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 servo_base::text::{RangeAny, Utf32CodeUnits};
16use smallvec::SmallVec;
17use style::context::SharedStyleContext;
18use style::properties::ComputedValues;
19use style::selector_parser::PseudoElement;
20use style::values::specified::box_::DisplayOutside as StyloDisplayOutside;
21use web_atoms::{local_name, ns};
22
23use crate::cell::{ArcRefCell, WeakRefCell};
24use crate::context::LayoutContext;
25use crate::dom_traversal::{Contents, NodeAndStyleInfo};
26use crate::flexbox::FlexLevelBox;
27use crate::flow::inline::text_run::TextRun;
28use crate::flow::inline::{InlineItem, SharedInlineStyles, WeakInlineItem};
29use crate::flow::{BlockLevelBox, BlockLevelCreator};
30use crate::fragment_tree::{Fragment, FragmentFlags};
31use crate::geom::PhysicalSize;
32use crate::layout_box_base::LayoutBoxBase;
33use crate::replaced::{CanvasInfo, IFrameInfo, ImageInfo, VideoInfo};
34use crate::style_ext::{
35    ComputedValuesExt, Display, DisplayGeneratingBox, DisplayLayoutInternal, DisplayOutside,
36};
37use crate::table::{TableLevelBox, WeakTableLevelBox};
38use crate::taffy::TaffyItemBox;
39
40#[derive(MallocSizeOf)]
41pub struct PseudoLayoutData {
42    pseudo: PseudoElement,
43    data: ArcRefCell<InnerDOMLayoutData>,
44}
45
46/// The data that is stored in each DOM node that is used by layout.
47#[derive(Default, MallocSizeOf)]
48pub struct InnerDOMLayoutData {
49    pub(super) self_box: ArcRefCell<Option<LayoutBox>>,
50    pub(super) pseudo_boxes: SmallVec<[PseudoLayoutData; 2]>,
51}
52
53impl InnerDOMLayoutData {
54    fn pseudo_layout_data(
55        &self,
56        pseudo_element: PseudoElement,
57    ) -> Option<ArcRefCell<InnerDOMLayoutData>> {
58        for pseudo_layout_data in self.pseudo_boxes.iter() {
59            if pseudo_element == pseudo_layout_data.pseudo {
60                return Some(pseudo_layout_data.data.clone());
61            }
62        }
63        None
64    }
65
66    fn create_pseudo_layout_data(
67        &mut self,
68        pseudo_element: PseudoElement,
69    ) -> ArcRefCell<InnerDOMLayoutData> {
70        let data: ArcRefCell<InnerDOMLayoutData> = Default::default();
71        self.pseudo_boxes.push(PseudoLayoutData {
72            pseudo: pseudo_element,
73            data: data.clone(),
74        });
75        data
76    }
77
78    fn fragments(&self) -> Vec<Fragment> {
79        self.with_fragments(<[Fragment]>::to_vec)
80            .unwrap_or_default()
81    }
82
83    /// Run `callback` on the fragments without cloning them. Returns `None` if the node has no box.
84    fn with_fragments<T>(&self, callback: impl FnOnce(&[Fragment]) -> T) -> Option<T> {
85        let self_box = self.self_box.borrow();
86        let layout_box = self_box.as_ref()?;
87        layout_box.with_base(|base| callback(&base.fragments()))
88    }
89
90    fn repair_style(&self, node: &ServoLayoutNode, context: &SharedStyleContext) {
91        if let Some(layout_object) = &*self.self_box.borrow() {
92            layout_object.repair_style(context, node, &node.style(context));
93        }
94
95        for pseudo_layout_data in self.pseudo_boxes.iter() {
96            let Some(node_with_pseudo) = node.with_pseudo(pseudo_layout_data.pseudo) else {
97                continue;
98            };
99            pseudo_layout_data
100                .data
101                .borrow()
102                .repair_style(&node_with_pseudo, context);
103        }
104    }
105
106    fn with_layout_box_base(&self, callback: impl FnOnce(&LayoutBoxBase)) {
107        if let Some(data) = self.self_box.borrow().as_ref() {
108            data.with_base(callback);
109        }
110    }
111
112    fn with_layout_box_base_including_pseudos(&self, mut callback: impl FnMut(&LayoutBoxBase)) {
113        self.with_layout_box_base(&mut callback);
114        for pseudo_layout_data in self.pseudo_boxes.iter() {
115            pseudo_layout_data
116                .data
117                .borrow()
118                .with_layout_box_base(&mut callback);
119        }
120    }
121}
122
123/// A box that is stored in one of the `DOMLayoutData` slots.
