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| 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 #include "cc/base/simple_enclosed_region.h" | |
| 6 | |
| 7 #include "base/logging.h" | |
| 8 #include "cc/base/region.h" | |
| 9 | |
| 10 namespace cc { | |
| 11 | |
| 12 static bool RectIsLargerArea(const gfx::Rect& a, const gfx::Rect b) { | |
| 13 int64 a_area = static_cast<int64>(a.width()) * a.height(); | |
| 14 int64 b_area = static_cast<int64>(b.width()) * b.height(); | |
| 15 return a_area > b_area; | |
| 16 } | |
| 17 | |
| 18 SimpleEnclosedRegion::SimpleEnclosedRegion(const Region& region) { | |
| 19 for (Region::Iterator it(region); it.has_rect(); it.next()) | |
| 20 Union(it.rect()); | |
| 21 } | |
| 22 | |
| 23 SimpleEnclosedRegion::~SimpleEnclosedRegion() { | |
| 24 } | |
| 25 | |
| 26 void SimpleEnclosedRegion::Subtract(const gfx::Rect& sub_rect) { | |
| 27 // We want to keep as much of the current rect as we can, so find the one | |
| 28 // largest rectangle inside |rect_| that does not intersect with |sub_rect|. | |
| 29 if (!rect_.Intersects(sub_rect)) | |
| 30 return; | |
| 31 if (sub_rect.Contains(rect_)) { | |
| 32 rect_ = gfx::Rect(); | |
| 33 return; | |
| 34 } | |
| 35 | |
| 36 int left = rect_.x(); | |
| 37 int right = rect_.right(); | |
| 38 int top = rect_.y(); | |
| 39 int bottom = rect_.bottom(); | |
| 40 | |
| 41 int delta_left = sub_rect.x() - left; | |
| 42 int delta_right = right - sub_rect.right(); | |
| 43 int delta_top = sub_rect.y() - top; | |
| 44 int delta_bottom = bottom - sub_rect.bottom(); | |
| 45 | |
| 46 // The horizontal rect is the larger of the two rectangles above or below | |
| 47 // |sub_rect| and inside rect_. | |
| 48 int horizontal_top = top; | |
| 49 int horizontal_bottom = bottom; | |
| 50 if (delta_top > delta_bottom) | |
| 51 horizontal_bottom = sub_rect.y(); | |
| 52 else | |
| 53 horizontal_top = sub_rect.bottom(); | |
| 54 // The vertical rect is the larger of the two rectangles to the left or the | |
| 55 // right of |sub_rect| and inside rect_. | |
| 56 int vertical_left = left; | |
| 57 int vertical_right = right; | |
| 58 if (delta_left > delta_right) | |
| 59 vertical_right = sub_rect.x(); | |
| 60 else | |
| 61 vertical_left = sub_rect.right(); | |
| 62 | |
| 63 rect_.SetRect( | |
| 64 left, horizontal_top, right - left, horizontal_bottom - horizontal_top); | |
| 65 | |
| 66 gfx::Rect vertical_rect( | |
| 67 vertical_left, top, vertical_right - vertical_left, bottom - top); | |
| 68 if (RectIsLargerArea(vertical_rect, rect_)) | |
| 69 rect_ = vertical_rect; | |
| 70 } | |
| 71 | |
| 72 void SimpleEnclosedRegion::Union(const gfx::Rect& new_rect) { | |
| 73 // We want to keep track of a region but bound its complexity at a constant | |
| 74 // size. We keep track of the largest rectangle seen by area. If we can add | |
| 75 // the |new_rect| to this rectangle then we do that, as that is the cheapest | |
| 76 // way to increase the area returned without increasing the complexity. | |
| 77 if (new_rect.IsEmpty()) | |
| 78 return; | |
| 79 if (rect_.Contains(new_rect)) | |
| 80 return; | |
| 81 if (new_rect.Contains(rect_)) { | |
| 82 rect_ = new_rect; | |
| 83 return; | |
| 84 } | |
| 85 | |
| 86 int left = rect_.x(); | |
| 87 int top = rect_.y(); | |
| 88 int right = rect_.right(); | |
| 89 int bottom = rect_.bottom(); | |
| 90 | |
| 91 int new_left = new_rect.x(); | |
| 92 int new_top = new_rect.y(); | |
| 93 int new_right = new_rect.right(); | |
| 94 int new_bottom = new_rect.bottom(); | |
| 95 | |
| 96 // This attempts to expand each edge of |rect_| if the |new_rect| entirely | |
| 97 // covers or is adjacent to an entire edge of |rect_|. If this is true for | |
| 98 // an edge of |rect_| then it can be expanded out to share that edge with the | |
| 99 // same edge of |new_rect|. After, the same thing is done to try expand | |
| 100 // |new_rect| relative to |rect_|. | |
| 101 if (new_top <= top && new_bottom >= bottom) { | |
| 102 if (new_left < left && new_right >= left) | |
| 103 left = new_left; | |
| 104 if (new_right > right && new_left <= right) | |
| 105 right = new_right; | |
| 106 } else if (new_left <= left && new_right >= right) { | |
| 107 if (new_top < top && new_bottom >= top) | |
| 108 top = new_top; | |
| 109 if (new_bottom > bottom && new_top <= bottom) | |
| 110 bottom = new_bottom; | |
| 111 } else if (top <= new_top && bottom >= new_bottom) { | |
| 112 if (left < new_left && right >= new_left) | |
| 113 new_left = left; | |
| 114 if (right > new_right && left <= new_right) | |
| 115 new_right = right; | |
| 116 } else if (left <= new_left && right >= new_right) { | |
| 117 if (top < new_top && bottom >= new_top) | |
| 118 new_top = top; | |
| 119 if (bottom > new_bottom && top <= new_bottom) | |
| 120 new_bottom = bottom; | |
| 121 } | |
| 122 | |
| 123 rect_.SetRect(left, top, right - left, bottom - top); | |
| 124 | |
| 125 gfx::Rect adjusted_new_rect( | |
| 126 new_left, new_top, new_right - new_left, new_bottom - new_top); | |
| 127 if (RectIsLargerArea(adjusted_new_rect, rect_)) | |
| 128 rect_ = adjusted_new_rect; | |
| 129 } | |
| 130 | |
| 131 gfx::Rect SimpleEnclosedRegion::GetRect(size_t i) const { | |
| 132 DCHECK_LT(i, GetRegionComplexity()); | |
| 133 return rect_; | |
| 134 } | |
| 135 | |
| 136 } // namespace cc | |
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