layout/
dom.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::marker::PhantomData;
6
7use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
8use layout_api::{
9    GenericLayoutDataTrait, LayoutDataTrait, LayoutElement, LayoutElementType, LayoutNode,
10    LayoutNodeType as ScriptLayoutNodeType, NodeRenderingType, SVGElementData,
11};
12use malloc_size_of_derive::MallocSizeOf;
13use script::layout_dom::ServoLayoutNode;
14use servo_arc::Arc as ServoArc;
15use smallvec::SmallVec;
16use style::context::SharedStyleContext;
17use style::properties::ComputedValues;
18use style::selector_parser::PseudoElement;
19use style::values::specified::box_::DisplayOutside as StyloDisplayOutside;
20use web_atoms::{local_name, ns};
21
22use crate::cell::{ArcRefCell, WeakRefCell};
23use crate::context::LayoutContext;
24use crate::dom_traversal::{Contents, NodeAndStyleInfo};
25use crate::flexbox::FlexLevelBox;
26use crate::flow::inline::text_run::TextRun;
27use crate::flow::inline::{InlineItem, SharedInlineStyles, WeakInlineItem};
28use crate::flow::{BlockLevelBox, BlockLevelCreator};
29use crate::fragment_tree::{Fragment, FragmentFlags};
30use crate::geom::PhysicalSize;
31use crate::layout_box_base::LayoutBoxBase;
32use crate::replaced::{CanvasInfo, IFrameInfo, ImageInfo, VideoInfo};
33use crate::style_ext::{
34    ComputedValuesExt, Display, DisplayGeneratingBox, DisplayLayoutInternal, DisplayOutside,
35};
36use crate::table::{TableLevelBox, WeakTableLevelBox};
37use crate::taffy::TaffyItemBox;
38
39#[derive(MallocSizeOf)]
40pub struct PseudoLayoutData {
41    pseudo: PseudoElement,
42    data: ArcRefCell<InnerDOMLayoutData>,
43}
44
45/// The data that is stored in each DOM node that is used by layout.
46#[derive(Default, MallocSizeOf)]
47pub struct InnerDOMLayoutData {
48    pub(super) self_box: ArcRefCell<Option<LayoutBox>>,
49    pub(super) pseudo_boxes: SmallVec<[PseudoLayoutData; 2]>,
50}
51
52impl InnerDOMLayoutData {
53    fn pseudo_layout_data(
54        &self,
55        pseudo_element: PseudoElement,
56    ) -> Option<ArcRefCell<InnerDOMLayoutData>> {
57        for pseudo_layout_data in self.pseudo_boxes.iter() {
58            if pseudo_element == pseudo_layout_data.pseudo {
59                return Some(pseudo_layout_data.data.clone());
60            }
61        }
62        None
63    }
64
65    fn create_pseudo_layout_data(
66        &mut self,
67        pseudo_element: PseudoElement,
68    ) -> ArcRefCell<InnerDOMLayoutData> {
69        let data: ArcRefCell<InnerDOMLayoutData> = Default::default();
70        self.pseudo_boxes.push(PseudoLayoutData {
71            pseudo: pseudo_element,
72            data: data.clone(),
73        });
74        data
75    }
76
77    fn fragments(&self) -> Vec<Fragment> {
78        self.self_box
79            .borrow()
80            .as_ref()
81            .and_then(|layout_box| layout_box.with_base(|base| base.fragments().clone()))
82            .unwrap_or_default()
83    }
84
85    fn repair_style(&self, node: &ServoLayoutNode, context: &SharedStyleContext) {
86        if let Some(layout_object) = &*self.self_box.borrow() {
87            layout_object.repair_style(context, node, &node.style(context));
88        }
89
90        for pseudo_layout_data in self.pseudo_boxes.iter() {
91            let Some(node_with_pseudo) = node.with_pseudo(pseudo_layout_data.pseudo) else {
92                continue;
93            };
94            pseudo_layout_data
95                .data
96                .borrow()
97                .repair_style(&node_with_pseudo, context);
98        }
99    }
100
101    fn with_layout_box_base(&self, callback: impl FnOnce(&LayoutBoxBase)) {
102        if let Some(data) = self.self_box.borrow().as_ref() {
103            data.with_base(callback);
104        }
105    }
106
107    fn with_layout_box_base_including_pseudos(&self, mut callback: impl FnMut(&LayoutBoxBase)) {
108        self.with_layout_box_base(&mut callback);
109        for pseudo_layout_data in self.pseudo_boxes.iter() {
110            pseudo_layout_data
111                .data
112                .borrow()
113                .with_layout_box_base(&mut callback);
114        }
115    }
116}
117
118/// A box that is stored in one of the `DOMLayoutData` slots.
