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/*
* Copyright (C) 2018 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "FormattingContext.h"
#if ENABLE(LAYOUT_FORMATTING_CONTEXT)
#include "FloatingState.h"
#include "FormattingState.h"
#include "InlineFormattingState.h"
namespace WebCore {
namespace Layout {
static inline bool isHeightAuto(const Box& layoutBox)
{
// 10.5 Content height: the 'height' property
//
// The percentage is calculated with respect to the height of the generated box's containing block.
// If the height of the containing block is not specified explicitly (i.e., it depends on content height),
// and this element is not absolutely positioned, the used height is calculated as if 'auto' was specified.
auto height = layoutBox.style().logicalHeight();
if (height.isAuto())
return true;
if (height.isPercent()) {
if (layoutBox.isOutOfFlowPositioned())
return false;
return !layoutBox.containingBlock()->style().logicalHeight().isFixed();
}
return false;
}
Optional<LayoutUnit> FormattingContext::Geometry::computedHeightValue(const LayoutState& layoutState, const Box& layoutBox, HeightType heightType)
{
auto& style = layoutBox.style();
auto height = heightType == HeightType::Normal ? style.logicalHeight() : heightType == HeightType::Min ? style.logicalMinHeight() : style.logicalMaxHeight();
if (height.isUndefined() || height.isAuto())
return { };
if (height.isFixed())
return LayoutUnit(height.value());
Optional<LayoutUnit> containingBlockHeightValue;
if (layoutBox.isOutOfFlowPositioned()) {
// Containing block's height is already computed since we layout the out-of-flow boxes as the last step.
containingBlockHeightValue = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock()).height();
} else {
if (layoutState.inQuirksMode())
containingBlockHeightValue = FormattingContext::Quirks::heightValueOfNearestContainingBlockWithFixedHeight(layoutState, layoutBox);
else {
auto containingBlockHeight = layoutBox.containingBlock()->style().logicalHeight();
if (containingBlockHeight.isFixed())
containingBlockHeightValue = LayoutUnit(containingBlockHeight.value());
}
}
if (!containingBlockHeightValue)
return { };
return valueForLength(height, *containingBlockHeightValue);
}
static LayoutUnit contentHeightForFormattingContextRoot(const LayoutState& layoutState, const Box& layoutBox)
{
ASSERT(isHeightAuto(layoutBox) && (layoutBox.establishesFormattingContext() || layoutBox.isDocumentBox()));
// 10.6.7 'Auto' heights for block formatting context roots
// If it only has inline-level children, the height is the distance between the top of the topmost line box and the bottom of the bottommost line box.
// If it has block-level children, the height is the distance between the top margin-edge of the topmost block-level
// child box and the bottom margin-edge of the bottommost block-level child box.
// In addition, if the element has any floating descendants whose bottom margin edge is below the element's bottom content edge,
// then the height is increased to include those edges. Only floats that participate in this block formatting context are taken
// into account, e.g., floats inside absolutely positioned descendants or other floats are not.
if (!is<Container>(layoutBox) || !downcast<Container>(layoutBox).hasInFlowOrFloatingChild())
return 0;
auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);
auto borderAndPaddingTop = displayBox.borderTop() + displayBox.paddingTop().valueOr(0);
auto top = borderAndPaddingTop;
auto bottom = borderAndPaddingTop;
auto& formattingRootContainer = downcast<Container>(layoutBox);
if (formattingRootContainer.establishesInlineFormattingContext()) {
auto& lineBoxes = downcast<InlineFormattingState>(layoutState.establishedFormattingState(layoutBox)).lineBoxes();
// Even empty containers generate one line.
ASSERT(!lineBoxes.isEmpty());
top = lineBoxes.first().logicalTop();
bottom = lineBoxes.last().logicalBottom();
} else if (formattingRootContainer.establishesBlockFormattingContext() || layoutBox.isDocumentBox()) {
if (formattingRootContainer.hasInFlowChild()) {
auto& firstDisplayBox = layoutState.displayBoxForLayoutBox(*formattingRootContainer.firstInFlowChild());
auto& lastDisplayBox = layoutState.displayBoxForLayoutBox(*formattingRootContainer.lastInFlowChild());
top = firstDisplayBox.rectWithMargin().top();
bottom = lastDisplayBox.rectWithMargin().bottom();
}
}
auto* formattingContextRoot = &layoutBox;
// TODO: The document renderer is not a formatting context root by default at all. Need to find out what it is.
if (!layoutBox.establishesFormattingContext()) {
ASSERT(layoutBox.isDocumentBox());
formattingContextRoot = &layoutBox.formattingContextRoot();
}
auto& floatingState = layoutState.establishedFormattingState(*formattingContextRoot).floatingState();
auto floatBottom = floatingState.bottom(*formattingContextRoot);
if (floatBottom) {
bottom = std::max<LayoutUnit>(*floatBottom, bottom);
auto floatTop = floatingState.top(*formattingContextRoot);
ASSERT(floatTop);
top = std::min<LayoutUnit>(*floatTop, top);
}
auto computedHeight = bottom - top;
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height] -> content height for formatting context root -> height(" << computedHeight << "px) layoutBox("<< &layoutBox << ")");
return computedHeight;
}
Optional<LayoutUnit> FormattingContext::Geometry::computedValueIfNotAuto(const Length& geometryProperty, LayoutUnit containingBlockWidth)
{
if (geometryProperty.isUndefined())
return WTF::nullopt;
if (geometryProperty.isAuto())
return WTF::nullopt;
return valueForLength(geometryProperty, containingBlockWidth);
}
Optional<LayoutUnit> FormattingContext::Geometry::fixedValue(const Length& geometryProperty)
{
if (!geometryProperty.isFixed())
return WTF::nullopt;
return LayoutUnit(geometryProperty.value());
}
// https://www.w3.org/TR/CSS22/visudet.html#min-max-heights
// Specifies a percentage for determining the used value. The percentage is calculated with respect to the height of the generated box's containing block.
// If the height of the containing block is not specified explicitly (i.e., it depends on content height), and this element is not absolutely positioned,
// the percentage value is treated as '0' (for 'min-height') or 'none' (for 'max-height').
Optional<LayoutUnit> FormattingContext::Geometry::computedMaxHeight(const LayoutState& layoutState, const Box& layoutBox)
{
return computedHeightValue(layoutState, layoutBox, HeightType::Max);
}
Optional<LayoutUnit> FormattingContext::Geometry::computedMinHeight(const LayoutState& layoutState, const Box& layoutBox)
{
if (auto minHeightValue = computedHeightValue(layoutState, layoutBox, HeightType::Min))
return minHeightValue;
return { 0 };
}
static LayoutUnit staticVerticalPositionForOutOfFlowPositioned(const LayoutState& layoutState, const Box& layoutBox)
{
ASSERT(layoutBox.isOutOfFlowPositioned());
// For the purposes of this section and the next, the term "static position" (of an element) refers, roughly, to the position an element would have
// had in the normal flow. More precisely, the static position for 'top' is the distance from the top edge of the containing block to the top margin
// edge of a hypothetical box that would have been the first box of the element if its specified 'position' value had been 'static' and its specified
// 'float' had been 'none' and its specified 'clear' had been 'none'. (Note that due to the rules in section 9.7 this might require also assuming a different
// computed value for 'display'.) The value is negative if the hypothetical box is above the containing block.
