diff options
Diffstat (limited to 'Libraries/LibWeb/Layout/BlockFormattingContext.cpp')
| -rw-r--r-- | Libraries/LibWeb/Layout/BlockFormattingContext.cpp | 632 |
1 files changed, 632 insertions, 0 deletions
diff --git a/Libraries/LibWeb/Layout/BlockFormattingContext.cpp b/Libraries/LibWeb/Layout/BlockFormattingContext.cpp new file mode 100644 index 0000000000..3c22fc1d52 --- /dev/null +++ b/Libraries/LibWeb/Layout/BlockFormattingContext.cpp @@ -0,0 +1,632 @@ +/* + * Copyright (c) 2020, Andreas Kling <kling@serenityos.org> + * 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT HOLDER OR 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 <LibWeb/CSS/Length.h> +#include <LibWeb/DOM/Node.h> +#include <LibWeb/Layout/BlockFormattingContext.h> +#include <LibWeb/Layout/InlineFormattingContext.h> +#include <LibWeb/Layout/LayoutBlock.h> +#include <LibWeb/Layout/LayoutBox.h> +#include <LibWeb/Layout/LayoutDocument.h> +#include <LibWeb/Layout/LayoutListItem.h> +#include <LibWeb/Layout/LayoutWidget.h> +#include <LibWeb/Page/Frame.h> + +namespace Web::Layout { + +BlockFormattingContext::BlockFormattingContext(LayoutBox& context_box) + : FormattingContext(context_box) +{ +} + +BlockFormattingContext::~BlockFormattingContext() +{ +} + +bool BlockFormattingContext::is_initial() const +{ + return context_box().is_root(); +} + +void BlockFormattingContext::run(LayoutMode layout_mode) +{ + if (is_initial()) { + layout_initial_containing_block(layout_mode); + return; + } + + // FIXME: BFC currently computes the width+height of the context box. + // This is necessary to be able to place absolutely positioned descendants. + // The same work is also done by the parent BFC for each of its blocks.. + + if (layout_mode == LayoutMode::Default) + compute_width(context_box()); + + if (context_box().children_are_inline()) { + layout_inline_children(layout_mode); + } else { + layout_block_level_children(layout_mode); + } + + if (layout_mode == LayoutMode::Default) + compute_height(context_box()); + + // No need to layout absolute positioned boxes during shrink-to-fit layouts. + if (layout_mode == LayoutMode::Default) + layout_absolutely_positioned_descendants(); +} + +void BlockFormattingContext::compute_width(LayoutBox& box) +{ + if (box.is_replaced()) { + // FIXME: This should not be done *by* LayoutReplaced + auto& replaced = downcast<LayoutReplaced>(box); + replaced.prepare_for_replaced_layout(); + auto width = replaced.calculate_width(); + replaced.set_width(width); + return; + } + + if (box.is_absolutely_positioned()) { + compute_width_for_absolutely_positioned_block(box); + return; + } + + auto& style = box.style(); + float width_of_containing_block = box.width_of_logical_containing_block(); + + auto zero_value = CSS::Length::make_px(0); + + auto margin_left = CSS::Length::make_auto(); + auto margin_right = CSS::Length::make_auto(); + const auto padding_left = style.padding().left.resolved_or_zero(box, width_of_containing_block); + const auto padding_right = style.padding().right.resolved_or_zero(box, width_of_containing_block); + + auto try_compute_width = [&](const auto& a_width) { + CSS::Length width = a_width; + margin_left = style.margin().left.resolved_or_zero(box, width_of_containing_block); + margin_right = style.margin().right.resolved_or_zero(box, width_of_containing_block); + + float total_px = style.border_left().width + style.border_right().width; + for (auto& value : { margin_left, padding_left, width, padding_right, margin_right }) { + total_px += value.to_px(box); + } + + if (!box.is_replaced() && !box.is_inline()) { + // 10.3.3 Block-level, non-replaced elements in normal flow + // If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero. + if (width.is_auto() && total_px > width_of_containing_block) { + if (margin_left.is_auto()) + margin_left = zero_value; + if (margin_right.is_auto()) + margin_right = zero_value; + } + + // 10.3.3 cont'd. + auto underflow_px = width_of_containing_block - total_px; + + if (width.is_auto()) { + if (margin_left.is_auto()) + margin_left = zero_value; + if (margin_right.is_auto()) + margin_right = zero_value; + if (underflow_px >= 0) { + width = CSS::Length(underflow_px, CSS::Length::Type::Px); + } else { + width = zero_value; + margin_right = CSS::Length(margin_right.to_px(box) + underflow_px, CSS::Length::Type::Px); + } + } else { + if (!margin_left.is_auto() && !margin_right.is_auto()) { + margin_right = CSS::Length(margin_right.to_px(box) + underflow_px, CSS::Length::Type::Px); + } else if (!margin_left.is_auto() && margin_right.is_auto()) { + margin_right = CSS::Length(underflow_px, CSS::Length::Type::Px); + } else if (margin_left.is_auto() && !margin_right.is_auto()) { + margin_left = CSS::Length(underflow_px, CSS::Length::Type::Px); + } else { // margin_left.is_auto() && margin_right.is_auto() + auto half_of_the_underflow = CSS::Length(underflow_px / 2, CSS::Length::Type::Px); + margin_left = half_of_the_underflow; + margin_right = half_of_the_underflow; + } + } + } else if (!box.is_replaced() && box.is_inline_block()) { + + // 10.3.9 'Inline-block', non-replaced elements in normal flow + + // A computed value of 'auto' for 'margin-left' or 'margin-right' becomes a used value of '0'. + if (margin_left.is_auto()) + margin_left = zero_value; + if (margin_right.is_auto()) + margin_right = zero_value; + + // If 'width' is 'auto', the used value is the shrink-to-fit width as for floating elements. + if (width.is_auto()) { + + // 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. + float available_width = width_of_containing_block + - margin_left.to_px(box) - style.border_left().width - padding_left.to_px(box) + - padding_right.to_px(box) - style.border_right().width - margin_right.to_px(box); + + auto result = calculate_shrink_to_fit_widths(box); + + // Then the shrink-to-fit width is: min(max(preferred minimum width, available width), preferred width). + width = CSS::Length(min(max(result.preferred_minimum_width, available_width), result.preferred_width), CSS::Length::Type::Px); + } + } + + return width; + }; + + auto specified_width = style.width().resolved_or_auto(box, width_of_containing_block); + + // 1. The tentative used width is calculated (without 'min-width' and 'max-width') + auto used_width = try_compute_width(specified_width); + + // 2. The tentative used width is greater than 'max-width', the rules above are applied again, + // but this time using the computed value of 'max-width' as the computed value for 'width'. + auto specified_max_width = style.max_width().resolved_or_auto(box, width_of_containing_block); + if (!specified_max_width.is_auto()) { + if (used_width.to_px(box) > specified_max_width.to_px(box)) { + used_width = try_compute_width(specified_max_width); + } + } + + // 3. If the resulting width is smaller than 'min-width', the rules above are applied again, + // but this time using the value of 'min-width' as the computed value for 'width'. + auto specified_min_width = style.min_width().resolved_or_auto(box, width_of_containing_block); + if (!specified_min_width.is_auto()) { + if (used_width.to_px(box) < specified_min_width.to_px(box)) { + used_width = try_compute_width(specified_min_width); + } + } + + box.set_width(used_width.to_px(box)); + box.box_model().margin.left = margin_left; + box.box_model().margin.right = margin_right; + box.box_model().border.left = CSS::Length::make_px(style.border_left().width); + box.box_model().border.right = CSS::Length::make_px(style.border_right().width); + box.box_model().padding.left = padding_left; + box.box_model().padding.right = padding_right; +} + +void BlockFormattingContext::compute_width_for_absolutely_positioned_block(LayoutBox& box) +{ + auto& containing_block = context_box(); + auto& style = box.style(); + auto zero_value = CSS::Length::make_px(0); + + auto margin_left = CSS::Length::make_auto(); + auto margin_right = CSS::Length::make_auto(); + const auto border_left = style.border_left().width; + const auto border_right = style.border_right().width; + const auto padding_left = style.padding().left.resolved(zero_value, box, containing_block.width()); + const auto padding_right = style.padding().right.resolved(zero_value, box, containing_block.width()); + + auto try_compute_width = [&](const auto& a_width) { + margin_left = style.margin().left.resolved(zero_value, box, containing_block.width()); + margin_right = style.margin().right.resolved(zero_value, box, containing_block.width()); + + auto left = style.offset().left.resolved_or_auto(box, containing_block.width()); + auto right = style.offset().right.resolved_or_auto(box, containing_block.width()); + auto width = a_width; + + auto solve_for_left = [&] { + return CSS::Length(containing_block.width() - margin_left.to_px(box) - border_left - padding_left.to_px(box) - width.to_px(box) - padding_right.to_px(box) - border_right - margin_right.to_px(box) - right.to_px(box), CSS::Length::Type::Px); + }; + + auto solve_for_width = [&] { + return CSS::Length(containing_block.width() - left.to_px(box) - margin_left.to_px(box) - border_left - padding_left.to_px(box) - padding_right.to_px(box) - border_right - margin_right.to_px(box) - right.to_px(box), CSS::Length::Type::Px); + }; + + auto solve_for_right = [&] { + return CSS::Length(containing_block.width() - left.to_px(box) - margin_left.to_px(box) - border_left - padding_left.to_px(box) - width.to_px(box) - padding_right.to_px(box) - border_right - margin_right.to_px(box), CSS::Length::Type::Px); + }; + + // If all three of 'left', 'width', and 'right' are 'auto': + if (left.is_auto() && width.is_auto() && right.is_auto()) { + // First set any 'auto' values for 'margin-left' and 'margin-right' to 0. + if (margin_left.is_auto()) + margin_left = CSS::Length::make_px(0); + if (margin_right.is_auto()) + margin_right = CSS::Length::make_px(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. + // FIXME: This is very hackish. + left = CSS::Length::make_px(0); + goto Rule3; + } + + if (!left.is_auto() && !width.is_auto() && !right.is_auto()) { + // FIXME: This should be solved in a more complicated way. + return width; + } + + if (margin_left.is_auto()) + margin_left = CSS::Length::make_px(0); + if (margin_right.is_auto()) + margin_right = CSS::Length::make_px(0); + + // 1. 'left' and 'width' are 'auto' and 'right' is not 'auto', + // then the width is shrink-to-fit. Then solve for 'left' + if (left.is_auto() && width.is_auto() && !right.is_auto()) { + auto result = calculate_shrink_to_fit_widths(box); + solve_for_left(); + auto available_width = solve_for_width(); + width = CSS::Length(min(max(result.preferred_minimum_width, available_width.to_px(box)), result.preferred_width), CSS::Length::Type::Px); + } + + // 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'). + else if (left.is_auto() && right.is_auto() && !width.is_auto()) { + // FIXME: Check direction + // FIXME: Use the static-position containing block + left = zero_value; + right = solve_for_right(); + } + + // 3. 'width' and 'right' are 'auto' and 'left' is not 'auto', + // then the width is shrink-to-fit. Then solve for 'right' + else if (width.is_auto() && right.is_auto() && !left.is_auto()) { + Rule3: + auto result = calculate_shrink_to_fit_widths(box); + right = solve_for_right(); + auto available_width = solve_for_width(); + width = CSS::Length(min(max(result.preferred_minimum_width, available_width.to_px(box)), result.preferred_width), CSS::Length::Type::Px); + } + + // 4. 'left' is 'auto', 'width' and 'right' are not 'auto', then solve for 'left' + else if (left.is_auto() && !width.is_auto() && !right.is_auto()) { + left = solve_for_left(); + } + + // 5. 'width' is 'auto', 'left' and 'right' are not 'auto', then solve for 'width' + else if (width.is_auto() && !left.is_auto() && !right.is_auto()) { + width = solve_for_width(); + } + + // 6. 'right' is 'auto', 'left' and 'width' are not 'auto', then solve for 'right' + else if (right.is_auto() && !left.is_auto() && !width.is_auto()) { + right = solve_for_right(); + } + + return width; + }; + + auto specified_width = style.width().resolved_or_auto(box, containing_block.width()); + + // 1. The tentative used width is calculated (without 'min-width' and 'max-width') + auto used_width = try_compute_width(specified_width); + + // 2. The tentative used width is greater than 'max-width', the rules above are applied again, + // but this time using the computed value of 'max-width' as the computed value for 'width'. + auto specified_max_width = style.max_width().resolved_or_auto(box, containing_block.width()); + if (!specified_max_width.is_auto()) { + if (used_width.to_px(box) > specified_max_width.to_px(box)) { + used_width = try_compute_width(specified_max_width); + } + } + + // 3. If the resulting width is smaller than 'min-width', the rules above are applied again, + // but this time using the value of 'min-width' as the