119#[derive(Debug, MallocSizeOf)]
120pub(super) enum LayoutBox {
121    DisplayContents(SharedInlineStyles),
122    BlockLevel(ArcRefCell<BlockLevelBox>),
123    InlineLevel(InlineItem),
124    FlexLevel(ArcRefCell<FlexLevelBox>),
125    TableLevelBox(TableLevelBox),
126    TaffyItemBox(ArcRefCell<TaffyItemBox>),
127    Text(ArcRefCell<TextRun>),
128}
129
130impl LayoutBox {
131    pub(crate) fn with_base<T>(&self, callback: impl FnOnce(&LayoutBoxBase) -> T) -> Option<T> {
132        Some(match self {
133            LayoutBox::DisplayContents(..) | LayoutBox::Text(..) => return None,
134            LayoutBox::BlockLevel(block_level_box) => block_level_box.borrow().with_base(callback),
135            LayoutBox::InlineLevel(inline_item) => inline_item.with_base(callback),
136            LayoutBox::FlexLevel(flex_level_box) => flex_level_box.borrow().with_base(callback),
137            LayoutBox::TaffyItemBox(taffy_item_box) => taffy_item_box.borrow().with_base(callback),
138            LayoutBox::TableLevelBox(table_box) => table_box.with_base(callback),
139        })
140    }
141
142    pub(crate) fn with_base_mut<T>(
143        &mut self,
144        callback: impl FnOnce(&mut LayoutBoxBase) -> T,
145    ) -> Option<T> {
146        Some(match self {
147            LayoutBox::DisplayContents(..) | LayoutBox::Text(..) => return None,
148            LayoutBox::BlockLevel(block_level_box) => {
149                block_level_box.borrow_mut().with_base_mut(callback)
150            },
151            LayoutBox::InlineLevel(inline_item) => inline_item.with_base_mut(callback),
152            LayoutBox::FlexLevel(flex_level_box) => {
153                flex_level_box.borrow_mut().with_base_mut(callback)
154            },
155            LayoutBox::TaffyItemBox(taffy_item_box) => {
156                taffy_item_box.borrow_mut().with_base_mut(callback)
157            },
158            LayoutBox::TableLevelBox(table_box) => table_box.with_base_mut(callback),
159        })
160    }
161
162    fn repair_style(
163        &self,
164        context: &SharedStyleContext,
165        node: &ServoLayoutNode,
166        new_style: &ServoArc<ComputedValues>,
167    ) {
168        match self {
169            LayoutBox::DisplayContents(inline_shared_styles) => {
170                *inline_shared_styles.style.borrow_mut() = new_style.clone();
171                *inline_shared_styles.selected.borrow_mut() = node.selected_style(context);
172            },
173            LayoutBox::BlockLevel(block_level_box) => {
174                block_level_box
175                    .borrow_mut()
176                    .repair_style(context, node, new_style);
177            },
178            LayoutBox::InlineLevel(inline_item) => {
179                inline_item.repair_style(context, node, new_style);
180            },
181            LayoutBox::FlexLevel(flex_level_box) => flex_level_box
182                .borrow_mut()
183                .repair_style(context, node, new_style),
184            LayoutBox::TableLevelBox(table_level_box) => {
185                table_level_box.repair_style(context, node, new_style)
186            },
187            LayoutBox::TaffyItemBox(taffy_item_box) => taffy_item_box
188                .borrow_mut()
189                .repair_style(context, node, new_style),
190            LayoutBox::Text(..) => {
191                // There is nothing to update in this case.
192            },
193        }
194    }
195
196    fn attached_to_tree(&self, layout_box: WeakLayoutBox) {
197        match self {
198            Self::DisplayContents(_) => {
199                // This box can't have children, its contents get reparented to its parent.
200                // Therefore, no need to do anything.