// Start with this box's border box offset from the parent's border box.
LayoutUnit top;
if (auto* previousInFlowSibling = layoutBox.previousInFlowSibling()) {
// Add sibling offset
auto& previousInFlowDisplayBox = layoutState.displayBoxForLayoutBox(*previousInFlowSibling);
top += previousInFlowDisplayBox.bottom() + previousInFlowDisplayBox.nonCollapsedMarginAfter();
} else {
ASSERT(layoutBox.parent());
top = layoutState.displayBoxForLayoutBox(*layoutBox.parent()).contentBoxTop();
}
// Resolve top all the way up to the containing block.
auto& containingBlock = *layoutBox.containingBlock();
// Start with the parent since we pretend that this box is normal flow.
for (auto* container = layoutBox.parent(); container != &containingBlock; container = container->containingBlock()) {
auto& displayBox = layoutState.displayBoxForLayoutBox(*container);
// Display::Box::top is the border box top position in its containing block's coordinate system.
top += displayBox.top();
ASSERT(!container->isPositioned() || layoutBox.isFixedPositioned());
}
// Move the static position relative to the padding box. This is very specific to abolutely positioned boxes.
auto paddingBoxTop = layoutState.displayBoxForLayoutBox(containingBlock).paddingBoxTop();
return top - paddingBoxTop;
}
static LayoutUnit staticHorizontalPositionForOutOfFlowPositioned(const LayoutState& layoutState, const Box& layoutBox)
{
ASSERT(layoutBox.isOutOfFlowPositioned());
// See staticVerticalPositionForOutOfFlowPositioned for the definition of the static position.
// Start with this box's border box offset from the parent's border box.
ASSERT(layoutBox.parent());
auto left = layoutState.displayBoxForLayoutBox(*layoutBox.parent()).contentBoxLeft();
// Resolve left all the way up to the containing block.
auto& containingBlock = *layoutBox.containingBlock();
// Start with the parent since we pretend that this box is normal flow.
for (auto* container = layoutBox.parent(); container != &containingBlock; container = container->containingBlock()) {
auto& displayBox = layoutState.displayBoxForLayoutBox(*container);
// Display::Box::left is the border box left position in its containing block's coordinate system.
left += displayBox.left();
ASSERT(!container->isPositioned() || layoutBox.isFixedPositioned());
}
// Move the static position relative to the padding box. This is very specific to abolutely positioned boxes.
auto paddingBoxLeft = layoutState.displayBoxForLayoutBox(containingBlock).paddingBoxLeft();
return left - paddingBoxLeft;
}
LayoutUnit FormattingContext::Geometry::shrinkToFitWidth(LayoutState& layoutState, const Box& formattingRoot, UsedHorizontalValues usedValues)
{
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width] -> shrink to fit -> unsupported -> width(" << LayoutUnit { } << "px) layoutBox: " << &formattingRoot << ")");
ASSERT(formattingRoot.establishesFormattingContext());
ASSERT(usedValues.containingBlockWidth.hasValue());
// Calculation of the shrink-to-fit width is similar to calculating the width of a table cell using the automatic table layout algorithm.
// Roughly: calculate the preferred width by formatting the content without breaking lines other than where explicit line breaks occur,
// and also calculate the preferred minimum width, e.g., by trying all possible line breaks. CSS 2.2 does not define the exact algorithm.
// Thirdly, find the available width: in this case, this is the width of the containing block minus the used values of 'margin-left', 'border-left-width',
// 'padding-left', 'padding-right', 'border-right-width', 'margin-right', and the widths of any relevant scroll bars.
// Then the shrink-to-fit width is: min(max(preferred minimum width, available width), preferred width).
auto& formattingStateForRoot = layoutState.formattingStateForBox(formattingRoot);
auto intrinsicWidthConstraints = formattingStateForRoot.intrinsicWidthConstraints(formattingRoot);
if (!intrinsicWidthConstraints) {
layoutState.createFormattingContext(formattingRoot)->computeIntrinsicWidthConstraints();
intrinsicWidthConstraints = formattingStateForRoot.intrinsicWidthConstraints(formattingRoot);
}
auto availableWidth = *usedValues.containingBlockWidth;
return std::min(std::max(intrinsicWidthConstraints->minimum, availableWidth), intrinsicWidthConstraints->maximum);
}
VerticalGeometry FormattingContext::Geometry::outOfFlowNonReplacedVerticalGeometry(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedValues)
{
ASSERT(layoutBox.isOutOfFlowPositioned() && !layoutBox.replaced());
// 10.6.4 Absolutely positioned, non-replaced elements
//
// For absolutely positioned elements, the used values of the vertical dimensions must satisfy this constraint:
// 'top' + 'margin-top' + 'border-top-width' + 'padding-top' + 'height' + 'padding-bottom' + 'border-bottom-width' + 'margin-bottom' + 'bottom'
// = height of containing block
// If all three of 'top', 'height', and 'bottom' are auto, set 'top' to the static position and apply rule number three below.
// If none of the three are 'auto': If both 'margin-top' and 'margin-bottom' are 'auto', solve the equation under the extra
// constraint that the two margins get equal values. If one of 'margin-top' or 'margin-bottom' is 'auto', solve the equation for that value.
// If the values are over-constrained, ignore the value for 'bottom' and solve for that value.
// Otherwise, pick the one of the following six rules that applies.
// 1. 'top' and 'height' are 'auto' and 'bottom' is not 'auto', then the height is based on the content per 10.6.7,
// set 'auto' values for 'margin-top' and 'margin-bottom' to 0, and solve for 'top'
// 2. 'top' and 'bottom' are 'auto' and 'height' is not 'auto', then set 'top' to the static position, set 'auto' values for
// 'margin-top' and 'margin-bottom' to 0, and solve for 'bottom'
// 3. 'height' and 'bottom' are 'auto' and 'top' is not 'auto', then the height is based on the content per 10.6.7, set 'auto'
// values for 'margin-top' and 'margin-bottom' to 0, and solve for 'bottom'
// 4. 'top' is 'auto', 'height' and 'bottom' are not 'auto', then set 'auto' values for 'margin-top' and 'margin-bottom' to 0, and solve for 'top'
// 5. 'height' is 'auto', 'top' and 'bottom' are not 'auto', then 'auto' values for 'margin-top' and 'margin-bottom' are set to 0 and solve for 'height'
// 6. 'bottom' is 'auto', 'top' and 'height' are not 'auto', then set 'auto' values for 'margin-top' and 'margin-bottom' to 0 and solve for 'bottom'
auto& style = layoutBox.style();
auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);
auto& containingBlockDisplayBox = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock());
auto containingBlockHeight = containingBlockDisplayBox.paddingBoxHeight();
auto containingBlockWidth = containingBlockDisplayBox.paddingBoxWidth();
auto top = computedValueIfNotAuto(style.logicalTop(), containingBlockWidth);
auto bottom = computedValueIfNotAuto(style.logicalBottom(), containingBlockWidth);
auto height = usedValues.height ? usedValues.height.value() : computedHeightValue(layoutState, layoutBox, HeightType::Normal);
auto computedVerticalMargin = Geometry::computedVerticalMargin(layoutBox, UsedHorizontalValues { containingBlockWidth });
UsedVerticalMargin::NonCollapsedValues usedVerticalMargin;
auto paddingTop = displayBox.paddingTop().valueOr(0);
auto paddingBottom = displayBox.paddingBottom().valueOr(0);
auto borderTop = displayBox.borderTop();
auto borderBottom = displayBox.borderBottom();
auto contentHeight = [&] {
ASSERT(height);
return style.boxSizing() == BoxSizing::ContentBox ? *height : *height - (borderTop + paddingTop + paddingBottom + borderBottom);
};
if (!top && !height && !bottom)
top = staticVerticalPositionForOutOfFlowPositioned(layoutState, layoutBox);
if (top && height && bottom) {
if (!computedVerticalMargin.before && !computedVerticalMargin.after) {
auto marginBeforeAndAfter = containingBlockHeight - (*top + borderTop + paddingTop + contentHeight() + paddingBottom + borderBottom + *bottom);
usedVerticalMargin = { marginBeforeAndAfter / 2, marginBeforeAndAfter / 2 };
} else if (!computedVerticalMargin.before) {
usedVerticalMargin.after = *computedVerticalMargin.after;
usedVerticalMargin.before = containingBlockHeight - (*top + borderTop + paddingTop + contentHeight() + paddingBottom + borderBottom + usedVerticalMargin.after + *bottom);
} else if (!computedVerticalMargin.after) {
usedVerticalMargin.before = *computedVerticalMargin.before;
usedVerticalMargin.after = containingBlockHeight - (*top + usedVerticalMargin.before + borderTop + paddingTop + contentHeight() + paddingBottom + borderBottom + *bottom);
} else
usedVerticalMargin = { *computedVerticalMargin.before, *computedVerticalMargin.after };
// Over-constrained?
