282 lines
12 KiB
C++
282 lines
12 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <LibWeb/Dump.h>
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#include <LibWeb/Layout/BlockBox.h>
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#include <LibWeb/Layout/BlockFormattingContext.h>
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#include <LibWeb/Layout/Box.h>
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#include <LibWeb/Layout/FormattingContext.h>
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#include <LibWeb/Layout/InlineFormattingContext.h>
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#include <LibWeb/Layout/ReplacedBox.h>
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#include <LibWeb/Layout/TableBox.h>
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#include <LibWeb/Layout/TableCellBox.h>
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#include <LibWeb/Layout/TableFormattingContext.h>
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#include <LibWeb/Layout/TableRowBox.h>
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namespace Web::Layout {
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FormattingContext::FormattingContext(Box& context_box, FormattingContext* parent)
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: m_parent(parent)
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, m_context_box(&context_box)
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{
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}
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FormattingContext::~FormattingContext()
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{
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}
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bool FormattingContext::creates_block_formatting_context(const Box& box)
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{
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if (box.is_root_element())
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return true;
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if (box.is_floating())
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return true;
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if (box.is_absolutely_positioned())
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return true;
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if (box.is_inline_block())
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return true;
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if (is<TableCellBox>(box))
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return true;
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// FIXME: table-caption
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// FIXME: anonymous table cells
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// FIXME: Block elements where overflow has a value other than visible and clip.
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// FIXME: display: flow-root
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// FIXME: Elements with contain: layout, content, or paint.
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// FIXME: flex
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// FIXME: grid
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// FIXME: multicol
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// FIXME: column-span: all
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return false;
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}
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void FormattingContext::layout_inside(Box& box, LayoutMode layout_mode)
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{
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if (creates_block_formatting_context(box)) {
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BlockFormattingContext context(box, this);
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context.run(box, layout_mode);
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return;
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}
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if (is<TableBox>(box)) {
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TableFormattingContext context(box, this);
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context.run(box, layout_mode);
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} else if (box.children_are_inline()) {
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InlineFormattingContext context(box, this);
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context.run(box, layout_mode);
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} else {
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// FIXME: This needs refactoring!
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ASSERT(is_block_formatting_context());
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run(box, layout_mode);
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}
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}
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static float greatest_child_width(const Box& box)
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{
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float max_width = 0;
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if (box.children_are_inline()) {
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for (auto& child : box.line_boxes()) {
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max_width = max(max_width, child.width());
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}
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} else {
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box.for_each_child_of_type<Box>([&](auto& child) {
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max_width = max(max_width, child.border_box_width());
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});
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}
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return max_width;
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}
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FormattingContext::ShrinkToFitResult FormattingContext::calculate_shrink_to_fit_widths(Box& box)
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{
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// Calculate the preferred width by formatting the content without breaking lines
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// other than where explicit line breaks occur.
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layout_inside(box, LayoutMode::OnlyRequiredLineBreaks);
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float preferred_width = greatest_child_width(box);
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// Also calculate the preferred minimum width, e.g., by trying all possible line breaks.
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// CSS 2.2 does not define the exact algorithm.
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layout_inside(box, LayoutMode::AllPossibleLineBreaks);
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float preferred_minimum_width = greatest_child_width(box);
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return { preferred_width, preferred_minimum_width };
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}
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static Gfx::FloatSize solve_replaced_size_constraint(float w, float h, const ReplacedBox& box)
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{
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// 10.4 Minimum and maximum widths: 'min-width' and 'max-width'
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auto& containing_block = *box.containing_block();
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auto specified_min_width = box.computed_values().min_width().resolved_or_zero(box, containing_block.width()).to_px(box);
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auto specified_max_width = box.computed_values().max_width().resolved(CSS::Length::make_px(w), box, containing_block.width()).to_px(box);
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auto specified_min_height = box.computed_values().min_height().resolved_or_auto(box, containing_block.height()).to_px(box);
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auto specified_max_height = box.computed_values().max_height().resolved(CSS::Length::make_px(h), box, containing_block.height()).to_px(box);
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auto min_width = min(specified_min_width, specified_max_width);
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auto max_width = max(specified_min_width, specified_max_width);
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auto min_height = min(specified_min_height, specified_max_height);
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auto max_height = max(specified_min_height, specified_max_height);
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if (w > max_width)
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return { w, max(max_width * h / w, min_height) };
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if (w < min_width)
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return { max_width, min(min_width * h / w, max_height) };
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if (h > max_height)
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return { max(max_height * w / h, min_width), max_height };
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if (h < min_height)
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return { min(min_height * w / h, max_width), min_height };
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if ((w > max_width && h > max_height) && (max_width / w < max_height / h))
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return { max_width, max(min_height, max_width * h / w) };
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if ((w > max_width && h > max_height) && (max_width / w > max_height / h))
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return { max(min_width, max_height * w / h), max_height };
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if ((w < min_width && h < min_height) && (min_width / w < min_height / h))
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return { min(max_width, min_height * w / h), min_height };
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if ((w < min_width && h < min_height) && (min_width / w > min_height / h))
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return { min_width, min(max_height, min_width * h / w) };
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if (w < min_width && h > max_height)
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return { min_width, max_height };
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if (w > max_width && h < min_height)
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return { max_width, min_height };
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return { w, h };
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}
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float FormattingContext::tentative_width_for_replaced_element(const ReplacedBox& box, const CSS::Length& width)
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{
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auto& containing_block = *box.containing_block();
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auto specified_height = box.computed_values().height().resolved_or_auto(box, containing_block.height());
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float used_width = width.to_px(box);
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// If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic width,
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// then that intrinsic width is the used value of 'width'.
