Bug Summary

File:Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/Source/WebCore/rendering/PositionedLayoutConstraints.cpp
Warning:line 450, column 23
Local variable 'view' is uncounted and unsafe

Annotated Source Code

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clang -cc1 -cc1 -triple arm64-apple-ios26.2.0-simulator -O3 -Wundef-prefix=TARGET_OS_ -Werror=undef-prefix -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -Werror=implicit-function-declaration -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name UnifiedSource409.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=osx -analyzer-checker=security.insecureAPI.decodeValueOfObjCType -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer 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/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk/usr/local/include -I /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/Release-iphonesimulator/usr/local/include/webrtc -I /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk/usr/local/include/webrtc -I /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/Release-iphonesimulator/usr/local/include/webm -I /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk/usr/local/include/webm -I /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/PAL.build/PAL.build/DerivedSources -I /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/PAL.build/Release-iphonesimulator/PAL.build/DerivedSources -I /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/Source/WebCore -I /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/WebCore.build/Release-iphonesimulator/WebCore.build/DerivedSources-normal/arm64 -I /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/WebCore.build/Release-iphonesimulator/WebCore.build/DerivedSources/arm64 -I /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/WebCore.build/Release-iphonesimulator/WebCore.build/DerivedSources -F/Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/Release-iphonesimulator -F/Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/Release-iphonesimulator -I/usr/local/include -stdlib=libc++ -internal-isystem /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk/usr/include/c++/v1 -internal-isystem /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk/usr/local/include 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alpha.webkit.ForwardDeclChecker,alpha.webkit.MemoryUnsafeCastChecker,alpha.webkit.NoDeleteChecker,alpha.webkit.NoUncheckedPtrMemberChecker,alpha.webkit.NoUnretainedMemberChecker,alpha.webkit.RetainPtrCtorAdoptChecker,alpha.webkit.UncheckedCallArgsChecker,alpha.webkit.UncheckedLocalVarsChecker,alpha.webkit.UncountedCallArgsChecker,alpha.webkit.UncountedLocalVarsChecker,alpha.webkit.UnretainedCallArgsChecker,alpha.webkit.UnretainedLambdaCapturesChecker,alpha.webkit.UnretainedLocalVarsChecker,webkit.NoUncountedMemberChecker,webkit.RefCntblBaseVirtualDtor,webkit.UncountedLambdaCapturesChecker -analyzer-config max-nodes=10000000 -analyzer-config verbose-report-filename=true -fdwarf2-cfi-asm -o /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/scan-build-output/StaticAnalyzer/WebCore/WebCore/normal/arm64/UnifiedSource409.plist -x c++ /Volumes/Data/worker/Apple-iOS-26-Safer-CPP-Checks-EWS/build/WebKitBuild/Release-iphonesimulator/DerivedSources/WebCore/unified-sources/UnifiedSource409.cpp
1/*
2 * Copyright (C) 2025 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 "PositionedLayoutConstraints.h"
28
29#include "AnchorPositionEvaluator.h"
30#include "ContainerNodeInlines.h"
31#include "InlineIteratorBoxInlines.h"
32#include "InlineIteratorInlineBox.h"
33#include "RenderGrid.h"
34#include "RenderInline.h"
35#include "RenderLayer.h"
36#include "RenderStyle.h"
37#include "RenderTableRow.h"
38#include "RenderView.h"
39#include "StylePositionArea.h"
40
41namespace WebCore {
42
43using namespace CSS::Literals;
44
45PositionedLayoutConstraints::PositionedLayoutConstraints(const RenderBox& renderer, LogicalBoxAxis selfAxis)
46 : PositionedLayoutConstraints(renderer, renderer.style(), selfAxis)
47{
48}
49
50PositionedLayoutConstraints::PositionedLayoutConstraints(const RenderBox& renderer, const RenderStyle& style, LogicalBoxAxis selfAxis)
51 : m_renderer(renderer)
52 , m_container(downcast<RenderBoxModelObject>(*renderer.container())) // Using containingBlock() would be wrong for relpositioned inlines.
53 , m_containingWritingMode(m_container->writingMode())
54 , m_writingMode(style.writingMode())
55 , m_selfAxis(selfAxis)
56 , m_containingAxis(!isOrthogonal() ? selfAxis : oppositeAxis(selfAxis))
57 , m_physicalAxis(selfAxis == LogicalBoxAxis::Inline ? m_writingMode.inlineAxis() : m_writingMode.blockAxis())
58 , m_style(style)
59 , m_alignment(m_containingAxis == LogicalBoxAxis::Inline ? style.justifySelf().resolve() : style.alignSelf().resolve())
60 , m_defaultAnchorBox(needsAnchor() ? Style::AnchorPositionEvaluator::defaultAnchorForBox(renderer) : nullptr)
61 , m_marginBefore { 0_css_px }
62 , m_marginAfter { 0_css_px }
63 , m_insetBefore { 0_css_px }
64 , m_insetAfter { 0_css_px }
65{
66 ASSERT(m_container)((void)0);
67
68 // Compute basic containing block info.
69 m_originalContainingRange = renderer.containingBlockRangeForPositioned(*m_container, m_physicalAxis);
70 m_containingRange = m_originalContainingRange;
71 m_containingInlineSize = (LogicalBoxAxis::Inline == m_containingAxis) ? m_containingRange.size()
72 : renderer.containingBlockRangeForPositioned(*m_container, oppositeAxis(m_physicalAxis)).size();
73
74 // Adjust for grid-area.
75 captureGridArea();
76
77 // Capture the anchor geometry and adjust for position-area.