124#[derive(Debug, MallocSizeOf)]
125pub(super) enum LayoutBox {
126    DisplayContents(SharedInlineStyles),
127    BlockLevel(ArcRefCell<BlockLevelBox>),
128    InlineLevel(InlineItem),
129    FlexLevel(ArcRefCell<FlexLevelBox>),
130    TableLevelBox(TableLevelBox),
131    TaffyItemBox(ArcRefCell<TaffyItemBox>),
132    Text(ArcRefCell<TextRun>),
133}
134
135impl LayoutBox {
136    pub(crate) fn with_base<T>(&self, callback: impl FnOnce(&LayoutBoxBase) -> T) -> Option<T> {
137        Some(match self {
138            LayoutBox::DisplayContents(..) | LayoutBox::Text(..) => return None,
139            LayoutBox::BlockLevel(block_level_box) => block_level_box.borrow().with_base(callback),
140            LayoutBox::InlineLevel(inline_item) => inline_item.with_base(callback),
141            LayoutBox::FlexLevel(flex_level_box) => flex_level_box.borrow().with_base(callback),
142            LayoutBox::TaffyItemBox(taffy_item_box) => taffy_item_box.borrow().with_base(callback),
143            LayoutBox::TableLevelBox(table_box) => table_box.with_base(callback),
144        })
145    }
146
147    pub(crate) fn with_base_mut<T>(
148        &mut self,
149        callback: impl FnOnce(&mut LayoutBoxBase) -> T,
150    ) -> Option<T> {
151        Some(match self {
152            LayoutBox::DisplayContents(..) | LayoutBox::Text(..) => return None,
153            LayoutBox::BlockLevel(block_level_box) => {
154                block_level_box.borrow_mut().with_base_mut(callback)
155            },
156            LayoutBox::InlineLevel(inline_item) => inline_item.with_base_mut(callback),
157            LayoutBox::FlexLevel(flex_level_box) => {
158                flex_level_box.borrow_mut().with_base_mut(callback)
159            },
160            LayoutBox::TaffyItemBox(taffy_item_box) => {
161                taffy_item_box.borrow_mut().with_base_mut(callback)
162            },
163            LayoutBox::TableLevelBox(table_box) => table_box.with_base_mut(callback),
164        })
165    }
166
167    fn repair_style(
168        &self,
169        context: &SharedStyleContext,
170        node: &ServoLayoutNode,
171        new_style: &ServoArc<ComputedValues>,
172    ) {
173        match self {
174            LayoutBox::DisplayContents(inline_shared_styles) => {
175                *inline_shared_styles.style.borrow_mut() = new_style.clone();
176                *inline_shared_styles.selected.borrow_mut() = node.selected_style(context);
177            },
178            LayoutBox::BlockLevel(block_level_box) => {
179                block_level_box
180                    .borrow_mut()
181                    .repair_style(context, node, new_style);
182            },
183            LayoutBox::InlineLevel(inline_item) => {
184                inline_item.repair_style(context, node, new_style);
185            },
186            LayoutBox::FlexLevel(flex_level_box) => flex_level_box
187                .borrow_mut()
188                .repair_style(context, node, new_style),
189            LayoutBox::TableLevelBox(table_level_box) => {
190                table_level_box.repair_style(context, node, new_style)
191            },
192            LayoutBox::TaffyItemBox(taffy_item_box) => taffy_item_box
193                .borrow_mut()
194                .repair_style(context, node, new_style),
195            LayoutBox::Text(..) => {
196                // There is nothing to update in this case.
197            },
198        }
199    }
200
201    fn attached_to_tree(&self, layout_box: WeakLayoutBox) {
202        match self {
203            Self::DisplayContents(_) => {
204                // This box can't have children, its contents get reparented to its parent.
205                // Therefore, no need to do anything.
206            },
207            Self::BlockLevel(block_level_box) => {
208                block_level_box.borrow().attached_to_tree(layout_box)
209            },
210            Self::InlineLevel(inline_item) => inline_item.attached_to_tree(layout_box),
211            Self::FlexLevel(flex_level_box) => flex_level_box.borrow().attached_to_tree(layout_box),
212            Self::TableLevelBox(table_level_box) => table_level_box.attached_to_tree(layout_box),
213            Self::TaffyItemBox(taffy_item_box) => {
214                taffy_item_box.borrow().attached_to_tree(layout_box)
215            },
216            Self::Text(..) => {
217                // This kind of box cannot have children, so no need to do anything.
