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615a4d4f71
Boxes can now be floated left or right, which makes text within the same block formatting context flow around them. We were creating way too many block formatting contexts. As it turns out, we don't need one for every new block, but rather there's a set of rules that determines whether a given block creates a new block formatting context. Each BFC keeps track of the floating boxes within it, and IFC's can then query it to find the available space for line boxes. There's a huge hack in here where we assume all lines are the exact line-height. Making this work with vertically non-uniform lines will require some architectural changes.
124 lines
4.3 KiB
C++
124 lines
4.3 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/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/TableFormattingContext.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 (box.is_table_cell())
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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(layout_mode);
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return;
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}
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if (box.is_table()) {
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TableFormattingContext context(box, this);
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context.run(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(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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auto& old_box = context_box();
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set_context_box(box);
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run(layout_mode);
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set_context_box(old_box);
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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.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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}
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