1 /*
2 * Copyright (C) 2012 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #include "config.h"
27 #include "core/rendering/RenderMultiColumnBlock.h"
28
29 #include "core/rendering/RenderMultiColumnFlowThread.h"
30 #include "core/rendering/RenderMultiColumnSet.h"
31 #include "core/rendering/RenderView.h"
32
33 using namespace std;
34
35 namespace WebCore {
36
RenderMultiColumnBlock(Element * element)37 RenderMultiColumnBlock::RenderMultiColumnBlock(Element* element)
38 : RenderBlockFlow(element)
39 , m_flowThread(0)
40 , m_columnCount(1)
41 , m_columnWidth(0)
42 , m_columnHeightAvailable(0)
43 , m_inBalancingPass(false)
44 {
45 }
46
styleDidChange(StyleDifference diff,const RenderStyle * oldStyle)47 void RenderMultiColumnBlock::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
48 {
49 RenderBlock::styleDidChange(diff, oldStyle);
50 for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox())
51 child->setStyle(RenderStyle::createAnonymousStyleWithDisplay(style(), BLOCK));
52 }
53
computeColumnCountAndWidth()54 void RenderMultiColumnBlock::computeColumnCountAndWidth()
55 {
56 // Calculate our column width and column count.
57 // FIXME: Can overflow on fast/block/float/float-not-removed-from-next-sibling4.html, see https://bugs.webkit.org/show_bug.cgi?id=68744
58 m_columnCount = 1;
59 m_columnWidth = contentLogicalWidth();
60
61 ASSERT(!style()->hasAutoColumnCount() || !style()->hasAutoColumnWidth());
62
63 LayoutUnit availWidth = m_columnWidth;
64 LayoutUnit colGap = columnGap();
65 LayoutUnit colWidth = max<LayoutUnit>(1, LayoutUnit(style()->columnWidth()));
66 int colCount = max<int>(1, style()->columnCount());
67
68 if (style()->hasAutoColumnWidth() && !style()->hasAutoColumnCount()) {
69 m_columnCount = colCount;
70 m_columnWidth = max<LayoutUnit>(0, (availWidth - ((m_columnCount - 1) * colGap)) / m_columnCount);
71 } else if (!style()->hasAutoColumnWidth() && style()->hasAutoColumnCount()) {
72 m_columnCount = max<LayoutUnit>(1, (availWidth + colGap) / (colWidth + colGap));
73 m_columnWidth = ((availWidth + colGap) / m_columnCount) - colGap;
74 } else {
75 m_columnCount = max<LayoutUnit>(min<LayoutUnit>(colCount, (availWidth + colGap) / (colWidth + colGap)), 1);
76 m_columnWidth = ((availWidth + colGap) / m_columnCount) - colGap;
77 }
78 }
79
updateLogicalWidthAndColumnWidth()80 bool RenderMultiColumnBlock::updateLogicalWidthAndColumnWidth()
81 {
82 bool relayoutChildren = RenderBlock::updateLogicalWidthAndColumnWidth();
83 LayoutUnit oldColumnWidth = m_columnWidth;
84 computeColumnCountAndWidth();
85 if (m_columnWidth != oldColumnWidth)
86 relayoutChildren = true;
87 return relayoutChildren;
88 }
89
checkForPaginationLogicalHeightChange(LayoutUnit &,bool &,bool &)90 void RenderMultiColumnBlock::checkForPaginationLogicalHeightChange(LayoutUnit& /*pageLogicalHeight*/, bool& /*pageLogicalHeightChanged*/, bool& /*hasSpecifiedPageLogicalHeight*/)
91 {
92 // We don't actually update any of the variables. We just subclassed to adjust our column height.
93 updateLogicalHeight();
94 m_columnHeightAvailable = max<LayoutUnit>(contentLogicalHeight(), 0);
95 setLogicalHeight(0);
96 }
97
relayoutForPagination(bool,LayoutUnit,LayoutStateMaintainer & statePusher)98 bool RenderMultiColumnBlock::relayoutForPagination(bool, LayoutUnit, LayoutStateMaintainer& statePusher)
99 {
100 if (m_inBalancingPass || !requiresBalancing())
101 return false;
102 m_inBalancingPass = true; // Prevent re-entering this method (and recursion into layout).
