Struct layout_2020::fragment_tree::containing_block::ContainingBlockManager

pub(crate) struct ContainingBlockManager<'a, T> {
    pub for_non_absolute_descendants: &'a T,
    pub for_absolute_descendants: Option<&'a T>,
    pub for_absolute_and_fixed_descendants: &'a T,
}

A data structure used to track the containing block when recursing through the Fragment tree. It tracks the three types of containing blocks (for all descendants, for absolute and fixed position descendants, and for fixed position descendants).

Fields

for_non_absolute_descendants: &'a T

The containing block for all non-absolute descendants. “…if the element’s position is ‘relative’ or ‘static’, the containing block is formed by the content edge of the nearest block container ancestor box.” This is also the case for ‘position: sticky’ elements. https://www.w3.org/TR/CSS2/visudet.html#containing-block-details

for_absolute_descendants: Option<&'a T>

The containing block for absolute descendants. “If the element has ‘position: absolute’, the containing block is established by the nearest ancestor with a ‘position’ of ‘absolute’, ‘relative’ or ‘fixed’, in the following way:

1. In the case that the ancestor is an inline element, the containing block is the bounding box around the padding boxes of the first and the last inline boxes generated for that element. In CSS 2.1, if the inline element is split across multiple lines, the containing block is undefined.
2. Otherwise, the containing block is formed by the padding edge of the ancestor.

https://www.w3.org/TR/CSS2/visudet.html#containing-block-details If the ancestor forms a containing block for all descendants (see below), this value will be None and absolute descendants will use the containing block for fixed descendants.

for_absolute_and_fixed_descendants: &'a T

The containing block for fixed and absolute descendants. “For elements whose layout is governed by the CSS box model, any value other than none for the transform property also causes the element to establish a containing block for all descendants. Its padding box will be used to layout for all of its absolute-position descendants, fixed-position descendants, and descendant fixed background attachments.” https://w3c.github.io/csswg-drafts/css-transforms-1/#containing-block-for-all-descendants See ComputedValues::establishes_containing_block_for_all_descendants for a list of conditions where an element forms a containing block for all descendants.

Implementations

impl<'a, T> ContainingBlockManager<'a, T>

pub(crate) fn get_containing_block_for_fragment( &self, fragment: &Fragment, ) -> &T

pub(crate) fn new_for_non_absolute_descendants( &self, for_non_absolute_descendants: &'a T, ) -> Self

pub(crate) fn new_for_absolute_descendants( &self, for_non_absolute_descendants: &'a T, for_absolute_descendants: &'a T, ) -> Self

pub(crate) fn new_for_absolute_and_fixed_descendants( &self, for_non_absolute_descendants: &'a T, for_absolute_and_fixed_descendants: &'a T, ) -> Self