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construct.rs
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construct.rs
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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Creates flows and fragments from a DOM tree via a bottom-up, incremental traversal of the DOM.
//!
//! Each step of the traversal considers the node and existing flow, if there is one. If a node is
//! not dirty and an existing flow exists, then the traversal reuses that flow. Otherwise, it
//! proceeds to construct either a flow or a `ConstructionItem`. A construction item is a piece of
//! intermediate data that goes with a DOM node and hasn't found its "home" yet-maybe it's a box,
//! maybe it's an absolute or fixed position thing that hasn't found its containing block yet.
//! Construction items bubble up the tree from children to parents until they find their homes.
#![deny(unsafe_code)]
use app_units::Au;
use block::BlockFlow;
use context::LayoutContext;
use data::{HAS_NEWLY_CONSTRUCTED_FLOW, PrivateLayoutData};
use flex::FlexFlow;
use floats::FloatKind;
use flow::{self, AbsoluteDescendants, IS_ABSOLUTELY_POSITIONED, ImmutableFlowUtils};
use flow::{CAN_BE_FRAGMENTED, MutableFlowUtils, MutableOwnedFlowUtils};
use flow_ref::{self, FlowRef};
use fragment::{CanvasFragmentInfo, ImageFragmentInfo, InlineAbsoluteFragmentInfo};
use fragment::{Fragment, GeneratedContentInfo, IframeFragmentInfo};
use fragment::{InlineAbsoluteHypotheticalFragmentInfo, TableColumnFragmentInfo};
use fragment::{InlineBlockFragmentInfo, SpecificFragmentInfo, UnscannedTextFragmentInfo};
use fragment::WhitespaceStrippingResult;
use gfx::display_list::OpaqueNode;
use inline::{FIRST_FRAGMENT_OF_ELEMENT, InlineFlow, InlineFragmentNodeFlags};
use inline::{InlineFragmentNodeInfo, LAST_FRAGMENT_OF_ELEMENT};
use linked_list::prepend_from;
use list_item::{ListItemFlow, ListStyleTypeContent};
use multicol::{MulticolColumnFlow, MulticolFlow};
use parallel;
use script_layout_interface::{LayoutElementType, LayoutNodeType, is_image_data};
use script_layout_interface::restyle_damage::{BUBBLE_ISIZES, RECONSTRUCT_FLOW, RestyleDamage};
use script_layout_interface::wrapper_traits::{PseudoElementType, ThreadSafeLayoutElement, ThreadSafeLayoutNode};
use std::borrow::ToOwned;
use std::collections::LinkedList;
use std::marker::PhantomData;
use std::mem;
use std::sync::Arc;
use std::sync::atomic::Ordering;
use style::computed_values::{caption_side, display, empty_cells, float, list_style_position};
use style::computed_values::content::ContentItem;
use style::computed_values::position;
use style::context::SharedStyleContext;
use style::properties::{self, ServoComputedValues};
use style::servo_selector_impl::PseudoElement;
use table::TableFlow;
use table_caption::TableCaptionFlow;
use table_cell::TableCellFlow;
use table_colgroup::TableColGroupFlow;
use table_row::TableRowFlow;
use table_rowgroup::TableRowGroupFlow;
use table_wrapper::TableWrapperFlow;
use text::TextRunScanner;
use traversal::PostorderNodeMutTraversal;
use url::Url;
use util::opts;
use wrapper::{TextContent, ThreadSafeLayoutNodeHelpers};
/// The results of flow construction for a DOM node.
#[derive(Clone)]
pub enum ConstructionResult {
/// This node contributes nothing at all (`display: none`). Alternately, this is what newly
/// created nodes have their `ConstructionResult` set to.
None,
/// This node contributed a flow at the proper position in the tree.
/// Nothing more needs to be done for this node. It has bubbled up fixed
/// and absolute descendant flows that have a containing block above it.
Flow(FlowRef, AbsoluteDescendants),
/// This node contributed some object or objects that will be needed to construct a proper flow
/// later up the tree, but these objects have not yet found their home.