201            },
202            Self::BlockLevel(block_level_box) => {
203                block_level_box.borrow().attached_to_tree(layout_box)
204            },
205            Self::InlineLevel(inline_item) => inline_item.attached_to_tree(layout_box),
206            Self::FlexLevel(flex_level_box) => flex_level_box.borrow().attached_to_tree(layout_box),
207            Self::TableLevelBox(table_level_box) => table_level_box.attached_to_tree(layout_box),
208            Self::TaffyItemBox(taffy_item_box) => {
209                taffy_item_box.borrow().attached_to_tree(layout_box)
210            },
211            Self::Text(..) => {
212                // This kind of box cannot have children, so no need to do anything.
213            },
214        }
215    }
216
217    fn downgrade(&self) -> WeakLayoutBox {
218        match self {
219            Self::DisplayContents(inline_shared_styles) => {
220                WeakLayoutBox::DisplayContents(inline_shared_styles.clone())
221            },
222            Self::BlockLevel(block_level_box) => {
223                WeakLayoutBox::BlockLevel(block_level_box.downgrade())
224            },
225            Self::InlineLevel(inline_item) => WeakLayoutBox::InlineLevel(inline_item.downgrade()),
226            Self::FlexLevel(flex_level_box) => WeakLayoutBox::FlexLevel(flex_level_box.downgrade()),
227            Self::TableLevelBox(table_level_box) => {
228                WeakLayoutBox::TableLevelBox(table_level_box.downgrade())
229            },
230            Self::TaffyItemBox(taffy_item_box) => {
231                WeakLayoutBox::TaffyItemBox(taffy_item_box.downgrade())
232            },
233            Self::Text(text_run) => WeakLayoutBox::Text(text_run.downgrade()),
234        }
235    }
236}
237
238#[derive(Clone, Debug, MallocSizeOf)]
239pub(super) enum WeakLayoutBox {
240    DisplayContents(SharedInlineStyles),
241    BlockLevel(WeakRefCell<BlockLevelBox>),
242    InlineLevel(WeakInlineItem),
243    FlexLevel(WeakRefCell<FlexLevelBox>),
244    TableLevelBox(WeakTableLevelBox),
245    TaffyItemBox(WeakRefCell<TaffyItemBox>),
246    Text(WeakRefCell<TextRun>),
247}
248
249impl WeakLayoutBox {
250    pub(crate) fn upgrade(&self) -> Option<LayoutBox> {
251        Some(match self {
252            Self::DisplayContents(inline_shared_styles) => {
253                LayoutBox::DisplayContents(inline_shared_styles.clone())
254            },
255            Self::BlockLevel(block_level_box) => LayoutBox::BlockLevel(block_level_box.upgrade()?),
256            Self::InlineLevel(inline_item) => LayoutBox::InlineLevel(inline_item.upgrade()?),
257            Self::FlexLevel(flex_level_box) => LayoutBox::FlexLevel(flex_level_box.upgrade()?),
258            Self::TableLevelBox(table_level_box) => {
259                LayoutBox::TableLevelBox(table_level_box.upgrade()?)
260            },
261            Self::TaffyItemBox(taffy_item_box) => {
262                LayoutBox::TaffyItemBox(taffy_item_box.upgrade()?)
263            },
264            Self::Text(text_run) => LayoutBox::Text(text_run.upgrade()?),
265        })
266    }
267}
268
269/// A wrapper for [`InnerDOMLayoutData`]. This is necessary to give the entire data
270/// structure interior mutability, as we will need to mutate the layout data of
271/// non-mutable DOM nodes.
272#[derive(Default, MallocSizeOf)]
273pub struct DOMLayoutData(AtomicRefCell<InnerDOMLayoutData>);
274
275// The implementation of this trait allows the data to be stored in the DOM.
276impl LayoutDataTrait for DOMLayoutData {}
277impl GenericLayoutDataTrait for DOMLayoutData {
278    fn as_any(&self) -> &dyn std::any::Any {
279        self
280    }
281}
282
283pub struct BoxSlot<'dom> {
284    pub(crate) slot: ArcRefCell<Option<LayoutBox>>,
285    pub(crate) marker: PhantomData<&'dom ()>,
286}
287
288impl From<ArcRefCell<Option<LayoutBox>>> for BoxSlot<'_> {
289    fn from(slot: ArcRefCell<Option<LayoutBox>>) -> Self {
290        Self {
291            slot,
292            marker: PhantomData,
293        }
294    }
295}
296
297/// A mutable reference to a `LayoutBox` stored in a DOM element.