78 captureAnchorGeometry();
79}
80
81void PositionedLayoutConstraints::computeInsets()
82{
83 // Cache insets and margins, etc.
84 captureInsets();
85
86 if (m_useStaticPosition)
87 computeStaticPosition();
88
89 if (containingCoordsAreFlipped()) {
90 // Ideally this check is incorporated into captureInsets() but currently it needs to happen after computeStaticPosition() because containingCoordsAreFlipped() depends on m_useStaticPosition.
91 std::swap(m_marginBefore, m_marginAfter);
92 std::swap(m_insetBefore, m_insetAfter);
93 }
94
95 // Compute the inset-modified containing block.
96 m_insetModifiedContainingRange = m_containingRange;
97 m_insetModifiedContainingRange.shiftMinEdgeBy(insetBeforeValue());
98 m_insetModifiedContainingRange.shiftMaxEdgeBy(-insetAfterValue());
99}
100
101bool PositionedLayoutConstraints::needsAnchor() const
102{
103 return !m_style.positionArea().isNone() || m_alignment.position() == ItemPosition::AnchorCenter;
104}
105
106bool PositionedLayoutConstraints::containingCoordsAreFlipped() const
107{
108 bool orthogonalOpposing = (m_containingAxis == LogicalBoxAxis::Inline && m_writingMode.isBlockFlipped()) || (m_containingAxis == LogicalBoxAxis::Block && m_containingWritingMode.isBlockFlipped());
109 // FIXME: Static position has a confusing implementation. Leaving it alone for now.
110 return !m_useStaticPosition && ((isBlockOpposing() && m_containingAxis == LogicalBoxAxis::Block) || (isOrthogonal() && orthogonalOpposing));
111}
112
113void PositionedLayoutConstraints::captureInsets()
114{
115 bool isHorizontal = BoxAxis::Horizontal == m_physicalAxis;
116
117 if (isHorizontal) {
118 m_bordersPlusPadding = m_renderer->borderLeft() + m_renderer->paddingLeft() + m_renderer->paddingRight() + m_renderer->borderRight();
119 m_useStaticPosition = m_style.left().isAuto() && m_style.right().isAuto() && !m_defaultAnchorBox;
120 } else {
121 m_bordersPlusPadding = m_renderer->borderTop() + m_renderer->paddingTop() + m_renderer->paddingBottom() + m_renderer->borderBottom();
122 m_useStaticPosition = m_style.top().isAuto() && m_style.bottom().isAuto() && !m_defaultAnchorBox;
123 }
124
125 if (LogicalBoxAxis::Inline == m_selfAxis) {
126 m_marginBefore = isHorizontal ? m_style.marginLeft() : m_style.marginTop();
127 m_marginAfter = isHorizontal ? m_style.marginRight() : m_style.marginBottom();
128 m_insetBefore = m_style.logicalLeft();
129 m_insetAfter = m_style.logicalRight();
130 } else {
131 m_marginBefore = m_style.marginBefore();
132 m_marginAfter = m_style.marginAfter();
133 m_insetBefore = m_style.logicalTop();
134 m_insetAfter = m_style.logicalBottom();
135 }
136
137 if (m_defaultAnchorBox) {
138 // If the box uses anchor-center or position-area and does have a default anchor box,
139 // then it doesn't use static positioning.
140 m_useStaticPosition = false;
141 }
142}
143
144// MARK: - Adjustments to the containing block.
145
146void PositionedLayoutConstraints::expandToScrollableArea(LayoutRange& containingRange, const std::optional<ScrollPosition> fromScrollPosition) const
147{
148 auto containingBlock = dynamicDowncast<RenderBox>(m_container.get());
149 if (!containingBlock || !containingBlock->hasRenderOverflow()
150 || (!containingBlock->isRenderView() && !containingBlock->hasPotentiallyScrollableOverflow()))
151 return;
152
153 auto scrollableArea = containingBlock->scrollablePaddingAreaOverflowRect();
154 auto scrollableRange = BoxAxis::Horizontal == m_physicalAxis ? scrollableArea.xRange() : scrollableArea.yRange();
155 containingRange.capMinEdgeTo(scrollableRange.min());
156 containingRange.floorMaxEdgeTo(scrollableRange.max());
157
158 if (fromScrollPosition) {
159 auto scrollOffset = BoxAxis::Horizontal == m_physicalAxis ? fromScrollPosition->x() : fromScrollPosition->y();
160 containingRange.moveBy(-scrollOffset);
161 }
162}
163
164void PositionedLayoutConstraints::captureGridArea()
165{
166 const CheckedPtr gridContainer = dynamicDowncast<RenderGrid>(m_container.get());
167 if (!gridContainer)
168 return;
169
170 if (LogicalBoxAxis::Inline == m_containingAxis) {
171 m_containingRange = gridContainer->gridAreaRangeForOutOfFlow(m_renderer, Style::GridTrackSizingDirection::Columns);
172 m_containingInlineSize = m_containingRange.size();
173 } else {
174 m_containingRange = gridContainer->gridAreaRangeForOutOfFlow(m_renderer, Style::GridTrackSizingDirection::Rows);
175 m_containingInlineSize = gridContainer->gridAreaRangeForOutOfFlow(m_renderer, Style::GridTrackSizingDirection::Columns).size();
176 }
177
178 if (!startIsBefore()) {
179 auto containerSize = BoxAxis::Horizontal == m_physicalAxis
180 ? gridContainer->width() : gridContainer->height();
181 m_containingRange.moveTo(containerSize - m_containingRange.max());
182 }
183
184 // FIXME: Get PositionedLayoutConstraints to work in pre-corrected coordinates instead of assuming it's wrong and doing "fixup" afterwards, so we don't have to "unfixup" here.