computed value for 'width'. + auto specified_min_width = style.min_width().resolved_or_auto(box, containing_block.width()); + if (!specified_min_width.is_auto()) { + if (used_width.to_px(box) < specified_min_width.to_px(box)) { + used_width = try_compute_width(specified_min_width); + } + } + + box.set_width(used_width.to_px(box)); + + box.box_model().margin.left = margin_left; + box.box_model().margin.right = margin_right; + box.box_model().border.left = CSS::Length::make_px(border_left); + box.box_model().border.right = CSS::Length::make_px(border_right); + box.box_model().padding.left = padding_left; + box.box_model().padding.right = padding_right; +} + +void BlockFormattingContext::compute_height(LayoutBox& box) +{ + if (box.is_replaced()) { + // FIXME: This should not be done *by* LayoutReplaced + auto height = downcast<LayoutReplaced>(box).calculate_height(); + box.set_height(height); + return; + } + + auto& style = box.style(); + auto& containing_block = context_box(); + + CSS::Length specified_height; + + if (style.height().is_percentage() && !containing_block.style().height().is_absolute()) { + specified_height = CSS::Length::make_auto(); + } else { + specified_height = style.height().resolved_or_auto(box, containing_block.height()); + } + + auto specified_max_height = style.max_height().resolved_or_auto(box, containing_block.height()); + + box.box_model().margin.top = style.margin().top.resolved_or_zero(box, containing_block.width()); + box.box_model().margin.bottom = style.margin().bottom.resolved_or_zero(box, containing_block.width()); + box.box_model().border.top = CSS::Length::make_px(style.border_top().width); + box.box_model().border.bottom = CSS::Length::make_px(style.border_bottom().width); + box.box_model().padding.top = style.padding().top.resolved_or_zero(box, containing_block.width()); + box.box_model().padding.bottom = style.padding().bottom.resolved_or_zero(box, containing_block.width()); + + if (!specified_height.is_auto()) { + float used_height = specified_height.to_px(box); + if (!specified_max_height.is_auto()) + used_height = min(used_height, specified_max_height.to_px(box)); + box.set_height(used_height); + } +} + +void BlockFormattingContext::layout_inline_children(LayoutMode layout_mode) +{ + InlineFormattingContext context(context_box()); + context.run(layout_mode); +} + +void BlockFormattingContext::layout_block_level_children(LayoutMode layout_mode) +{ + float content_height = 0; + float content_width = 0; + + context_box().for_each_in_subtree_of_type<LayoutBox>([&](auto& box) { + if (box.is_absolutely_positioned() || box.containing_block() != &context_box()) + return IterationDecision::Continue; + + compute_width(box); + layout_inside(box, layout_mode); + compute_height(box); + + if (box.is_replaced()) + place_block_level_replaced_element_in_normal_flow(box); + else if (box.is_block()) + place_block_level_non_replaced_element_in_normal_flow(box); + else + dbgln("FIXME: LayoutBlock::layout_contained_boxes doesn't know how to place a {}", box.class_name()); + + // FIXME: This should be factored differently. It's uncool that we mutate the tree *during* layout! + // Instead, we should generate the marker box during the tree build. + if (is<LayoutListItem>(box)) + downcast<LayoutListItem>(box).layout_marker(); + + content_height = max(content_height, box.effective_offset().y() + box.height() + box.box_model().margin_box(box).bottom); + content_width = max(content_width, downcast<LayoutBox>(box).width()); + return IterationDecision::Continue; + }); + + if (layout_mode != LayoutMode::Default) { + if (context_box().style().width().is_undefined() || context_box().style().width().is_auto()) + context_box().set_width(content_width); + } + + // FIXME: It's not right to always shrink-wrap the context box to the content here. + context_box().set_height(content_height); +} + +void BlockFormattingContext::place_block_level_replaced_element_in_normal_flow(LayoutBox& box) +{ + auto& containing_block = context_box(); + ASSERT(!containing_block.is_absolutely_positioned()); + auto& replaced_element_box_model = box.box_model(); + + replaced_element_box_model.margin.top = box.style().margin().top.resolved_or_zero(context_box(), containing_block.width()); + replaced_element_box_model.margin.bottom = box.style().margin().bottom.resolved_or_zero(context_box(), containing_block.width()); + replaced_element_box_model.border.top = CSS::Length::make_px(box.style().border_top().width); + replaced_element_box_model.border.bottom = CSS::Length::make_px(box.style().border_bottom().width); + replaced_element_box_model.padding.top = box.style().padding().top.resolved_or_zero(context_box(), containing_block.width()); + replaced_element_box_model.padding.bottom = box.style().padding().bottom.resolved_or_zero(context_box(), containing_block.width()); + + float x = replaced_element_box_model.margin.left.to_px(context_box()) + + replaced_element_box_model.border.left.to_px(context_box()) + + replaced_element_box_model.padding.left.to_px(context_box()) + + replaced_element_box_model.offset.left.to_px(context_box()); + + float y = replaced_element_box_model.margin_box(context_box()).top + context_box().box_model().offset.top.to_px(context_box()); + + box.set_offset(x, y); +} + +void BlockFormattingContext::place_block_level_non_replaced_element_in_normal_flow(LayoutBox& box) +{ + auto zero_value = CSS::Length::make_px(0); + auto& containing_block = context_box(); + auto& box_model = box.box_model(); + auto& style = box.style(); + + box_model.margin.top = style.margin().top.resolved(zero_value, containing_block, containing_block.width()); + box_model.margin.bottom = style.margin().bottom.resolved(zero_value, containing_block, containing_block.width()); + box_model.border.top = CSS::Length::make_px(style.border_top().width); + box_model.border.bottom = CSS::Length::make_px(style.border_bottom().width); + box_model.padding.top = style.padding().top.resolved(zero_value, containing_block, containing_block.width()); + box_model.padding.bottom = style.padding().bottom.resolved(zero_value, containing_block, containing_block.width()); + + float x = box_model.margin.left.to_px(containing_block) + + box_model.border.left.to_px(containing_block) + + box_model.padding.left.to_px(containing_block) + + box_model.offset.left.to_px(containing_block); + + if (containing_block.style().text_align() == CSS::TextAlign::VendorSpecificCenter) { + x = (containing_block.width() / 2) - box.width() / 2; + } + + float y = box_model.margin_box(containing_block).top + + box_model.offset.top.to_px(containing_block); + + // NOTE: Empty (0-height) preceding siblings have their margins collapsed with *their* preceding sibling, etc. + float collapsed_bottom_margin_of_preceding_siblings = 0; + + auto* relevant_sibling = box.previous_sibling_of_type<LayoutBlock>(); + while (relevant_sibling != nullptr) { + if (!relevant_sibling->is_absolutely_positioned() && !relevant_sibling->is_floating()) { + collapsed_bottom_margin_of_preceding_siblings = max(collapsed_bottom_margin_of_preceding_siblings, relevant_sibling->box_model().margin.bottom.to_px(*relevant_sibling)); + if (relevant_sibling->height() > 0) + break; + } + relevant_sibling = relevant_sibling->previous_sibling(); + } + + if (relevant_sibling) { + y += relevant_sibling->effective_offset().y() + relevant_sibling->height() + relevant_sibling->box_model().padding.bottom.to_px(*relevant_sibling); + + // Collapse top margin with bottom margin of preceding siblings if needed + float my_margin_top = box_model.margin.top.to_px(containing_block); + + if (my_margin_top < 0 || collapsed_bottom_margin_of_preceding_siblings < 0) { + // Negative margins present. + float largest_negative_margin = -min(my_margin_top, collapsed_bottom_margin_of_preceding_siblings); + float largest_positive_margin = (my_margin_top < 0 && collapsed_bottom_margin_of_preceding_siblings < 0) ? 0 : max(my_margin_top, collapsed_bottom_margin_of_preceding_siblings); + float final_margin = largest_positive_margin - largest_negative_margin; + y += final_margin - my_margin_top; + } else if (collapsed_bottom_margin_of_preceding_siblings > my_margin_top) { + // Sibling's margin is larger than mine, adjust so we use sibling's. + y += collapsed_bottom_margin_of_preceding_siblings - my_margin_top; + } + } + + box.set_offset(x, y); +} + +void BlockFormattingContext::layout_initial_containing_block(LayoutMode layout_mode) +{ + auto viewport_rect = context_box().frame().viewport_rect(); + + auto& icb = downcast<LayoutDocument>(context_box()); + icb.build_stacking_context_tree(); + + icb.set_width(viewport_rect.width()); + + layout_block_level_children(layout_mode); + + ASSERT(!icb.children_are_inline()); + + // FIXME: The ICB should have the height of the viewport. + // Instead of auto-sizing the ICB, we should spill into overflow. + float lowest_bottom = 0; + icb.for_each_child_of_type<LayoutBox>([&](auto& child) { + lowest_bottom = max(lowest_bottom, child.absolute_rect().bottom()); + }); + icb.set_height(lowest_bottom); + + // No need to layout absolute positioned boxes during shrink-to-fit layouts. + if (layout_mode == LayoutMode::Default) + layout_absolutely_positioned_descendants(); + + // FIXME: This is a total hack. Make sure any GUI::Widgets are moved into place after layout. + // We should stop embedding GUI::Widgets entirely, since that won't work out-of-process. + icb.for_each_in_subtree_of_type<LayoutWidget>([&](auto& widget) { + widget.update_widget(); + return IterationDecision::Continue; + }); +} + +void BlockFormattingContext::layout_absolutely_positioned_descendants() +{ + context_box().for_each_in_subtree_of_type<LayoutBox>([&](auto& box) { + if (box.is_absolutely_positioned() && box.containing_block() == &context_box()) { + layout_absolutely_positioned_descendant(box); + } + return IterationDecision::Continue; + }); +} + +void BlockFormattingContext::layout_absolutely_positioned_descendant(LayoutBox& box) +{ + auto& containing_block = context_box(); + auto& box_model = box.box_model(); + auto zero_value = CSS::Length::make_px(0); + + auto specified_width = box.style().width().resolved_or_auto(box, containing_block.width()); + + compute_width(box); + layout_inside(box, LayoutMode::Default); + compute_height(box); + + box_model.margin.left = box.style().margin().left.resolved_or_auto(box, containing_block.width()); + box_model.margin.top = box.style().margin().top.resolved_or_auto(box, containing_block.height()); + box_model.margin.right = box.style().margin().right.resolved_or_auto(box, containing_block.width()); + box_model.margin.bottom = box.style().margin().bottom.resolved_or_auto(box, containing_block.height()); + + box_model.border.left = CSS::Length::make_px(box.style().border_left().width); + box_model.border.right = CSS::Length::make_px(box.style().border_right().width); + box_model.border.top = CSS::Length::make_px(box.style().border_top().width); + box_model.border.bottom = CSS::Length::make_px(box.style().border_bottom().width); + + box_model.offset.left = box.style().offset().left.resolved_or_auto(box, containing_block.width()); + box_model.offset.top = box.style().offset().top.resolved_or_auto(box, containing_block.height()); + box_model.offset.right = box.style().offset().right.resolved_or_auto(box, containing_block.width()); + box_model.offset.bottom = box.style().offset().bottom.resolved_or_auto(box, containing_block.height()); + + if (box_model.offset.left.is_auto() && specified_width.is_auto() && box_model.offset.right.is_auto()) { + if (box_model.margin.left.is_auto()) + box_model.margin.left = zero_value; + if (box_model.margin.right.is_auto()) + box_model.margin.right = zero_value; + } + + Gfx::FloatPoint used_offset; + + if (!box_model.offset.left.is_auto()) { + float x_offset = box_model.offset.left.to_px(box) + + box_model.border_box(box).left; + used_offset.set_x(x_offset + box_model.margin.left.to_px(box)); + } else if (!box_model.offset.right.is_auto()) { + float x_offset = 0 + - box_model.offset.right.to_px(box) + - box_model.border_box(box).right; + used_offset.set_x(containing_block.width() + x_offset - box.width() - box_model.margin.right.to_px(box)); + } else { + float x_offset = box_model.margin_box(box).left; + used_offset.set_x(x_offset); + } + + if (!box_model.offset.top.is_auto()) { + float y_offset = box_model.offset.top.to_px(box) + + box_model.border_box(box).top; + used_offset.set_y(y_offset + box_model.margin.top.to_px(box)); + } else if (!box_model.offset.bottom.is_auto()) { + float y_offset = 0 + - box_model.offset.bottom.to_px(box) + - box_model.border_box(box).bottom; + used_offset.set_y(containing_block.height() + y_offset - box.height() - box_model.margin.bottom.to_px(box)); + } else { + float y_offset = box_model.margin_box(box).top; + used_offset.set_y(y_offset); + } + + box.set_offset(used_offset); +} + +} |