1/*
2 * Copyright (C) 2018 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. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "BlockFormattingContext.h"
28
29#if ENABLE(LAYOUT_FORMATTING_CONTEXT)
30
31#include "FormattingContext.h"
32#include "InlineFormattingState.h"
33#include "LayoutChildIterator.h"
34#include "Logging.h"
35#include <wtf/text/TextStream.h>
36
37namespace WebCore {
38namespace Layout {
39
40HeightAndMargin BlockFormattingContext::Geometry::inFlowNonReplacedHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedValues)
41{
42 ASSERT(layoutBox.isInFlow() && !layoutBox.replaced());
43 ASSERT(layoutBox.isOverflowVisible());
44
45 auto compute = [&]() -> HeightAndMargin {
46
47 // 10.6.3 Block-level non-replaced elements in normal flow when 'overflow' computes to 'visible'
48 //
49 // If 'margin-top', or 'margin-bottom' are 'auto', their used value is 0.
50 // If 'height' is 'auto', the height depends on whether the element has any block-level children and whether it has padding or borders:
51 // The element's height is the distance from its top content edge to the first applicable of the following:
52 // 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
53 // 2. the bottom edge of the bottom (possibly collapsed) margin of its last in-flow child, if the child's bottom margin
54 // does not collapse with the element's bottom margin
55 // 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
56 // 4. zero, otherwise
57 // Only children in the normal flow are taken into account (i.e., floating boxes and absolutely positioned boxes are ignored,
58 // and relatively positioned boxes are considered without their offset). Note that the child box may be an anonymous block box.
59
60 auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);
61 auto containingBlockWidth = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock()).contentBoxWidth();
62 auto computedVerticalMargin = Geometry::computedVerticalMargin(layoutBox, UsedHorizontalValues { containingBlockWidth });
63 auto nonCollapsedMargin = UsedVerticalMargin::NonCollapsedValues { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
64 auto borderAndPaddingTop = displayBox.borderTop() + displayBox.paddingTop().valueOr(0);
65 auto height = usedValues.height ? usedValues.height.value() : computedHeightValue(layoutState, layoutBox, HeightType::Normal);
66
67 if (height) {
68 auto borderAndPaddingBottom = displayBox.borderBottom() + displayBox.paddingBottom().valueOr(0);
69 auto contentHeight = layoutBox.style().boxSizing() == BoxSizing::ContentBox ? *height : *height - (borderAndPaddingTop + borderAndPaddingBottom);
70 return { contentHeight, nonCollapsedMargin };
71 }
72
73 if (!is<Container>(layoutBox) || !downcast<Container>(layoutBox).hasInFlowChild())
74 return { 0, nonCollapsedMargin };
75
76 // 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
77 if (layoutBox.establishesInlineFormattingContext()) {
78 // This is temp and will be replaced by the correct display box once inline runs move over to the display tree.
79 auto& inlineRuns = downcast<InlineFormattingState>(layoutState.establishedFormattingState(layoutBox)).inlineRuns();
80 auto bottomEdge = inlineRuns.isEmpty() ? LayoutUnit() : inlineRuns.last().logicalBottom();
81 return { bottomEdge - borderAndPaddingTop, nonCollapsedMargin };
82 }
83
84 // 2. the bottom edge of the bottom (possibly collapsed) margin of its last in-flow child, if the child's bottom margin...