185 if (LogicalBoxAxis::Inline == m_containingAxis) {
186 if (BoxAxis::Horizontal == m_physicalAxis) {
187 if (gridContainer->shouldPlaceVerticalScrollbarOnLeft())
188 m_containingRange.moveBy(-gridContainer->verticalScrollbarWidth());
189 } else {
190 if (!m_containingWritingMode.isInlineTopToBottom())
191 m_containingRange.moveBy(-gridContainer->horizontalScrollbarHeight());
192 }
193 }
194}
195
196LayoutRange PositionedLayoutConstraints::extractRange(LayoutRect anchorRect)
197{
198 LayoutRange anchorRange;
199 if (BoxAxis::Horizontal == m_physicalAxis)
200 anchorRange.set(anchorRect.x(), anchorRect.width());
201 else
202 anchorRange.set(anchorRect.y(), anchorRect.height());
203
204 if (m_containingWritingMode.isBlockFlipped() && LogicalBoxAxis::Block == m_containingAxis) {
205 // Coordinate fixup for flipped blocks.
206 anchorRange.moveTo(m_containingRange.max() - anchorRange.max() + m_container->borderAfter());
207 }
208 return anchorRange;
209}
210
211void PositionedLayoutConstraints::captureAnchorGeometry()
212{
213 if (!m_defaultAnchorBox)
214 return;
215
216 // Store the anchor geometry.
217 LayoutRect anchorRect = Style::AnchorPositionEvaluator::computeAnchorRectRelativeToContainingBlock(*m_defaultAnchorBox, *m_container, m_renderer.get());
218 m_anchorArea = extractRange(anchorRect);
219
220 // Adjust containing block for position-area.
221 if (m_style.positionArea().isNone())
222 return;
223 m_containingRange = adjustForPositionArea(m_containingRange, m_anchorArea, m_physicalAxis);
224
225 // Margin basis is always against the inline axis.
226 if (LogicalBoxAxis::Inline == m_containingAxis) {
227 m_containingInlineSize = m_containingRange.size();
228 return;
229 }
230 // Else we're representing the block axis, but need the inline dimensions.
231 auto inlineAxis = oppositeAxis(m_physicalAxis);
232 LayoutRange inlineContainingBlock(m_container->borderLogicalLeft(), m_containingInlineSize);
233 auto inlineAnchorArea = BoxAxis::Horizontal == inlineAxis
234 ? LayoutRange { anchorRect.x(), anchorRect.width() }
235 : LayoutRange { anchorRect.y(), anchorRect.height() };
236 m_containingInlineSize = adjustForPositionArea(inlineContainingBlock, inlineAnchorArea, inlineAxis).size();
237}
238
239LayoutRange PositionedLayoutConstraints::adjustForPositionArea(const LayoutRange rangeToAdjust, const LayoutRange anchorArea, const BoxAxis containerAxis)
240{
241 ASSERT(!m_style.positionArea().isNone())((void)0);
242 ASSERT(m_defaultAnchorBox)((void)0);
243 ASSERT(needsAnchor())((void)0);
244 ASSERT(anchorArea.size() >= 0)((void)0);
245
246 auto adjustedRange = rangeToAdjust;
247 switch (m_style.positionArea().tryValue()->coordMatchedTrackForAxis(containerAxis, m_containingWritingMode, m_writingMode)) {
248 case Style::PositionAreaTrack::Start:
249 adjustedRange.shiftMaxEdgeTo(anchorArea.min());
250 adjustedRange.floorSizeFromMaxEdge();
251 return adjustedRange;
252 case Style::PositionAreaTrack::SpanStart:
253 adjustedRange.shiftMaxEdgeTo(anchorArea.max());
254 adjustedRange.capMinEdgeTo(anchorArea.min());
255 return adjustedRange;
256 case Style::PositionAreaTrack::End:
257 adjustedRange.shiftMinEdgeTo(anchorArea.max());
258 adjustedRange.floorSizeFromMinEdge();
259 return adjustedRange;
260 case Style::PositionAreaTrack::SpanEnd:
261 adjustedRange.shiftMinEdgeTo(anchorArea.min());
262 adjustedRange.floorMaxEdgeTo(anchorArea.max());
263 return adjustedRange;
264 case Style::PositionAreaTrack::Center:
265 adjustedRange = anchorArea;
266 return adjustedRange;
267 case Style::PositionAreaTrack::SpanAll:
268 adjustedRange.capMinEdgeTo(anchorArea.min());
269 adjustedRange.floorMaxEdgeTo(anchorArea.max());
270 return adjustedRange;
271 default:
272 ASSERT_NOT_REACHED()((void)0);
273 return adjustedRange;
274 };
275}
276
277// MARK: - Resolving margins and alignment (after sizing).
278
279std::optional<LayoutUnit> PositionedLayoutConstraints::remainingSpaceForStaticAlignment(LayoutUnit itemSize) const
280{
281 if (!m_useStaticPosition || m_containingAxis == LogicalBoxAxis::Inline)
282 return { };
283
284 if (auto* parent = dynamicDowncast<RenderGrid>(m_renderer->parent())) {
285 auto& itemStyle = m_renderer->style();
286 auto itemResolvedAlignSelf = itemStyle.alignSelf().resolve(&parent->style());
287
288 switch (itemResolvedAlignSelf.position()) {
289 case ItemPosition::Center:
290 case ItemPosition::FlexEnd:
291 case ItemPosition::SelfEnd:
292 case ItemPosition::End: {
293 if (m_container.get() == parent)
294 return { };
295
296 // FIXME: This is probably not the correct set of writing mode checks.
