_ >= -top_controls_show_height_) {
    218       // If we're showing so much that the hide threshold won't trigger, show.
    219       show_controls = SHOWING_CONTROLS;
    220     } else if (controls_top_offset_ <= -top_controls_hide_height_) {
    221       // If we're showing so little that the show threshold won't trigger, hide.
    222       show_controls = HIDING_CONTROLS;
    223     } else {
    224       // If we could be either showing or hiding, we determine which one to
    225       // do based on whether or not the total scroll delta was moving up or
    226       // down.
    227       show_controls = current_scroll_delta_ <= 0.f ?
    228           SHOWING_CONTROLS : HIDING_CONTROLS;
    229     }
    230 
    231     if (show_controls != NO_ANIMATION)
    232       SetupAnimation(show_controls);
    233   }
    234 }
    235 
    236 bool TopControlsManager::IsAnimationCompleteAtTime(base::TimeTicks time) {
    237   if (!top_controls_animation_)
    238     return true;
    239 
    240   double time_ms = (time - base::TimeTicks()).InMillisecondsF();
    241   float new_offset = top_controls_animation_->GetValue(time_ms);
    242 
    243   if ((animation_direction_ == SHOWING_CONTROLS && new_offset >= 0) ||
    244       (animation_direction_ == HIDING_CONTROLS
    245           && new_offset <= -top_controls_height_)) {
    246     return true;
    247   }
    248   return false;
    249 }
    250 
    251 }  // namespace cc
    252