85 auto* lastInFlowChild = downcast<Container>(layoutBox).lastInFlowChild();
86 ASSERT(lastInFlowChild);
87 if (!MarginCollapse::marginAfterCollapsesWithParentMarginAfter(layoutState, *lastInFlowChild)) {
88 auto& lastInFlowDisplayBox = layoutState.displayBoxForLayoutBox(*lastInFlowChild);
89 auto bottomEdgeOfBottomMargin = lastInFlowDisplayBox.bottom() + (lastInFlowDisplayBox.hasCollapsedThroughMargin() ? LayoutUnit() : lastInFlowDisplayBox.marginAfter());
90 return { bottomEdgeOfBottomMargin - borderAndPaddingTop, nonCollapsedMargin };
91 }
92
93 // 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
94 auto* inFlowChild = lastInFlowChild;
95 while (inFlowChild && MarginCollapse::marginBeforeCollapsesWithParentMarginAfter(layoutState, *inFlowChild))
96 inFlowChild = inFlowChild->previousInFlowSibling();
97 if (inFlowChild) {
98 auto& inFlowDisplayBox = layoutState.displayBoxForLayoutBox(*inFlowChild);
99 return { inFlowDisplayBox.top() + inFlowDisplayBox.borderBox().height() - borderAndPaddingTop, nonCollapsedMargin };
100 }
101
102 // 4. zero, otherwise
103 return { 0, nonCollapsedMargin };
104 };
105
106 auto heightAndMargin = compute();
107 LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> inflow non-replaced -> height(" << heightAndMargin.height << "px) margin(" << heightAndMargin.nonCollapsedMargin.before << "px, " << heightAndMargin.nonCollapsedMargin.after << "px) -> layoutBox(" << &layoutBox << ")");
108 return heightAndMargin;
109}
110
111WidthAndMargin BlockFormattingContext::Geometry::inFlowNonReplacedWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
112{
113 ASSERT(layoutBox.isInFlow());
114
115 auto compute = [&]() {
116
117 // 10.3.3 Block-level, non-replaced elements in normal flow
118 //
119 // The following constraints must hold among the used values of the other properties:
120 // 'margin-left' + 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' + 'margin-right' = width of containing block
121 //
122 // 1. If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width'
123 // (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then
124 // any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
125 //
126 // 2. If all of the above have a computed value other than 'auto', the values are said to be "over-constrained" and one of the used values will
127 // have to be different from its computed value. If the 'direction' property of the containing block has the value 'ltr', the specified value
128 // of 'margin-right' is ignored and the value is calculated so as to make the equality true. If the value of 'direction' is 'rtl',
129 // this happens to 'margin-left' instead.
130 //
131 // 3. If there is exactly one value specified as 'auto', its used value follows from the equality.
132 //
133 // 4. If 'width' is set to 'auto', any other 'auto' values become '0' and 'width' follows from the resulting equality.
134 //
135 // 5. If both 'margin-left' and 'margin-right' are 'auto', their used values are equal. This horizontally centers the element with respect to the
136 // edges of the containing block.
137
138 auto& style = layoutBox.style();
139 auto* containingBlock = layoutBox.containingBlock();
140 auto containingBlockWidth = usedValues.containingBlockWidth.valueOr(0);
141 auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);
142
143 auto width = computedValueIfNotAuto(usedValues.width ? Length { usedValues.width.value(), Fixed } : style.logicalWidth(), containingBlockWidth);
144 auto computedHorizontalMargin = Geometry::computedHorizontalMargin(layoutBox, usedValues);
145 UsedHorizontalMargin usedHorizontalMargin;
146 auto borderLeft = displayBox.borderLeft();
147 auto borderRight = displayBox.borderRight();
148 auto paddingLeft = displayBox.paddingLeft().valueOr(0);
149 auto paddingRight = displayBox.paddingRight().valueOr(0);
150 auto contentWidth = [&] {
151 ASSERT(width);
152 return style.boxSizing() == BoxSizing::ContentBox ? *width : *width - (borderLeft + paddingLeft + paddingRight + borderRight);
153 };
154
155 // #1
156 if (width) {
157 auto horizontalSpaceForMargin = containingBlockWidth - (computedHorizontalMargin.start.valueOr(0) + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + computedHorizontalMargin.end.valueOr(0));
158 if (horizontalSpaceForMargin < 0)
159 usedHorizontalMargin = { computedHorizontalMargin.start.valueOr(0), computedHorizontalMargin.end.valueOr(0) };
160 }
161
162 // #2
163 if (width && computedHorizontalMargin.start && computedHorizontalMargin.end) {
164 if (containingBlock->style().isLeftToRightDirection()) {
165 usedHorizontalMargin.start = *computedHorizontalMargin.start;
166 usedHorizontalMargin.end = containingBlockWidth - (usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight);
167 } else {
168 usedHorizontalMargin.end = *computedHorizontalMargin.end;
169 usedHorizontalMargin.start = containingBlockWidth - (borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end);
170 }
171 }
172
173 // #3
