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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/core/style/position_area.h"
#include "base/check_op.h"
#include "third_party/blink/renderer/core/layout/geometry/axis.h"
#include "third_party/blink/renderer/core/style/anchor_specifier_value.h"
#include "third_party/blink/renderer/platform/geometry/calculation_value.h"
#include "third_party/blink/renderer/platform/text/writing_mode_utils.h"
#include "third_party/blink/renderer/platform/wtf/static_constructors.h"
namespace blink {
namespace {
inline PhysicalAxes PhysicalAxisFromRegion(
PositionAreaRegion region,
const WritingDirectionMode& container_writing_direction,
const WritingDirectionMode& self_writing_direction) {
switch (region) {
case PositionAreaRegion::kTop:
case PositionAreaRegion::kBottom:
case PositionAreaRegion::kYStart:
case PositionAreaRegion::kYEnd:
case PositionAreaRegion::kYSelfStart:
case PositionAreaRegion::kYSelfEnd:
return kPhysicalAxesVertical;
case PositionAreaRegion::kLeft:
case PositionAreaRegion::kRight:
case PositionAreaRegion::kXStart:
case PositionAreaRegion::kXEnd:
case PositionAreaRegion::kXSelfStart:
case PositionAreaRegion::kXSelfEnd:
return kPhysicalAxesHorizontal;
case PositionAreaRegion::kInlineStart:
case PositionAreaRegion::kInlineEnd:
return container_writing_direction.IsHorizontal()
? kPhysicalAxesHorizontal
: kPhysicalAxesVertical;
case PositionAreaRegion::kSelfInlineStart:
case PositionAreaRegion::kSelfInlineEnd:
return self_writing_direction.IsHorizontal() ? kPhysicalAxesHorizontal
: kPhysicalAxesVertical;
case PositionAreaRegion::kBlockStart:
case PositionAreaRegion::kBlockEnd:
return container_writing_direction.IsHorizontal()
? kPhysicalAxesVertical
: kPhysicalAxesHorizontal;
case PositionAreaRegion::kSelfBlockStart:
case PositionAreaRegion::kSelfBlockEnd:
return self_writing_direction.IsHorizontal() ? kPhysicalAxesVertical
: kPhysicalAxesHorizontal;
default:
// Neutral region. Axis depends on the other span or order of appearance
// if both spans are neutral.
return kPhysicalAxesNone;
}
}
// Return the physical axis for an position-area span if given by the regions, or
// kPhysicalAxesNone if we need the direction/writing-mode to decide.
inline PhysicalAxes PhysicalAxisFromSpan(
PositionAreaRegion start,
PositionAreaRegion end,
const WritingDirectionMode& container_writing_direction,
const WritingDirectionMode& self_writing_direction) {
if (start == PositionAreaRegion::kAll) {
return kPhysicalAxesNone;
}
PositionAreaRegion indicator = start == PositionAreaRegion::kCenter ? end : start;
return PhysicalAxisFromRegion(indicator, container_writing_direction,
self_writing_direction);
}
// Convert a logical region to the corresponding physical region based on the
// span's axis and the direction/writing-mode of the anchored element and its
// containing block.