auto boxHeight = *top + usedVerticalMargin.before + borderTop + paddingTop + contentHeight() + paddingBottom + borderBottom + usedVerticalMargin.after + *bottom;
if (boxHeight != containingBlockHeight)
bottom = containingBlockHeight - (*top + usedVerticalMargin.before + borderTop + paddingTop + contentHeight() + paddingBottom + borderBottom + usedVerticalMargin.after);
}
if (!top && !height && bottom) {
// #1
height = contentHeightForFormattingContextRoot(layoutState, layoutBox);
usedVerticalMargin = { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
top = containingBlockHeight - (usedVerticalMargin.before + borderTop + paddingTop + *height + paddingBottom + borderBottom + usedVerticalMargin.after + *bottom);
}
if (!top && !bottom && height) {
// #2
top = staticVerticalPositionForOutOfFlowPositioned(layoutState, layoutBox);
usedVerticalMargin = { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
bottom = containingBlockHeight - (*top + usedVerticalMargin.before + borderTop + paddingTop + contentHeight() + paddingBottom + borderBottom + usedVerticalMargin.after);
}
if (!height && !bottom && top) {
// #3
height = contentHeightForFormattingContextRoot(layoutState, layoutBox);
usedVerticalMargin = { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
bottom = containingBlockHeight - (*top + usedVerticalMargin.before + borderTop + paddingTop + *height + paddingBottom + borderBottom + usedVerticalMargin.after);
}
if (!top && height && bottom) {
// #4
usedVerticalMargin = { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
top = containingBlockHeight - (usedVerticalMargin.before + borderTop + paddingTop + contentHeight() + paddingBottom + borderBottom + usedVerticalMargin.after + *bottom);
}
if (!height && top && bottom) {
// #5
usedVerticalMargin = { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
height = containingBlockHeight - (*top + usedVerticalMargin.before + borderTop + paddingTop + paddingBottom + borderBottom + usedVerticalMargin.after + *bottom);
}
if (!bottom && top && height) {
// #6
usedVerticalMargin = { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
bottom = containingBlockHeight - (*top + usedVerticalMargin.before + borderTop + paddingTop + contentHeight() + paddingBottom + borderBottom + usedVerticalMargin.after);
}
ASSERT(top);
ASSERT(bottom);
ASSERT(height);
// For out-of-flow elements the containing block is formed by the padding edge of the ancestor.
// At this point the positioned value is in the coordinate system of the padding box. Let's convert it to border box coordinate system.
auto containingBlockPaddingVerticalEdge = containingBlockDisplayBox.paddingBoxTop();
*top += containingBlockPaddingVerticalEdge;
*bottom += containingBlockPaddingVerticalEdge;
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Position][Height][Margin] -> out-of-flow non-replaced -> top(" << *top << "px) bottom(" << *bottom << "px) height(" << *height << "px) margin(" << usedVerticalMargin.before << "px, " << usedVerticalMargin.after << "px) layoutBox(" << &layoutBox << ")");
return { *top, *bottom, { contentHeight(), usedVerticalMargin } };
}
HorizontalGeometry FormattingContext::Geometry::outOfFlowNonReplacedHorizontalGeometry(LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
{
ASSERT(layoutBox.isOutOfFlowPositioned() && !layoutBox.replaced());
// 10.3.7 Absolutely positioned, non-replaced elements
//
// 'left' + 'margin-left' + 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' + 'margin-right' + 'right'
// = width of containing block
// If all three of 'left', 'width', and 'right' are 'auto': First set any 'auto' values for 'margin-left' and 'margin-right' to 0.
// Then, if the 'direction' property of the element establishing the static-position containing block is 'ltr' set 'left' to the static
// position and apply rule number three below; otherwise, set 'right' to the static position and apply rule number one below.
//
// If none of the three is 'auto': If both 'margin-left' and 'margin-right' are 'auto', solve the equation under the extra constraint that the two margins get equal values,
// unless this would make them negative, in which case when direction of the containing block is 'ltr' ('rtl'), set 'margin-left' ('margin-right') to zero and
// solve for 'margin-right' ('margin-left'). If one of 'margin-left' or 'margin-right' is 'auto', solve the equation for that value.
// If the values are over-constrained, ignore the value for 'left' (in case the 'direction' property of the containing block is 'rtl') or 'right'
// (in case 'direction' is 'ltr') and solve for that value.
//
// Otherwise, set 'auto' values for 'margin-left' and 'margin-right' to 0, and pick the one of the following six rules that applies.
//
// 1. 'left' and 'width' are 'auto' and 'right' is not 'auto', then the width is shrink-to-fit. Then solve for 'left'
// 2. 'left' and 'right' are 'auto' and 'width' is not 'auto', then if the 'direction' property of the element establishing the static-position
// containing block is 'ltr' set 'left' to the static position, otherwise set 'right' to the static position.
// Then solve for 'left' (if 'direction is 'rtl') or 'right' (if 'direction' is 'ltr').
