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72302e2dae
During layout it is often useful, for various specification reasons, to know if an element is the `<body>` element of an `<html>` element root. There are a couple places where a brittle heuristic is used to detect `<body>` elements. This information is going to be even more important to properly handle `<html>` elements that inherit their overflow property from their `<body>` children. Implementing this properly requires updating the DOM wrapper interface. This check does reach up to the parent of thread-safe nodes, but this is essentially the same kind of operation that `parent_style()` does, so is ostensibly safe. This change should not change any behavior and is just a preparation step for properly handle `<body>` overflow.
117 lines
3.8 KiB
Rust
117 lines
3.8 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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use crate::layout_debug::DebugId;
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use bitflags::bitflags;
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use gfx_traits::{combine_id_with_fragment_type, FragmentType};
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use style::dom::OpaqueNode;
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use style::selector_parser::PseudoElement;
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/// This data structure stores fields that are common to all non-base
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/// Fragment types and should generally be the first member of all
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/// concrete fragments.
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#[derive(Debug, Serialize)]
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pub(crate) struct BaseFragment {
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/// A tag which identifies the DOM node and pseudo element of this
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/// Fragment's content. If this fragment isn't related to any DOM
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/// node at all, the tag will be None.
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pub tag: Option<Tag>,
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/// An id used to uniquely identify this Fragment in debug builds.
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pub debug_id: DebugId,
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/// Flags which various information about this fragment used during
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/// layout.
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pub flags: FragmentFlags,
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}
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impl BaseFragment {
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pub(crate) fn anonymous() -> Self {
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BaseFragment {
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tag: None,
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debug_id: DebugId::new(),
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flags: FragmentFlags::empty(),
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}
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}
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/// Returns true if this fragment is non-anonymous and it is for the given
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/// OpaqueNode, regardless of the pseudo element.
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pub(crate) fn is_for_node(&self, node: OpaqueNode) -> bool {
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self.tag.map(|tag| tag.node == node).unwrap_or(false)
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}
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}
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/// Information necessary to construct a new BaseFragment.
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#[derive(Clone, Copy, Debug, Serialize)]
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pub(crate) struct BaseFragmentInfo {
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/// The tag to use for the new BaseFragment.
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pub tag: Tag,
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/// The flags to use for the new BaseFragment.
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pub flags: FragmentFlags,
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}
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impl BaseFragmentInfo {
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pub(crate) fn new_for_node(node: OpaqueNode) -> Self {
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Self {
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tag: Tag::new(node),
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flags: FragmentFlags::empty(),
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}
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}
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}
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impl From<BaseFragmentInfo> for BaseFragment {
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fn from(info: BaseFragmentInfo) -> Self {
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Self {
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tag: Some(info.tag),
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debug_id: DebugId::new(),
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flags: info.flags,
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}
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}
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}
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bitflags! {
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#[doc = "Flags used to track various information about a DOM node during layout."]
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#[derive(Serialize)]
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pub(crate) struct FragmentFlags: u8 {
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#[doc = "Whether or not this node is a body element on an HTML document."]
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const IS_BODY_ELEMENT_OF_HTML_ELEMENT_ROOT = 0b00000001;
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}
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}
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/// A data structure used to hold DOM and pseudo-element information about
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/// a particular layout object.
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#[derive(Clone, Copy, Debug, Eq, PartialEq, Serialize)]
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pub(crate) struct Tag {
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pub(crate) node: OpaqueNode,
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pub(crate) pseudo: Option<PseudoElement>,
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}
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impl Tag {
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/// Create a new Tag for a non-pseudo element. This is mainly used for
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/// matching existing tags, since it does not accept an `info` argument.
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pub(crate) fn new(node: OpaqueNode) -> Self {
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Tag { node, pseudo: None }
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}
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/// Create a new Tag for a pseudo element. This is mainly used for
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/// matching existing tags, since it does not accept an `info` argument.
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pub(crate) fn new_pseudo(node: OpaqueNode, pseudo: Option<PseudoElement>) -> Self {
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Tag { node, pseudo }
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}
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/// Returns true if this tag is for a pseudo element.
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pub(crate) fn is_pseudo(&self) -> bool {
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self.pseudo.is_some()
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}
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pub(crate) fn to_display_list_fragment_id(&self) -> u64 {
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let fragment_type = match self.pseudo {
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Some(PseudoElement::Before) => FragmentType::BeforePseudoContent,
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Some(PseudoElement::After) => FragmentType::AfterPseudoContent,
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_ => FragmentType::FragmentBody,
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};
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combine_id_with_fragment_type(self.node.id() as usize, fragment_type) as u64
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}
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}
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