layout/fragment_tree/
base_fragment.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5use std::ops::Deref;
6
7use app_units::Au;
8use atomic_refcell::AtomicRef;
9use bitflags::bitflags;
10use html5ever::local_name;
11use layout_api::combine_id_with_fragment_type;
12use layout_api::wrapper_traits::{
13    PseudoElementChain, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
14};
15use malloc_size_of::malloc_size_of_is_0;
16use malloc_size_of_derive::MallocSizeOf;
17use script::layout_dom::ServoThreadSafeLayoutNode;
18use servo_arc::Arc as ServoArc;
19use style::dom::OpaqueNode;
20use style::properties::ComputedValues;
21use style::selector_parser::PseudoElement;
22
23use crate::SharedStyle;
24use crate::dom_traversal::NodeAndStyleInfo;
25use crate::geom::PhysicalRect;
26
27pub(crate) enum BaseFragmentStyleRef<'a> {
28    Owned(&'a ServoArc<ComputedValues>),
29    Shared(AtomicRef<'a, ServoArc<ComputedValues>>),
30}
31
32impl<'a> Deref for BaseFragmentStyleRef<'a> {
33    type Target = ServoArc<ComputedValues>;
34
35    fn deref(&self) -> &Self::Target {
36        match self {
37            BaseFragmentStyleRef::Owned(style) => style,
38            BaseFragmentStyleRef::Shared(style_ref) => style_ref.deref(),
39        }
40    }
41}
42
43#[derive(Clone, MallocSizeOf)]
44pub(crate) enum BaseFragmentStyle {
45    Owned(ServoArc<ComputedValues>),
46    Shared(SharedStyle),
47}
48
49impl From<ServoArc<ComputedValues>> for BaseFragmentStyle {
50    fn from(style: ServoArc<ComputedValues>) -> Self {
51        BaseFragmentStyle::Owned(style)
52    }
53}
54
55impl From<SharedStyle> for BaseFragmentStyle {
56    fn from(style: SharedStyle) -> Self {
57        BaseFragmentStyle::Shared(style)
58    }
59}
60
61impl std::fmt::Debug for BaseFragmentStyle {
62    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
63        match self {
64            BaseFragmentStyle::Owned(..) => write!(formatter, "BaseFragmentStyle::Owned"),
65            BaseFragmentStyle::Shared(..) => write!(formatter, "BaseFragmentStyle::Shared"),
66        }
67    }
68}
69
70/// This data structure stores fields that are common to all non-base
71/// Fragment types and should generally be the first member of all
72/// concrete fragments.
73#[derive(Clone, Debug, MallocSizeOf)]
74pub(crate) struct BaseFragment {
75    /// A tag which identifies the DOM node and pseudo element of this
76    /// Fragment's content. If this fragment is for an anonymous box,
77    /// the tag will be None.
78    pub tag: Option<Tag>,
79
80    /// Flags which various information about this fragment used during
81    /// layout.
82    pub flags: FragmentFlags,
83
84    /// The style for this [`BaseFragment`]. Depending on the fragment type this is either
85    /// a shared or non-shared style.
86    pub style: BaseFragmentStyle,
87
88    /// The content rect of this fragment in the parent fragment's content rectangle. This
89    /// does not include padding, border, or margin -- it only includes content. This is
90    /// relative to the parent containing block.
91    pub rect: PhysicalRect<Au>,
92}
93
94impl BaseFragment {
95    pub(crate) fn new(
96        base_fragment_info: BaseFragmentInfo,
97        style: BaseFragmentStyle,
98        rect: PhysicalRect<Au>,
99    ) -> Self {
100        Self {
101            tag: base_fragment_info.tag,
102            flags: base_fragment_info.flags,
103            style,
104            rect,
105        }
106    }
107
108    pub(crate) fn is_anonymous(&self) -> bool {
109        self.tag.is_none()
110    }
111
112    pub(crate) fn repair_style(&mut self, style: &ServoArc<ComputedValues>) {
113        self.style = style.clone().into();
114    }
115
116    pub(crate) fn style<'a>(&'a self) -> BaseFragmentStyleRef<'a> {
117        match &self.style {
118            BaseFragmentStyle::Owned(computed_values) => {
119                BaseFragmentStyleRef::Owned(computed_values)
120            },
121            BaseFragmentStyle::Shared(shared_style) => {
122                BaseFragmentStyleRef::Shared(shared_style.borrow())
123            },
124        }
125    }
126}
127
128/// Information necessary to construct a new BaseFragment.
129#[derive(Clone, Copy, Debug, MallocSizeOf)]
130pub(crate) struct BaseFragmentInfo {
131    /// The tag to use for the new BaseFragment, if it is not an anonymous Fragment.
132    pub tag: Option<Tag>,
133
134    /// The flags to use for the new BaseFragment.
135    pub flags: FragmentFlags,
136}
137
138impl BaseFragmentInfo {
139    pub(crate) fn anonymous() -> Self {
140        Self {
141            tag: None,
142            flags: FragmentFlags::empty(),
143        }
144    }
145
146    pub(crate) fn new_for_testing(id: usize) -> Self {
147        Self {
148            tag: Some(Tag {
149                node: OpaqueNode(id),
150                pseudo_element_chain: Default::default(),
151            }),
152            flags: FragmentFlags::empty(),
153        }
154    }
155
156    pub(crate) fn is_anonymous(&self) -> bool {
157        self.tag.is_none()
158    }
159}
160
161impl From<&NodeAndStyleInfo<'_>> for BaseFragmentInfo {
162    fn from(info: &NodeAndStyleInfo) -> Self {
163        info.node.into()
164    }
165}
166
167impl From<ServoThreadSafeLayoutNode<'_>> for BaseFragmentInfo {
168    fn from(node: ServoThreadSafeLayoutNode) -> Self {
169        let pseudo_element_chain = node.pseudo_element_chain();
170        let mut flags = FragmentFlags::empty();
171
172        // Anonymous boxes should not have a tag, because they should not take part in hit testing.