ConstructionItem(ConstructionItem),
}
impl ConstructionResult {
pub fn swap_out(&mut self) -> ConstructionResult {
if opts::get().nonincremental_layout {
return mem::replace(self, ConstructionResult::None)
}
// FIXME(pcwalton): Stop doing this with inline fragments. Cloning fragments is very
// inefficient!
(*self).clone()
}
pub fn debug_id(&self) -> usize {
match *self {
ConstructionResult::None => 0,
ConstructionResult::ConstructionItem(_) => 0,
ConstructionResult::Flow(ref flow_ref, _) => flow::base(&**flow_ref).debug_id(),
}
}
}
/// Represents the output of flow construction for a DOM node that has not yet resulted in a
/// complete flow. Construction items bubble up the tree until they find a `Flow` to be attached
/// to.
#[derive(Clone)]
pub enum ConstructionItem {
/// Inline fragments and associated {ib} splits that have not yet found flows.
InlineFragments(InlineFragmentsConstructionResult),
/// Potentially ignorable whitespace.
Whitespace(OpaqueNode, PseudoElementType<()>, Arc<ServoComputedValues>, RestyleDamage),
/// TableColumn Fragment
TableColumnFragment(Fragment),
}
/// Represents inline fragments and {ib} splits that are bubbling up from an inline.
#[derive(Clone)]
pub struct InlineFragmentsConstructionResult {
/// Any {ib} splits that we're bubbling up.
pub splits: LinkedList<InlineBlockSplit>,
/// Any fragments that succeed the {ib} splits.
pub fragments: IntermediateInlineFragments,
}
/// Represents an {ib} split that has not yet found the containing block that it belongs to. This
/// is somewhat tricky. An example may be helpful. For this DOM fragment:
///
/// ```html
/// <span>
/// A
/// <div>B</div>
/// C
/// </span>
/// ```
///
/// The resulting `ConstructionItem` for the outer `span` will be:
///
/// ```ignore
/// ConstructionItem::InlineFragments(Some(~[
/// InlineBlockSplit {
/// predecessor_fragments: ~[
/// A
/// ],
/// block: ~BlockFlow {
/// B
/// },
/// }),~[
/// C
/// ])
/// ```
#[derive(Clone)]
pub struct InlineBlockSplit {
/// The inline fragments that precede the flow.
pub predecessors: IntermediateInlineFragments,
/// The flow that caused this {ib} split.
pub flow: FlowRef,
}
/// Holds inline fragments and absolute descendants.
#[derive(Clone)]
pub struct IntermediateInlineFragments {
/// The list of fragments.
pub fragments: LinkedList<Fragment>,
/// The list of absolute descendants of those inline fragments.
pub absolute_descendants: AbsoluteDescendants,
}
impl IntermediateInlineFragments {
fn new() -> IntermediateInlineFragments {
IntermediateInlineFragments {
fragments: LinkedList::new(),
absolute_descendants: AbsoluteDescendants::new(),
}
}
fn is_empty(&self) -> bool {
self.fragments.is_empty() && self.absolute_descendants.is_empty()
}
fn push_all(&mut self, mut other: IntermediateInlineFragments) {
self.fragments.append(&mut other.fragments);
self.absolute_descendants.push_descendants(other.absolute_descendants);
}
}
/// Holds inline fragments that we're gathering for children of an inline node.
struct InlineFragmentsAccumulator {
/// The list of fragments.
fragments: IntermediateInlineFragments,
/// Whether we've created a range to enclose all the fragments. This will be Some() if the
/// outer node is an inline and None otherwise.
enclosing_node: Option<InlineFragmentNodeInfo>,
/// Restyle damage to use for fragments created in this node.
restyle_damage: RestyleDamage,
/// Bidi control characters to insert before and after these fragments.