218            },
219        }
220    }
221
222    fn downgrade(&self) -> WeakLayoutBox {
223        match self {
224            Self::DisplayContents(inline_shared_styles) => {
225                WeakLayoutBox::DisplayContents(inline_shared_styles.clone())
226            },
227            Self::BlockLevel(block_level_box) => {
228                WeakLayoutBox::BlockLevel(block_level_box.downgrade())
229            },
230            Self::InlineLevel(inline_item) => WeakLayoutBox::InlineLevel(inline_item.downgrade()),
231            Self::FlexLevel(flex_level_box) => WeakLayoutBox::FlexLevel(flex_level_box.downgrade()),
232            Self::TableLevelBox(table_level_box) => {
233                WeakLayoutBox::TableLevelBox(table_level_box.downgrade())
234            },
235            Self::TaffyItemBox(taffy_item_box) => {
236                WeakLayoutBox::TaffyItemBox(taffy_item_box.downgrade())
237            },
238            Self::Text(text_run) => WeakLayoutBox::Text(text_run.downgrade()),
239        }
240    }
241}
242
243#[derive(Clone, Debug, MallocSizeOf)]
244pub(super) enum WeakLayoutBox {
245    DisplayContents(SharedInlineStyles),
246    BlockLevel(WeakRefCell<BlockLevelBox>),
247    InlineLevel(WeakInlineItem),
248    FlexLevel(WeakRefCell<FlexLevelBox>),
249    TableLevelBox(WeakTableLevelBox),
250    TaffyItemBox(WeakRefCell<TaffyItemBox>),
251    Text(WeakRefCell<TextRun>),
252}
253
254impl WeakLayoutBox {
255    pub(crate) fn upgrade(&self) -> Option<LayoutBox> {
256        Some(match self {
257            Self::DisplayContents(inline_shared_styles) => {
258                LayoutBox::DisplayContents(inline_shared_styles.clone())
259            },
260            Self::BlockLevel(block_level_box) => LayoutBox::BlockLevel(block_level_box.upgrade()?),
261            Self::InlineLevel(inline_item) => LayoutBox::InlineLevel(inline_item.upgrade()?),
262            Self::FlexLevel(flex_level_box) => LayoutBox::FlexLevel(flex_level_box.upgrade()?),
263            Self::TableLevelBox(table_level_box) => {
264                LayoutBox::TableLevelBox(table_level_box.upgrade()?)
265            },
266            Self::TaffyItemBox(taffy_item_box) => {
267                LayoutBox::TaffyItemBox(taffy_item_box.upgrade()?)
268            },
269            Self::Text(text_run) => LayoutBox::Text(text_run.upgrade()?),
270        })
271    }
272}
273
274/// A wrapper for [`InnerDOMLayoutData`]. This is necessary to give the entire data
275/// structure interior mutability, as we will need to mutate the layout data of
276/// non-mutable DOM nodes.
277#[derive(Default, MallocSizeOf)]
278pub struct DOMLayoutData(AtomicRefCell<InnerDOMLayoutData>);
279
280// The implementation of this trait allows the data to be stored in the DOM.
281impl LayoutDataTrait for DOMLayoutData {}
282impl GenericLayoutDataTrait for DOMLayoutData {
283    fn as_any(&self) -> &dyn std::any::Any {
284        self
285    }
286
287    fn set_text_run_selection(&self, new_range: Option<RangeAny<Utf32CodeUnits>>) -> bool {
288        let inner = self.0.borrow();
289        // When `::first-letter` is used, one DOM text node can generate multiple text runs
290        // so there isn’t a single place to set the new range
291        if inner
292            .pseudo_boxes
293            .iter()
294            .any(|pseudo_box| matches!(pseudo_box.pseudo, PseudoElement::FirstLetter))
295        {
296            return false;
297        }
298        if let Some(LayoutBox::Text(text_run)) = &*inner.self_box.borrow() {
299            *text_run.borrow().run_data.selection.borrow_mut() = new_range;
300            true
301        } else {
302            false
303        }
304    }
305}
306
307pub struct BoxSlot<'dom> {
308    pub(crate) slot: ArcRefCell<Option<LayoutBox>>,
309    pub(crate) marker: PhantomData<&'dom ()>,
310}
311
312impl From<ArcRefCell<Option<LayoutBox>>> for BoxSlot<'_> {
313    fn from(slot: ArcRefCell<Option<LayoutBox>>) -> Self {
314        Self {
315            slot,
316            marker: PhantomData,
317        }
318    }
319}
320
321/// A mutable reference to a `LayoutBox` stored in a DOM element.