297
298 auto& containingBlockStyle = m_container->style();
299 if (!containingBlockStyle.writingMode().isHorizontal())
300 return { };
301
302 if (!containingBlockStyle.writingMode().isBidiLTR())
303 return { };
304
305 auto& parentStyle = parent->style();
306 if (!parentStyle.writingMode().isHorizontal())
307 return { };
308
309 if (!parentStyle.writingMode().isBidiLTR())
310 return { };
311
312 if (!itemStyle.writingMode().isHorizontal())
313 return { };
314
315 if (!itemStyle.writingMode().isBidiLTR())
316 return { };
317
318 if (itemResolvedAlignSelf.positionType() != ItemPositionType::NonLegacy)
319 return { };
320
321 if (itemResolvedAlignSelf.overflow() != OverflowAlignment::Default)
322 return { };
323
324 auto remainingSpace = parent->contentBoxLogicalHeight() - itemSize;
325#if ASSERT_ENABLED0
326 m_isEligibleForStaticRangeAlignment = remainingSpace >= 0_lu;
327#endif
328 if (remainingSpace >= 0_lu)
329 return remainingSpace;
330 return { };
331 }
332 default:
333 return { };
334 }
335 }
336 return { };
337}
338
339// See CSS2 § 10.3.7-8 and 10.6.4-5.
340void PositionedLayoutConstraints::resolvePosition(RenderBox::LogicalExtentComputedValues& computedValues) const
341{
342 // Static position should have resolved one of our insets by now.
343 ASSERT(!m_useStaticPosition || !(m_insetBefore.isAuto() && m_insetAfter.isAuto()))((void)0);
344
345 auto usedMarginBefore = marginBeforeValue();
346 auto usedMarginAfter = marginAfterValue();
347 auto alignmentShift = 0_lu;
348
349 auto outerSize = usedMarginBefore + computedValues.extent + usedMarginAfter;
350 auto remainingSpace = insetModifiedContainingSize() - outerSize;
351
352 bool honorAutoInsets = !m_defaultAnchorBox || m_alignment.isNormal();
353 bool hasAutoBeforeInset = m_insetBefore.isAuto() && honorAutoInsets;
354 bool hasAutoAfterInset = m_insetAfter.isAuto() && honorAutoInsets;
355 bool hasAutoBeforeMargin = m_marginBefore.isAuto() && !m_defaultAnchorBox;
356 bool hasAutoAfterMargin = m_marginAfter.isAuto() && !m_defaultAnchorBox;
357
358 if ((hasAutoBeforeMargin || hasAutoAfterMargin) && !hasAutoBeforeInset && !hasAutoAfterInset) {
359 // Distribute remainingSpace to auto margins.
360 if (hasAutoBeforeMargin && hasAutoAfterMargin) {
361 // Distribute usable space to both margins equally.
362 auto usableRemainingSpace = (LogicalBoxAxis::Inline == m_containingAxis)
363 ? std::max(0_lu, remainingSpace) : remainingSpace;
364 usedMarginBefore = usedMarginAfter = usableRemainingSpace / 2;
365
366 // Distribute unused space to the end side.
367 auto unusedSpace = remainingSpace - (usedMarginBefore + usedMarginAfter);
368 if (startIsBefore())
369 usedMarginAfter += unusedSpace;
370 else
371 usedMarginBefore += unusedSpace;
372 } else if (hasAutoBeforeMargin)
373 usedMarginBefore = remainingSpace;
374 else if (hasAutoAfterMargin)
375 usedMarginAfter = remainingSpace;
376 } else {
377 if (auto staticRemainingSpace = remainingSpaceForStaticAlignment(outerSize))
378 alignmentShift = resolveAlignmentShift(*staticRemainingSpace, outerSize);
379 else if (hasAutoBeforeInset != hasAutoAfterInset)
380 alignmentShift = hasAutoAfterInset ? 0_lu : remainingSpace;
381 else // Align into remaining space.
382 alignmentShift = resolveAlignmentShift(remainingSpace, outerSize);
383 };
384
385 auto position = m_insetModifiedContainingRange.min() + usedMarginBefore + alignmentShift;
386
387 computedValues.position = position;
388 if (LogicalBoxAxis::Inline == m_selfAxis) {
389 if (m_writingMode.isLogicalLeftInlineStart() == !containingCoordsAreFlipped()) {
390 computedValues.margins.start = usedMarginBefore;
391 computedValues.margins.end = usedMarginAfter;
392 } else {
393 computedValues.margins.start = usedMarginAfter;
394 computedValues.margins.end = usedMarginBefore;
395 }
396 } else if (containingCoordsAreFlipped()) {
397 computedValues.margins.before = usedMarginAfter;
398 computedValues.margins.after = usedMarginBefore;
399 } else {
400 computedValues.margins.before = usedMarginBefore;
401 computedValues.margins.after = usedMarginAfter;
402 }
403}
404
405LayoutUnit PositionedLayoutConstraints::resolveAlignmentShift(LayoutUnit unusedSpace, LayoutUnit itemSize) const
406{
407 bool startIsBefore = this->startIsBefore();
408 bool isOverflowing = unusedSpace < 0_lu;
409 if (isOverflowing && OverflowAlignment::Safe == m_alignment.overflow())
410 return startIsBefore ? 0_lu : unusedSpace;
411
412 ItemPosition resolvedAlignment = resolveAlignmentValue();
413 ASSERT(ItemPosition::Auto != resolvedAlignment)((void)0);
414
415 LayoutUnit shift;
416 if (ItemPosition::AnchorCenter == resolvedAlignment) {
417 auto anchorCenterPosition = m_anchorArea.min() + (m_anchorArea.size() - itemSize) / 2;
418 shift = anchorCenterPosition - m_insetModifiedContainingRange.min();
419 if (m_alignment.overflow() == OverflowAlignment::Safe) {
420 if (startIsBefore) {
421 if (shift < 0)
422 shift = 0;
423 } else {
424 if (shift > unusedSpace)
425 shift = unusedSpace;
426 }
427 }
428 if (!isOverflowing && OverflowAlignment::Default == m_alignment.overflow()) {
429 // Avoid introducing overflow of the IMCB.