298impl BoxSlot<'_> {
299    pub(crate) fn set(self, layout_box: LayoutBox) {
300        layout_box.attached_to_tree(layout_box.downgrade());
301        *self.slot.borrow_mut() = Some(layout_box);
302    }
303
304    pub(crate) fn take_layout_box(&self) -> Option<LayoutBox> {
305        self.slot.borrow_mut().take()
306    }
307
308    /// Call [`Self::take_layout_box`] and try to unwrap it into a [`TextRun`], returning `None` if
309    /// the slot is empty or it does not contain a [`TextRun`]. Note that this will *always* clear
310    /// the [`BoxSlot`].
311    pub(crate) fn take_layout_box_as_text_run(&self) -> Option<ArcRefCell<TextRun>> {
312        match self.take_layout_box()? {
313            LayoutBox::Text(old_text_run) => Some(old_text_run),
314            _ => None,
315        }
316    }
317}
318
319impl Drop for BoxSlot<'_> {
320    fn drop(&mut self) {
321        if !std::thread::panicking() {
322            assert!(self.slot.borrow().is_some(), "failed to set a layout box");
323        }
324    }
325}
326
327pub(crate) trait NodeExt<'dom> {
328    /// Returns the relevant data wrapping into respective struct and its size in pixels.
329    fn as_image(&self) -> Option<(ImageInfo, PhysicalSize<f64>)>;
330    fn as_canvas(&self) -> Option<(CanvasInfo, PhysicalSize<f64>)>;
331    fn as_iframe(&self) -> Option<IFrameInfo>;
332    fn as_video(&self) -> Option<(VideoInfo, Option<PhysicalSize<f64>>)>;
333    fn as_svg(&self) -> Option<SVGElementData<'dom>>;
334    fn as_typeless_object_with_data_attribute(&self) -> Option<String>;
335
336    fn ensure_inner_layout_data(&self) -> AtomicRefMut<'dom, InnerDOMLayoutData>;
337    fn inner_layout_data(&self) -> Option<AtomicRef<'dom, InnerDOMLayoutData>>;
338    fn inner_layout_data_mut(&self) -> Option<AtomicRefMut<'dom, InnerDOMLayoutData>>;
339    fn box_slot(&self) -> BoxSlot<'dom>;
340
341    /// Remove boxes for the element itself, and all of its pseudo-element boxes.
342    fn unset_all_boxes(&self);
343
344    /// Clear laid out `Fragment`s and dirty `Fragment` caches for all of this node's boxes,
345    /// ensuring that the next `FragmentTree` layout that happens at this node is complete.
346    fn clear_fragments_and_dirty_fragment_caches(&self);
347
348    /// Clear laid out `Fragment`s and dirty `Fragment` caches for all this node's boxes and
349    /// descendant's boxes, ensuring that the next `FragmentTree` layout that happens at and
350    /// below this node is complete.
351    fn clear_fragments_and_dirty_fragment_caches_recursively(&self);
352
353    /// Clear laid out `Fragment`s and dirty `Fragment` caches for all this node's descendant's
354    /// boxes.
355    fn clear_fragments_and_dirty_fragment_caches_of_descendants(&self);
356
357    /// Returns the [`NodeRenderingType`] for this [`LayoutNode`] which describes whether
358    /// the node is being rendered, delegating rendering, or not being rendered at all
359    /// based on whether it has a [`LayoutBox`] and what kind.
360    fn rendering_type(&self) -> NodeRenderingType;
361
362    fn fragments_for_pseudo(&self, pseudo_element: Option<PseudoElement>) -> Vec<Fragment>;
363    fn with_layout_box_base(&self, callback: impl FnMut(&LayoutBoxBase));
364    fn with_layout_box_base_including_pseudos(&self, callback: impl FnMut(&LayoutBoxBase));
365
366    fn repair_style(&self, context: &SharedStyleContext);
367
368    /// Whether or not this node isolates downward flowing box tree rebuild damage and
369    /// fragment tree layout cache damage. Roughly, this corresponds to independent
370    /// formatting context boundaries.