PositionAreaRegion ToPhysicalRegion(
PositionAreaRegion region,
PhysicalAxes axis,
const WritingDirectionMode& container_writing_direction,
const WritingDirectionMode& self_writing_direction) {
bool is_horizontal = axis == kPhysicalAxesHorizontal;
PositionAreaRegion axis_region = region;
switch (region) {
case PositionAreaRegion::kNone:
case PositionAreaRegion::kAll:
NOTREACHED() << "Should be handled directly in PositionArea::ToPhysical";
case PositionAreaRegion::kCenter:
case PositionAreaRegion::kTop:
case PositionAreaRegion::kBottom:
case PositionAreaRegion::kLeft:
case PositionAreaRegion::kRight:
return region;
case PositionAreaRegion::kStart:
case PositionAreaRegion::kInlineStart:
case PositionAreaRegion::kBlockStart:
axis_region =
is_horizontal ? PositionAreaRegion::kXStart : PositionAreaRegion::kYStart;
break;
case PositionAreaRegion::kEnd:
case PositionAreaRegion::kInlineEnd:
case PositionAreaRegion::kBlockEnd:
axis_region =
is_horizontal ? PositionAreaRegion::kXEnd : PositionAreaRegion::kYEnd;
break;
case PositionAreaRegion::kSelfStart:
case PositionAreaRegion::kSelfInlineStart:
case PositionAreaRegion::kSelfBlockStart:
axis_region = is_horizontal ? PositionAreaRegion::kXSelfStart
: PositionAreaRegion::kYSelfStart;
break;
case PositionAreaRegion::kSelfEnd:
case PositionAreaRegion::kSelfInlineEnd:
case PositionAreaRegion::kSelfBlockEnd:
axis_region = is_horizontal ? PositionAreaRegion::kXSelfEnd
: PositionAreaRegion::kYSelfEnd;
break;
default:
break;
}
if (is_horizontal) {
if ((axis_region == PositionAreaRegion::kXStart &&
container_writing_direction.IsFlippedX()) ||
(axis_region == PositionAreaRegion::kXEnd &&
!container_writing_direction.IsFlippedX()) ||
(axis_region == PositionAreaRegion::kXSelfStart &&
self_writing_direction.IsFlippedX()) ||
(axis_region == PositionAreaRegion::kXSelfEnd &&
!self_writing_direction.IsFlippedX())) {
return PositionAreaRegion::kRight;
}
return PositionAreaRegion::kLeft;
}
if ((axis_region == PositionAreaRegion::kYStart &&
container_writing_direction.IsFlippedY()) ||
(axis_region == PositionAreaRegion::kYEnd &&
!container_writing_direction.IsFlippedY()) ||
(axis_region == PositionAreaRegion::kYSelfStart &&
self_writing_direction.IsFlippedY()) ||
(axis_region == PositionAreaRegion::kYSelfEnd &&
!self_writing_direction.IsFlippedY())) {
return PositionAreaRegion::kBottom;
}
return PositionAreaRegion::kTop;
}
} // namespace
PositionArea PositionArea::ToPhysical(
const WritingDirectionMode& container_writing_direction,
const WritingDirectionMode& self_writing_direction) const {
if (IsNone()) {
return *this;
}
PhysicalAxes first_axis =
PhysicalAxisFromSpan(FirstStart(), FirstEnd(),
container_writing_direction, self_writing_direction);
PhysicalAxes second_axis =
PhysicalAxisFromSpan(SecondStart(), SecondEnd(),
container_writing_direction, self_writing_direction);
if (first_axis == second_axis) {
CHECK_EQ(first_axis, kPhysicalAxesNone)
<< "Both regions representing the same axis should not happen";
// If neither span includes a physical keyword, the first refers to the
// block axis of the containing block, and the second to the inline axis.
first_axis = ToPhysicalAxes(kLogicalAxesBlock,
container_writing_direction.GetWritingMode());
second_axis = ToPhysicalAxes(kLogicalAxesInline,
container_writing_direction.GetWritingMode());
} else {
if (first_axis == kPhysicalAxesNone) {
first_axis = second_axis ^ kPhysicalAxesBoth;
} else if (second_axis == kPhysicalAxesNone) {
second_axis = first_axis ^ kPhysicalAxesBoth;
}
}
DCHECK_EQ(first_axis ^ second_axis, kPhysicalAxesBoth)
<< "Both axes should be defined and orthogonal";
auto regions = std::to_array<PositionAreaRegion>(
{PositionAreaRegion::kTop, PositionAreaRegion::kBottom,
PositionAreaRegion::kLeft, PositionAreaRegion::kRight});
// Adjust the index to always make the first span the vertical one in the
// resulting PositionArea, regardless of the original ordering.