103
104 bool needsRelayout;
105 bool neededRelayout = false;
106 bool firstPass = true;
107 do {
108 // Column heights may change here because of balancing. We may have to do multiple layout
109 // passes, depending on how the contents is fitted to the changed column heights. In most
110 // cases, laying out again twice or even just once will suffice. Sometimes we need more
111 // passes than that, though, but the number of retries should not exceed the number of
112 // columns, unless we have a bug.
113 needsRelayout = false;
114 for (RenderBox* childBox = firstChildBox(); childBox; childBox = childBox->nextSiblingBox()) {
115 if (childBox != m_flowThread && childBox->isRenderMultiColumnSet()) {
116 RenderMultiColumnSet* multicolSet = toRenderMultiColumnSet(childBox);
117 if (multicolSet->calculateBalancedHeight(firstPass)) {
118 multicolSet->setChildNeedsLayout(MarkOnlyThis);
119 needsRelayout = true;
120 }
121 }
122 }
123
124 if (needsRelayout) {
125 // Layout again. Column balancing resulted in a new height.
126 neededRelayout = true;
127 m_flowThread->setChildNeedsLayout(MarkOnlyThis);
128 setChildNeedsLayout(MarkOnlyThis);
129 if (firstPass)
130 statePusher.pop();
131 layoutBlock(false);
132 }
133 firstPass = false;
134 } while (needsRelayout);
135 m_inBalancingPass = false;
136 return neededRelayout;
137 }
138
addChild(RenderObject * newChild,RenderObject * beforeChild)139 void RenderMultiColumnBlock::addChild(RenderObject* newChild, RenderObject* beforeChild)
140 {
141 if (!m_flowThread) {
142 m_flowThread = RenderMultiColumnFlowThread::createAnonymous(&document());
143 m_flowThread->setStyle(RenderStyle::createAnonymousStyleWithDisplay(style(), BLOCK));
144 RenderBlock::addChild(m_flowThread);
145 }
146 m_flowThread->addChild(newChild, beforeChild);
147 }
148
layoutSpecialExcludedChild(bool relayoutChildren,SubtreeLayoutScope & layoutScope)149 RenderObject* RenderMultiColumnBlock::layoutSpecialExcludedChild(bool relayoutChildren, SubtreeLayoutScope& layoutScope)
150 {
151 if (!m_flowThread)
152 return 0;
153
154 // Update the dimensions of our regions before we lay out the flow thread.
155 // FIXME: Eventually this is going to get way more complicated, and we will be destroying regions
156 // instead of trying to keep them around.
157 bool shouldInvalidateRegions = false;
158 for (RenderBox* childBox = firstChildBox(); childBox; childBox = childBox->nextSiblingBox()) {
159 if (childBox == m_flowThread)
160 continue;
161
162 if (relayoutChildren || childBox->needsLayout()) {
163 if (!m_inBalancingPass && childBox->isRenderMultiColumnSet())
164 toRenderMultiColumnSet(childBox)->prepareForLayout();
165 shouldInvalidateRegions = true;
166 }
167 }
168
169 if (shouldInvalidateRegions)
170 m_flowThread->invalidateRegions();
171
172 if (relayoutChildren)
173 layoutScope.setChildNeedsLayout(m_flowThread);
174
175 setLogicalTopForChild(m_flowThread, borderBefore() + paddingBefore());
176 m_flowThread->layoutIfNeeded();
177 determineLogicalLeftPositionForChild(m_flowThread);
178
179 return m_flowThread;
180 }
181
renderName() const182 const char* RenderMultiColumnBlock::renderName() const
183 {
184 if (isFloating())
185 return "RenderMultiColumnBlock (floating)";
186 if (isOutOfFlowPositioned())
187 return "RenderMultiColumnBlock (positioned)";
188 if (isAnonymousBlock())
189 return "RenderMultiColumnBlock (anonymous)";
190 // FIXME: Temporary hack while the new generated content system is being implemented.
191 if (isPseudoElement())
192 return "RenderMultiColumnBlock (generated)";
193 if (isAnonymous())
194 return "RenderMultiColumnBlock (generated)";
195 if (isRelPositioned())
196 return "RenderMultiColumnBlock (relative positioned)";
197 return "RenderMultiColumnBlock";
198 }
199
200 }
201