// 3. 'width' and 'right' are 'auto' and 'left' is not 'auto', then the width is shrink-to-fit . Then solve for 'right'
// 4. 'left' is 'auto', 'width' and 'right' are not 'auto', then solve for 'left'
// 5. 'width' is 'auto', 'left' and 'right' are not 'auto', then solve for 'width'
// 6. 'right' is 'auto', 'left' and 'width' are not 'auto', then solve for 'right'
auto& style = layoutBox.style();
auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);
auto& containingBlock = *layoutBox.containingBlock();
auto& containingBlockDisplayBox = layoutState.displayBoxForLayoutBox(containingBlock);
auto containingBlockWidth = usedValues.containingBlockWidth.valueOr(0);
auto isLeftToRightDirection = containingBlock.style().isLeftToRightDirection();
auto left = computedValueIfNotAuto(style.logicalLeft(), containingBlockWidth);
auto right = computedValueIfNotAuto(style.logicalRight(), containingBlockWidth);
auto width = computedValueIfNotAuto(usedValues.width ? Length { usedValues.width.value(), Fixed } : style.logicalWidth(), containingBlockWidth);
auto computedHorizontalMargin = Geometry::computedHorizontalMargin(layoutBox, usedValues);
UsedHorizontalMargin usedHorizontalMargin;
auto paddingLeft = displayBox.paddingLeft().valueOr(0);
auto paddingRight = displayBox.paddingRight().valueOr(0);
auto borderLeft = displayBox.borderLeft();
auto borderRight = displayBox.borderRight();
auto contentWidth = [&] {
ASSERT(width);
return style.boxSizing() == BoxSizing::ContentBox ? *width : *width - (borderLeft + paddingLeft + paddingRight + borderRight);
};
if (!left && !width && !right) {
// If all three of 'left', 'width', and 'right' are 'auto': First set any 'auto' values for 'margin-left' and 'margin-right' to 0.
// Then, if the 'direction' property of the element establishing the static-position containing block is 'ltr' set 'left' to the static
// position and apply rule number three below; otherwise, set 'right' to the static position and apply rule number one below.
usedHorizontalMargin = { computedHorizontalMargin.start.valueOr(0), computedHorizontalMargin.end.valueOr(0) };
auto staticHorizontalPosition = staticHorizontalPositionForOutOfFlowPositioned(layoutState, layoutBox);
if (isLeftToRightDirection)
left = staticHorizontalPosition;
else
right = staticHorizontalPosition;
} else if (left && width && right) {
// If none of the three is 'auto': If both 'margin-left' and 'margin-right' are 'auto', solve the equation under the extra constraint that the two margins get equal values,
// unless this would make them negative, in which case when direction of the containing block is 'ltr' ('rtl'), set 'margin-left' ('margin-right') to zero and
// solve for 'margin-right' ('margin-left'). If one of 'margin-left' or 'margin-right' is 'auto', solve the equation for that value.
// If the values are over-constrained, ignore the value for 'left' (in case the 'direction' property of the containing block is 'rtl') or 'right'
// (in case 'direction' is 'ltr') and solve for that value.
if (!computedHorizontalMargin.start && !computedHorizontalMargin.end) {
auto marginStartAndEnd = containingBlockWidth - (*left + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + *right);
if (marginStartAndEnd >= 0)
usedHorizontalMargin = { marginStartAndEnd / 2, marginStartAndEnd / 2 };
else {
if (isLeftToRightDirection) {
usedHorizontalMargin.start = 0_lu;
usedHorizontalMargin.end = containingBlockWidth - (*left + usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + *right);
} else {
usedHorizontalMargin.end = 0_lu;
usedHorizontalMargin.start = containingBlockWidth - (*left + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end + *right);
}
}
} else if (!computedHorizontalMargin.start) {
usedHorizontalMargin.end = *computedHorizontalMargin.end;
usedHorizontalMargin.start = containingBlockWidth - (*left + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end + *right);
} else if (!computedHorizontalMargin.end) {
usedHorizontalMargin.start = *computedHorizontalMargin.start;
usedHorizontalMargin.end = containingBlockWidth - (*left + usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + *right);
} else {
usedHorizontalMargin = { *computedHorizontalMargin.start, *computedHorizontalMargin.end };
// Overconstrained? Ignore right (left).
if (isLeftToRightDirection)
right = containingBlockWidth - (usedHorizontalMargin.start + *left + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end);
else
left = containingBlockWidth - (usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end + *right);
}
} else {
// Otherwise, set 'auto' values for 'margin-left' and 'margin-right' to 0, and pick the one of the following six rules that applies.
usedHorizontalMargin = { computedHorizontalMargin.start.valueOr(0), computedHorizontalMargin.end.valueOr(0) };
}
if (!left && !width && right) {
// #1
// Calculate the available width by solving for 'width' after setting 'left' (in case 1) to 0
left = LayoutUnit { 0 };
auto availableWidth = containingBlockWidth - (*left + usedHorizontalMargin.start + borderLeft + paddingLeft + paddingRight + borderRight + usedHorizontalMargin.end + *right);
width = shrinkToFitWidth(layoutState, layoutBox, UsedHorizontalValues { availableWidth, usedValues.width, usedValues.margin });
left = containingBlockWidth - (usedHorizontalMargin.start + borderLeft + paddingLeft + *width + paddingRight + borderRight + usedHorizontalMargin.end + *right);
} else if (!left && !right && width) {
// #2
auto staticHorizontalPosition = staticHorizontalPositionForOutOfFlowPositioned(layoutState, layoutBox);
if (isLeftToRightDirection) {
left = staticHorizontalPosition;
right = containingBlockWidth - (*left + usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end);
} else {
right = staticHorizontalPosition;
left = containingBlockWidth - (usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end + *right);
}
} else if (!width && !right && left) {
// #3
// Calculate the available width by solving for 'width' after setting 'right' (in case 3) to 0
right = LayoutUnit { 0 };
auto availableWidth = containingBlockWidth - (*left + usedHorizontalMargin.start + borderLeft + paddingLeft + paddingRight + borderRight + usedHorizontalMargin.end + *right);
width = shrinkToFitWidth(layoutState, layoutBox, UsedHorizontalValues { availableWidth, usedValues.width, usedValues.margin });
right = containingBlockWidth - (*left + usedHorizontalMargin.start + borderLeft + paddingLeft + *width + paddingRight + borderRight + usedHorizontalMargin.end);
} else if (!left && width && right) {
// #4
left = containingBlockWidth - (usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end + *right);
} else if (!width && left && right) {
// #5
width = containingBlockWidth - (*left + usedHorizontalMargin.start + borderLeft + paddingLeft + paddingRight + borderRight + usedHorizontalMargin.end + *right);
} else if (!right && left && width) {
// #6
right = containingBlockWidth - (*left + usedHorizontalMargin.start + borderLeft + paddingLeft + contentWidth() + paddingRight + borderRight + usedHorizontalMargin.end);
}
ASSERT(left);
ASSERT(right);
ASSERT(width);
// For out-of-flow elements the containing block is formed by the padding edge of the ancestor.
// At this point the positioned value is in the coordinate system of the padding box. Let's convert it to border box coordinate system.
auto containingBlockPaddingVerticalEdge = containingBlockDisplayBox.paddingBoxLeft();
*left += containingBlockPaddingVerticalEdge;
*right += containingBlockPaddingVerticalEdge;
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Position][Width][Margin] -> out-of-flow non-replaced -> left(" << *left << "px) right(" << *right << "px) width(" << *width << "px) margin(" << usedHorizontalMargin.start << "px, " << usedHorizontalMargin.end << "px) layoutBox(" << &layoutBox << ")");
return { *left, *right, { contentWidth(), usedHorizontalMargin, computedHorizontalMargin } };
}
VerticalGeometry FormattingContext::Geometry::outOfFlowReplacedVerticalGeometry(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedValues)
{
ASSERT(layoutBox.isOutOfFlowPositioned() && layoutBox.replaced());
// 10.6.5 Absolutely positioned, replaced elements
//
// The used value of 'height' is determined as for inline replaced elements.
