ui/app_list/pagination_model.cc

   1 // Copyright (c) 2012 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 "ui/app_list/pagination_model.h"
   6
   7 #include <algorithm>
   8
   9 #include "ui/app_list/pagination_model_observer.h"
  10 #include "ui/gfx/animation/slide_animation.h"
  11
  12 namespace app_list {
  13
  14 PaginationModel::PaginationModel()
  15     : total_pages_(-1),
  16       selected_page_(-1),
  17       transition_(-1, 0),
  18       pending_selected_page_(-1),
  19       transition_duration_ms_(0),
  20       overscroll_transition_duration_ms_(0),
  21       last_overscroll_target_page_(0) {
  22 }
  23
  24 PaginationModel::~PaginationModel() {
  25 }
  26
  27 void PaginationModel::SetTotalPages(int total_pages) {
  28   if (total_pages == total_pages_)
  29     return;
  30
  31   total_pages_ = total_pages;
  32   if (selected_page_ < 0)
  33     SelectPage(0, false /* animate */);
  34   if (selected_page_ >= total_pages_)
  35     SelectPage(std::max(total_pages_ - 1, 0), false /* animate */);
  36   FOR_EACH_OBSERVER(PaginationModelObserver, observers_, TotalPagesChanged());
  37 }
  38
  39 void PaginationModel::SelectPage(int page, bool animate) {
  40   if (animate) {
  41     // -1 and |total_pages_| are valid target page for animation.
  42     DCHECK(page >= -1 && page <= total_pages_);
  43
  44     if (!transition_animation_) {
  45       if (page == selected_page_)
  46         return;
  47
  48       // Suppress over scroll animation if the same one happens too fast.
  49       if (!is_valid_page(page)) {
  50         const base::TimeTicks now = base::TimeTicks::Now();
  51
  52         if (page == last_overscroll_target_page_) {
  53           const int kMinOverScrollTimeGapInMs = 500;
  54           const base::TimeDelta time_elapsed =
  55                now - last_overscroll_animation_start_time_;
  56           if (time_elapsed.InMilliseconds() < kMinOverScrollTimeGapInMs)
  57             return;
  58         }
  59
  60         last_overscroll_target_page_ = page;
  61         last_overscroll_animation_start_time_ = now;
  62       }
  63
  64       // Creates an animation if there is not one.
  65       StartTransitionAnimation(Transition(page, 0));
  66       return;
  67     } else {
  68       const bool showing = transition_animation_->IsShowing();
  69       const int from_page = showing ? selected_page_ : transition_.target_page;
  70       const int to_page = showing ? transition_.target_page : selected_page_;
  71
  72       if (from_page == page) {
  73         if (showing)
  74           transition_animation_->Hide();
  75         else
  76           transition_animation_->Show();
  77         pending_selected_page_ = -1;
  78       } else if (to_page != page) {
  79         pending_selected_page_ = page;
  80       } else {
  81         pending_selected_page_ = -1;
  82       }
  83     }
  84   } else {
  85     DCHECK(total_pages_ == 0 || (page >= 0 && page < total_pages_));
  86
  87     if (page == selected_page_)
  88       return;
  89
  90     ResetTransitionAnimation();
  91
  92     int old_selected = selected_page_;
  93     selected_page_ = page;
  94     NotifySelectedPageChanged(old_selected, selected_page_);
  95   }
  96 }
  97
  98 void PaginationModel::SelectPageRelative(int delta, bool animate) {
  99   SelectPage(CalculateTargetPage(delta), animate);
 100 }
 101
 102 void PaginationModel::FinishAnimation() {
 103   SelectPage(SelectedTargetPage(), false);
 104 }
 105
 106 void PaginationModel::SetTransition(const Transition& transition) {
 107   // -1 and |total_pages_| is a valid target page, which means user is at
 108   // the end and there is no target page for this scroll.
 109   DCHECK(transition.target_page >= -1 &&
 110          transition.target_page <= total_pages_);
 111   DCHECK(transition.progress >= 0 && transition.progress <= 1);
 112
 113   if (transition_.Equals(transition))
 114     return;
 115
 116   transition_ = transition;
 117   NotifyTransitionChanged();
 118 }
 119
 120 void PaginationModel::SetTransitionDurations(int duration_ms,
 121                                              int overscroll_duration_ms) {
 122   transition_duration_ms_ = duration_ms;
 123   overscroll_transition_duration_ms_ = overscroll_duration_ms;
 124 }
 125
 126 void PaginationModel::StartScroll() {
 127   // Cancels current transition animation (if any).
 128   transition_animation_.reset();
 129 }
 130
 131 void PaginationModel::UpdateScroll(double delta) {
 132   // Translates scroll delta to desired page change direction.
 133   int page_change_dir = delta > 0 ? -1 : 1;
 134
 135   // Initializes a transition if there is none.
 136   if (!has_transition())
 137     transition_.target_page = CalculateTargetPage(page_change_dir);
 138
 139   // Updates transition progress.