173        //
174        // TODO(mrobinson): It seems that anonymous boxes should take part in hit testing in some
175        // cases, but currently this means that the order of hit test results isn't as expected for
176        // some WPT tests. This needs more investigation.
177        if matches!(
178            pseudo_element_chain.innermost(),
179            Some(PseudoElement::ServoAnonymousBox) |
180                Some(PseudoElement::ServoAnonymousTable) |
181                Some(PseudoElement::ServoAnonymousTableCell) |
182                Some(PseudoElement::ServoAnonymousTableRow)
183        ) {
184            return Self::anonymous();
185        }
186
187        if let Some(element) = node.as_html_element() {
188            if element.is_body_element_of_html_element_root() {
189                flags.insert(FragmentFlags::IS_BODY_ELEMENT_OF_HTML_ELEMENT_ROOT);
190            }
191
192            match element.get_local_name() {
193                &local_name!("br") => {
194                    flags.insert(FragmentFlags::IS_BR_ELEMENT);
195                },
196                &local_name!("table") | &local_name!("th") | &local_name!("td") => {
197                    flags.insert(FragmentFlags::IS_TABLE_TH_OR_TD_ELEMENT);
198                },
199                _ => {},
200            }
201
202            if ThreadSafeLayoutElement::is_root(&element) {
203                flags.insert(FragmentFlags::IS_ROOT_ELEMENT);
204            }
205        };
206
207        Self {
208            tag: Some(node.into()),
209            flags,
210        }
211    }
212}
213
214bitflags! {
215    /// Flags used to track various information about a DOM node during layout.
216    #[derive(Clone, Copy, Debug)]
217    pub(crate) struct FragmentFlags: u16 {
218        /// Whether or not the node that created this fragment is a `<body>` element on an HTML document.
219        const IS_BODY_ELEMENT_OF_HTML_ELEMENT_ROOT = 1 << 0;
220        /// Whether or not the node that created this Fragment is a `<br>` element.
221        const IS_BR_ELEMENT = 1 << 1;
222        /// Whether or not the node that created this Fragment is a widget. Widgets behave similarly to
223        /// replaced elements, e.g. they are atomic when inline-level, and their automatic inline size
224        /// doesn't stretch when block-level.
225        /// <https://drafts.csswg.org/css-ui/#widget>
226        const IS_WIDGET = 1 << 2;
227        /// Whether or not this Fragment is a flex item or a grid item.
228        const IS_FLEX_OR_GRID_ITEM = 1 << 3;
229        /// Whether or not this Fragment was created to contain a replaced element or is
230        /// a replaced element.
231        const IS_REPLACED = 1 << 4;
232        /// Whether or not the node that created was a `<table>`, `<th>` or
233        /// `<td>` element. Note that this does *not* include elements with
234        /// `display: table` or `display: table-cell`.
235        const IS_TABLE_TH_OR_TD_ELEMENT = 1 << 5;
236        /// Whether or not this Fragment was created to contain a list item marker
237        /// with a used value of `list-style-position: outside`.
238        const IS_OUTSIDE_LIST_ITEM_MARKER = 1 << 6;
239        /// Avoid painting the borders, backgrounds, and drop shadow for this fragment, this is used
240        /// for empty table cells when 'empty-cells' is 'hide' and also table wrappers.  This flag
241        /// doesn't avoid hit-testing nor does it prevent the painting outlines.
242        const DO_NOT_PAINT = 1 << 7;
243        /// Whether or not the size of this fragment depends on the block size of its container
244        /// and the fragment can be a flex item. This flag is used to cache items during flex
245        /// layout.
246        const SIZE_DEPENDS_ON_BLOCK_CONSTRAINTS_AND_CAN_BE_CHILD_OF_FLEX_ITEM = 1 << 8;
247        /// Whether or not the node that created this fragment is the root element.
248        const IS_ROOT_ELEMENT = 1 << 9;
249        /// If element has propagated the overflow value to viewport.
250        const PROPAGATED_OVERFLOW_TO_VIEWPORT = 1 << 10;
251        /// Whether or not this is a table cell that is part of a collapsed row or column.
252        /// In that case it should not be painted.
253        const IS_COLLAPSED = 1 << 11;
254
255    }
256}
257
258malloc_size_of_is_0!(FragmentFlags);
259
260/// A data structure used to hold DOM and pseudo-element information about
261/// a particular layout object.
262#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq)]
263pub(crate) struct Tag {
264    pub(crate) node: OpaqueNode,
265    pub(crate) pseudo_element_chain: PseudoElementChain,
266}
267
268impl Tag {
269    pub(crate) fn to_display_list_fragment_id(self) -> u64 {
270        combine_id_with_fragment_type(self.node.id(), self.pseudo_element_chain.primary.into())
271    }
272}
273
274impl From<ServoThreadSafeLayoutNode<'_>> for Tag {
275    fn from(node: ServoThreadSafeLayoutNode<'_>) -> Self {
276        Self {
277            node: node.opaque(),
278            pseudo_element_chain: node.pseudo_element_chain(),
279        }
280    }
281}
layout/fragment_tree/base_fragment.rs

layout/fragment_tree/
base_fragment.rs