// If 'margin-top' or 'margin-bottom' is specified as 'auto' its used value is determined by the rules below.
// 1. If both 'top' and 'bottom' have the value 'auto', replace 'top' with the element's static position.
// 2. If 'bottom' is 'auto', replace any 'auto' on 'margin-top' or 'margin-bottom' with '0'.
// 3. If at this point both 'margin-top' and 'margin-bottom' are still 'auto', solve the equation under the extra constraint that the two margins must get equal values.
// 4. If at this point there is only one 'auto' left, solve the equation for that value.
// 5. If at this point the values are over-constrained, ignore the value for 'bottom' and solve for that value.
auto& style = layoutBox.style();
auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);
auto& containingBlockDisplayBox = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock());
auto containingBlockHeight = containingBlockDisplayBox.paddingBoxHeight();
auto containingBlockWidth = containingBlockDisplayBox.paddingBoxWidth();
auto top = computedValueIfNotAuto(style.logicalTop(), containingBlockWidth);
auto bottom = computedValueIfNotAuto(style.logicalBottom(), containingBlockWidth);
auto height = inlineReplacedHeightAndMargin(layoutState, layoutBox, usedValues).height;
auto computedVerticalMargin = Geometry::computedVerticalMargin(layoutBox, UsedHorizontalValues { containingBlockWidth });
Optional<LayoutUnit> usedMarginBefore = computedVerticalMargin.before;
Optional<LayoutUnit> usedMarginAfter = computedVerticalMargin.after;
auto paddingTop = displayBox.paddingTop().valueOr(0);
auto paddingBottom = displayBox.paddingBottom().valueOr(0);
auto borderTop = displayBox.borderTop();
auto borderBottom = displayBox.borderBottom();
if (!top && !bottom) {
// #1
top = staticVerticalPositionForOutOfFlowPositioned(layoutState, layoutBox);
}
if (!bottom) {
// #2
usedMarginBefore = computedVerticalMargin.before.valueOr(0);
usedMarginAfter = usedMarginBefore;
}
if (!usedMarginBefore && !usedMarginAfter) {
// #3
auto marginBeforeAndAfter = containingBlockHeight - (*top + borderTop + paddingTop + height + paddingBottom + borderBottom + *bottom);
usedMarginBefore = marginBeforeAndAfter / 2;
usedMarginAfter = usedMarginBefore;
}
// #4
if (!top)
top = containingBlockHeight - (*usedMarginBefore + borderTop + paddingTop + height + paddingBottom + borderBottom + *usedMarginAfter + *bottom);
if (!bottom)
bottom = containingBlockHeight - (*top + *usedMarginBefore + borderTop + paddingTop + height + paddingBottom + borderBottom + *usedMarginAfter);
if (!usedMarginBefore)
usedMarginBefore = containingBlockHeight - (*top + borderTop + paddingTop + height + paddingBottom + borderBottom + *usedMarginAfter + *bottom);
if (!usedMarginAfter)
usedMarginAfter = containingBlockHeight - (*top + *usedMarginBefore + borderTop + paddingTop + height + paddingBottom + borderBottom + *bottom);
// #5
auto boxHeight = *top + *usedMarginBefore + borderTop + paddingTop + height + paddingBottom + borderBottom + *usedMarginAfter + *bottom;
if (boxHeight > containingBlockHeight)
bottom = containingBlockHeight - (*top + *usedMarginBefore + borderTop + paddingTop + height + paddingBottom + borderBottom + *usedMarginAfter);
// For out-of-flow elements the containing block is formed by the padding edge of the ancestor.
// At this point the positioned value is in the coordinate system of the padding box. Let's convert it to border box coordinate system.
auto containingBlockPaddingVerticalEdge = containingBlockDisplayBox.paddingBoxTop();
*top += containingBlockPaddingVerticalEdge;
*bottom += containingBlockPaddingVerticalEdge;
ASSERT(top);
ASSERT(bottom);
ASSERT(usedMarginBefore);
ASSERT(usedMarginAfter);
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Position][Height][Margin] -> out-of-flow replaced -> top(" << *top << "px) bottom(" << *bottom << "px) height(" << height << "px) margin(" << *usedMarginBefore << "px, " << *usedMarginAfter << "px) layoutBox(" << &layoutBox << ")");
return { *top, *bottom, { height, { *usedMarginBefore, *usedMarginAfter } } };
}
HorizontalGeometry FormattingContext::Geometry::outOfFlowReplacedHorizontalGeometry(const LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
{
ASSERT(layoutBox.isOutOfFlowPositioned() && layoutBox.replaced());
// 10.3.8 Absolutely positioned, replaced elements
// In this case, section 10.3.7 applies up through and including the constraint equation, but the rest of section 10.3.7 is replaced by the following rules:
//
// The used value of 'width' is determined as for inline replaced elements. If 'margin-left' or 'margin-right' is specified as 'auto' its used value is determined by the rules below.
// 1. If both 'left' and 'right' have the value 'auto', then if the 'direction' property of the element establishing the static-position containing block is 'ltr',
// set 'left' to the static position; else if 'direction' is 'rtl', set 'right' to the static position.
// 2. If 'left' or 'right' are 'auto', replace any 'auto' on 'margin-left' or 'margin-right' with '0'.
// 3. If at this point both 'margin-left' and 'margin-right' are still 'auto', solve the equation under the extra constraint that the two margins must get equal values,
// unless this would make them negative, in which case when the direction of the containing block is 'ltr' ('rtl'), set 'margin-left' ('margin-right') to zero and
// solve for 'margin-right' ('margin-left').
// 4. If at this point there is an 'auto' left, solve the equation for that value.
// 5. If at this point the values are over-constrained, ignore the value for either 'left' (in case the 'direction' property of the containing block is 'rtl') or
// 'right' (in case 'direction' is 'ltr') and solve for that value.