371    ///
372    /// - The node's boxes themselves will be rebuilt, but not the descendant node's
373    ///   boxes.
374    /// - The node's fragment tree layout will be rebuilt, not the descendent node's
375    ///   fragment tree layout cache.
376    ///
377    /// When this node has no box yet, `false` is returned.
378    fn isolates_damage_for_damage_propagation(&self) -> bool;
379
380    /// Try to re-run box tree reconstruction from this point. This can succeed if the
381    /// node itself is still valid and isolates box tree damage from ancestors (for
382    /// instance, if it starts an independent formatting context). **Note:** This assumes
383    /// that no ancestors have box damage.
384    ///
385    /// Returns `true` if box tree reconstruction was sucessful and `false` otherwise.
386    fn rebuild_box_tree_from_independent_formatting_context(
387        &self,
388        layout_context: &LayoutContext,
389    ) -> bool;
390
391    /// Whether or not the style of this node indicates that it should be absolutely
392    /// positioned.
393    fn is_absolutely_positioned(&self) -> bool;
394}
395
396impl<'dom> NodeExt<'dom> for ServoLayoutNode<'dom> {
397    fn as_image(&self) -> Option<(ImageInfo, PhysicalSize<f64>)> {
398        let (resource, metadata) = self.image_data()?;
399        let width = metadata.map(|metadata| metadata.width).unwrap_or_default();
400        let height = metadata.map(|metadata| metadata.height).unwrap_or_default();
401        let (mut width, mut height) = (width as f64, height as f64);
402        // Take `image_density` into account for calculating the size in pixels for images.
403        if let Some(density) = self.image_density().filter(|density| *density != 1.) {
404            width /= density;
405            height /= density;
406        }
407        Some((
408            ImageInfo {
409                image: resource,
410                showing_broken_image_icon: self.showing_broken_image_icon(),
411                url: self.image_url(),
412            },
413            PhysicalSize::new(width, height),
414        ))
415    }
416
417    fn as_svg(&self) -> Option<SVGElementData<'dom>> {
418        self.svg_data()
419    }
420
421    fn as_video(&self) -> Option<(VideoInfo, Option<PhysicalSize<f64>>)> {
422        let data = self.media_data()?;
423        let natural_size = if let Some(frame) = data.current_frame {
424            Some(PhysicalSize::new(frame.width.into(), frame.height.into()))
425        } else {
426            data.metadata
427                .map(|meta| PhysicalSize::new(meta.width.into(), meta.height.into()))
428        };
429        Some((
430            VideoInfo {
431                image_key: data.current_frame.map(|frame| frame.image_key),
432            },
433            natural_size,
434        ))
435    }
436
437    fn as_canvas(&self) -> Option<(CanvasInfo, PhysicalSize<f64>)> {
438        let canvas_data = self.canvas_data()?;
439        let source = canvas_data.image_key;
440        Some((
441            CanvasInfo { source },
442            PhysicalSize::new(canvas_data.width.into(), canvas_data.height.into()),
443        ))
444    }
445
446    fn as_iframe(&self) -> Option<IFrameInfo> {
447        match (self.iframe_pipeline_id(), self.iframe_browsing_context_id()) {
448            (Some(pipeline_id), Some(browsing_context_id)) => Some(IFrameInfo {
449                pipeline_id,
450                browsing_context_id,
451            }),
452            _ => None,
453        }
454    }
455
456    fn as_typeless_object_with_data_attribute(&self) -> Option<String> {
457        if self.type_id() !=
458            Some(ScriptLayoutNodeType::Element(
459                LayoutElementType::HTMLObjectElement,
460            ))
461        {
462            return None;
463        }
464
465        // TODO: This is the what the legacy layout system did, but really if Servo
466        // supports any `<object>` that's an image, it should support those with URLs
467        // and `type` attributes with image mime types.
