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LibWeb: Tidy up and add spec comments to FFC layout algorithm step 3

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This commit is contained in:
Andreas Kling 2021-10-13 23:26:31 +02:00
parent 1e832dd91a
commit 82bb5ef8b7
1 changed files with 58 additions and 41 deletions
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99
Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
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@ -447,50 +447,67 @@ float FlexFormattingContext::layout_for_maximum_main_size(Box& box)
void FlexFormattingContext::determine_flex_base_size_and_hypothetical_main_size(FlexItem& flex_item)
{
auto& child_box = flex_item.box;
auto const& flex_basis = child_box.computed_values().flex_basis();
if (flex_basis.type == CSS::FlexBasis::Length) {
// A
auto specified_base_size = get_pixel_size(child_box, flex_basis.length);
if (specified_base_size == 0)
flex_item.flex_base_size = calculated_main_size(flex_item.box);
else
flex_item.flex_base_size = specified_base_size;
} else if (flex_basis.type == CSS::FlexBasis::Content
&& has_definite_cross_size(child_box)
// FIXME: && has intrinsic aspect ratio.
&& false) {
// B
TODO();
// flex_base_size is calculated from definite cross size and intrinsic aspect ratio
} else if (flex_basis.type == CSS::FlexBasis::Content
// FIXME: && sized under min-content or max-content contstraints
&& false) {
// C
TODO();
// Size child_box under the constraints, flex_base_size is then the resulting main_size.
} else if (flex_basis.type == CSS::FlexBasis::Content
// FIXME: && main_size is infinite && inline axis is parallel to the main axis
&& false && false) {
// D
TODO();
// Use rules for a flex_container in orthogonal flow
} else {
// E
flex_item.flex_base_size = [&] {
auto const& used_flex_basis = child_box.computed_values().flex_basis();
// A. If the item has a definite used flex basis, that’s the flex base size.
if (used_flex_basis.is_definite()) {
auto specified_base_size = get_pixel_size(child_box, used_flex_basis.length);
if (specified_base_size == 0)
return calculated_main_size(flex_item.box);
return specified_base_size;
}
// B. If the flex item has ...
// - an intrinsic aspect ratio,
// - a used flex basis of content, and
// - a definite cross size,
bool has_intrinsic_aspect_ratio = false; // FIXME: Populate this.
if (has_intrinsic_aspect_ratio
&& used_flex_basis.type == CSS::FlexBasis::Content
&& has_definite_cross_size(child_box)) {
TODO();
// flex_base_size is calculated from definite cross size and intrinsic aspect ratio
}
// C. If the used flex basis is content or depends on its available space,
// and the flex container is being sized under a min-content or max-content constraint
// (e.g. when performing automatic table layout [CSS21]), size the item under that constraint.
// The flex base size is the item’s resulting main size.
if (used_flex_basis.type == CSS::FlexBasis::Content
// FIXME: && sized under min-content or max-content constraints
&& false) {
TODO();
// Size child_box under the constraints, flex_base_size is then the resulting main_size.
}
// D. Otherwise, if the used flex basis is content or depends on its available space,
// the available main size is infinite, and the flex item’s inline axis is parallel to the main axis,
// lay the item out using the rules for a box in an orthogonal flow [CSS3-WRITING-MODES].
// The flex base size is the item’s max-content main size.
if (used_flex_basis.type == CSS::FlexBasis::Content
// FIXME: && main_size is infinite && inline axis is parallel to the main axis
&& false && false) {
TODO();
// Use rules for a flex_container in orthogonal flow
}
// E. Otherwise, size the item into the available space using its used flex basis in place of its main size,
// treating a value of content as max-content. If a cross size is needed to determine the main size
// (e.g. when the flex item’s main size is in its block axis) and the flex item’s cross size is auto and not definite,
// in this calculation use fit-content as the flex item’s cross size.
// The flex base size is the item’s resulting main size.
// FIXME: This is probably too naive.
// FIXME: Care about FlexBasis::Auto
if (has_definite_main_size(child_box)) {
flex_item.flex_base_size = specified_main_size_of_child_box(child_box);
} else {
flex_item.flex_base_size = layout_for_maximum_main_size(child_box);
}
}
auto clamp_min = has_main_min_size(child_box)
? specified_main_min_size(child_box)
: 0;
auto clamp_max = has_main_max_size(child_box)
? specified_main_max_size(child_box)
: NumericLimits<float>::max();
if (has_definite_main_size(child_box))
return specified_main_size_of_child_box(child_box);
return layout_for_maximum_main_size(child_box);
}();
// The hypothetical main size is the item’s flex base size clamped according to its used min and max main sizes (and flooring the content box size at zero).
auto clamp_min = has_main_min_size(child_box) ? specified_main_min_size(child_box) : 0;
auto clamp_max = has_main_max_size(child_box) ? specified_main_max_size(child_box) : NumericLimits<float>::max();
flex_item.hypothetical_main_size = clamp(flex_item.flex_base_size, clamp_min, clamp_max);
}