430 if (shift < 0)
431 shift = 0;
432 else if (shift > unusedSpace)
433 shift = unusedSpace;
434 }
435 } else {
436 auto alignmentSpace = StyleSelfAlignmentData::adjustmentFromStartEdge(unusedSpace, resolvedAlignment, m_containingAxis, m_containingWritingMode, m_writingMode);
437 shift = startIsBefore ? alignmentSpace : unusedSpace - alignmentSpace;
438 }
439
440 if (isOverflowing && ItemPosition::Normal != resolvedAlignment
441 && OverflowAlignment::Default == m_alignment.overflow()) {
442 // Allow overflow, but try to stay within the containing block.
443 // See https://www.w3.org/TR/css-align-3/#auto-safety-position
444
445 auto containingRange = m_originalContainingRange;
446 if (m_defaultAnchorBox && PositionType::Fixed == m_style.position()) {
447 // We didn't modify the m_containingRange to include scrollable area for positioning,
448 // but we should allow it for overflow management if we can scroll to reach that overflow.
449 if (auto renderView = dynamicDowncast<RenderView>(m_container.get())) {
450 auto& view = renderView->frameView();
Local variable 'view' is uncounted and unsafe
451 auto scrollPosition = view.constrainedScrollPosition(ScrollPosition(view.scrollPositionRespectingCustomFixedPosition()));
452 expandToScrollableArea(containingRange, scrollPosition);
453 }
454 }
455
456 auto spaceAfter = std::max(0_lu, containingRange.max() - m_insetModifiedContainingRange.max());
457 auto spaceBefore = std::max(0_lu, m_insetModifiedContainingRange.min() - containingRange.min());
458
459 auto [allowsInfiniteOverflowBefore, allowsInfiniteOverflowAfter] = containerAllowsInfiniteOverflow();
460
461 if (startIsBefore) {
462 // Avoid overflow on the end side
463 spaceAfter += (unusedSpace - shift);
464 if (spaceAfter < 0 && !allowsInfiniteOverflowAfter)
465 shift += spaceAfter;
466 // Disallow overflow on the start side.
467 spaceBefore += shift;
468 if (spaceBefore < 0 && !allowsInfiniteOverflowBefore)
469 shift -= spaceBefore;
470 } else {
471 // Avoid overflow on the end side
472 spaceBefore += shift;
473 if (spaceBefore < 0 && !allowsInfiniteOverflowBefore)
474 shift -= spaceBefore;
475 // Disallow overflow on the start side.
476 spaceAfter += (unusedSpace - shift);
477 if (spaceAfter < 0 && !allowsInfiniteOverflowAfter)
478 shift += spaceAfter;
479 }
480
481 }
482 return shift;
483}
484
485ItemPosition PositionedLayoutConstraints::resolveAlignmentValue() const
486{
487 if (m_useStaticPosition) {
488#if ASSERT_ENABLED0
489 ASSERT(m_isEligibleForStaticRangeAlignment)((void)0);
490#endif
491 return m_style.alignSelf().resolve(m_renderer->parentStyle()).position();
492 }
493
494 auto alignmentPosition = [&] {
495 auto itemPosition = m_alignment.position();
496 return (ItemPosition::Auto == itemPosition) ? ItemPosition::Normal : itemPosition;
497 }();
498
499 if (auto positionAreaValue = m_style.positionArea().tryValue(); positionAreaValue && ItemPosition::Normal == alignmentPosition)
500 alignmentPosition = positionAreaValue->defaultAlignmentForAxis(m_physicalAxis, m_containingWritingMode, m_writingMode);
501
502 if (!m_defaultAnchorBox && alignmentPosition == ItemPosition::AnchorCenter)
503 return ItemPosition::Center;
504 return alignmentPosition;
505}
506
507std::pair<bool, bool> PositionedLayoutConstraints::containerAllowsInfiniteOverflow() const
508{
509 if (!(m_container->hasPotentiallyScrollableOverflow() || (is<RenderView>(m_container) && PositionType::Fixed != m_style.position())))
510 return { false, false };
511 auto* containerBox = dynamicDowncast<RenderBox>(m_container.get());
512 ASSERT(containerBox)((void)0);
513 if (!containerBox)
514 return { false, false };
515
516 auto overflowLimits = containerBox->allowedLayoutOverflow(); // Already in flipped coordinates.
