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1 /* | |
2 * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved. | |
3 * | |
4 * Portions are Copyright (C) 1998 Netscape Communications Corporation. | |
5 * | |
6 * Other contributors: | |
7 * Robert O'Callahan <roc+@cs.cmu.edu> | |
8 * David Baron <dbaron@fas.harvard.edu> | |
9 * Christian Biesinger <cbiesinger@web.de> | |
10 * Randall Jesup <rjesup@wgate.com> | |
11 * Roland Mainz <roland.mainz@informatik.med.uni-giessen.de> | |
12 * Josh Soref <timeless@mac.com> | |
13 * Boris Zbarsky <bzbarsky@mit.edu> | |
14 * | |
15 * This library is free software; you can redistribute it and/or | |
16 * modify it under the terms of the GNU Lesser General Public | |
17 * License as published by the Free Software Foundation; either | |
18 * version 2.1 of the License, or (at your option) any later version. | |
19 * | |
20 * This library is distributed in the hope that it will be useful, | |
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
23 * Lesser General Public License for more details. | |
24 * | |
25 * You should have received a copy of the GNU Lesser General Public | |
26 * License along with this library; if not, write to the Free Software | |
27 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 US
A | |
28 * | |
29 * Alternatively, the contents of this file may be used under the terms | |
30 * of either the Mozilla Public License Version 1.1, found at | |
31 * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public | |
32 * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html | |
33 * (the "GPL"), in which case the provisions of the MPL or the GPL are | |
34 * applicable instead of those above. If you wish to allow use of your | |
35 * version of this file only under the terms of one of those two | |
36 * licenses (the MPL or the GPL) and not to allow others to use your | |
37 * version of this file under the LGPL, indicate your decision by | |
38 * deletingthe provisions above and replace them with the notice and | |
39 * other provisions required by the MPL or the GPL, as the case may be. | |
40 * If you do not delete the provisions above, a recipient may use your | |
41 * version of this file under any of the LGPL, the MPL or the GPL. | |
42 */ | |
43 | |
44 #include "config.h" | |
45 #include "core/rendering/ScrollBehavior.h" | |
46 | |
47 #include "platform/geometry/LayoutRect.h" | |
48 | |
49 namespace WebCore { | |
50 | |
51 const ScrollAlignment ScrollAlignment::alignCenterIfNeeded = { noScroll, alignCe
nter, alignToClosestEdge }; | |
52 const ScrollAlignment ScrollAlignment::alignToEdgeIfNeeded = { noScroll, alignTo
ClosestEdge, alignToClosestEdge }; | |
53 const ScrollAlignment ScrollAlignment::alignCenterAlways = { alignCenter, alignC
enter, alignCenter }; | |
54 const ScrollAlignment ScrollAlignment::alignTopAlways = { alignTop, alignTop, al
ignTop }; | |
55 const ScrollAlignment ScrollAlignment::alignBottomAlways = { alignBottom, alignB
ottom, alignBottom }; | |
56 | |
57 #define MIN_INTERSECT_FOR_REVEAL 32 | |
58 | |
59 LayoutRect ScrollAlignment::getRectToExpose(const LayoutRect& visibleRect, const
LayoutRect& exposeRect, const ScrollAlignment& alignX, const ScrollAlignment& a
lignY) | |
60 { | |
61 // Determine the appropriate X behavior. | |
62 ScrollBehavior scrollX; | |
63 LayoutRect exposeRectX(exposeRect.x(), visibleRect.y(), exposeRect.width(),
visibleRect.height()); | |
64 LayoutUnit intersectWidth = intersection(visibleRect, exposeRectX).width(); | |
65 if (intersectWidth == exposeRect.width() || intersectWidth >= MIN_INTERSECT_
FOR_REVEAL) { | |
66 // If the rectangle is fully visible, use the specified visible behavior
. | |
