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LibWeb: Add spec comments to FFC layout algorithm step 5

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This commit is contained in:
Andreas Kling 2021-10-13 23:38:04 +02:00
parent 82bb5ef8b7
commit 1d0c4a07ff
2 changed files with 28 additions and 15 deletions
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42
Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
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@ -555,26 +555,38 @@ void FlexFormattingContext::determine_main_size_of_flex_container(bool const mai
void FlexFormattingContext::collect_flex_items_into_flex_lines(float const main_available_size)
{
// FIXME: Also support wrap-reverse
if (flex_container().computed_values().flex_wrap() == CSS::FlexWrap::Nowrap) {
// If the flex container is single-line, collect all the flex items into a single flex line.
if (is_single_line()) {
FlexLine line;
for (auto& flex_item : m_flex_items) {
line.items.append(&flex_item);
}
m_flex_lines.append(line);
} else {
FlexLine line;
float line_main_size = 0;
for (auto& flex_item : m_flex_items) {
if ((line_main_size + flex_item.hypothetical_main_size) > main_available_size) {
m_flex_lines.append(line);
line = {};
line_main_size = 0;
}
line.items.append(&flex_item);
line_main_size += flex_item.hypothetical_main_size;
}
m_flex_lines.append(line);
m_flex_lines.append(move(line));
return;
}
// Otherwise, starting from the first uncollected item, collect consecutive items one by one
// until the first time that the next collected item would not fit into the flex container’s inner main size
// (or until a forced break is encountered, see §10 Fragmenting Flex Layout).
// If the very first uncollected item wouldn't fit, collect just it into the line.
// For this step, the size of a flex item is its outer hypothetical main size. (Note: This can be negative.)
// Repeat until all flex items have been collected into flex lines.
FlexLine line;
float line_main_size = 0;
for (auto& flex_item : m_flex_items) {
if ((line_main_size + flex_item.hypothetical_main_size) > main_available_size) {
m_flex_lines.append(move(line));
line = {};
line_main_size = 0;
}
line.items.append(&flex_item);
line_main_size += flex_item.hypothetical_main_size;
}
m_flex_lines.append(move(line));
}
// https://www.w3.org/TR/css-flexbox-1/#resolve-flexible-lengths

1
Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
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@ -113,6 +113,7 @@ private:
void align_all_flex_lines();
bool is_row_layout() const { return m_flex_direction == CSS::FlexDirection::Row || m_flex_direction == CSS::FlexDirection::RowReverse; }
bool is_single_line() const { return flex_container().computed_values().flex_wrap() == CSS::FlexWrap::Nowrap; }
void populate_specified_margins(FlexItem&, CSS::FlexDirection) const;