/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #ifndef mozilla_layout_ScrollSnap_h_ #define mozilla_layout_ScrollSnap_h_ namespace mozilla { namespace layers { struct ScrollSnapInfo; } struct ScrollSnapUtils { /** * GetSnapPointForDestination determines which point to snap to after * scrolling. |aStartPos| gives the position before scrolling and * |aDestination| gives the position after scrolling, with no snapping. * Behaviour is dependent on the value of |aUnit|. * |aSnapInfo|, |aScrollPortSize|, and |aScrollRange| are characteristics * of the scroll frame for which snapping is being performed. * If a suitable snap point could be found, it is returned. Otherwise, an * empty Maybe is returned. * IMPORTANT NOTE: This function is designed to be called both on and off * the main thread. If modifying its implementation, be sure * not to touch main-thread-only data structures without * appropriate locking. */ static Maybe<nsPoint> GetSnapPointForDestination( const layers::ScrollSnapInfo& aSnapInfo, nsIScrollableFrame::ScrollUnit aUnit, const nsSize& aScrollPortSize, const nsRect& aScrollRange, const nsPoint& aStartPos, const nsPoint& aDestination); }; } // namespace mozilla #endif // mozilla_layout_ScrollSnap_h_