67 // If the rectangle is partially visible, but over a certain threshold, | |
68 // then treat it as fully visible to avoid unnecessary horizontal scroll
ing | |
69 scrollX = getVisibleBehavior(alignX); | |
70 } else if (intersectWidth == visibleRect.width()) { | |
71 // If the rect is bigger than the visible area, don't bother trying to c
enter. Other alignments will work. | |
72 scrollX = getVisibleBehavior(alignX); | |
73 if (scrollX == alignCenter) | |
74 scrollX = noScroll; | |
75 } else if (intersectWidth > 0) { | |
76 // If the rectangle is partially visible, but not above the minimum thre
shold, use the specified partial behavior | |
77 scrollX = getPartialBehavior(alignX); | |
78 } else { | |
79 scrollX = getHiddenBehavior(alignX); | |
80 } | |
81 | |
82 if (scrollX == alignToClosestEdge) { | |
83 // Closest edge is the right in two cases: | |
84 // (1) exposeRect to the right of and smaller than visibleRect | |
85 // (2) exposeRect to the left of and larger than visibleRect | |
86 if ((exposeRect.maxX() > visibleRect.maxX() && exposeRect.width() < visi
bleRect.width()) | |
87 || (exposeRect.maxX() < visibleRect.maxX() && exposeRect.width() > v
isibleRect.width())) { | |
88 scrollX = alignRight; | |
89 } | |
90 } | |
91 | |
92 // Given the X behavior, compute the X coordinate. | |
93 LayoutUnit x; | |
94 if (scrollX == noScroll) | |
95 x = visibleRect.x(); | |
96 else if (scrollX == alignRight) | |
97 x = exposeRect.maxX() - visibleRect.width(); | |
98 else if (scrollX == alignCenter) | |
99 x = exposeRect.x() + (exposeRect.width() - visibleRect.width()) / 2; | |
100 else | |
101 x = exposeRect.x(); | |
102 | |
103 // Determine the appropriate Y behavior. | |
104 ScrollBehavior scrollY; | |
105 LayoutRect exposeRectY(visibleRect.x(), exposeRect.y(), visibleRect.width(),
exposeRect.height()); | |
106 LayoutUnit intersectHeight = intersection(visibleRect, exposeRectY).height()
; | |
107 if (intersectHeight == exposeRect.height()) { | |
108 // If the rectangle is fully visible, use the specified visible behavior
. | |
109 scrollY = getVisibleBehavior(alignY); | |
110 } else if (intersectHeight == visibleRect.height()) { | |
111 // If the rect is bigger than the visible area, don't bother trying to c
enter. Other alignments will work. | |
112 scrollY = getVisibleBehavior(alignY); | |
113 if (scrollY == alignCenter) | |
114 scrollY = noScroll; | |
115 } else if (intersectHeight > 0) { | |
116 // If the rectangle is partially visible, use the specified partial beha
vior | |
117 scrollY = getPartialBehavior(alignY); | |
118 } else { | |
119 scrollY = getHiddenBehavior(alignY); | |
120 } | |
121 | |
122 if (scrollY == alignToClosestEdge) { | |
123 // Closest edge is the bottom in two cases: | |
124 // (1) exposeRect below and smaller than visibleRect | |
125 // (2) exposeRect above and larger than visibleRect | |
126 if ((exposeRect.maxY() > visibleRect.maxY() && exposeRect.height() < vis
ibleRect.height()) | |
127 || (exposeRect.maxY() < visibleRect.maxY() && exposeRect.height() >
visibleRect.height())) { | |
128 scrollY = alignBottom; | |
129 } | |
130 } | |
131 | |
132 // Given the Y behavior, compute the Y coordinate. | |
133 LayoutUnit y; | |
134 if (scrollY == noScroll) | |
135 y = visibleRect.y(); | |
136 else if (scrollY == alignBottom) | |
137 y = exposeRect.maxY() - visibleRect.height(); | |
138 else if (scrollY == alignCenter) | |
139 y = exposeRect.y() + (exposeRect.height() - visibleRect.height()) / 2; | |
140 else | |
141 y = exposeRect.y(); | |
142 | |
143 return LayoutRect(LayoutPoint(x, y), visibleRect.size()); | |
144 } | |
145 | |
146 }; // namespace WebCore | |
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