bidi_control_chars: Option<(&'static str, &'static str)>,
}
impl InlineFragmentsAccumulator {
fn new() -> InlineFragmentsAccumulator {
InlineFragmentsAccumulator {
fragments: IntermediateInlineFragments::new(),
enclosing_node: None,
bidi_control_chars: None,
restyle_damage: RestyleDamage::empty(),
}
}
fn from_inline_node<N>(node: &N, style_context: &SharedStyleContext) -> InlineFragmentsAccumulator
where N: ThreadSafeLayoutNode {
InlineFragmentsAccumulator {
fragments: IntermediateInlineFragments::new(),
enclosing_node: Some(InlineFragmentNodeInfo {
address: node.opaque(),
pseudo: node.get_pseudo_element_type().strip(),
style: node.style(style_context).clone(),
selected_style: node.selected_style(style_context).clone(),
flags: InlineFragmentNodeFlags::empty(),
}),
bidi_control_chars: None,
restyle_damage: node.restyle_damage(),
}
}
fn push(&mut self, fragment: Fragment) {
self.fragments.fragments.push_back(fragment)
}
fn push_all(&mut self, mut fragments: IntermediateInlineFragments) {
self.fragments.fragments.append(&mut fragments.fragments);
self.fragments.absolute_descendants.push_descendants(fragments.absolute_descendants);
}
fn to_intermediate_inline_fragments(self) -> IntermediateInlineFragments {
let InlineFragmentsAccumulator {
mut fragments,
enclosing_node,
bidi_control_chars,
restyle_damage,
} = self;
if let Some(enclosing_node) = enclosing_node {
let fragment_count = fragments.fragments.len();
for (index, fragment) in fragments.fragments.iter_mut().enumerate() {
let mut enclosing_node = enclosing_node.clone();
if index == 0 {
enclosing_node.flags.insert(FIRST_FRAGMENT_OF_ELEMENT)
}
if index == fragment_count - 1 {
enclosing_node.flags.insert(LAST_FRAGMENT_OF_ELEMENT)
}
fragment.add_inline_context_style(enclosing_node);
}
// Control characters are later discarded in transform_text, so they don't affect the
// is_first/is_last styles above.
if let Some((start, end)) = bidi_control_chars {
fragments.fragments.push_front(
control_chars_to_fragment(&enclosing_node, start, restyle_damage));
fragments.fragments.push_back(
control_chars_to_fragment(&enclosing_node, end, restyle_damage));
}
}
fragments
}
}
/// An object that knows how to create flows.
pub struct FlowConstructor<'a, N: ThreadSafeLayoutNode> {
/// The layout context.
pub layout_context: &'a LayoutContext<'a>,
/// Satisfy the compiler about the unused parameters, which we use to improve the ergonomics of
/// the ensuing impl {} by removing the need to parameterize all the methods individually.
phantom2: PhantomData<N>,
}
impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
FlowConstructor<'a, ConcreteThreadSafeLayoutNode> {
/// Creates a new flow constructor.
pub fn new(layout_context: &'a LayoutContext<'a>) -> Self {
FlowConstructor {
layout_context: layout_context,
phantom2: PhantomData,
}
}
#[inline]
fn style_context(&self) -> &SharedStyleContext {
self.layout_context.style_context()
}
#[inline]
fn set_flow_construction_result(&self,
node: &ConcreteThreadSafeLayoutNode,
result: ConstructionResult) {
node.set_flow_construction_result(result);
}
/// Builds the fragment for the given block or subclass thereof.
fn build_fragment_for_block(&mut self, node: &ConcreteThreadSafeLayoutNode) -> Fragment {
let specific_fragment_info = match node.type_id() {
Some(LayoutNodeType::Element(LayoutElementType::HTMLIFrameElement)) => {
SpecificFragmentInfo::Iframe(IframeFragmentInfo::new(node))
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLImageElement)) => {
let image_info = box ImageFragmentInfo::new(node,
node.image_url(),
&self.layout_context.shared);
SpecificFragmentInfo::Image(image_info)
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLObjectElement)) => {
let image_info = box ImageFragmentInfo::new(node,
node.object_data(),
&self.layout_context.shared);
SpecificFragmentInfo::Image(image_info)
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableElement)) => {
SpecificFragmentInfo::TableWrapper
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableColElement)) => {
SpecificFragmentInfo::TableColumn(TableColumnFragmentInfo::new(node))
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableCellElement)) => {
SpecificFragmentInfo::TableCell
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableRowElement)) |
Some(LayoutNodeType::Element(LayoutElementType::HTMLTableSectionElement)) => {
SpecificFragmentInfo::TableRow
}
Some(LayoutNodeType::Element(LayoutElementType::HTMLCanvasElement)) => {
let data = node.canvas_data().unwrap();
SpecificFragmentInfo::Canvas(box CanvasFragmentInfo::new(node, data, self.style_context()))
}
_ => {
// This includes pseudo-elements.
