android: move overscroll effects to ui/

content/browser/android/overscroll_refresh.h

-// 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_