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LibWeb: Obey CSS aspect-ratio property during layout

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Calculate a "preferred aspect ratio" based on the value of
`aspect-ratio` and the presence of a natural aspect ratio, and use that
in layout.

This is by no means complete or perfect, but we do now apply the given
aspect-ratio to things.

The spec is a bit vague, just saying to calculate sizes for
aspect-ratio'ed boxes the same as you would for replaced elements. My
naive solution here is to find everywhere we were checking for a
ReplacedBox, and then also accept a regular Box with a preferred aspect
ratio. This gets us pretty far. :^)

https://www.w3.org/TR/css-sizing-4/#aspect-ratio-minimum is not at all
implemented.
This commit is contained in:
Sam Atkins 2023-06-08 16:47:50 +01:00 • committed by Andreas Kling
parent 84e7216603
commit 1051624084
14 changed files with 131 additions and 55 deletions
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57
Userland/Libraries/LibWeb/Layout/FormattingContext.cpp
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@ -256,7 +256,7 @@ FormattingContext::ShrinkToFitResult FormattingContext::calculate_shrink_to_fit_
};
}
CSSPixelSize FormattingContext::solve_replaced_size_constraint(CSSPixels input_width, CSSPixels input_height, ReplacedBox const& box) const
CSSPixelSize FormattingContext::solve_replaced_size_constraint(CSSPixels input_width, CSSPixels input_height, Box const& box) const
{
// 10.4 Minimum and maximum widths: 'min-width' and 'max-width'
@ -365,7 +365,7 @@ CSSPixels FormattingContext::compute_auto_height_for_block_formatting_context_ro
}
// 10.3.2 Inline, replaced elements, https://www.w3.org/TR/CSS22/visudet.html#inline-replaced-width
CSSPixels FormattingContext::tentative_width_for_replaced_element(ReplacedBox const& box, CSS::Size const& computed_width, AvailableSpace const& available_space) const
CSSPixels FormattingContext::tentative_width_for_replaced_element(Box const& box, CSS::Size const& computed_width, AvailableSpace const& available_space) const
{
// Treat percentages of indefinite containing block widths as 0 (the initial width).
if (computed_width.is_percentage() && !m_state.get(*box.containing_block()).has_definite_width())
@ -387,16 +387,16 @@ CSSPixels FormattingContext::tentative_width_for_replaced_element(ReplacedBox co
// 'height' has some other computed value, and the element does have an intrinsic ratio; then the used value of 'width' is:
//
// (used height) * (intrinsic ratio)
if ((computed_height.is_auto() && computed_width.is_auto() && !box.has_natural_width() && box.has_natural_height() && box.has_natural_aspect_ratio())
|| (computed_width.is_auto() && !computed_height.is_auto() && box.has_natural_aspect_ratio())) {
return compute_height_for_replaced_element(box, available_space) * static_cast<double>(box.natural_aspect_ratio().value());
if ((computed_height.is_auto() && computed_width.is_auto() && !box.has_natural_width() && box.has_natural_height() && box.has_preferred_aspect_ratio())
|| (computed_width.is_auto() && !computed_height.is_auto() && box.has_preferred_aspect_ratio())) {
return compute_height_for_replaced_element(box, available_space) * static_cast<double>(box.preferred_aspect_ratio().value());
}
// If 'height' and 'width' both have computed values of 'auto' and the element has an intrinsic ratio but no intrinsic height or width,
// then the used value of 'width' is undefined in CSS 2.2. However, it is suggested that, if the containing block's width does not itself
// depend on the replaced element's width, then the used value of 'width' is calculated from the constraint equation used for block-level,
// non-replaced elements in normal flow.