468        let element = self.as_element()?;
469        if element.attribute(&ns!(), &local_name!("type")).is_some() {
470            return None;
471        }
472        element
473            .attribute_as_str(&ns!(), &local_name!("data"))
474            .map(|string| string.to_owned())
475    }
476
477    fn ensure_inner_layout_data(&self) -> AtomicRefMut<'dom, InnerDOMLayoutData> {
478        if self.layout_data().is_none() {
479            self.initialize_layout_data::<DOMLayoutData>();
480        }
481        self.layout_data()
482            .unwrap()
483            .as_any()
484            .downcast_ref::<DOMLayoutData>()
485            .unwrap()
486            .0
487            .borrow_mut()
488    }
489
490    fn inner_layout_data(&self) -> Option<AtomicRef<'dom, InnerDOMLayoutData>> {
491        self.layout_data().map(|data| {
492            data.as_any()
493                .downcast_ref::<DOMLayoutData>()
494                .unwrap()
495                .0
496                .borrow()
497        })
498    }
499
500    fn inner_layout_data_mut(&self) -> Option<AtomicRefMut<'dom, InnerDOMLayoutData>> {
501        self.layout_data().map(|data| {
502            data.as_any()
503                .downcast_ref::<DOMLayoutData>()
504                .unwrap()
505                .0
506                .borrow_mut()
507        })
508    }
509
510    fn box_slot(&self) -> BoxSlot<'dom> {
511        let pseudo_element_chain = self.pseudo_element_chain();
512        let Some(primary) = pseudo_element_chain.primary else {
513            return self.ensure_inner_layout_data().self_box.clone().into();
514        };
515
516        let Some(secondary) = pseudo_element_chain.secondary else {
517            let primary_layout_data = self
518                .ensure_inner_layout_data()
519                .create_pseudo_layout_data(primary);
520            return primary_layout_data.borrow().self_box.clone().into();
521        };
522
523        // It's *very* important that this not borrow the element's main
524        // `InnerLayoutData`. Primary pseudo-elements are processed at the same recursion
525        // level as the main data, so the `BoxSlot` is created sequentially with other
526        // primary pseudo-elements and the element itself. The secondary pseudo-element is
527        // one level deep, so could be happening in parallel with the primary
528        // pseudo-elements or main element layout.
529        let primary_layout_data = self
530            .inner_layout_data()
531            .expect("Should already have element InnerLayoutData here.")
532            .pseudo_layout_data(primary)
533            .expect("Should already have primary pseudo-element InnerLayoutData here");
534        let secondary_layout_data = primary_layout_data
535            .borrow_mut()
536            .create_pseudo_layout_data(secondary);
537        secondary_layout_data.borrow().self_box.clone().into()
538    }
539
540    fn unset_all_boxes(&self) {
541        let mut layout_data = self.ensure_inner_layout_data();
542        *layout_data.self_box.borrow_mut() = None;
543        layout_data.pseudo_boxes.clear();
544
545        // Stylo already takes care of removing all layout data
546        // for DOM descendants of elements with `display: none`.
547    }
548
549    fn clear_fragments_and_dirty_fragment_caches_recursively(&self) {
550        self.clear_fragments_and_dirty_fragment_caches();
551        self.clear_fragments_and_dirty_fragment_caches_of_descendants();
552    }
553
554    fn clear_fragments_and_dirty_fragment_caches(&self) {
555        self.with_layout_box_base_including_pseudos(|base| {
556            base.clear_fragments_and_dirty_fragment_cache()
557        });
558    }
559
560    fn clear_fragments_and_dirty_fragment_caches_of_descendants(&self) {
561        for child in self.flat_tree_children() {
562            child.clear_fragments_and_dirty_fragment_caches_recursively();
563        }
564    }
565
566    fn rendering_type(&self) -> NodeRenderingType {
567        let Some(layout_data) = self.inner_layout_data() else {
568            return NodeRenderingType::NotRendered;
569        };
570        match &*layout_data.self_box.borrow() {
571            Some(LayoutBox::DisplayContents(..)) => NodeRenderingType::DelegatesRendering,
572            Some(..) => NodeRenderingType::Rendered,
573            None => NodeRenderingType::NotRendered,
574        }
575    }
576
577    fn with_layout_box_base(&self, callback: impl FnMut(&LayoutBoxBase)) {
578        if let Some(inner_layout_data) = self.inner_layout_data() {
579            inner_layout_data.with_layout_box_base(callback);
580        }
581    }
582
583    fn with_layout_box_base_including_pseudos(&self, callback: impl FnMut(&LayoutBoxBase)) {
584        if let Some(inner_layout_data) = self.inner_layout_data() {
585            inner_layout_data.with_layout_box_base_including_pseudos(callback);
586        }
587    }
588
589    fn fragments_for_pseudo(&self, pseudo_element: Option<PseudoElement>) -> Vec<Fragment> {
590        let Some(layout_data) = self.inner_layout_data() else {
591            return vec![];
592        };
593        match pseudo_element {
594            Some(pseudo_element) => layout_data
595                .pseudo_layout_data(pseudo_element)
596                .map(|pseudo_layout_data| pseudo_layout_data.borrow().fragments())
597                .unwrap_or_default(),
598            None => layout_data.fragments(),
599        }
600    }
601
602    fn repair_style(&self, context: &SharedStyleContext) {
603        if let Some(layout_data) = self.inner_layout_data() {
604            layout_data.repair_style(self, context);
605        }
606    }
607
608    fn isolates_damage_for_damage_propagation(&self) -> bool {
609        // Do not run incremental box and fragment tree layout at the `<body>` or root element as
610        // there is some special processing that must happen for these elements and it currently
611        // only happens when doing a full box tree construction traversal.