SpecificFragmentInfo::Generic
}
};
Fragment::new(node, specific_fragment_info, self.layout_context)
}
/// Generates anonymous table objects per CSS 2.1 § 17.2.1.
fn generate_anonymous_table_flows_if_necessary(&mut self,
flow: &mut FlowRef,
child: &mut FlowRef,
child_node: &ConcreteThreadSafeLayoutNode) {
if !flow.is_block_flow() {
return
}
let style_context = self.style_context();
if child.is_table_cell() {
let mut style = child_node.style(style_context).clone();
properties::modify_style_for_anonymous_table_object(&mut style, display::T::table_row);
let fragment = Fragment::from_opaque_node_and_style(child_node.opaque(),
PseudoElementType::Normal,
style,
child_node.selected_style(style_context).clone(),
child_node.restyle_damage(),
SpecificFragmentInfo::TableRow);
let mut new_child: FlowRef = Arc::new(TableRowFlow::from_fragment(fragment));
new_child.add_new_child(child.clone());
child.finish();
*child = new_child
}
if child.is_table_row() || child.is_table_rowgroup() {
let mut style = child_node.style(style_context).clone();
properties::modify_style_for_anonymous_table_object(&mut style, display::T::table);
let fragment = Fragment::from_opaque_node_and_style(child_node.opaque(),
PseudoElementType::Normal,
style,
child_node.selected_style(style_context).clone(),
child_node.restyle_damage(),
SpecificFragmentInfo::Table);
let mut new_child: FlowRef = Arc::new(TableFlow::from_fragment(fragment));
new_child.add_new_child(child.clone());
child.finish();
*child = new_child
}
if child.is_table() {
let mut style = child_node.style(style_context).clone();
properties::modify_style_for_anonymous_table_object(&mut style, display::T::table);
let fragment =
Fragment::from_opaque_node_and_style(child_node.opaque(),
PseudoElementType::Normal,
style,
child_node.selected_style(style_context).clone(),
child_node.restyle_damage(),
SpecificFragmentInfo::TableWrapper);
let mut new_child: FlowRef = Arc::new(TableWrapperFlow::from_fragment(fragment, None));
new_child.add_new_child(child.clone());
child.finish();
*child = new_child
}
}
/// Creates an inline flow from a set of inline fragments, then adds it as a child of the given
/// flow or pushes it onto the given flow list.
///
/// `#[inline(always)]` because this is performance critical and LLVM will not inline it
/// otherwise.
#[inline(always)]
fn flush_inline_fragments_to_flow_or_list(&mut self,
fragment_accumulator: InlineFragmentsAccumulator,
flow: &mut FlowRef,
flow_list: &mut Vec<FlowRef>,
absolute_descendants: &mut AbsoluteDescendants,
node: &ConcreteThreadSafeLayoutNode) {
let mut fragments = fragment_accumulator.to_intermediate_inline_fragments();
if fragments.is_empty() {
return
};
strip_ignorable_whitespace_from_start(&mut fragments.fragments);
strip_ignorable_whitespace_from_end(&mut fragments.fragments);
if fragments.fragments.is_empty() {
absolute_descendants.push_descendants(fragments.absolute_descendants);
return
}
// Build a list of all the inline-block fragments before fragments is moved.
let mut inline_block_flows = vec!();
for fragment in &fragments.fragments {
match fragment.specific {
SpecificFragmentInfo::InlineBlock(ref info) => {
inline_block_flows.push(info.flow_ref.clone())
}
SpecificFragmentInfo::InlineAbsoluteHypothetical(ref info) => {
inline_block_flows.push(info.flow_ref.clone())
}
SpecificFragmentInfo::InlineAbsolute(ref info) => {
inline_block_flows.push(info.flow_ref.clone())
}
_ => {}
}
}
// We must scan for runs before computing minimum ascent and descent because scanning
// for runs might collapse so much whitespace away that only hypothetical fragments
// remain. In that case the inline flow will compute its ascent and descent to be zero.