322impl BoxSlot<'_> {
323    pub(crate) fn set(self, layout_box: LayoutBox) {
324        layout_box.attached_to_tree(layout_box.downgrade());
325        *self.slot.borrow_mut() = Some(layout_box);
326    }
327
328    pub(crate) fn take_layout_box(&self) -> Option<LayoutBox> {
329        self.slot.borrow_mut().take()
330    }
331
332    /// Call [`Self::take_layout_box`] and try to unwrap it into a [`TextRun`], returning `None` if
333    /// the slot is empty or it does not contain a [`TextRun`]. Note that this will *always* clear
334    /// the [`BoxSlot`].
335    pub(crate) fn take_layout_box_as_text_run(&self) -> Option<ArcRefCell<TextRun>> {
336        match self.take_layout_box()? {
337            LayoutBox::Text(old_text_run) => Some(old_text_run),
338            _ => None,
339        }
340    }
341}
342
343impl Drop for BoxSlot<'_> {
344    fn drop(&mut self) {
345        if !std::thread::panicking() {
346            assert!(self.slot.borrow().is_some(), "failed to set a layout box");
347        }
348    }
349}
350
351pub(crate) trait NodeExt<'dom> {
352    /// Returns the relevant data wrapping into respective struct and its size in pixels.
353    fn as_image(&self) -> Option<(ImageInfo, PhysicalSize<f64>)>;
354    fn as_canvas(&self) -> Option<(CanvasInfo, PhysicalSize<f64>)>;
355    fn as_iframe(&self) -> Option<IFrameInfo>;
356    fn as_video(&self) -> Option<(VideoInfo, Option<PhysicalSize<f64>>)>;
357    fn as_svg(&self) -> Option<SVGElementData<'dom>>;
358    fn as_typeless_object_with_data_attribute(&self) -> Option<String>;
359
360    fn ensure_inner_layout_data(&self) -> AtomicRefMut<'dom, InnerDOMLayoutData>;
361    fn inner_layout_data(&self) -> Option<AtomicRef<'dom, InnerDOMLayoutData>>;
362    fn inner_layout_data_mut(&self) -> Option<AtomicRefMut<'dom, InnerDOMLayoutData>>;
363    fn box_slot(&self) -> BoxSlot<'dom>;
364
365    /// Remove boxes for the element itself, and all of its pseudo-element boxes.
366    fn unset_all_boxes(&self);
367
368    /// Clear laid out `Fragment`s and dirty `Fragment` caches for all of this node's boxes,
369    /// ensuring that the next `FragmentTree` layout that happens at this node is complete.
370    fn clear_fragments_and_dirty_fragment_caches(&self);
371
372    /// Clear laid out `Fragment`s and dirty `Fragment` caches for all this node's boxes and
373    /// descendant's boxes, ensuring that the next `FragmentTree` layout that happens at and
374    /// below this node is complete.
375    fn clear_fragments_and_dirty_fragment_caches_recursively(&self);
376
377    /// Clear laid out `Fragment`s and dirty `Fragment` caches for all this node's descendant's
378    /// boxes.
379    fn clear_fragments_and_dirty_fragment_caches_of_descendants(&self);
380
381    /// Returns the [`NodeRenderingType`] for this [`LayoutNode`] which describes whether
382    /// the node is being rendered, delegating rendering, or not being rendered at all
383    /// based on whether it has a [`LayoutBox`] and what kind.
384    fn rendering_type(&self) -> NodeRenderingType;
385
386    fn fragments_for_pseudo(&self, pseudo_element: Option<PseudoElement>) -> Vec<Fragment>;
387
388    /// Run `callback` on the fragments without cloning them. Returns `None` if the node has no box.
389    fn with_fragments<T>(&self, callback: impl FnOnce(&[Fragment]) -> T) -> Option<T>;
390    fn with_layout_box_base(&self, callback: impl FnMut(&LayoutBoxBase));
391    fn with_layout_box_base_including_pseudos(&self, callback: impl FnMut(&LayoutBoxBase));
392
393    fn repair_style(&self, context: &SharedStyleContext);
394
395    /// Whether or not this node isolates downward flowing box tree rebuild damage and
396    /// fragment tree layout cache damage. Roughly, this corresponds to independent
397    /// formatting context boundaries.