auto& style = layoutBox.style();
auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);
auto& containingBlock = *layoutBox.containingBlock();
auto containingBlockWidth = usedValues.containingBlockWidth.valueOr(0);
auto isLeftToRightDirection = containingBlock.style().isLeftToRightDirection();
auto left = computedValueIfNotAuto(style.logicalLeft(), containingBlockWidth);
auto right = computedValueIfNotAuto(style.logicalRight(), containingBlockWidth);
auto computedHorizontalMargin = Geometry::computedHorizontalMargin(layoutBox, usedValues);
Optional<LayoutUnit> usedMarginStart = computedHorizontalMargin.start;
Optional<LayoutUnit> usedMarginEnd = computedHorizontalMargin.end;
auto width = inlineReplacedWidthAndMargin(layoutState, layoutBox, usedValues).width;
auto paddingLeft = displayBox.paddingLeft().valueOr(0);
auto paddingRight = displayBox.paddingRight().valueOr(0);
auto borderLeft = displayBox.borderLeft();
auto borderRight = displayBox.borderRight();
if (!left && !right) {
// #1
auto staticHorizontalPosition = staticHorizontalPositionForOutOfFlowPositioned(layoutState, layoutBox);
if (isLeftToRightDirection)
left = staticHorizontalPosition;
else
right = staticHorizontalPosition;
}
if (!left || !right) {
// #2
usedMarginStart = computedHorizontalMargin.start.valueOr(0);
usedMarginEnd = computedHorizontalMargin.end.valueOr(0);
}
if (!usedMarginStart && !usedMarginEnd) {
// #3
auto marginStartAndEnd = containingBlockWidth - (*left + borderLeft + paddingLeft + width + paddingRight + borderRight + *right);
if (marginStartAndEnd >= 0) {
usedMarginStart = marginStartAndEnd / 2;
usedMarginEnd = usedMarginStart;
} else {
if (isLeftToRightDirection) {
usedMarginStart = 0_lu;
usedMarginEnd = containingBlockWidth - (*left + *usedMarginStart + borderLeft + paddingLeft + width + paddingRight + borderRight + *right);
} else {
usedMarginEnd = 0_lu;
usedMarginStart = containingBlockWidth - (*left + borderLeft + paddingLeft + width + paddingRight + borderRight + *usedMarginEnd + *right);
}
}
}
// #4
if (!left)
left = containingBlockWidth - (*usedMarginStart + borderLeft + paddingLeft + width + paddingRight + borderRight + *usedMarginEnd + *right);
if (!right)
right = containingBlockWidth - (*left + *usedMarginStart + borderLeft + paddingLeft + width + paddingRight + borderRight + *usedMarginEnd);
if (!usedMarginStart)
usedMarginStart = containingBlockWidth - (*left + borderLeft + paddingLeft + width + paddingRight + borderRight + *usedMarginEnd + *right);
if (!usedMarginEnd)
usedMarginEnd = containingBlockWidth - (*left + *usedMarginStart + borderLeft + paddingLeft + width + paddingRight + borderRight + *right);
auto boxWidth = (*left + *usedMarginStart + borderLeft + paddingLeft + width + paddingRight + borderRight + *usedMarginEnd + *right);
if (boxWidth > containingBlockWidth) {
// #5 Over-constrained?
if (isLeftToRightDirection)
right = containingBlockWidth - (*left + *usedMarginStart + borderLeft + paddingLeft + width + paddingRight + borderRight + *usedMarginEnd);
else
left = containingBlockWidth - (*usedMarginStart + borderLeft + paddingLeft + width + paddingRight + borderRight + *usedMarginEnd + *right);
}
ASSERT(left);
ASSERT(right);
ASSERT(usedMarginStart);
ASSERT(usedMarginEnd);
// For out-of-flow elements the containing block is formed by the padding edge of the ancestor.
// At this point the positioned value is in the coordinate system of the padding box. Let's convert it to border box coordinate system.
auto containingBlockPaddingVerticalEdge = layoutState.displayBoxForLayoutBox(containingBlock).paddingBoxLeft();
*left += containingBlockPaddingVerticalEdge;
*right += containingBlockPaddingVerticalEdge;
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Position][Width][Margin] -> out-of-flow replaced -> left(" << *left << "px) right(" << *right << "px) width(" << width << "px) margin(" << *usedMarginStart << "px, " << *usedMarginEnd << "px) layoutBox(" << &layoutBox << ")");
return { *left, *right, { width, { *usedMarginStart, *usedMarginEnd }, computedHorizontalMargin } };
}
HeightAndMargin FormattingContext::Geometry::complicatedCases(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedValues, UsedHorizontalValues usedHorizontalValues)
{
ASSERT(!layoutBox.replaced());
// TODO: Use complicated-case for document renderer for now (see BlockFormattingContext::Geometry::inFlowHeightAndMargin).
ASSERT((layoutBox.isBlockLevelBox() && layoutBox.isInFlow() && !layoutBox.isOverflowVisible()) || layoutBox.isInlineBlockBox() || layoutBox.isFloatingPositioned() || layoutBox.isDocumentBox());
// 10.6.6 Complicated cases
//
// 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).
// 'Inline-block', non-replaced elements.
// Floating, non-replaced elements.
//
// 1. If 'margin-top', or 'margin-bottom' are 'auto', their used value is 0.
// 2. If 'height' is 'auto', the height depends on the element's descendants per 10.6.7.
auto height = usedValues.height ? usedValues.height.value() : computedHeightValue(layoutState, layoutBox, HeightType::Normal);
auto computedVerticalMargin = Geometry::computedVerticalMargin(layoutBox, usedHorizontalValues);
// #1
auto usedVerticalMargin = UsedVerticalMargin::NonCollapsedValues { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
// #2
if (!height) {
ASSERT(isHeightAuto(layoutBox));
height = contentHeightForFormattingContextRoot(layoutState, layoutBox);
}
ASSERT(height);
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> floating non-replaced -> height(" << *height << "px) margin(" << usedVerticalMargin.before << "px, " << usedVerticalMargin.after << "px) -> layoutBox(" << &layoutBox << ")");
return HeightAndMargin { *height, usedVerticalMargin };
}
WidthAndMargin FormattingContext::Geometry::floatingNonReplacedWidthAndMargin(LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
{
ASSERT(layoutBox.isFloatingPositioned() && !layoutBox.replaced());
// 10.3.5 Floating, non-replaced elements
//
// 1. If 'margin-left', or 'margin-right' are computed as 'auto', their used value is '0'.
// 2. If 'width' is computed as 'auto', the used value is the "shrink-to-fit" width.
auto computedHorizontalMargin = Geometry::computedHorizontalMargin(layoutBox, usedValues);
// #1
auto usedHorizontallMargin = UsedHorizontalMargin { computedHorizontalMargin.start.valueOr(0), computedHorizontalMargin.end.valueOr(0) };
// #2
auto width = computedValueIfNotAuto(usedValues.width ? Length { usedValues.width.value(), Fixed } : layoutBox.style().logicalWidth(), usedValues.containingBlockWidth.valueOr(0));
if (!width)
width = shrinkToFitWidth(layoutState, layoutBox, usedValues);
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width][Margin] -> floating non-replaced -> width(" << *width << "px) margin(" << usedHorizontallMargin.start << "px, " << usedHorizontallMargin.end << "px) -> layoutBox(" << &layoutBox << ")");
return WidthAndMargin { *width, usedHorizontallMargin, computedHorizontalMargin };
}
HeightAndMargin FormattingContext::Geometry::floatingReplacedHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedValues)
{
ASSERT(layoutBox.isFloatingPositioned() && layoutBox.replaced());
// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block'
// replaced elements in normal flow and floating replaced elements
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> floating replaced -> redirected to inline replaced");
return inlineReplacedHeightAndMargin(layoutState, layoutBox, usedValues);
}
WidthAndMargin FormattingContext::Geometry::floatingReplacedWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
{
ASSERT(layoutBox.isFloatingPositioned() && layoutBox.replaced());
// 10.3.6 Floating, replaced elements
//
// 1. If 'margin-left' or 'margin-right' are computed as 'auto', their used value is '0'.