if (computed_height.is_auto() && computed_width.is_auto() && !box.has_natural_width() && !box.has_natural_height() && box.has_natural_aspect_ratio()) {
if (computed_height.is_auto() && computed_width.is_auto() && !box.has_natural_width() && !box.has_natural_height() && box.has_preferred_aspect_ratio()) {
return calculate_stretch_fit_width(box, available_space.width);
}
@ -414,21 +414,21 @@ CSSPixels FormattingContext::tentative_width_for_replaced_element(ReplacedBox co
void FormattingContext::compute_width_for_absolutely_positioned_element(Box const& box, AvailableSpace const& available_space)
{
if (is<ReplacedBox>(box))
compute_width_for_absolutely_positioned_replaced_element(verify_cast<ReplacedBox>(box), available_space);
if (box_is_sized_as_replaced_element(box))
compute_width_for_absolutely_positioned_replaced_element(box, available_space);
else
compute_width_for_absolutely_positioned_non_replaced_element(box, available_space);
}
void FormattingContext::compute_height_for_absolutely_positioned_element(Box const& box, AvailableSpace const& available_space, BeforeOrAfterInsideLayout before_or_after_inside_layout)
{
if (is<ReplacedBox>(box))
compute_height_for_absolutely_positioned_replaced_element(static_cast<ReplacedBox const&>(box), available_space, before_or_after_inside_layout);
if (box_is_sized_as_replaced_element(box))
compute_height_for_absolutely_positioned_replaced_element(box, available_space, before_or_after_inside_layout);
else
compute_height_for_absolutely_positioned_non_replaced_element(box, available_space, before_or_after_inside_layout);
}
CSSPixels FormattingContext::compute_width_for_replaced_element(ReplacedBox const& box, AvailableSpace const& available_space) const
CSSPixels FormattingContext::compute_width_for_replaced_element(Box const& box, AvailableSpace const& available_space) const
{
// 10.3.4 Block-level, replaced elements in normal flow...
// 10.3.2 Inline, replaced elements
@ -443,7 +443,7 @@ CSSPixels FormattingContext::compute_width_for_replaced_element(ReplacedBox cons
// 1. The tentative used width is calculated (without 'min-width' and 'max-width')
auto used_width = tentative_width_for_replaced_element(box, computed_width, available_space);
if (computed_width.is_auto() && computed_height.is_auto() && box.has_natural_aspect_ratio()) {
if (computed_width.is_auto() && computed_height.is_auto() && box.has_preferred_aspect_ratio()) {
CSSPixels w = used_width;
CSSPixels h = tentative_height_for_replaced_element(box, computed_height, available_space);
used_width = solve_replaced_size_constraint(w, h, box).width();
@ -473,7 +473,7 @@ CSSPixels FormattingContext::compute_width_for_replaced_element(ReplacedBox cons
// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block' replaced elements in normal flow and floating replaced elements
// https://www.w3.org/TR/CSS22/visudet.html#inline-replaced-height
CSSPixels FormattingContext::tentative_height_for_replaced_element(ReplacedBox const& box, CSS::Size const& computed_height, AvailableSpace const& available_space) const
CSSPixels FormattingContext::tentative_height_for_replaced_element(Box const& box, CSS::Size const& computed_height, AvailableSpace const& available_space) const
{
// If 'height' and 'width' both have computed values of 'auto' and the element also has
// an intrinsic height, then that intrinsic height is the used value of 'height'.
@ -483,8 +483,8 @@ CSSPixels FormattingContext::tentative_height_for_replaced_element(ReplacedBox c
// Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic ratio then the used value of 'height' is:
//
// (used width) / (intrinsic ratio)
if (computed_height.is_auto() && box.has_natural_aspect_ratio())
return m_state.get(box).content_width() / static_cast<double>(box.natural_aspect_ratio().value());
if (computed_height.is_auto() && box.has_preferred_aspect_ratio())
return m_state.get(box).content_width() / static_cast<double>(box.preferred_aspect_ratio().value());
// Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic height, then that intrinsic height is the used value of 'height'.