let scanned_fragments =
TextRunScanner::new().scan_for_runs(&mut self.layout_context.font_context(),
fragments.fragments);
let mut inline_flow_ref: FlowRef = Arc::new(
InlineFlow::from_fragments(scanned_fragments, node.style(self.style_context()).writing_mode));
// Add all the inline-block fragments as children of the inline flow.
for inline_block_flow in &inline_block_flows {
inline_flow_ref.add_new_child(inline_block_flow.clone());
}
// Set up absolute descendants as necessary.
//
// The inline flow itself may need to become the containing block for absolute descendants
// in order to handle cases like:
//
// <div>
// <span style="position: relative">
// <span style="position: absolute; ..."></span>
// </span>
// </div>
//
// See the comment above `flow::AbsoluteDescendantInfo` for more information.
inline_flow_ref.take_applicable_absolute_descendants(&mut fragments.absolute_descendants);
absolute_descendants.push_descendants(fragments.absolute_descendants);
{
// FIXME(#6503): Use Arc::get_mut().unwrap() here.
let inline_flow = flow_ref::deref_mut(&mut inline_flow_ref).as_mut_inline();
let (ascent, descent) =
inline_flow.compute_minimum_ascent_and_descent(&mut self.layout_context
.font_context(),
&**node.style(self.style_context()));
inline_flow.minimum_block_size_above_baseline = ascent;
inline_flow.minimum_depth_below_baseline = descent;
}
inline_flow_ref.finish();
if flow.need_anonymous_flow(&*inline_flow_ref) {
flow_list.push(inline_flow_ref)
} else {
flow.add_new_child(inline_flow_ref)
}
}
fn build_block_flow_using_construction_result_of_child(
&mut self,
flow: &mut FlowRef,
consecutive_siblings: &mut Vec<FlowRef>,
node: &ConcreteThreadSafeLayoutNode,
kid: ConcreteThreadSafeLayoutNode,
inline_fragment_accumulator: &mut InlineFragmentsAccumulator,
abs_descendants: &mut AbsoluteDescendants) {
match kid.swap_out_construction_result() {
ConstructionResult::None => {}
ConstructionResult::Flow(mut kid_flow, kid_abs_descendants) => {
// If kid_flow is TableCaptionFlow, kid_flow should be added under
// TableWrapperFlow.
if flow.is_table() && kid_flow.is_table_caption() {
self.set_flow_construction_result(&kid,
ConstructionResult::Flow(kid_flow,
AbsoluteDescendants::new()))
} else if flow.need_anonymous_flow(&*kid_flow) {
consecutive_siblings.push(kid_flow)
} else {
if !flow::base(&*kid_flow).flags.contains(IS_ABSOLUTELY_POSITIONED) {
// Flush any inline fragments that we were gathering up. This allows us to
// handle {ib} splits.
let old_inline_fragment_accumulator =
mem::replace(inline_fragment_accumulator,
InlineFragmentsAccumulator::new());
self.flush_inline_fragments_to_flow_or_list(
old_inline_fragment_accumulator,
flow,
consecutive_siblings,
abs_descendants,
node);
}
if !consecutive_siblings.is_empty() {
let consecutive_siblings = mem::replace(consecutive_siblings, vec!());
self.generate_anonymous_missing_child(consecutive_siblings, flow, node);
}
self.generate_anonymous_table_flows_if_necessary(flow, &mut kid_flow, &kid);
flow.add_new_child(kid_flow);
}
abs_descendants.push_descendants(kid_abs_descendants);
}
ConstructionResult::ConstructionItem(ConstructionItem::InlineFragments(
InlineFragmentsConstructionResult {
splits,
fragments: successor_fragments,
})) => {
// Add any {ib} splits.
for split in splits {
// Pull apart the {ib} split object and push its predecessor fragments
// onto the list.
let InlineBlockSplit {
predecessors,
flow: kid_flow
} = split;
inline_fragment_accumulator.push_all(predecessors);
// Flush any inline fragments that we were gathering up.