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if (specified_height.is_auto() && width.is_auto() && box.has_intrinsic_width()) {
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used_width = box.intrinsic_width();
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}
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// If 'height' and 'width' both have computed values of 'auto' and the element has no intrinsic width,
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// but does have an intrinsic height and intrinsic ratio;
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// or if 'width' has a computed value of 'auto',
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// 'height' has some other computed value, and the element does have an intrinsic ratio; then the used value of 'width' is:
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//
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// (used height) * (intrinsic ratio)
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else if ((specified_height.is_auto() && width.is_auto() && !box.has_intrinsic_width() && box.has_intrinsic_height() && box.has_intrinsic_ratio()) || (width.is_auto() && box.has_intrinsic_ratio())) {
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used_width = compute_height_for_replaced_element(box) * box.intrinsic_ratio();
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}
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else if (width.is_auto() && box.has_intrinsic_width()) {
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used_width = box.intrinsic_width();
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}
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else if (width.is_auto()) {
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used_width = 300;
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}
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return used_width;
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}
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float FormattingContext::compute_width_for_replaced_element(const ReplacedBox& box)
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{
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// 10.3.4 Block-level, replaced elements in normal flow...
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// 10.3.2 Inline, replaced elements
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auto zero_value = CSS::Length::make_px(0);
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auto& containing_block = *box.containing_block();
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auto margin_left = box.computed_values().margin().left.resolved_or_zero(box, containing_block.width());
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auto margin_right = box.computed_values().margin().right.resolved_or_zero(box, containing_block.width());
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// A computed value of 'auto' for 'margin-left' or 'margin-right' becomes a used value of '0'.
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if (margin_left.is_auto())
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margin_left = zero_value;
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if (margin_right.is_auto())
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margin_right = zero_value;
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auto specified_width = box.computed_values().width().resolved_or_auto(box, containing_block.width());
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// 1. The tentative used width is calculated (without 'min-width' and 'max-width')
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auto used_width = tentative_width_for_replaced_element(box, specified_width);
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// 2. The tentative used width is greater than 'max-width', the rules above are applied again,
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// but this time using the computed value of 'max-width' as the computed value for 'width'.
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auto specified_max_width = box.computed_values().max_width().resolved_or_auto(box, containing_block.width());
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if (!specified_max_width.is_auto()) {
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if (used_width > specified_max_width.to_px(box)) {
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used_width = tentative_width_for_replaced_element(box, specified_max_width);
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}
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}
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// 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
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// but this time using the value of 'min-width' as the computed value for 'width'.
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auto specified_min_width = box.computed_values().min_width().resolved_or_auto(box, containing_block.width());
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if (!specified_min_width.is_auto()) {
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if (used_width < specified_min_width.to_px(box)) {
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used_width = tentative_width_for_replaced_element(box, specified_min_width);
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}
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}
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return used_width;
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}
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float FormattingContext::tentative_height_for_replaced_element(const ReplacedBox& box, const CSS::Length& height)
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{
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auto& containing_block = *box.containing_block();
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auto specified_width = box.computed_values().width().resolved_or_auto(box, containing_block.width());
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float used_height = height.to_px(box);
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// If 'height' and 'width' both have computed values of 'auto' and the element also has
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// an intrinsic height, then that intrinsic height is the used value of 'height'.
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if (specified_width.is_auto() && height.is_auto() && box.has_intrinsic_height())
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used_height = box.intrinsic_height();
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else if (height.is_auto() && box.has_intrinsic_ratio())
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used_height = compute_width_for_replaced_element(box) / box.intrinsic_ratio();
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else if (height.is_auto() && box.has_intrinsic_height())
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used_height = box.intrinsic_height();
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else if (height.is_auto())
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used_height = 150;
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return used_height;
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}
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float FormattingContext::compute_height_for_replaced_element(const ReplacedBox& box)
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{
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// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow,
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// 'inline-block' replaced elements in normal flow and floating replaced elements
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auto& containing_block = *box.containing_block();
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auto specified_width = box.computed_values().width().resolved_or_auto(box, containing_block.width());
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auto specified_height = box.computed_values().height().resolved_or_auto(box, containing_block.height());
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float used_height = tentative_height_for_replaced_element(box, specified_height);
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if (specified_width.is_auto() && specified_height.is_auto() && box.has_intrinsic_ratio()) {
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float w = tentative_width_for_replaced_element(box, specified_width);
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float h = used_height;
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used_height = solve_replaced_size_constraint(w, h, box).height();
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}
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return used_height;
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}
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}
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