ui/app_list/pagination_model.h

   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 #ifndef UI_APP_LIST_PAGINATION_MODEL_H_
   6 #define UI_APP_LIST_PAGINATION_MODEL_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/compiler_specific.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/observer_list.h"
  12 #include "base/time/time.h"
  13 #include "ui/app_list/app_list_export.h"
  14 #include "ui/gfx/animation/animation_delegate.h"
  15
  16 namespace gfx {
  17 class SlideAnimation;
  18 }
  19
  20 namespace app_list {
  21
  22 class PaginationModelObserver;
  23
  24 // A simple pagination model that consists of two numbers: the total pages and
  25 // the currently selected page. The model is a single selection model that at
  26 // the most one page can become selected at any time.
  27 class APP_LIST_EXPORT PaginationModel : public gfx::AnimationDelegate {
  28  public:
  29   // Holds info for transition animation and touch scroll.
  30   struct Transition {
  31     Transition(int target_page, double progress)
  32         : target_page(target_page),
  33           progress(progress) {
  34     }
  35
  36     bool Equals(const Transition& rhs) const {
  37       return target_page == rhs.target_page && progress == rhs.progress;
  38     }
  39
  40     // Target page for the transition or -1 if there is no target page. For
  41     // page switcher, this is the target selected page. For touch scroll,
  42     // this is usually the previous or next page (or -1 when there is no
  43     // previous or next page).
  44     int target_page;
  45
  46     // A [0, 1] progress indicates how much of the current page is being
  47     // transitioned.
  48     double progress;
  49   };
  50
  51   PaginationModel();
  52   ~PaginationModel() override;
  53
  54   void SetTotalPages(int total_pages);
  55
  56   // Selects a page. |animate| is true if the transition should be animated.
  57   void SelectPage(int page, bool animate);
  58
  59   // Selects a page by relative |delta|.
  60   void SelectPageRelative(int delta, bool animate);
  61
  62   // Immediately completes all queued animations, jumping directly to the final
  63   // target page.
  64   void FinishAnimation();
  65
  66   void SetTransition(const Transition& transition);
  67   void SetTransitionDurations(int duration_ms, int overscroll_duration_ms);
  68
  69   // Starts a scroll transition. If there is a running transition animation,
  70   // cancels it but keeps the transition info.
  71   void StartScroll();
  72
  73   // Updates transition progress from |delta|. |delta| > 0 means transit to
  74   // previous page (moving pages to the right). |delta| < 0 means transit
  75   // to next page (moving pages to the left).
  76   void UpdateScroll(double delta);
  77
  78   // Finishes the current scroll transition if |cancel| is false. Otherwise,
  79   // reverses it.
  80   void EndScroll(bool cancel);
  81
  82   // Returns true if current transition is being reverted.
  83   bool IsRevertingCurrentTransition() const;
  84
  85   void AddObserver(PaginationModelObserver* observer);
  86   void RemoveObserver(PaginationModelObserver* observer);
  87
  88   int total_pages() const { return total_pages_; }
  89   int selected_page() const { return selected_page_; }
  90   const Transition& transition() const { return transition_; }
  91
  92   bool is_valid_page(int page) const {
  93     return page >= 0 && page < total_pages_;
  94   }
  95
  96   bool has_transition() const {
  97     return transition_.target_page != -1 || transition_.progress != 0;
  98   }
  99
 100   // Gets the page that the animation will eventually land on. If there is no
 101   // active animation, just returns selected_page().
 102   int SelectedTargetPage() const;
 103
 104  private:
 105   void NotifySelectedPageChanged(int old_selected, int new_selected);
 106   void NotifyTransitionStarted();
 107   void NotifyTransitionChanged();
 108
 109   void clear_transition() {
 110     SetTransition(Transition(-1, 0));
 111   }
 112
 113   // Calculates a target page number by combining current page and |delta|.
 114   // When there is no transition, current page is the currently selected page.
 115   // If there is a transition, current page is the transition target page or the
 116   // pending transition target page. When current page + |delta| goes beyond
 117   // valid range and |selected_page_| is at the range ends, invalid page number
 118   // -1 or |total_pages_| is returned to indicate the situation.
 119   int CalculateTargetPage(int delta) const;
 120
 121   void StartTransitionAnimation(const Transition& transition);
 122   void ResetTransitionAnimation();
 123
 124   // gfx::AnimationDelegate overrides:
 125   void AnimationProgressed(const gfx::Animation* animation) override;
 126   void AnimationEnded(const gfx::Animation* animation) override;
 127
 128   int total_pages_;
 129   int selected_page_;
 130
 131   Transition transition_;
 132
 133   // Pending selected page when SelectedPage is called during a transition. If
 134   // multiple SelectPage is called while a transition is in progress, only the
 135   // last target page is remembered here.
 136   int pending_selected_page_;
 137
 138   scoped_ptr<gfx::SlideAnimation> transition_animation_;
 139   int transition_duration_ms_;  // Transition duration in millisecond.
 140   int overscroll_transition_duration_ms_;
 141
 142   int last_overscroll_target_page_;
 143   base::TimeTicks last_overscroll_animation_start_time_;
 144
 145   base::ObserverList<PaginationModelObserver> observers_;
 146
 147   DISALLOW_COPY_AND_ASSIGN(PaginationModel);
 148 };
 149
 150 }  // namespace app_list
 151
 152 #endif  // UI_APP_LIST_PAGINATION_MODEL_H_