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Resolve cyclic margin and padding percentages against zero (#30085)

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From https://drafts.csswg.org/css-sizing-3/#min-percentage-contribution

> For the min size properties, as well as for margins and paddings
> (and gutters), a cyclic percentage is resolved against zero
> for determining intrinsic size contributions.
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Oriol Brufau 2023-08-10 13:38:44 +02:00 • committed by GitHub
parent 8dceb8e412
commit c264993da8
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5 changed files with 31 additions and 79 deletions
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51
components/layout_2020/sizing.rs
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@ -8,7 +8,7 @@ use crate::style_ext::ComputedValuesExt;
use style::logical_geometry::WritingMode;
use style::properties::longhands::box_sizing::computed_value::T as BoxSizing;
use style::properties::ComputedValues;
use style::values::computed::{Length, LengthPercentage, Percentage};
use style::values::computed::Length;
use style::Zero;
#[derive(Clone, Debug, Serialize)]
@ -46,19 +46,6 @@ impl ContentSizes {
max_content: self.max_content + other.max_content,
}
}
/// Relevant to outer intrinsic inline sizes, for percentages from padding and margin.
pub fn adjust_for_pbm_percentages(&mut self, percentages: Percentage) {
// " Note that this may yield an infinite result, but undefined results
// (zero divided by zero) must be treated as zero. "
if self.max_content.px() == 0. {
// Avoid a potential `NaN`.
// Zero is already the result we want regardless of `denominator`.
} else {
let denominator = (1. - percentages.0).max(0.);
self.max_content = Length::new(self.max_content.px() / denominator);
}
}
}
impl ContentSizes {
@ -73,34 +60,23 @@ pub(crate) fn outer_inline(
containing_block_writing_mode: WritingMode,
get_content_size: impl FnOnce() -> ContentSizes,
) -> ContentSizes {
let (mut outer, percentages) =
outer_inline_and_percentages(style, containing_block_writing_mode, get_content_size);
outer.adjust_for_pbm_percentages(percentages);
outer
}
pub(crate) fn outer_inline_and_percentages(
style: &ComputedValues,
containing_block_writing_mode: WritingMode,
get_content_size: impl FnOnce() -> ContentSizes,
) -> (ContentSizes, Percentage) {
let padding = style.padding(containing_block_writing_mode);
let border = style.border_width(containing_block_writing_mode);
let margin = style.margin(containing_block_writing_mode);
let mut pbm_percentages = Percentage::zero();
let mut decompose = |x: &LengthPercentage| {
pbm_percentages += x.to_percentage().unwrap_or_else(Zero::zero);
x.to_length().unwrap_or_else(Zero::zero)
};
let pb_lengths =
border.inline_sum() + decompose(padding.inline_start) + decompose(padding.inline_end);
let mut m_lengths = Length::zero();
// For margins and paddings, a cyclic percentage is resolved against zero
// for determining intrinsic size contributions.
// https://drafts.csswg.org/css-sizing-3/#min-percentage-contribution
let zero = Length::zero();
let pb_lengths = border.inline_sum() +
padding.inline_start.percentage_relative_to(zero) +
padding.inline_end.percentage_relative_to(zero);
let mut m_lengths = zero;
if let Some(m) = margin.inline_start.non_auto() {
m_lengths += decompose(m)
m_lengths += m.percentage_relative_to(zero)
}
if let Some(m) = margin.inline_end.non_auto() {
m_lengths += decompose(m)
m_lengths += m.percentage_relative_to(zero)
}
let box_sizing = style.get_position().box_sizing;
@ -114,7 +90,7 @@ pub(crate) fn outer_inline_and_percentages(
.min_box_size(containing_block_writing_mode)
.inline
// Percentages for 'min-width' are treated as zero
.percentage_relative_to(Length::zero())
.percentage_relative_to(zero)
// FIXME: 'auto' is not zero in Flexbox
.auto_is(Length::zero);
let max_inline_size = style
@ -145,6 +121,5 @@ pub(crate) fn outer_inline_and_percentages(
}),
};
let outer = border_box_sizes.map(|s| s + m_lengths);
(outer, pbm_percentages)
border_box_sizes.map(|s| s + m_lengths)
}