// 2. The used value of 'width' is determined as for inline replaced elements.
auto computedHorizontalMargin = Geometry::computedHorizontalMargin(layoutBox, usedValues);
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> floating replaced -> redirected to inline replaced");
return inlineReplacedWidthAndMargin(layoutState, layoutBox, UsedHorizontalValues { usedValues.containingBlockWidth.valueOr(0),
usedValues.width, UsedHorizontalMargin { computedHorizontalMargin.start.valueOr(0), computedHorizontalMargin.end.valueOr(0) } });
}
VerticalGeometry FormattingContext::Geometry::outOfFlowVerticalGeometry(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedValues)
{
ASSERT(layoutBox.isOutOfFlowPositioned());
if (!layoutBox.replaced())
return outOfFlowNonReplacedVerticalGeometry(layoutState, layoutBox, usedValues);
return outOfFlowReplacedVerticalGeometry(layoutState, layoutBox, usedValues);
}
HorizontalGeometry FormattingContext::Geometry::outOfFlowHorizontalGeometry(LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
{
ASSERT(layoutBox.isOutOfFlowPositioned());
if (!layoutBox.replaced())
return outOfFlowNonReplacedHorizontalGeometry(layoutState, layoutBox, usedValues);
return outOfFlowReplacedHorizontalGeometry(layoutState, layoutBox, usedValues);
}
HeightAndMargin FormattingContext::Geometry::floatingHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedVerticalValues, UsedHorizontalValues usedHorizontalValues)
{
ASSERT(layoutBox.isFloatingPositioned());
if (!layoutBox.replaced())
return complicatedCases(layoutState, layoutBox, usedVerticalValues, usedHorizontalValues);
return floatingReplacedHeightAndMargin(layoutState, layoutBox, usedVerticalValues);
}
WidthAndMargin FormattingContext::Geometry::floatingWidthAndMargin(LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
{
ASSERT(layoutBox.isFloatingPositioned());
if (!layoutBox.replaced())
return floatingNonReplacedWidthAndMargin(layoutState, layoutBox, usedValues);
return floatingReplacedWidthAndMargin(layoutState, layoutBox, usedValues);
}
HeightAndMargin FormattingContext::Geometry::inlineReplacedHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedVerticalValues usedValues)
{
ASSERT((layoutBox.isOutOfFlowPositioned() || layoutBox.isFloatingPositioned() || layoutBox.isInFlow()) && layoutBox.replaced());
// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block' replaced elements in normal flow and floating replaced elements
//
// 1. If 'margin-top', or 'margin-bottom' are 'auto', their used value is 0.
// 2. If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic height, then that intrinsic height is the used value of 'height'.
// 3. Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic ratio then the used value of 'height' is:
// (used width) / (intrinsic ratio)
// 4. Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic height, then that intrinsic height is the used value of 'height'.
// 5. Otherwise, if 'height' has a computed value of 'auto', but none of the conditions above are met, then the used value of 'height' must be set to
// the height of the largest rectangle that has a 2:1 ratio, has a height not greater than 150px, and has a width not greater than the device width.
// #1
auto containingBlockWidth = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock()).contentBoxWidth();
auto computedVerticalMargin = Geometry::computedVerticalMargin(layoutBox, UsedHorizontalValues { containingBlockWidth });
auto usedVerticalMargin = UsedVerticalMargin::NonCollapsedValues { computedVerticalMargin.before.valueOr(0), computedVerticalMargin.after.valueOr(0) };
auto& style = layoutBox.style();
auto replaced = layoutBox.replaced();
auto height = usedValues.height ? usedValues.height.value() : computedHeightValue(layoutState, layoutBox, HeightType::Normal);
auto heightIsAuto = !usedValues.height && isHeightAuto(layoutBox);
auto widthIsAuto = style.logicalWidth().isAuto();
if (heightIsAuto && widthIsAuto && replaced->hasIntrinsicHeight()) {
// #2
height = replaced->intrinsicHeight();
} else if (heightIsAuto && replaced->hasIntrinsicRatio()) {
// #3
auto usedWidth = layoutState.displayBoxForLayoutBox(layoutBox).width();
height = usedWidth / replaced->intrinsicRatio();
} else if (heightIsAuto && replaced->hasIntrinsicHeight()) {
// #4
height = replaced->intrinsicHeight();
} else if (heightIsAuto) {
// #5
height = { 150 };
}
ASSERT(height);
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> inflow replaced -> height(" << *height << "px) margin(" << usedVerticalMargin.before << "px, " << usedVerticalMargin.after << "px) -> layoutBox(" << &layoutBox << ")");
return { *height, usedVerticalMargin };
}
WidthAndMargin FormattingContext::Geometry::inlineReplacedWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, UsedHorizontalValues usedValues)
{
ASSERT((layoutBox.isOutOfFlowPositioned() || layoutBox.isFloatingPositioned() || layoutBox.isInFlow()) && layoutBox.replaced());
// 10.3.2 Inline, replaced elements
//
// A computed value of 'auto' for 'margin-left' or 'margin-right' becomes a used value of '0'.
//
// 1. If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic width, then that intrinsic width is the used value of 'width'.
//
// 2. If 'height' and 'width' both have computed values of 'auto' and the element has no intrinsic width, but does have an intrinsic height and intrinsic ratio;
// or if 'width' has a computed value of 'auto', 'height' has some other computed value, and the element does have an intrinsic ratio;
// then the used value of 'width' is: (used height) * (intrinsic ratio)
//
// 3. If 'height' and 'width' both have computed values of 'auto' and the element has an intrinsic ratio but no intrinsic height or width,
// then the used value of 'width' is undefined in CSS 2.2. However, it is suggested that, if the containing block's width does not itself depend on the replaced
// element's width, then the used value of 'width' is calculated from the constraint equation used for block-level, non-replaced elements in normal flow.
//
// 4. Otherwise, if 'width' has a computed value of 'auto', and the element has an intrinsic width, then that intrinsic width is the used value of 'width'.
//
// 5. Otherwise, if 'width' has a computed value of 'auto', but none of the conditions above are met, then the used value of 'width' becomes 300px.
// If 300px is too wide to fit the device, UAs should use the width of the largest rectangle that has a 2:1 ratio and fits the device instead.
auto& style = layoutBox.style();
auto containingBlockWidth = usedValues.containingBlockWidth.valueOr(0);
auto computedHorizontalMargin = Geometry::computedHorizontalMargin(layoutBox, usedValues);
auto usedMarginStart = [&] {
if (usedValues.margin)
return usedValues.margin->start;
return computedHorizontalMargin.start.valueOr(0_lu);
};
auto usedMarginEnd = [&] {
if (usedValues.margin)
return usedValues.margin->end;
return computedHorizontalMargin.end.valueOr(0_lu);
};
auto replaced = layoutBox.replaced();
ASSERT(replaced);
auto width = computedValueIfNotAuto(usedValues.width ? Length { usedValues.width.value(), Fixed } : style.logicalWidth(), containingBlockWidth);
auto heightIsAuto = isHeightAuto(layoutBox);
auto height = computedHeightValue(layoutState, layoutBox, HeightType::Normal);
if (!width && heightIsAuto && replaced->hasIntrinsicWidth()) {
// #1
width = replaced->intrinsicWidth();
} else if ((!width && heightIsAuto && !replaced->hasIntrinsicWidth() && replaced->hasIntrinsicHeight() && replaced->hasIntrinsicRatio())
|| (!width && height && replaced->hasIntrinsicRatio())) {
// #2
width = height.valueOr(replaced->hasIntrinsicHeight()) * replaced->intrinsicRatio();
} else if (!width && heightIsAuto && replaced->hasIntrinsicRatio() && !replaced->hasIntrinsicWidth() && !replaced->hasIntrinsicHeight()) {
// #3
// FIXME: undefined but surely doable.
