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LibWeb: Render flex line items RTL (reversed items) for FlexEnd

This is a basic attempt at trying to handle parent container case
justify-content: flex-end.

Test-scenario:
Head to https://ryanwatkins.me and note that now the header nav is on
the right as opposed to the left in-line with how Chrome/Firefox would
respectively handle it also, i.e. 'flex-end'

Implementation:
Move cursor to the end and render in reverse backwards shifting the
cursor leftwards.
This commit is contained in:
watkinsr 2022-07-31 19:18:31 +01:00 committed by Linus Groh
parent 279caade73
commit 35dbeb064a

View file

@ -1179,28 +1179,40 @@ void FlexFormattingContext::distribute_any_remaining_free_space()
// 12.2.
float space_between_items = 0;
float space_before_first_item = 0;
float initial_offset = 0;
auto number_of_items = flex_line.items.size();
enum class FlexRegionRenderCursor {
Left,
Right
};
auto flex_region_render_cursor = FlexRegionRenderCursor::Left;
switch (flex_container().computed_values().justify_content()) {
case CSS::JustifyContent::FlexStart:
initial_offset = 0;
break;
case CSS::JustifyContent::FlexEnd:
space_before_first_item = 0;
flex_region_render_cursor = FlexRegionRenderCursor::Right;
initial_offset = m_available_space->main.value_or(NumericLimits<float>::max());
break;
case CSS::JustifyContent::Center:
space_before_first_item = (m_available_space->main.value_or(NumericLimits<float>::max()) - used_main_space) / 2.0f;
initial_offset = (m_available_space->main.value_or(NumericLimits<float>::max()) - used_main_space) / 2.0f;
break;
case CSS::JustifyContent::SpaceBetween:
space_between_items = flex_line.remaining_free_space / (number_of_items - 1);
break;
case CSS::JustifyContent::SpaceAround:
space_between_items = flex_line.remaining_free_space / number_of_items;
space_before_first_item = space_between_items / 2.0f;
initial_offset = space_between_items / 2.0f;
break;
}
// FIXME: Support reverse
float main_offset = space_before_first_item;
// For reverse, we use FlexRegionRenderCursor::Right
// to indicate the cursor offset is the end and render backwards
// Otherwise the cursor offset is the 'start' of the region or initial offset
float cursor_offset = initial_offset;
auto place_item = [&](FlexItem& item) {
auto amount_of_main_size_used = item.main_size
@ -1213,15 +1225,18 @@ void FlexFormattingContext::distribute_any_remaining_free_space()
+ space_between_items;
if (is_direction_reverse()) {
item.main_offset = main_offset - item.main_size - item.margins.main_after - item.borders.main_after - item.padding.main_after;
main_offset -= amount_of_main_size_used;
item.main_offset = cursor_offset - item.main_size - item.margins.main_after - item.borders.main_after - item.padding.main_after;
cursor_offset -= amount_of_main_size_used;
} else if (flex_region_render_cursor == FlexRegionRenderCursor::Right) {
cursor_offset -= amount_of_main_size_used;
item.main_offset = cursor_offset + item.margins.main_before + item.borders.main_before + item.padding.main_before;
} else {
item.main_offset = main_offset + item.margins.main_before + item.borders.main_before + item.padding.main_before;
main_offset += amount_of_main_size_used;
item.main_offset = cursor_offset + item.margins.main_before + item.borders.main_before + item.padding.main_before;
cursor_offset += amount_of_main_size_used;
}
};
if (is_direction_reverse()) {
if (is_direction_reverse() || flex_region_render_cursor == FlexRegionRenderCursor::Right) {
for (auto& item : flex_line.items.in_reverse()) {
place_item(*item);
}