debug!("flushing {} inline box(es) to flow A",
inline_fragment_accumulator.fragments.fragments.len());
let old_inline_fragment_accumulator =
mem::replace(inline_fragment_accumulator,
InlineFragmentsAccumulator::new());
self.flush_inline_fragments_to_flow_or_list(
old_inline_fragment_accumulator,
flow,
consecutive_siblings,
&mut inline_fragment_accumulator.fragments.absolute_descendants,
node);
// Push the flow generated by the {ib} split onto our list of
// flows.
if flow.need_anonymous_flow(&*kid_flow) {
consecutive_siblings.push(kid_flow)
} else {
flow.add_new_child(kid_flow)
}
}
// Add the fragments to the list we're maintaining.
inline_fragment_accumulator.push_all(successor_fragments);
}
ConstructionResult::ConstructionItem(ConstructionItem::Whitespace(
whitespace_node,
whitespace_pseudo,
mut whitespace_style,
whitespace_damage)) => {
// Add whitespace results. They will be stripped out later on when
// between block elements, and retained when between inline elements.
let fragment_info = SpecificFragmentInfo::UnscannedText(
box UnscannedTextFragmentInfo::new(" ".to_owned(), None));
properties::modify_style_for_replaced_content(&mut whitespace_style);
properties::modify_style_for_text(&mut whitespace_style);
let style_context = self.style_context();
let fragment = Fragment::from_opaque_node_and_style(whitespace_node,
whitespace_pseudo,
whitespace_style,
node.selected_style(style_context).clone(),
whitespace_damage,
fragment_info);
inline_fragment_accumulator.fragments.fragments.push_back(fragment);
}
ConstructionResult::ConstructionItem(ConstructionItem::TableColumnFragment(_)) => {
// TODO: Implement anonymous table objects for missing parents
// CSS 2.1 § 17.2.1, step 3-2
}
}
}
/// Constructs a block flow, beginning with the given `initial_fragments` if present and then
/// appending the construction results of children to the child list of the block flow. {ib}
/// splits and absolutely-positioned descendants are handled correctly.
fn build_flow_for_block_starting_with_fragments(
&mut self,
mut flow: FlowRef,
node: &ConcreteThreadSafeLayoutNode,
initial_fragments: IntermediateInlineFragments)
-> ConstructionResult {
// Gather up fragments for the inline flows we might need to create.
let mut inline_fragment_accumulator = InlineFragmentsAccumulator::new();
let mut consecutive_siblings = vec!();
inline_fragment_accumulator.fragments.push_all(initial_fragments);
// List of absolute descendants, in tree order.
let mut abs_descendants = AbsoluteDescendants::new();
if !node.is_replaced_content() {
for kid in node.children() {
if kid.get_pseudo_element_type() != PseudoElementType::Normal {
self.process(&kid);
}
self.build_block_flow_using_construction_result_of_child(
&mut flow,
&mut consecutive_siblings,
node,
kid,
&mut inline_fragment_accumulator,
&mut abs_descendants);
}
}
// Perform a final flush of any inline fragments that we were gathering up to handle {ib}
// splits, after stripping ignorable whitespace.
self.flush_inline_fragments_to_flow_or_list(inline_fragment_accumulator,
&mut flow,
&mut consecutive_siblings,
&mut abs_descendants,
node);
if !consecutive_siblings.is_empty() {
self.generate_anonymous_missing_child(consecutive_siblings, &mut flow, node);
}
// The flow is done.
flow.finish();
// Set up the absolute descendants.
let contains_positioned_fragments = flow.contains_positioned_fragments();
let is_absolutely_positioned = flow::base(&*flow).flags.contains(IS_ABSOLUTELY_POSITIONED);
if contains_positioned_fragments {
// This is the containing block for all the absolute descendants.
flow.set_absolute_descendants(abs_descendants);
abs_descendants = AbsoluteDescendants::new();
if is_absolutely_positioned {
// This is now the only absolute flow in the subtree which hasn't yet
// reached its CB.
abs_descendants.push(flow.clone());
}
}
ConstructionResult::Flow(flow, abs_descendants)
}
/// Constructs a flow for the given block node and its children. This method creates an
/// initial fragment as appropriate and then dispatches to
/// `build_flow_for_block_starting_with_fragments`. Currently the following kinds of flows get
/// initial content:
///
/// * Generated content gets the initial content specified by the `content` attribute of the
/// CSS.