517 return m_physicalAxis == BoxAxis::Vertical
518 ? std::pair<bool, bool> { !overflowLimits.top(), !overflowLimits.bottom() }
519 : std::pair<bool, bool> { !overflowLimits.left(), !overflowLimits.right() };
520}
521
522bool PositionedLayoutConstraints::alignmentAppliesStretch(ItemPosition normalAlignment) const
523{
524 auto alignmentPosition = m_alignment.position();
525 if (m_style.positionArea().isNone() && (ItemPosition::Auto == alignmentPosition || ItemPosition::Normal == alignmentPosition))
526 alignmentPosition = normalAlignment;
527 return ItemPosition::Stretch == alignmentPosition;
528}
529
530bool NODELETE[[clang::annotate_type("webkit.nodelete")]] PositionedLayoutConstraints::insetFitsContent() const
531{
532 return (m_insetBefore.isAuto() || m_insetAfter.isAuto())
533 && !m_defaultAnchorBox; // position-area and align-center zero out auto insets.
534}
535
536bool PositionedLayoutConstraints::needsGridAreaAdjustmentBeforeStaticPositioning() const
537{
538 if (m_containingAxis == LogicalBoxAxis::Block)
539 return true;
540
541 auto* parent = m_renderer->parent();
542 // When the grid container is a parent we do not take the normal static positioning path.
543 if (!m_container->isRenderGrid() || parent == m_container)
544 return false;
545
546 auto parentWritingMode = parent->writingMode();
547 if (parentWritingMode.isLogicalLeftInlineStart() && !parentWritingMode.isOrthogonal(m_writingMode))
548 return false;
549
550 return true;
551}
552
553// MARK: - Static Position Computation
554
555void PositionedLayoutConstraints::computeStaticPosition()
556{
557 ASSERT(m_useStaticPosition)((void)0);
558
559 if (is<RenderGrid>(m_container)) {
560 // Grid Containers have special behavior, see https://www.w3.org/TR/css-grid/#abspos
561 if (m_container.get() == m_renderer->parent()) {
562 // Fake the static layout right here so it integrates with grid-area properly.
563 m_useStaticPosition = false; // Avoid the static position code path.
564 m_insetBefore = 0_css_px;
565 m_insetAfter = 0_css_px;
566
567 if (m_alignment.isNormal()) {
568 // This very likely was 'auto' before resolution, so re-resolve it against the static position containing block.
569 if (LogicalBoxAxis::Inline == m_containingAxis) {
570 m_alignment = m_style.justifySelf().resolve(&m_container->style());
571 } else
572 m_alignment = m_style.alignSelf().resolve(&m_container->style());
573 }
574 if (m_alignment.isNormal())
575 m_alignment.setPosition(ItemPosition::Start);
576 if (OverflowAlignment::Default == m_alignment.overflow())
577 m_alignment.setOverflow(OverflowAlignment::Unsafe);
578
579 // Unclear if this is spec-compliant, but it is the current interop behavior.
580 if (m_marginBefore.isAuto())
581 m_marginBefore = 0_css_px;
582 if (m_marginAfter.isAuto())
583 m_marginAfter = 0_css_px;
584 return;
585 }
586 // Rewind grid-area adjustments and fall through to the existing static position code.
587 if (needsGridAreaAdjustmentBeforeStaticPositioning())
588 m_containingRange.moveTo(m_originalContainingRange.min());
589 }
590
591 auto staticDistance = m_selfAxis == LogicalBoxAxis::Inline ? computedInlineStaticDistance() : computedBlockStaticDistance();
592 auto shouldUseInsetBefore = [&] {
593 if (m_selfAxis == LogicalBoxAxis::Block)
594 return true;
595 auto parentWritingMode = m_renderer->parent()->writingMode();
596 auto shouldUseInsetBefore = parentWritingMode.isOrthogonal(selfWritingMode()) || !parentWritingMode.isInlineFlipped(); // This is what trunk has.
597 if (!shouldUseInsetBefore) {
598 // FIXME: Figure out why.
599 shouldUseInsetBefore = m_containingWritingMode.isOrthogonal(parentWritingMode) && m_containingWritingMode.isBlockFlipped();
600 }
601 return shouldUseInsetBefore;
602 };
603 // Since the static position is computed during in flow layout, the computed
604 // position should already have zoom computed in. We need to divide out the zoom
605 // so that we get the same position when evaluating the inset.
606 if (shouldUseInsetBefore())
607 m_insetBefore = Style::InsetEdge::Fixed { staticDistance / m_style.usedZoomForLength().value };
608 else
609 m_insetAfter = Style::InsetEdge::Fixed { (containingSize() - staticDistance) / m_style.usedZoomForLength().value };
610}
611
612static LayoutPoint positionInContainer(const RenderBox& container, const RenderBox& child, LayoutPoint positionInChild)
613{
614 auto containerWritingMode = container.writingMode();
615 auto childWritingMode = child.writingMode();
616 auto childInFlowOffset = child.writingMode().isHorizontal() ? child.offsetForInFlowPosition() : child.offsetForInFlowPosition().transposedSize();
617 auto childLogicalLeft = childInFlowOffset.width() + child.logicalLeft();
618 auto childLogicalTop = childInFlowOffset.height() + child.logicalTop();
619
620 if (containerWritingMode.isOrthogonal(childWritingMode)) {
621 auto topLeft = LayoutPoint { childLogicalLeft + positionInChild.x(), childLogicalTop + positionInChild.y() };
622 if (childWritingMode.isBlockFlipped())
623 topLeft.setY(childLogicalTop + child.logicalHeight() - positionInChild.y());
624 if (containerWritingMode.isBlockFlipped())
625 topLeft.setX(childLogicalLeft + child.logicalWidth() - positionInChild.x());
626 return topLeft.transposedPoint();
627 }
628
629 if (containerWritingMode.isBlockOpposing(childWritingMode))
630 return { childLogicalLeft + positionInChild.x(), childLogicalTop + child.logicalHeight() - positionInChild.y() };
631
632 return { childLogicalLeft + positionInChild.x(), childLogicalTop + positionInChild.y() };
633}
634
635static LayoutPoint staticDistance(const RenderBoxModelObject& container, const RenderBox& outOfFlowBox)
636{
637 // Static position is relative to the candidate box's parent (it is computed during normal in-flow layout as if the candidate box was in-flow)
638 // 1. traverse the ancestor chain and convert static position relative to each container all the way up to the containing block
639 // 2. adjust the final static position with the containing block's border
640 // 3. pick x or y depending on what direction we are actually interested in (note that it's always the block directon from the
641 // candidate box's point of view but it could very well be the inline distance from the containing block's point of view.)