if (computed_height.is_auto() && box.has_natural_height())
@ -500,7 +500,7 @@ CSSPixels FormattingContext::tentative_height_for_replaced_element(ReplacedBox c
return calculate_inner_height(box, available_space.height, computed_height).to_px(box);
}
CSSPixels FormattingContext::compute_height_for_replaced_element(ReplacedBox const& box, AvailableSpace const& available_space) const
CSSPixels FormattingContext::compute_height_for_replaced_element(Box const& box, AvailableSpace const& available_space) const
{
// 10.6.2 Inline replaced elements
// 10.6.4 Block-level replaced elements in normal flow
@ -518,7 +518,7 @@ CSSPixels FormattingContext::compute_height_for_replaced_element(ReplacedBox con
// use the algorithm under 'Minimum and maximum widths'
// https://www.w3.org/TR/CSS22/visudet.html#min-max-widths
// to find the used width and height.
if (computed_width.is_auto() && computed_height.is_auto() && box.has_natural_aspect_ratio()) {
if (computed_width.is_auto() && computed_height.is_auto() && box.has_preferred_aspect_ratio()) {
CSSPixels w = tentative_width_for_replaced_element(box, computed_width, available_space);
CSSPixels h = used_height;
used_height = solve_replaced_size_constraint(w, h, box).height();
@ -689,12 +689,14 @@ void FormattingContext::compute_width_for_absolutely_positioned_non_replaced_ele
box_state.padding_right = padding_right;
}
void FormattingContext::compute_width_for_absolutely_positioned_replaced_element(ReplacedBox const& box, AvailableSpace const& available_space)
void FormattingContext::compute_width_for_absolutely_positioned_replaced_element(Box const& box, AvailableSpace const& available_space)
{
// 10.3.8 Absolutely positioned, replaced elements
// The used value of 'width' is determined as for inline replaced elements.
// FIXME: This const_cast is gross.
const_cast<ReplacedBox&>(box).prepare_for_replaced_layout();
if (is<ReplacedBox>(box)) {
// FIXME: This const_cast is gross.
static_cast<ReplacedBox&>(const_cast<Box&>(box)).prepare_for_replaced_layout();
}
m_state.get_mutable(box).set_content_width(compute_width_for_replaced_element(box, available_space));
}
@ -1061,7 +1063,7 @@ void FormattingContext::layout_absolutely_positioned_element(Box const& box, Ava
independent_formatting_context->parent_context_did_dimension_child_root_box();
}
void FormattingContext::compute_height_for_absolutely_positioned_replaced_element(ReplacedBox const& box, AvailableSpace const& available_space, BeforeOrAfterInsideLayout)
void FormattingContext::compute_height_for_absolutely_positioned_replaced_element(Box const& box, AvailableSpace const& available_space, BeforeOrAfterInsideLayout)
{
// 10.6.5 Absolutely positioned, replaced elements
// The used value of 'height' is determined as for inline replaced elements.
@ -1283,8 +1285,8 @@ CSSPixels FormattingContext::calculate_min_content_height(Layout::Box const& box
CSSPixels FormattingContext::calculate_max_content_height(Layout::Box const& box, AvailableSize const& available_width) const
{
if (box.has_natural_aspect_ratio() && available_width.is_definite())
return available_width.to_px() / static_cast<double>(*box.natural_aspect_ratio());
if (box.has_preferred_aspect_ratio() && available_width.is_definite())
return available_width.to_px() / static_cast<double>(*box.preferred_aspect_ratio());
if (box.has_natural_height())
return *box.natural_height();
@ -1623,4 +1625,13 @@ CSSPixelRect FormattingContext::margin_box_rect_in_ancestor_coordinate_space(Box
VERIFY_NOT_REACHED();
}
bool box_is_sized_as_replaced_element(Box const& box)
{
// When a box has a preferred aspect ratio, its automatic sizes are calculated the same as for a
// replaced element with a natural aspect ratio and no natural size in that axis, see e.g. CSS2 §10
// and CSS Flexible Box Model Level 1 §9.2.
// https://www.w3.org/TR/css-sizing-4/#aspect-ratio-automatic
return is<ReplacedBox>(box) || box.has_preferred_aspect_ratio();
}
}