/// * `<input>` and `<textarea>` elements get their content.
///
/// FIXME(pcwalton): It is not clear to me that there isn't a cleaner way to handle
/// `<textarea>`.
fn build_flow_for_block_like(&mut self, flow: FlowRef, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let mut initial_fragments = IntermediateInlineFragments::new();
let node_is_input_or_text_area =
node.type_id() == Some(LayoutNodeType::Element(LayoutElementType::HTMLInputElement)) ||
node.type_id() == Some(LayoutNodeType::Element(LayoutElementType::HTMLTextAreaElement));
if node.get_pseudo_element_type().is_replaced_content() ||
node_is_input_or_text_area {
// A TextArea's text contents are displayed through the input text
// box, so don't construct them.
if node.type_id() == Some(LayoutNodeType::Element(LayoutElementType::HTMLTextAreaElement)) {
for kid in node.children() {
self.set_flow_construction_result(&kid, ConstructionResult::None)
}
}
let mut style = node.style(self.style_context()).clone();
if node_is_input_or_text_area {
style = self.style_context().stylist.
precomputed_values_for_pseudo(&PseudoElement::ServoInputText, Some(&style)).unwrap();
}
self.create_fragments_for_node_text_content(&mut initial_fragments, node, &style)
}
self.build_flow_for_block_starting_with_fragments(flow, node, initial_fragments)
}
/// Pushes fragments appropriate for the content of the given node onto the given list.
fn create_fragments_for_node_text_content(&self,
fragments: &mut IntermediateInlineFragments,
node: &ConcreteThreadSafeLayoutNode,
style: &Arc<ServoComputedValues>) {
// Fast path: If there is no text content, return immediately.
let text_content = node.text_content();
if text_content.is_empty() {
return
}
let mut style = (*style).clone();
match node.get_pseudo_element_type() {
PseudoElementType::Before(_) |
PseudoElementType::After(_) => {}
_ => properties::modify_style_for_text(&mut style)
}
let selected_style = node.selected_style(self.style_context());
match text_content {
TextContent::Text(string) => {
let info = box UnscannedTextFragmentInfo::new(string, node.selection());
let specific_fragment_info = SpecificFragmentInfo::UnscannedText(info);
fragments.fragments.push_back(Fragment::from_opaque_node_and_style(
node.opaque(),
node.get_pseudo_element_type().strip(),
style,
selected_style.clone(),
node.restyle_damage(),
specific_fragment_info))
}
TextContent::GeneratedContent(content_items) => {
for content_item in content_items.into_iter() {
let specific_fragment_info = match content_item {
ContentItem::String(string) => {
let info = box UnscannedTextFragmentInfo::new(string, None);
SpecificFragmentInfo::UnscannedText(info)
}
content_item => {
let content_item = box GeneratedContentInfo::ContentItem(content_item);
SpecificFragmentInfo::GeneratedContent(content_item)
}
};
fragments.fragments.push_back(Fragment::from_opaque_node_and_style(
node.opaque(),
node.get_pseudo_element_type().strip(),
style.clone(),
selected_style.clone(),
node.restyle_damage(),
specific_fragment_info))
}
}
}
}
/// Builds a flow for a node with `display: block`. This yields a `BlockFlow` with possibly
/// other `BlockFlow`s or `InlineFlow`s underneath it, depending on whether {ib} splits needed
/// to happen.
fn build_flow_for_block(&mut self, node: &ConcreteThreadSafeLayoutNode, float_kind: Option<FloatKind>)
-> ConstructionResult {
if node.style(self.style_context()).is_multicol() {
return self.build_flow_for_multicol(node, float_kind)
}
let flow: FlowRef = Arc::new(
BlockFlow::from_fragment(self.build_fragment_for_block(node), float_kind));
self.build_flow_for_block_like(flow, node)
}
/// Bubbles up {ib} splits.
