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// Copyright (c) 2012 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.
#ifndef UI_APP_LIST_PAGINATION_MODEL_H_
#define UI_APP_LIST_PAGINATION_MODEL_H_
#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"
#include "base/time/time.h"
#include "ui/app_list/app_list_export.h"
#include "ui/gfx/animation/animation_delegate.h"
namespace gfx {
class SlideAnimation;
}
namespace app_list {
class PaginationModelObserver;
// A simple pagination model that consists of two numbers: the total pages and
// the currently selected page. The model is a single selection model that at
// the most one page can become selected at any time.
class APP_LIST_EXPORT PaginationModel : public gfx::AnimationDelegate {
public:
// Holds info for transition animation and touch scroll.
struct Transition {
Transition(int target_page, double progress)
: target_page(target_page),
progress(progress) {
}
bool Equals(const Transition& rhs) const {
return target_page == rhs.target_page && progress == rhs.progress;
}
// Target page for the transition or -1 if there is no target page. For
// page switcher, this is the target selected page. For touch scroll,
// this is usually the previous or next page (or -1 when there is no
// previous or next page).
int target_page;
// A [0, 1] progress indicates how much of the current page is being
// transitioned.
double progress;
};
PaginationModel();
virtual ~PaginationModel();
void SetTotalPages(int total_pages);
// Selects a page. |animate| is true if the transition should be animated.
void SelectPage(int page, bool animate);
// Selects a page by relative |delta|.
void SelectPageRelative(int delta, bool animate);
void SetTransition(const Transition& transition);
void SetTransitionDurations(int duration_ms, int overscroll_duration_ms);
// Starts a scroll transition. If there is a running transition animation,
// cancels it but keeps the transition info.
void StartScroll();
// Updates transition progress from |delta|. |delta| > 0 means transit to
// previous page (moving pages to the right). |delta| < 0 means transit
// to next page (moving pages to the left).
void UpdateScroll(double delta);
// Finishes the current scroll transition if |cancel| is false. Otherwise,
// reverses it.
void EndScroll(bool cancel);
// Returns true if current transition is being reverted.
bool IsRevertingCurrentTransition() const;
void AddObserver(PaginationModelObserver* observer);
void RemoveObserver(PaginationModelObserver* observer);
int total_pages() const { return total_pages_; }
int selected_page() const { return selected_page_; }
const Transition& transition() const { return transition_; }
bool is_valid_page(int page) const {
return page >= 0 && page < total_pages_;
}
bool has_transition() const {
return transition_.target_page != -1 || transition_.progress != 0;
}
private:
void NotifySelectedPageChanged(int old_selected, int new_selected);
void NotifyTransitionStarted();
void NotifyTransitionChanged();
void clear_transition() {
SetTransition(Transition(-1, 0));
}
// Calculates a target page number by combining current page and |delta|.
// When there is no transition, current page is the currently selected page.
// If there is a transition, current page is the transition target page or the
// pending transition target page. When current page + |delta| goes beyond
// valid range and |selected_page_| is at the range ends, invalid page number
// -1 or |total_pages_| is returned to indicate the situation.
int CalculateTargetPage(int delta) const;
void StartTransitionAnimation(const Transition& transition);
void ResetTransitionAnimation();
// gfx::AnimationDelegate overrides:
virtual void AnimationProgressed(const gfx::Animation* animation) OVERRIDE;
virtual void AnimationEnded(const gfx::Animation* animation) OVERRIDE;
int total_pages_;
int selected_page_;
Transition transition_;
// Pending selected page when SelectedPage is called during a transition. If
// multiple SelectPage is called while a transition is in progress, only the
// last target page is remembered here.
int pending_selected_page_;
scoped_ptr<gfx::SlideAnimation> transition_animation_;
int transition_duration_ms_; // Transition duration in millisecond.
int overscroll_transition_duration_ms_;
int last_overscroll_target_page_;
base::TimeTicks last_overscroll_animation_start_time_;
ObserverList<PaginationModelObserver> observers_;
DISALLOW_COPY_AND_ASSIGN(PaginationModel);
};
} // namespace app_list
#endif // UI_APP_LIST_PAGINATION_MODEL_H_
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