612        if self.as_element().is_some_and(|element| {
613            element.is_body_element_of_html_element_root() || element.is_root()
614        }) {
615            return false;
616        }
617
618        let Some(inner_layout_data) = self.inner_layout_data() else {
619            return false;
620        };
621        let self_box = inner_layout_data.self_box.borrow();
622        let Some(self_box) = &*self_box else {
623            return false;
624        };
625
626        match self_box {
627            LayoutBox::DisplayContents(..) => false,
628            LayoutBox::BlockLevel(block_level) => matches!(
629                &*block_level.borrow(),
630                BlockLevelBox::Independent(..) |
631                    BlockLevelBox::OutOfFlowFloatBox(..) |
632                    BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(..)
633            ),
634            LayoutBox::InlineLevel(inline_level) => matches!(
635                inline_level,
636                InlineItem::OutOfFlowAbsolutelyPositionedBox(..) | InlineItem::Atomic(..)
637            ),
638            LayoutBox::FlexLevel(..) => true,
639            LayoutBox::TableLevelBox(table_level_box) => matches!(
640                table_level_box,
641                TableLevelBox::Cell(..) | TableLevelBox::Caption(..),
642            ),
643            LayoutBox::TaffyItemBox(..) => true,
644            LayoutBox::Text(..) => unreachable!("An element should never be a text node"),
645        }
646    }
647
648    fn rebuild_box_tree_from_independent_formatting_context(
649        &self,
650        layout_context: &LayoutContext,
651    ) -> bool {
652        // Do not run incremental box tree layout at the `<body>` or root element as there
653        // is some special processing that must happen for these elements and it currently
654        // only happens when doing a full box tree construction traversal.
655        if self.as_element().is_some_and(|element| {
656            element.is_body_element_of_html_element_root() || element.is_root()
657        }) {
658            return false;
659        }
660
661        let layout_box = {
662            let Some(mut inner_layout_data) = self.inner_layout_data_mut() else {
663                return false;
664            };
665            inner_layout_data.pseudo_boxes.clear();
666            inner_layout_data.self_box.clone()
667        };
668
669        let layout_box = layout_box.borrow();
670        let Some(layout_box) = &*layout_box else {
671            return false;
672        };
673
674        let info = NodeAndStyleInfo::new(*self, self.style(&layout_context.style_context));
675        let box_style = info.style.get_box();
676        let Display::GeneratingBox(display) = box_style.display.into() else {
677            return false;
678        };
679        let contents = || {
680            assert!(
681                self.pseudo_element_chain().is_empty(),
682                "Shouldn't try to rebuild box tree from a pseudo-element"
683            );
684            Contents::for_element(info.node, layout_context)
685        };
686        match layout_box {
687            LayoutBox::DisplayContents(..) => false,
688            LayoutBox::BlockLevel(block_level) => {
689                let mut block_level = block_level.borrow_mut();
690                match &mut *block_level {
691                    BlockLevelBox::Independent(independent_formatting_context) => {
692                        let DisplayGeneratingBox::OutsideInside {
693                            outside: DisplayOutside::Block,
694                            inside: display_inside,
695                        } = display
696                        else {
697                            return false;
698                        };
699                        if !matches!(
700                            BlockLevelCreator::new_for_inflow_block_level_element(
701                                &info,
702                                display_inside,
703                                contents(),
704                                independent_formatting_context.propagated_data,
705                            ),
706                            BlockLevelCreator::Independent { .. }
707                        ) {
708                            return false;
709                        }
710                        independent_formatting_context.rebuild(layout_context, &info);
711                        true
712                    },
713                    BlockLevelBox::OutOfFlowFloatBox(float_box) => {
714                        if !info.style.clone_float().is_floating() {
715                            return false;
716                        }
717                        float_box.contents.rebuild(layout_context, &info);
718                        true
719                    },
720                    BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(positioned_box) => {
721                        // Even if absolute positioning blockifies the outer display type, if the
722                        // original display was inline-level, then the box needs to be handled as
723                        // an inline-level in order to compute the static position correctly.