398    ///
399    /// - The node's boxes themselves will be rebuilt, but not the descendant node's
400    ///   boxes.
401    /// - The node's fragment tree layout will be rebuilt, not the descendent node's
402    ///   fragment tree layout cache.
403    ///
404    /// When this node has no box yet, `false` is returned.
405    fn isolates_damage_for_damage_propagation(&self) -> bool;
406
407    /// Try to re-run box tree reconstruction from this point. This can succeed if the
408    /// node itself is still valid and isolates box tree damage from ancestors (for
409    /// instance, if it starts an independent formatting context). **Note:** This assumes
410    /// that no ancestors have box damage.
411    ///
412    /// Returns `true` if box tree reconstruction was sucessful and `false` otherwise.
413    fn rebuild_box_tree_from_independent_formatting_context(
414        &self,
415        layout_context: &LayoutContext,
416    ) -> bool;
417
418    /// Whether or not the style of this node indicates that it should be absolutely
419    /// positioned.
420    fn is_absolutely_positioned(&self) -> bool;
421}
422
423impl<'dom> NodeExt<'dom> for ServoLayoutNode<'dom> {
424    fn as_image(&self) -> Option<(ImageInfo, PhysicalSize<f64>)> {
425        let (resource, metadata) = self.image_data()?;
426        let width = metadata.map(|metadata| metadata.width).unwrap_or_default();
427        let height = metadata.map(|metadata| metadata.height).unwrap_or_default();
428        let (mut width, mut height) = (width as f64, height as f64);
429        // Take `image_density` into account for calculating the size in pixels for images.
430        if let Some(density) = self.image_density().filter(|density| *density != 1.) {
431            width /= density;
432            height /= density;
433        }
434        Some((
435            ImageInfo {
436                image: resource,
437                showing_broken_image_icon: self.showing_broken_image_icon(),
438                url: self.image_url(),
439            },
440            PhysicalSize::new(width, height),
441        ))
442    }
443
444    fn as_svg(&self) -> Option<SVGElementData<'dom>> {
445        self.svg_data()
446    }
447
448    fn as_video(&self) -> Option<(VideoInfo, Option<PhysicalSize<f64>>)> {
449        let data = self.media_data()?;
450        let natural_size = if let Some(frame) = data.current_frame {
451            Some(PhysicalSize::new(frame.width.into(), frame.height.into()))
452        } else {
453            data.metadata
454                .map(|meta| PhysicalSize::new(meta.width.into(), meta.height.into()))
455        };
456        Some((
457            VideoInfo {
458                image_key: data.current_frame.map(|frame| frame.image_key),
459                poster_url: data.poster_url,
460            },
461            natural_size,
462        ))
463    }
464
465    fn as_canvas(&self) -> Option<(CanvasInfo, PhysicalSize<f64>)> {
466        let canvas_data = self.canvas_data()?;
467        let source = canvas_data.image_key;
468        Some((
469            CanvasInfo { source },
470            PhysicalSize::new(canvas_data.width.into(), canvas_data.height.into()),
471        ))
472    }
473
474    fn as_iframe(&self) -> Option<IFrameInfo> {
475        match (self.iframe_pipeline_id(), self.iframe_browsing_context_id()) {
476            (Some(pipeline_id), Some(browsing_context_id)) => Some(IFrameInfo {
477                pipeline_id,
478                browsing_context_id,
479            }),
480            _ => None,
481        }
482    }
483
484    fn as_typeless_object_with_data_attribute(&self) -> Option<String> {
485        if self.type_id() !=
486            Some(ScriptLayoutNodeType::Element(
487                LayoutElementType::HTMLObjectElement,
488            ))
489        {
490            return None;
491        }
492
493        // TODO: This is the what the legacy layout system did, but really if Servo
494        // supports any `<object>` that's an image, it should support those with URLs
495        // and `type` attributes with image mime types.