 140   int transition_dir = transition_.target_page > selected_page_ ? 1 : -1;
 141   double progress = transition_.progress +
 142       fabs(delta) * page_change_dir * transition_dir;
 143
 144   if (progress < 0) {
 145     if (transition_.progress) {
 146       transition_.progress = 0;
 147       NotifyTransitionChanged();
 148     }
 149     clear_transition();
 150   } else if (progress > 1) {
 151     if (is_valid_page(transition_.target_page)) {
 152       SelectPage(transition_.target_page, false);
 153       clear_transition();
 154     }
 155   } else {
 156     transition_.progress = progress;
 157     NotifyTransitionChanged();
 158   }
 159 }
 160
 161 void PaginationModel::EndScroll(bool cancel) {
 162   if (!has_transition())
 163     return;
 164
 165   StartTransitionAnimation(transition_);
 166
 167   if (cancel)
 168     transition_animation_->Hide();
 169 }
 170
 171 bool PaginationModel::IsRevertingCurrentTransition() const {
 172   // Use !IsShowing() so that we return true at the end of hide animation.
 173   return transition_animation_ && !transition_animation_->IsShowing();
 174 }
 175
 176 void PaginationModel::AddObserver(PaginationModelObserver* observer) {
 177   observers_.AddObserver(observer);
 178 }
 179
 180 void PaginationModel::RemoveObserver(PaginationModelObserver* observer) {
 181   observers_.RemoveObserver(observer);
 182 }
 183
 184 int PaginationModel::SelectedTargetPage() const {
 185   // If no animation, or animation is in reverse, just the selected page.
 186   if (!transition_animation_ || !transition_animation_->IsShowing())
 187     return selected_page_;
 188
 189   // If, at the end of the current animation, we will animate to another page,
 190   // return that eventual page.
 191   if (pending_selected_page_ >= 0)
 192     return pending_selected_page_;
 193
 194   // Just the target of the current animation.
 195   return transition_.target_page;
 196 }
 197
 198 void PaginationModel::NotifySelectedPageChanged(int old_selected,
 199                                                 int new_selected) {
 200   FOR_EACH_OBSERVER(PaginationModelObserver,
 201                     observers_,
 202                     SelectedPageChanged(old_selected, new_selected));
 203 }
 204
 205 void PaginationModel::NotifyTransitionStarted() {
 206   FOR_EACH_OBSERVER(PaginationModelObserver, observers_, TransitionStarted());
 207 }
 208
 209 void PaginationModel::NotifyTransitionChanged() {
 210   FOR_EACH_OBSERVER(PaginationModelObserver, observers_, TransitionChanged());
 211 }
 212
 213 int PaginationModel::CalculateTargetPage(int delta) const {
 214   DCHECK_GT(total_pages_, 0);
 215   const int target_page = SelectedTargetPage() + delta;
 216
 217   int start_page = 0;
 218   int end_page = total_pages_ - 1;
 219
 220   // Use invalid page when |selected_page_| is at ends.
 221   if (target_page < start_page && selected_page_ == start_page)
 222     start_page = -1;
 223   else if (target_page > end_page && selected_page_ == end_page)
 224     end_page = total_pages_;
 225
 226   return std::max(start_page, std::min(end_page, target_page));
 227 }
 228
 229 void PaginationModel::StartTransitionAnimation(const Transition& transition) {
 230   DCHECK(selected_page_ != transition.target_page);
 231
 232   NotifyTransitionStarted();
 233   SetTransition(transition);
 234
 235   transition_animation_.reset(new gfx::SlideAnimation(this));
 236   transition_animation_->SetTweenType(gfx::Tween::LINEAR);
 237   transition_animation_->Reset(transition_.progress);
 238
 239   const int duration = is_valid_page(transition_.target_page) ?
 240       transition_duration_ms_ : overscroll_transition_duration_ms_;
 241   if (duration)
 242     transition_animation_->SetSlideDuration(duration);
 243
 244   transition_animation_->Show();
 245 }
 246
 247 void PaginationModel::ResetTransitionAnimation() {
 248   transition_animation_.reset();
 249   transition_.target_page = -1;
 250   transition_.progress = 0;
 251   pending_selected_page_ = -1;
 252 }
 253
 254 void PaginationModel::AnimationProgressed(const gfx::Animation* animation) {
 255   transition_.progress = transition_animation_->GetCurrentValue();
 256   NotifyTransitionChanged();
 257 }
 258
 259 void PaginationModel::AnimationEnded(const gfx::Animation* animation) {
 260   // Save |pending_selected_page_| because SelectPage resets it.
 261   int next_target = pending_selected_page_;
 262
 263   if (transition_animation_->GetCurrentValue() == 1) {
 264     // Showing animation ends.
 265     if (!is_valid_page(transition_.target_page)) {
 266       // If target page is not in valid range, reverse the animation.
 267       transition_animation_->Hide();
 268       return;
 269     }
 270
 271     // Otherwise, change page and finish the transition.
 272     DCHECK(selected_page_ != transition_.target_page);
 273     SelectPage(transition_.target_page, false /* animate */);
 274   } else if (transition_animation_->GetCurrentValue() == 0) {
 275     // Hiding animation ends. No page change should happen.
 276     ResetTransitionAnimation();
 277   }
 278
 279   if (next_target >= 0)
 280     SelectPage(next_target, true);
 281 }
 282
 283 }  // namespace app_list