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// Copyright 2014 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 CONTENT_BROWSER_ANDROID_OVERSCROLL_REFRESH_H_
#define CONTENT_BROWSER_ANDROID_OVERSCROLL_REFRESH_H_
#include "base/macros.h"
#include "content/common/content_export.h"
#include "ui/gfx/geometry/size_f.h"
#include "ui/gfx/geometry/vector2d_f.h"
namespace content {
class CONTENT_EXPORT OverscrollRefreshHandler {
public:
// Signals the start of an overscrolling pull. Returns whether the handler
// will consume the overscroll gesture, in which case it will receive the
// remaining pull updates.
virtual bool PullStart() = 0;
// Signals a pull update, where |delta| is in device pixels.
virtual void PullUpdate(float delta) = 0;
// Signals the release of the pull, and whether the release is allowed to
// trigger the refresh action.
virtual void PullRelease(bool allow_refresh) = 0;
// Reset the active pull state.
virtual void PullReset() = 0;
protected:
virtual ~OverscrollRefreshHandler() {}
};
// Simple pull-to-refresh styled effect. Listens to scroll events, conditionally
// activating when:
// 1) The scroll begins when the page's root layer 1) has no vertical scroll
// offset and 2) lacks the overflow-y:hidden property.
// 2) The page doesn't consume the initial scroll events.
// 3) The initial scroll direction is upward.
// The actuall pull response, animation and action are delegated to the
// provided refresh handler.
class CONTENT_EXPORT OverscrollRefresh {
public:
// Minmum number of overscrolling pull events required to activate the effect.
// Useful for avoiding accidental triggering when a scroll janks (is delayed),
// capping the impulse per event.
enum { kMinPullsToActivate = 3 };
explicit OverscrollRefresh(OverscrollRefreshHandler* handler);
~OverscrollRefresh();
// Scroll event stream listening methods.
void OnScrollBegin();
// Returns whether the refresh was activated.
void OnScrollEnd(const gfx::Vector2dF& velocity);
// Scroll ack listener. The effect will only be activated if the initial
// updates go unconsumed.
void OnScrollUpdateAck(bool was_consumed);
// Returns true if the effect has consumed the |scroll_delta|.
bool WillHandleScrollUpdate(const gfx::Vector2dF& scroll_delta);
// Release the effect (if active), preventing any associated refresh action.
void ReleaseWithoutActivation();
// Notify the effect of the latest scroll offset and overflow properties.
// The effect will be disabled when the offset is non-zero or overflow is
// hidden. Note: All dimensions are in device pixels.
void OnFrameUpdated(const gfx::Vector2dF& content_scroll_offset,
bool root_overflow_y_hidden);
// Reset the effect to its inactive state, immediately detaching and
// disabling any active effects.
void Reset();
// Returns true if the refresh effect is either being manipulated or animated.
bool IsActive() const;
// Returns true if the effect is waiting for an unconsumed scroll to start.
bool IsAwaitingScrollUpdateAck() const;
private:
void Release(bool allow_refresh);
bool scrolled_to_top_;
bool overflow_y_hidden_;
enum ScrollConsumptionState {
DISABLED,
AWAITING_SCROLL_UPDATE_ACK,
ENABLED,
} scroll_consumption_state_;
OverscrollRefreshHandler* const handler_;
DISALLOW_COPY_AND_ASSIGN(OverscrollRefresh);
};
} // namespace content
#endif // CONTENT_BROWSER_ANDROID_OVERSCROLL_REFRESH_H_
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