496        let element = self.as_element()?;
497        if element.attribute(&ns!(), &local_name!("type")).is_some() {
498            return None;
499        }
500        element
501            .attribute_as_str(&ns!(), &local_name!("data"))
502            .map(|string| string.to_owned())
503    }
504
505    fn ensure_inner_layout_data(&self) -> AtomicRefMut<'dom, InnerDOMLayoutData> {
506        if self.layout_data().is_none() {
507            self.initialize_layout_data::<DOMLayoutData>();
508        }
509        self.layout_data()
510            .unwrap()
511            .as_any()
512            .downcast_ref::<DOMLayoutData>()
513            .unwrap()
514            .0
515            .borrow_mut()
516    }
517
518    fn inner_layout_data(&self) -> Option<AtomicRef<'dom, InnerDOMLayoutData>> {
519        self.layout_data().map(|data| {
520            data.as_any()
521                .downcast_ref::<DOMLayoutData>()
522                .unwrap()
523                .0
524                .borrow()
525        })
526    }
527
528    fn inner_layout_data_mut(&self) -> Option<AtomicRefMut<'dom, InnerDOMLayoutData>> {
529        self.layout_data().map(|data| {
530            data.as_any()
531                .downcast_ref::<DOMLayoutData>()
532                .unwrap()
533                .0
534                .borrow_mut()
535        })
536    }
537
538    fn box_slot(&self) -> BoxSlot<'dom> {
539        let pseudo_element_chain = self.pseudo_element_chain();
540        let Some(primary) = pseudo_element_chain.primary else {
541            return self.ensure_inner_layout_data().self_box.clone().into();
542        };
543
544        let Some(secondary) = pseudo_element_chain.secondary else {
545            let primary_layout_data = self
546                .ensure_inner_layout_data()
547                .create_pseudo_layout_data(primary);
548            return primary_layout_data.borrow().self_box.clone().into();
549        };
550
551        // It's *very* important that this not borrow the element's main
552        // `InnerLayoutData`. Primary pseudo-elements are processed at the same recursion
553        // level as the main data, so the `BoxSlot` is created sequentially with other
554        // primary pseudo-elements and the element itself. The secondary pseudo-element is
555        // one level deep, so could be happening in parallel with the primary
556        // pseudo-elements or main element layout.
557        let primary_layout_data = self
558            .inner_layout_data()
559            .expect("Should already have element InnerLayoutData here.")
560            .pseudo_layout_data(primary)
561            .expect("Should already have primary pseudo-element InnerLayoutData here");
562        let secondary_layout_data = primary_layout_data
563            .borrow_mut()
564            .create_pseudo_layout_data(secondary);
565        secondary_layout_data.borrow().self_box.clone().into()
566    }
567
568    fn unset_all_boxes(&self) {
569        let mut layout_data = self.ensure_inner_layout_data();
570        *layout_data.self_box.borrow_mut() = None;
571        layout_data.pseudo_boxes.clear();
572
573        // Stylo already takes care of removing all layout data
574        // for DOM descendants of elements with `display: none`.
575    }
576
577    fn clear_fragments_and_dirty_fragment_caches_recursively(&self) {
578        self.clear_fragments_and_dirty_fragment_caches();
579        self.clear_fragments_and_dirty_fragment_caches_of_descendants();
580    }
581
582    fn clear_fragments_and_dirty_fragment_caches(&self) {
583        self.with_layout_box_base_including_pseudos(|base| {
584            base.clear_fragments_and_dirty_fragment_cache()
585        });
586    }
587
588    fn clear_fragments_and_dirty_fragment_caches_of_descendants(&self) {
589        for child in self.flat_tree_children() {
590            child.clear_fragments_and_dirty_fragment_caches_recursively();
591        }
592    }
593
594    fn rendering_type(&self) -> NodeRenderingType {
595        let Some(layout_data) = self.inner_layout_data() else {
596            return NodeRenderingType::NotRendered;
597        };
598        match &*layout_data.self_box.borrow() {
599            Some(LayoutBox::DisplayContents(..)) => NodeRenderingType::DelegatesRendering,
600            Some(..) => NodeRenderingType::Rendered,
601            None => NodeRenderingType::NotRendered,
602        }
603    }
604
605    fn with_layout_box_base(&self, callback: impl FnMut(&LayoutBoxBase)) {
606        if let Some(inner_layout_data) = self.inner_layout_data() {
607            inner_layout_data.with_layout_box_base(callback);
608        }
609    }
610
611    fn with_layout_box_base_including_pseudos(&self, callback: impl FnMut(&LayoutBoxBase)) {
612        if let Some(inner_layout_data) = self.inner_layout_data() {
613            inner_layout_data.with_layout_box_base_including_pseudos(callback);
614        }
615    }
616
617    fn fragments_for_pseudo(&self, pseudo_element: Option<PseudoElement>) -> Vec<Fragment> {
618        let Some(layout_data) = self.inner_layout_data() else {
619            return vec![];
620        };
621        match pseudo_element {
622            Some(pseudo_element) => layout_data
623                .pseudo_layout_data(pseudo_element)
624                .map(|pseudo_layout_data| pseudo_layout_data.borrow().fragments())
625                .unwrap_or_default(),
626            None => layout_data.fragments(),
627        }
628    }
629
630    fn with_fragments<T>(&self, callback: impl FnOnce(&[Fragment]) -> T) -> Option<T> {
631        self.inner_layout_data()?.with_fragments(callback)
632    }
633
634    fn repair_style(&self, context: &SharedStyleContext) {
635        if let Some(layout_data) = self.inner_layout_data() {
636            layout_data.repair_style(self, context);
637        }
638    }
639
640    fn isolates_damage_for_damage_propagation(&self) -> bool {
641        // Do not run incremental box and fragment tree layout at the `<body>` or root element as
642        // there is some special processing that must happen for these elements and it currently
643        // only happens when doing a full box tree construction traversal.