174 if (!computedHorizontalMargin.start && width && computedHorizontalMargin.end) {
175 usedHorizontalMargin.end = *computedHorizontalMargin.end;
176 usedHorizontalMargin.start = containingBlockWidth - (borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end);
177 } else if (computedHorizontalMargin.start && !width && computedHorizontalMargin.end) {
178 usedHorizontalMargin = { *computedHorizontalMargin.start, *computedHorizontalMargin.end };
179 width = containingBlockWidth - (usedHorizontalMargin.start + borderLeft + paddingLeft + paddingRight + borderRight + usedHorizontalMargin.end);
180 } else if (computedHorizontalMargin.start && width && !computedHorizontalMargin.end) {
181 usedHorizontalMargin.start = *computedHorizontalMargin.start;
182 usedHorizontalMargin.end = containingBlockWidth - (usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight);
183 }
184
185 // #4
186 if (!width) {
187 usedHorizontalMargin = { computedHorizontalMargin.start.valueOr(0), computedHorizontalMargin.end.valueOr(0) };
188 width = containingBlockWidth - (usedHorizontalMargin.start + borderLeft + paddingLeft + paddingRight + borderRight + usedHorizontalMargin.end);
189 }
190
191 // #5
192 if (!computedHorizontalMargin.start && !computedHorizontalMargin.end) {
193 auto horizontalSpaceForMargin = containingBlockWidth - (borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight);
194 usedHorizontalMargin = { horizontalSpaceForMargin / 2, horizontalSpaceForMargin / 2 };
195 }
196
197 ASSERT(width);
198
199 return WidthAndMargin { contentWidth(), usedHorizontalMargin, computedHorizontalMargin };
200 };
201
202 auto widthAndMargin = compute();
203 LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width][Margin] -> inflow non-replaced -> width(" << widthAndMargin.width << "px) margin(" << widthAndMargin.usedMargin.start << "px, " << widthAndMargin.usedMargin.end << "px) -> layoutBox(" << &layoutBox << ")");
204 return widthAndMargin;
205}
206
207WidthAndMargin BlockFormattingContext::Geometry::inFlowReplacedWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
208{
209 ASSERT(layoutBox.isInFlow() && layoutBox.replaced());
210
211 // 10.3.4 Block-level, replaced elements in normal flow
212 //
213 // 1. The used value of 'width' is determined as for inline replaced elements.
214 // 2. Then the rules for non-replaced block-level elements are applied to determine the margins.
215
216 // #1
217 usedValues.width = inlineReplacedWidthAndMargin(layoutState, layoutBox, usedValues).width;
218 // #2
219 auto nonReplacedWidthAndMargin = inFlowNonReplacedWidthAndMargin(layoutState, layoutBox, usedValues);
220
221 LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width][Margin] -> inflow replaced -> width(" << *usedValues.width << "px) margin(" << nonReplacedWidthAndMargin.usedMargin.start << "px, " << nonReplacedWidthAndMargin.usedMargin.end << "px) -> layoutBox(" << &layoutBox << ")");
222 return { *usedValues.width, nonReplacedWidthAndMargin.usedMargin, nonReplacedWidthAndMargin.computedMargin };
223}
224
225Point BlockFormattingContext::Geometry::staticPosition(const LayoutState& layoutState, const Box& layoutBox)
226{
227 // https://www.w3.org/TR/CSS22/visuren.html#block-formatting
228 // In a block formatting context, boxes are laid out one after the other, vertically, beginning at the top of a containing block.
229 // The vertical distance between two sibling boxes is determined by the 'margin' properties.
230 // Vertical margins between adjacent block-level boxes in a block formatting context collapse.
231 // In a block formatting context, each box's left outer edge touches the left edge of the containing block (for right-to-left formatting, right edges touch).
232
233 LayoutUnit top;
234 auto& containingBlockDisplayBox = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock());
235 if (auto* previousInFlowSibling = layoutBox.previousInFlowSibling()) {
236 auto& previousInFlowDisplayBox = layoutState.displayBoxForLayoutBox(*previousInFlowSibling);
237 top = previousInFlowDisplayBox.bottom() + previousInFlowDisplayBox.marginAfter();
238 } else
239 top = containingBlockDisplayBox.contentBoxTop();
240
241 auto left = containingBlockDisplayBox.contentBoxLeft() + layoutState.displayBoxForLayoutBox(layoutBox).marginStart();
242 LOG_WITH_STREAM(FormattingContextLayout, stream << "[Position] -> static -> top(" << top << "px) left(" << left << "px) layoutBox(" << &layoutBox << ")");
243 return { left, top };
244}
245
246HeightAndMargin BlockFormattingContext::Geometry::inFlowHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedValues)
247{
248 ASSERT(layoutBox.isInFlow());
249
250 // 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block'
251 // replaced elements in normal flow and floating replaced elements
252 if (layoutBox.replaced())
253 return inlineReplacedHeightAndMargin(layoutState, layoutBox, usedValues);
254
255 HeightAndMargin heightAndMargin;
256 // TODO: Figure out the case for the document element. Let's just complicated-case it for now.