642
643 auto initialStaticPosition = [&] {
644 // Static position is already in the coordinate system of the container (minus the flip in inline direction).
645 auto staticPosition = LayoutPoint { outOfFlowBox.layer()->staticInlinePosition(), outOfFlowBox.layer()->staticBlockPosition() };
646 // We are relative to a RenderBox ancestor unless the containing block itself is an inline box.
647 auto* staticPositionContainingBlock = outOfFlowBox.parent();
648 for (; staticPositionContainingBlock && !is<RenderBox>(staticPositionContainingBlock) && staticPositionContainingBlock != &container; staticPositionContainingBlock = staticPositionContainingBlock->container()) { }
649 if (CheckedPtr renderBox = dynamicDowncast<RenderBox>(staticPositionContainingBlock); renderBox && renderBox->writingMode().isInlineFlipped())
650 staticPosition.setX(renderBox->logicalWidth() - staticPosition.x());
651 return staticPosition;
652 };
653
654 auto staticPosition = LayoutPoint { };
655 auto* child = &outOfFlowBox;
656 auto hasSeenNonInlineBoxContainer = false;
657 for (auto* ancestorContainer = child->parent(); ancestorContainer && ancestorContainer != &container; ancestorContainer = ancestorContainer->container()) {
658 CheckedPtr containerBox = dynamicDowncast<RenderBox>(*ancestorContainer);
659 if (!containerBox || is<RenderTableRow>(*containerBox))
660 continue;
661
662 staticPosition = child == &outOfFlowBox ? initialStaticPosition() : positionInContainer(*containerBox, *child, staticPosition);
663 child = containerBox.get();
664 hasSeenNonInlineBoxContainer = true;
665 }
666
667 if (!hasSeenNonInlineBoxContainer && is<RenderInline>(container)) {
668 // This is a simple case of when the containing block is formed by a positioned inline box with no block boxes in-between (e.g <span style="position: relative">)
669 return initialStaticPosition();
670 }
671
672 auto* containingBlock = dynamicDowncast<RenderBox>(container);
673 // m_insetBefore is expected to be relative to the padding box (while staticPosition is relative to the border box).
674 auto containingBlockBorderSize = LayoutSize { };
675 if (containingBlock)
676 containingBlockBorderSize = containingBlock->writingMode().isInlineFlipped() ? LayoutSize(containingBlock->borderEnd(), containingBlock->borderBefore()) : LayoutSize(containingBlock->borderStart(), containingBlock->borderBefore());
677 else {
678 containingBlock = child->containingBlock();
679 ASSERT(containingBlock)((void)0);
680 // Note that we don't take the border here as we passed the real containing block.
681 }
682
683 staticPosition = child == &outOfFlowBox ? initialStaticPosition() : positionInContainer(*containingBlock, *child, staticPosition);
684 staticPosition -= containingBlockBorderSize;
685 return staticPosition;
686}
687
688LayoutUnit PositionedLayoutConstraints::computedInlineStaticDistance() const
689{
690 // Note that at this point staticPosition is relative to the containing block (x is inline direction, y is block direction) which may not match with the box's slef writing mode.
691 auto staticPosition = staticDistance(*m_container, m_renderer.get());
692 auto staticDistance = !isOrthogonal() ? staticPosition.x() : staticPosition.y();
693 if (CheckedPtr gridContainer = dynamicDowncast<RenderGrid>(m_container.get())) {
694 // Special grid handling: move static distance back to relative to border box and adjust with our offset.
695 auto containingBlockBorderSize = !isOrthogonal() ? (gridContainer->writingMode().isInlineFlipped() ? gridContainer->borderEnd() : gridContainer->borderStart()) : gridContainer->borderBefore();
696 staticDistance += containingBlockBorderSize;
697 staticDistance -= m_containingRange.min();
698 }
699 return staticDistance;
700}
701
702LayoutUnit PositionedLayoutConstraints::computedBlockStaticDistance() const
703{
704 // Note that at this point staticPosition is relative to the containing block (x is inline direction, y is block direction) which may not match with the box's slef writing mode.