644        if self.as_element().is_some_and(|element| {
645            element.is_body_element_of_html_element_root() || element.is_root()
646        }) {
647            return false;
648        }
649
650        let Some(inner_layout_data) = self.inner_layout_data() else {
651            return false;
652        };
653        let self_box = inner_layout_data.self_box.borrow();
654        let Some(self_box) = &*self_box else {
655            return false;
656        };
657
658        match self_box {
659            LayoutBox::DisplayContents(..) => false,
660            LayoutBox::BlockLevel(block_level) => matches!(
661                &*block_level.borrow(),
662                BlockLevelBox::Independent(..) |
663                    BlockLevelBox::OutOfFlowFloatBox(..) |
664                    BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(..)
665            ),
666            LayoutBox::InlineLevel(inline_level) => matches!(
667                inline_level,
668                InlineItem::OutOfFlowAbsolutelyPositionedBox(..) | InlineItem::Atomic(..)
669            ),
670            LayoutBox::FlexLevel(..) => true,
671            LayoutBox::TableLevelBox(table_level_box) => matches!(
672                table_level_box,
673                TableLevelBox::Cell(..) | TableLevelBox::Caption(..),
674            ),
675            LayoutBox::TaffyItemBox(..) => true,
676            LayoutBox::Text(..) => unreachable!("An element should never be a text node"),
677        }
678    }
679
680    fn rebuild_box_tree_from_independent_formatting_context(
681        &self,
682        layout_context: &LayoutContext,
683    ) -> bool {
684        // Do not run incremental box tree layout at the `<body>` or root element as there
685        // is some special processing that must happen for these elements and it currently
686        // only happens when doing a full box tree construction traversal.
687        if self.as_element().is_some_and(|element| {
688            element.is_body_element_of_html_element_root() || element.is_root()
689        }) {
690            return false;
691        }
692
693        let layout_box = {
694            let Some(mut inner_layout_data) = self.inner_layout_data_mut() else {
695                return false;
696            };
697            inner_layout_data.pseudo_boxes.clear();
698            inner_layout_data.self_box.clone()
699        };
700
701        let layout_box = layout_box.borrow();
702        let Some(layout_box) = &*layout_box else {
703            return false;
704        };
705
706        let info = NodeAndStyleInfo::new(*self, self.style(&layout_context.style_context));
707        let box_style = info.style.get_box();
708        let Display::GeneratingBox(display) = box_style.display.into() else {
709            return false;
710        };
711        let contents = || {
712            assert!(
713                self.pseudo_element_chain().is_empty(),
714                "Shouldn't try to rebuild box tree from a pseudo-element"
715            );
716            Contents::for_element(info.node, layout_context)
717        };
718        match layout_box {
719            LayoutBox::DisplayContents(..) => false,
720            LayoutBox::BlockLevel(block_level) => {
721                let mut block_level = block_level.borrow_mut();
722                match &mut *block_level {
723                    BlockLevelBox::Independent(independent_formatting_context) => {
724                        let DisplayGeneratingBox::OutsideInside {
725                            outside: DisplayOutside::Block,
726                            inside: display_inside,
727                        } = display
728                        else {
729                            return false;
730                        };
731                        if !matches!(
732                            BlockLevelCreator::new_for_inflow_block_level_element(
733                                &info,
734                                display_inside,
735                                contents(),
736                                independent_formatting_context.propagated_data,
737                            ),
738                            BlockLevelCreator::Independent { .. }
739                        ) {
740                            return false;
741                        }
742                        independent_formatting_context.rebuild(layout_context, &info);
743                        true
744                    },
745                    BlockLevelBox::OutOfFlowFloatBox(float_box) => {
746                        if !info.style.clone_float().is_floating() {
747                            return false;
748                        }
749                        float_box.contents.rebuild(layout_context, &info);
750                        true
751                    },
752                    BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(positioned_box) => {
753                        // Even if absolute positioning blockifies the outer display type, if the
754                        // original display was inline-level, then the box needs to be handled as
755                        // an inline-level in order to compute the static position correctly.