257 if (layoutBox.isOverflowVisible() && !layoutBox.isDocumentBox())
258 heightAndMargin = inFlowNonReplacedHeightAndMargin(layoutState, layoutBox, usedValues);
259 else {
260 // 10.6.6 Complicated cases
261 // Block-level, non-replaced elements in normal flow when 'overflow' does not compute to 'visible' (except if the 'overflow' property's value has been propagated to the viewport).
262 auto usedHorizontalValues = UsedHorizontalValues { layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock()).contentBoxWidth() };
263 heightAndMargin = complicatedCases(layoutState, layoutBox, usedValues, usedHorizontalValues);
264 }
265
266 if (!Quirks::needsStretching(layoutState, layoutBox))
267 return heightAndMargin;
268
269 heightAndMargin = Quirks::stretchedInFlowHeight(layoutState, layoutBox, heightAndMargin);
270
271 LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> inflow non-replaced -> streched to viewport -> height(" << heightAndMargin.height << "px) margin(" << heightAndMargin.nonCollapsedMargin.before << "px, " << heightAndMargin.nonCollapsedMargin.after << "px) -> layoutBox(" << &layoutBox << ")");
272 return heightAndMargin;
273}
274
275WidthAndMargin BlockFormattingContext::Geometry::inFlowWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
276{
277 ASSERT(layoutBox.isInFlow());
278
279 if (!layoutBox.replaced())
280 return inFlowNonReplacedWidthAndMargin(layoutState, layoutBox, usedValues);
281 return inFlowReplacedWidthAndMargin(layoutState, layoutBox, usedValues);
282}
283
284bool BlockFormattingContext::Geometry::intrinsicWidthConstraintsNeedChildrenWidth(const Box& layoutBox)
285{
286 if (!is<Container>(layoutBox) || !downcast<Container>(layoutBox).hasInFlowOrFloatingChild())
287 return false;
288 return layoutBox.style().width().isAuto();
289}
290
291FormattingContext::IntrinsicWidthConstraints BlockFormattingContext::Geometry::intrinsicWidthConstraints(const LayoutState& layoutState, const Box& layoutBox)
292{
293 auto computedIntrinsicWidthConstraints = [&]() -> IntrinsicWidthConstraints {
294 auto& style = layoutBox.style();
295 if (auto width = fixedValue(style.logicalWidth()))
296 return { *width, *width };
297
298 // Minimum/maximum width can't be depending on the containing block's width.
299 if (!style.logicalWidth().isAuto())
300 return { };
301
302 if (layoutBox.isReplaced()) {
303 auto& replaced = *layoutBox.replaced();
304 if (replaced.hasIntrinsicWidth()) {
305 auto replacedWidth = replaced.intrinsicWidth();
306 return { replacedWidth, replacedWidth };
307 }
308 return { };
309 }
310
311 if (!is<Container>(layoutBox))
312 return { };
313
314 auto intrinsicWidthConstraints = IntrinsicWidthConstraints { };
315 for (auto& child : childrenOfType<Box>(downcast<Container>(layoutBox))) {
316 if (child.isOutOfFlowPositioned())
317 continue;
318 const auto& formattingState = layoutState.formattingStateForBox(child);
319 ASSERT(formattingState.isBlockFormattingState());
320 auto childIntrinsicWidthConstraints = formattingState.intrinsicWidthConstraints(child);
321 ASSERT(childIntrinsicWidthConstraints);
322
323 auto& childStyle = child.style();
324 auto marginBorderAndPadding = fixedValue(childStyle.marginStart()).valueOr(0)
325 + LayoutUnit { childStyle.borderLeftWidth() }
326 + fixedValue(childStyle.paddingLeft()).valueOr(0)
327 + fixedValue(childStyle.paddingRight()).valueOr(0)
328 + LayoutUnit { childStyle.borderRightWidth() }
329 + fixedValue(childStyle.marginEnd()).valueOr(0);
330 intrinsicWidthConstraints.minimum = std::max(intrinsicWidthConstraints.minimum, childIntrinsicWidthConstraints->minimum + marginBorderAndPadding);
331 intrinsicWidthConstraints.maximum = std::max(intrinsicWidthConstraints.maximum, childIntrinsicWidthConstraints->maximum + marginBorderAndPadding);
332 }
333 return intrinsicWidthConstraints;
334 };
335
336 return constrainByMinMaxWidth(layoutBox, computedIntrinsicWidthConstraints());
337}
338
339}
340}
341
342#endif
343