ASSERT_NOT_IMPLEMENTED_YET();
} else if (!width && replaced->hasIntrinsicWidth()) {
// #4
width = replaced->intrinsicWidth();
} else if (!width) {
// #5
width = { 300 };
}
ASSERT(width);
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width][Margin] -> inflow replaced -> width(" << *width << "px) margin(" << usedMarginStart() << "px, " << usedMarginEnd() << "px) -> layoutBox(" << &layoutBox << ")");
return { *width, { usedMarginStart(), usedMarginEnd() }, computedHorizontalMargin };
}
LayoutSize FormattingContext::Geometry::inFlowPositionedPositionOffset(const LayoutState& layoutState, const Box& layoutBox)
{
ASSERT(layoutBox.isInFlowPositioned());
// 9.4.3 Relative positioning
//
// The 'top' and 'bottom' properties move relatively positioned element(s) up or down without changing their size.
// Top' moves the boxes down, and 'bottom' moves them up. Since boxes are not split or stretched as a result of 'top' or 'bottom', the used values are always: top = -bottom.
//
// 1. If both are 'auto', their used values are both '0'.
// 2. If one of them is 'auto', it becomes the negative of the other.
// 3. If neither is 'auto', 'bottom' is ignored (i.e., the used value of 'bottom' will be minus the value of 'top').
auto& style = layoutBox.style();
auto& containingBlock = *layoutBox.containingBlock();
auto containingBlockWidth = layoutState.displayBoxForLayoutBox(containingBlock).contentBoxWidth();
auto top = computedValueIfNotAuto(style.logicalTop(), containingBlockWidth);
auto bottom = computedValueIfNotAuto(style.logicalBottom(), containingBlockWidth);
if (!top && !bottom) {
// #1
top = bottom = { 0 };
} else if (!top) {
// #2
top = -*bottom;
} else if (!bottom) {
// #3
bottom = -*top;
} else {
// #4
bottom = WTF::nullopt;
}
// For relatively positioned elements, 'left' and 'right' move the box(es) horizontally, without changing their size.
// 'Left' moves the boxes to the right, and 'right' moves them to the left.
// Since boxes are not split or stretched as a result of 'left' or 'right', the used values are always: left = -right.
//
// 1. If both 'left' and 'right' are 'auto' (their initial values), the used values are '0' (i.e., the boxes stay in their original position).
// 2. If 'left' is 'auto', its used value is minus the value of 'right' (i.e., the boxes move to the left by the value of 'right').
// 3. If 'right' is specified as 'auto', its used value is minus the value of 'left'.
// 4. If neither 'left' nor 'right' is 'auto', the position is over-constrained, and one of them has to be ignored.
// If the 'direction' property of the containing block is 'ltr', the value of 'left' wins and 'right' becomes -'left'.
// If 'direction' of the containing block is 'rtl', 'right' wins and 'left' is ignored.
auto left = computedValueIfNotAuto(style.logicalLeft(), containingBlockWidth);
auto right = computedValueIfNotAuto(style.logicalRight(), containingBlockWidth);
if (!left && !right) {
// #1
left = right = { 0 };
} else if (!left) {
// #2
left = -*right;
} else if (!right) {
// #3
right = -*left;
} else {
// #4
auto isLeftToRightDirection = containingBlock.style().isLeftToRightDirection();
if (isLeftToRightDirection)
right = -*left;
else
left = WTF::nullopt;
}
ASSERT(!bottom || *top == -*bottom);
ASSERT(!left || *left == -*right);
auto topPositionOffset = *top;
auto leftPositionOffset = left.valueOr(-*right);
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Position] -> positioned inflow -> top offset(" << topPositionOffset << "px) left offset(" << leftPositionOffset << "px) layoutBox(" << &layoutBox << ")");
return { leftPositionOffset, topPositionOffset };
}
Edges FormattingContext::Geometry::computedBorder(const Box& layoutBox)
{
auto& style = layoutBox.style();
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Border] -> layoutBox: " << &layoutBox);
return {
{ LayoutUnit(style.borderLeft().boxModelWidth()), LayoutUnit(style.borderRight().boxModelWidth()) },
{ LayoutUnit(style.borderTop().boxModelWidth()), LayoutUnit(style.borderBottom().boxModelWidth()) }
};
}
Optional<Edges> FormattingContext::Geometry::computedPadding(const Box& layoutBox, UsedHorizontalValues usedValues)
{
if (!layoutBox.isPaddingApplicable())
return WTF::nullopt;
auto& style = layoutBox.style();
auto containingBlockWidth = usedValues.containingBlockWidth.valueOr(0);
LOG_WITH_STREAM(FormattingContextLayout, stream << "[Padding] -> layoutBox: " << &layoutBox);
return Edges {
{ valueForLength(style.paddingLeft(), containingBlockWidth), valueForLength(style.paddingRight(), containingBlockWidth) },
{ valueForLength(style.paddingTop(), containingBlockWidth), valueForLength(style.paddingBottom(), containingBlockWidth) }
};
}
ComputedHorizontalMargin FormattingContext::Geometry::computedHorizontalMargin(const Box& layoutBox, UsedHorizontalValues usedValues)
{
auto& style = layoutBox.style();
auto containingBlockWidth = usedValues.containingBlockWidth.valueOr(0);
return { computedValueIfNotAuto(style.marginStart(), containingBlockWidth), computedValueIfNotAuto(style.marginEnd(), containingBlockWidth) };
}
ComputedVerticalMargin FormattingContext::Geometry::computedVerticalMargin(const Box& layoutBox, UsedHorizontalValues usedValues)
{
auto& style = layoutBox.style();
auto containingBlockWidth = usedValues.containingBlockWidth.valueOr(0);
return { computedValueIfNotAuto(style.marginBefore(), containingBlockWidth), computedValueIfNotAuto(style.marginAfter(), containingBlockWidth) };
}
FormattingContext::IntrinsicWidthConstraints FormattingContext::Geometry::constrainByMinMaxWidth(const Box& layoutBox, IntrinsicWidthConstraints intrinsicWidth)
{
auto& style = layoutBox.style();
auto minWidth = fixedValue(style.logicalMinWidth());
auto maxWidth = fixedValue(style.logicalMaxWidth());
if (!minWidth && !maxWidth)
return intrinsicWidth;
if (maxWidth) {
intrinsicWidth.minimum = std::min(*maxWidth, intrinsicWidth.minimum);
intrinsicWidth.maximum = std::min(*maxWidth, intrinsicWidth.maximum);
}
if (minWidth) {
intrinsicWidth.minimum = std::max(*minWidth, intrinsicWidth.minimum);
intrinsicWidth.maximum = std::max(*minWidth, intrinsicWidth.maximum);
}
ASSERT(intrinsicWidth.minimum <= intrinsicWidth.maximum);
return intrinsicWidth;
}
}
}
#endif