756                        // See `BlockContainerBuilder::handle_absolutely_positioned_element()`.
757                        if !info.style.clone_position().is_absolutely_positioned() ||
758                            box_style.original_display.outside() != StyloDisplayOutside::Block
759                        {
760                            return false;
761                        }
762                        positioned_box
763                            .borrow_mut()
764                            .context
765                            .rebuild(layout_context, &info);
766                        true
767                    },
768                    _ => false,
769                }
770            },
771            LayoutBox::InlineLevel(inline_level) => match inline_level {
772                InlineItem::OutOfFlowAbsolutelyPositionedBox(positioned_box, ..) => {
773                    if !info.style.clone_position().is_absolutely_positioned() {
774                        return false;
775                    }
776                    positioned_box
777                        .borrow_mut()
778                        .context
779                        .rebuild(layout_context, &info);
780                    true
781                },
782                InlineItem::Atomic(atomic_box, _, _) => {
783                    let flags = match contents() {
784                        Contents::NonReplaced(_) => FragmentFlags::empty(),
785                        Contents::Replaced(_) => FragmentFlags::IS_REPLACED,
786                        Contents::Widget(_) => FragmentFlags::IS_WIDGET,
787                    };
788                    if !info.style.is_atomic_inline_level(flags) {
789                        return false;
790                    }
791                    atomic_box.borrow_mut().rebuild(layout_context, &info);
792                    true
793                },
794                _ => false,
795            },
796            LayoutBox::FlexLevel(flex_level_box) => {
797                let mut flex_level_box = flex_level_box.borrow_mut();
798                match &mut *flex_level_box {
799                    FlexLevelBox::FlexItem(flex_item_box) => {
800                        if info.style.clone_position().is_absolutely_positioned() ||
801                            flex_item_box.style().clone_order() != info.style.clone_order()
802                        {
803                            return false;
804                        }
805                        flex_item_box
806                            .independent_formatting_context
807                            .rebuild(layout_context, &info)
808                    },
809                    FlexLevelBox::OutOfFlowAbsolutelyPositionedBox(positioned_box) => {
810                        if !info.style.clone_position().is_absolutely_positioned() {
811                            return false;
812                        }
813                        positioned_box
814                            .borrow_mut()
815                            .context
816                            .rebuild(layout_context, &info);
817                    },
818                }
819                true
820            },
821            LayoutBox::TableLevelBox(table_level_box) => match table_level_box {
822                TableLevelBox::Caption(caption) => {
823                    if display !=
824                        DisplayGeneratingBox::LayoutInternal(DisplayLayoutInternal::TableCaption)
825                    {
826                        return false;
827                    }
828                    caption.borrow_mut().context.rebuild(layout_context, &info);
829                    true
830                },
831                TableLevelBox::Cell(table_cell) => {
832                    if display !=
833                        DisplayGeneratingBox::LayoutInternal(DisplayLayoutInternal::TableCell)
834                    {
835                        return false;
836                    }
837                    table_cell
838                        .borrow_mut()
839                        .context
840                        .rebuild(layout_context, &info);
841                    true
842                },
843                _ => false,
844            },
845            LayoutBox::TaffyItemBox(..) => false,
846            LayoutBox::Text(..) => unreachable!("An element should never be a text node"),
847        }
848    }
849
850    fn is_absolutely_positioned(&self) -> bool {
851        self.as_element().is_some_and(|element| {
852            element
853                .element_data()
854                .styles
855                .primary()
856                .clone_position()
857                .is_absolutely_positioned()
858        })
859    }
860}
layout/dom.rs

layout/
dom.rs