size_t index = first_axis == kPhysicalAxesHorizontal ? 2 : 0;
if (FirstStart() != PositionAreaRegion::kAll) {
regions[index] =
ToPhysicalRegion(FirstStart(), first_axis, container_writing_direction,
self_writing_direction);
regions[index + 1] =
ToPhysicalRegion(FirstEnd(), first_axis, container_writing_direction,
self_writing_direction);
}
index = (index + 2) % 4;
if (SecondStart() != PositionAreaRegion::kAll) {
regions[index] =
ToPhysicalRegion(SecondStart(), second_axis,
container_writing_direction, self_writing_direction);
regions[index + 1] =
ToPhysicalRegion(SecondEnd(), second_axis, container_writing_direction,
self_writing_direction);
}
if (regions[0] == PositionAreaRegion::kBottom ||
regions[1] == PositionAreaRegion::kTop) {
std::swap(regions[0], regions[1]);
}
if (regions[2] == PositionAreaRegion::kRight ||
regions[3] == PositionAreaRegion::kLeft) {
std::swap(regions[2], regions[3]);
}
return PositionArea(regions[0], regions[1], regions[2], regions[3]);
}
std::pair<StyleSelfAlignmentData, StyleSelfAlignmentData>
PositionArea::AlignJustifySelfFromPhysical(
WritingDirectionMode container_writing_direction,
bool is_containing_block_scrollable) const {
const OverflowAlignment overflow = is_containing_block_scrollable
? OverflowAlignment::kUnsafe
: OverflowAlignment::kDefault;
StyleSelfAlignmentData align(ItemPosition::kStart, overflow);
StyleSelfAlignmentData align_reverse(ItemPosition::kEnd, overflow);
StyleSelfAlignmentData justify(ItemPosition::kStart, overflow);
StyleSelfAlignmentData justify_reverse(ItemPosition::kEnd, overflow);
if ((FirstStart() == PositionAreaRegion::kTop &&
FirstEnd() == PositionAreaRegion::kBottom) ||
(FirstStart() == PositionAreaRegion::kCenter &&
FirstEnd() == PositionAreaRegion::kCenter)) {
// 'center' or 'all' should align with anchor center.
align = align_reverse = {ItemPosition::kAnchorCenter, overflow};
} else {
// 'top' and 'top center' aligns with end, 'bottom' and 'center bottom' with
// start.
if (FirstStart() == PositionAreaRegion::kTop) {
std::swap(align, align_reverse);
}
}
if ((SecondStart() == PositionAreaRegion::kLeft &&
SecondEnd() == PositionAreaRegion::kRight) ||
(SecondStart() == PositionAreaRegion::kCenter &&
SecondEnd() == PositionAreaRegion::kCenter)) {
// 'center' or 'all' should align with anchor center.
justify = justify_reverse = {ItemPosition::kAnchorCenter, overflow};
} else {
// 'left' and 'left center' aligns with end, 'right' and 'center right' with
// start.
if (SecondStart() == PositionAreaRegion::kLeft) {
std::swap(justify, justify_reverse);
}
}
if ((FirstStart() == PositionAreaRegion::kTop &&
FirstEnd() == PositionAreaRegion::kTop) ||
(FirstStart() == PositionAreaRegion::kBottom &&
FirstEnd() == PositionAreaRegion::kBottom)) {
align.SetOverflow(OverflowAlignment::kUnsafe);
align_reverse.SetOverflow(OverflowAlignment::kUnsafe);
}
if ((SecondStart() == PositionAreaRegion::kLeft &&
SecondEnd() == PositionAreaRegion::kLeft) ||
(SecondStart() == PositionAreaRegion::kRight &&
SecondEnd() == PositionAreaRegion::kRight)) {
justify.SetOverflow(OverflowAlignment::kUnsafe);
justify_reverse.SetOverflow(OverflowAlignment::kUnsafe);
}
PhysicalToLogical converter(container_writing_direction, align,
justify_reverse, align_reverse, justify);
return {converter.BlockStart(), converter.InlineStart()};
}
AnchorQuery PositionArea::AnchorTop() {
return AnchorQuery(CSSAnchorQueryType::kAnchor,
AnchorSpecifierValue::Default(), /* percentage */ 0,
CSSAnchorValue::kTop);
}
AnchorQuery PositionArea::AnchorBottom() {
return AnchorQuery(CSSAnchorQueryType::kAnchor,
AnchorSpecifierValue::Default(), /* percentage */ 0,
CSSAnchorValue::kBottom);
}
AnchorQuery PositionArea::AnchorLeft() {
return AnchorQuery(CSSAnchorQueryType::kAnchor,
AnchorSpecifierValue::Default(), /* percentage */ 0,
CSSAnchorValue::kLeft);
}
AnchorQuery PositionArea::AnchorRight() {
return AnchorQuery(CSSAnchorQueryType::kAnchor,
AnchorSpecifierValue::Default(), /* percentage */ 0,
CSSAnchorValue::kRight);
}
} // namespace blink
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