724                        // See `BlockContainerBuilder::handle_absolutely_positioned_element()`.
725                        if !info.style.clone_position().is_absolutely_positioned() ||
726                            box_style.original_display.outside() != StyloDisplayOutside::Block
727                        {
728                            return false;
729                        }
730                        positioned_box
731                            .borrow_mut()
732                            .context
733                            .rebuild(layout_context, &info);
734                        true
735                    },
736                    _ => false,
737                }
738            },
739            LayoutBox::InlineLevel(inline_level) => match inline_level {
740                InlineItem::OutOfFlowAbsolutelyPositionedBox(positioned_box, ..) => {
741                    if !info.style.clone_position().is_absolutely_positioned() {
742                        return false;
743                    }
744                    positioned_box
745                        .borrow_mut()
746                        .context
747                        .rebuild(layout_context, &info);
748                    true
749                },
750                InlineItem::Atomic(atomic_box, _, _) => {
751                    let flags = match contents() {
752                        Contents::NonReplaced(_) => FragmentFlags::empty(),
753                        Contents::Replaced(_) => FragmentFlags::IS_REPLACED,
754                        Contents::Widget(_) => FragmentFlags::IS_WIDGET,
755                    };
756                    if !info.style.is_atomic_inline_level(flags) {
757                        return false;
758                    }
759                    atomic_box.borrow_mut().rebuild(layout_context, &info);
760                    true
761                },
762                _ => false,
763            },
764            LayoutBox::FlexLevel(flex_level_box) => {
765                let mut flex_level_box = flex_level_box.borrow_mut();
766                match &mut *flex_level_box {
767                    FlexLevelBox::FlexItem(flex_item_box) => {
768                        if info.style.clone_position().is_absolutely_positioned() ||
769                            flex_item_box.style().clone_order() != info.style.clone_order()
770                        {
771                            return false;
772                        }
773                        flex_item_box
774                            .independent_formatting_context
775                            .rebuild(layout_context, &info)
776                    },
777                    FlexLevelBox::OutOfFlowAbsolutelyPositionedBox(positioned_box) => {
778                        if !info.style.clone_position().is_absolutely_positioned() {
779                            return false;
780                        }
781                        positioned_box
782                            .borrow_mut()
783                            .context
784                            .rebuild(layout_context, &info);
785                    },
786                }
787                true
788            },
789            LayoutBox::TableLevelBox(table_level_box) => match table_level_box {
790                TableLevelBox::Caption(caption) => {
791                    if display !=
792                        DisplayGeneratingBox::LayoutInternal(DisplayLayoutInternal::TableCaption)
793                    {
794                        return false;
795                    }
796                    caption.borrow_mut().context.rebuild(layout_context, &info);
797                    true
798                },
799                TableLevelBox::Cell(table_cell) => {
800                    if display !=
801                        DisplayGeneratingBox::LayoutInternal(DisplayLayoutInternal::TableCell)
802                    {
803                        return false;
804                    }
805                    table_cell
806                        .borrow_mut()
807                        .context
808                        .rebuild(layout_context, &info);
809                    true
810                },
811                _ => false,
812            },
813            LayoutBox::TaffyItemBox(..) => false,
814            LayoutBox::Text(..) => unreachable!("An element should never be a text node"),
815        }
816    }
817
818    fn is_absolutely_positioned(&self) -> bool {
819        self.as_element().is_some_and(|element| {
820            element
821                .element_data()
822                .styles
823                .primary()
824                .clone_position()
825                .is_absolutely_positioned()
826        })
827    }
828}
layout/dom.rs

layout/
dom.rs
