| // 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 UI_ANDROID_OVERSCROLL_REFRESH_H_ |
| #define UI_ANDROID_OVERSCROLL_REFRESH_H_ |
| |
| #include "base/macros.h" |
| #include "ui/android/ui_android_export.h" |
| #include "ui/gfx/geometry/size_f.h" |
| #include "ui/gfx/geometry/vector2d_f.h" |
| |
| namespace ui { |
| |
| class UI_ANDROID_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 UI_ANDROID_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 // UI_ANDROID_OVERSCROLL_REFRESH_H_ |