705 auto staticPosition = staticDistance(*m_container, m_renderer.get());
706 return !isOrthogonal() ? staticPosition.y() : staticPosition.x();
707}
708
709static bool NODELETE[[clang::annotate_type("webkit.nodelete")]] shouldInlineStaticDistanceAdjustedWithBoxHeight(WritingMode containinigBlockWritingMode, WritingMode parentWritingMode, WritingMode outOfFlowBoxWritingMode)
710{
711 if (!containinigBlockWritingMode.isOrthogonal(parentWritingMode))
712 return false;
713
714 if (parentWritingMode.isOrthogonal(outOfFlowBoxWritingMode))
715 return parentWritingMode.isBlockFlipped();
716
717 return containinigBlockWritingMode.isBlockFlipped() && !parentWritingMode.isInlineFlipped();
718}
719
720void PositionedLayoutConstraints::fixupLogicalLeftPosition(RenderBox::LogicalExtentComputedValues& computedValues) const
721{
722 if (m_useStaticPosition) {
723 if (m_container.get() != m_renderer->parent() && shouldInlineStaticDistanceAdjustedWithBoxHeight(m_containingWritingMode, m_renderer->parent()->writingMode(), selfWritingMode()))
724 computedValues.position -= computedValues.extent;
725 return;
726 }
727
728 if (m_writingMode.isHorizontal()) {
729 CheckedPtr containingBox = dynamicDowncast<RenderBox>(container());
730 if (containingBox && containingBox->shouldPlaceVerticalScrollbarOnLeft())
731 computedValues.position += containingBox->verticalScrollbarWidth();
732 }
733
734 // FIXME: This hack is needed to calculate the logical left position for a 'rtl' relatively
735 // positioned, inline because right now, it is using the logical left position
736 // of the first line box when really it should use the last line box. When
737 // this is fixed elsewhere, this adjustment should be removed.
738
739 CheckedPtr renderInline = dynamicDowncast<RenderInline>(container());
740 if (!renderInline || m_containingWritingMode.isLogicalLeftInlineStart())
741 return;
742
743 auto firstInlineBox = InlineIterator::lineLeftmostInlineBoxFor(*renderInline);
744 if (!firstInlineBox)
745 return;
746
747 auto lastInlineBox = [&] {
748 auto inlineBox = firstInlineBox;
749 for (; inlineBox->nextInlineBoxLineRightward(); inlineBox.traverseInlineBoxLineRightward()) { }
750 return inlineBox;
751 }();
752 if (firstInlineBox == lastInlineBox)
753 return;
754
755 auto lastInlineBoxPaddingBoxVisualRight = lastInlineBox->logicalLeftIgnoringInlineDirection() + renderInline->borderLogicalLeft();
756 // FIXME: This does not work with decoration break clone.
757 auto firstInlineBoxPaddingBoxVisualRight = firstInlineBox->logicalLeftIgnoringInlineDirection();
758 auto adjustment = lastInlineBoxPaddingBoxVisualRight - firstInlineBoxPaddingBoxVisualRight;
759 computedValues.position += adjustment - m_containingRange.min();
760}
761
762// FIXME: Let's move this over to RenderBoxModelObject and collapse some of the logic here.
763static bool NODELETE[[clang::annotate_type("webkit.nodelete")]] shouldBlockStaticDistanceAdjustedWithBoxHeight(const RenderBoxModelObject& containingBlock, const RenderElement& parent, WritingMode outOfFlowBoxWritingMode)
764{
765 // This is where we check if the final static position needs to be adjusted with the height of the out-of-flow box.
766 // In ::computeBlockStaticDistance we convert the static position relative to the containing block but in some cases
767 // this final static position still points to the wrong side of the box (i.e. at computeBlockStaticDistance we don't know yet the height
768 // which may contribute to the logical top position. see details below.)
769
770 auto parentWritingMode = parent.writingMode();
771 auto containinigBlockWritingMode = containingBlock.writingMode();
772
773 if (containinigBlockWritingMode.blockDirection() == parentWritingMode.blockDirection() && parentWritingMode.blockDirection() == outOfFlowBoxWritingMode.blockDirection())
774 return false;
775
776 auto isParentInlineFlipped = parentWritingMode.isInlineFlipped();
777 if (containinigBlockWritingMode.isOrthogonal(outOfFlowBoxWritingMode)) {
778 if (&containingBlock == &parent) {
779 // <div id=containinigBlock class=rtl>
780 // <div id=outOfFlowBox class=ltr>
781 return isParentInlineFlipped;
782 }
783
784 if (!containinigBlockWritingMode.isOrthogonal(parentWritingMode))
785 return isParentInlineFlipped;
786
787 return parentWritingMode.isBlockFlipped();
788 }
789
790 ASSERT(containinigBlockWritingMode.blockDirection() == outOfFlowBoxWritingMode.blockDirection() || containinigBlockWritingMode.isBlockOpposing(outOfFlowBoxWritingMode))((void)0);
791 if (!parentWritingMode.isOrthogonal(containinigBlockWritingMode)) {
792 // inline direction does not matter as all participants are on the same axis.
793 if (containinigBlockWritingMode.blockDirection() == outOfFlowBoxWritingMode.blockDirection()) {
794 // <div id=containinigBlock class=vrl>
795 // <div id=parent class=vlr>
796 // <div id=outOfFlowBox class=vrl>
797 return true;
798 }
799
800 // <div id=containinigBlock class=vlr>
801 // <div id=parent class=vrl>
802 // <div id=outOfFlowBox class=vrl>
803 return parentWritingMode.isBlockOpposing(containinigBlockWritingMode);
804 }
805
806 // Orhogonal parent.
807 // <div id=containinigBlock class=vrl>
808 // <div id=parent class=htb>
809 // <div id=outOfFlowBox class=vlr>
810 return containinigBlockWritingMode.isBlockFlipped() != isParentInlineFlipped;
811}
812
813void PositionedLayoutConstraints::adjustLogicalTopWithLogicalHeightIfNeeded(RenderBox::LogicalExtentComputedValues& computedValues) const
814{
815 if (!m_useStaticPosition || m_selfAxis != LogicalBoxAxis::Block)
816 return;
817 if (shouldBlockStaticDistanceAdjustedWithBoxHeight(*m_container, *m_renderer->parent(), m_writingMode))
818 computedValues.position -= computedValues.extent;
819}
820
821}