ccameron | 4163cc35 | 2014-11-13 19:06:36 | [diff] [blame^] | 1 | // Copyright 2014 The Chromium Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef CC_INPUT_SCROLL_ELASTICITY_HELPER_H_ |
| 6 | #define CC_INPUT_SCROLL_ELASTICITY_HELPER_H_ |
| 7 | |
| 8 | #include "base/time/time.h" |
| 9 | #include "cc/base/cc_export.h" |
| 10 | #include "ui/gfx/geometry/vector2d_f.h" |
| 11 | |
| 12 | namespace cc { |
| 13 | |
| 14 | class LayerTreeHostImpl; |
| 15 | |
| 16 | // ScrollElasticityHelper is based on |
| 17 | // WebKit/Source/platform/mac/ScrollElasticityController.h |
| 18 | /* |
| 19 | * Copyright (C) 2011 Apple Inc. All rights reserved. |
| 20 | * |
| 21 | * Redistribution and use in source and binary forms, with or without |
| 22 | * modification, are permitted provided that the following conditions |
| 23 | * are met: |
| 24 | * 1. Redistributions of source code must retain the above copyright |
| 25 | * notice, this list of conditions and the following disclaimer. |
| 26 | * 2. Redistributions in binary form must reproduce the above copyright |
| 27 | * notice, this list of conditions and the following disclaimer in the |
| 28 | * documentation and/or other materials provided with the distribution. |
| 29 | * |
| 30 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' |
| 31 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| 32 | * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 33 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS |
| 34 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 35 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 36 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 37 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 38 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 39 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF |
| 40 | * THE POSSIBILITY OF SUCH DAMAGE. |
| 41 | */ |
| 42 | |
| 43 | // Interface between a LayerTreeHostImpl and the ScrollElasticityController. It |
| 44 | // would be possible, in principle, for LayerTreeHostImpl to implement this |
| 45 | // interface itself. This artificial boundary is introduced to reduce the amount |
| 46 | // of logic and state held directly inside LayerTreeHostImpl. |
| 47 | class CC_EXPORT ScrollElasticityHelper { |
| 48 | public: |
| 49 | explicit ScrollElasticityHelper(LayerTreeHostImpl* layer_tree); |
| 50 | ~ScrollElasticityHelper(); |
| 51 | |
| 52 | bool AllowsHorizontalStretching(); |
| 53 | bool AllowsVerticalStretching(); |
| 54 | // The amount that the view is stretched past the normal allowable bounds. |
| 55 | // The "overhang" amount. |
| 56 | gfx::Vector2dF StretchAmount(); |
| 57 | bool PinnedInDirection(const gfx::Vector2dF& direction); |
| 58 | bool CanScrollHorizontally(); |
| 59 | bool CanScrollVertically(); |
| 60 | |
| 61 | // Return the absolute scroll position, not relative to the scroll origin. |
| 62 | gfx::Vector2dF AbsoluteScrollPosition(); |
| 63 | |
| 64 | void ImmediateScrollBy(const gfx::Vector2dF& scroll); |
| 65 | void ImmediateScrollByWithoutContentEdgeConstraints( |
| 66 | const gfx::Vector2dF& scroll); |
| 67 | void StartSnapRubberbandTimer(); |
| 68 | void StopSnapRubberbandTimer(); |
| 69 | void SnapRubberbandTimerFired(); |
| 70 | |
| 71 | // If the current scroll position is within the overhang area, this function |
| 72 | // will cause |
| 73 | // the page to scroll to the nearest boundary point. |
| 74 | void AdjustScrollPositionToBoundsIfNecessary(); |
| 75 | |
| 76 | private: |
| 77 | LayerTreeHostImpl* layer_tree_host_impl_; |
| 78 | gfx::Vector2dF stretch_offset_; |
| 79 | bool timer_active_; |
| 80 | }; |
| 81 | |
| 82 | } // namespace cc |
| 83 | |
| 84 | #endif // CC_INPUT_SCROLL_ELASTICITY_HELPER_H_ |