fn accumulate_inline_block_splits(&mut self,
splits: LinkedList<InlineBlockSplit>,
node: &ConcreteThreadSafeLayoutNode,
fragment_accumulator: &mut InlineFragmentsAccumulator,
opt_inline_block_splits: &mut LinkedList<InlineBlockSplit>) {
for split in splits {
let InlineBlockSplit {
predecessors,
flow: kid_flow
} = split;
fragment_accumulator.push_all(predecessors);
let split = InlineBlockSplit {
predecessors: mem::replace(
fragment_accumulator,
InlineFragmentsAccumulator::from_inline_node(
node, self.style_context())).to_intermediate_inline_fragments(),
flow: kid_flow,
};
opt_inline_block_splits.push_back(split)
}
}
/// Concatenates the fragments of kids, adding in our own borders/padding/margins if necessary.
/// Returns the `InlineFragmentsConstructionResult`, if any. There will be no
/// `InlineFragmentsConstructionResult` if this node consisted entirely of ignorable
/// whitespace.
fn build_fragments_for_nonreplaced_inline_content(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let mut opt_inline_block_splits: LinkedList<InlineBlockSplit> = LinkedList::new();
let mut fragment_accumulator = InlineFragmentsAccumulator::from_inline_node(node, self.style_context());
fragment_accumulator.bidi_control_chars = bidi_control_chars(&*node.style(self.style_context()));
let mut abs_descendants = AbsoluteDescendants::new();
// Concatenate all the fragments of our kids, creating {ib} splits as necessary.
let mut is_empty = true;
for kid in node.children() {
is_empty = false;
if kid.get_pseudo_element_type() != PseudoElementType::Normal {
self.process(&kid);
}
match kid.swap_out_construction_result() {
ConstructionResult::None => {}
ConstructionResult::Flow(flow, kid_abs_descendants) => {
if !flow::base(&*flow).flags.contains(IS_ABSOLUTELY_POSITIONED) {
// {ib} split. Flush the accumulator to our new split and make a new
// accumulator to hold any subsequent fragments we come across.
let split = InlineBlockSplit {
predecessors:
mem::replace(
&mut fragment_accumulator,
InlineFragmentsAccumulator::from_inline_node(
node, self.style_context())).to_intermediate_inline_fragments(),
flow: flow,
};
opt_inline_block_splits.push_back(split);
abs_descendants.push_descendants(kid_abs_descendants);
} else {
// Push the absolutely-positioned kid as an inline containing block.
let kid_node = flow.as_block().fragment.node;
let kid_pseudo = flow.as_block().fragment.pseudo.clone();
let kid_style = flow.as_block().fragment.style.clone();
let kid_selected_style = flow.as_block().fragment.selected_style.clone();
let kid_restyle_damage = flow.as_block().fragment.restyle_damage;
let fragment_info = SpecificFragmentInfo::InlineAbsolute(
InlineAbsoluteFragmentInfo::new(flow));
fragment_accumulator.push(Fragment::from_opaque_node_and_style(
kid_node,
kid_pseudo,
kid_style,
kid_selected_style,
kid_restyle_damage,
fragment_info));
fragment_accumulator.fragments
.absolute_descendants
.push_descendants(kid_abs_descendants);
}
}
ConstructionResult::ConstructionItem(ConstructionItem::InlineFragments(
InlineFragmentsConstructionResult {
splits,
fragments: successors,
})) => {
// Bubble up {ib} splits.
self.accumulate_inline_block_splits(splits,
node,
&mut fragment_accumulator,
&mut opt_inline_block_splits);
// Push residual fragments.
fragment_accumulator.push_all(successors);
}
ConstructionResult::ConstructionItem(ConstructionItem::Whitespace(
whitespace_node,
whitespace_pseudo,
mut whitespace_style,
whitespace_damage)) => {
// Instantiate the whitespace fragment.
let fragment_info = SpecificFragmentInfo::UnscannedText(
box UnscannedTextFragmentInfo::new(" ".to_owned(), None));
properties::modify_style_for_replaced_content(&mut whitespace_style);
properties::modify_style_for_text(&mut whitespace_style);
let fragment =
Fragment::from_opaque_node_and_style(whitespace_node,
whitespace_pseudo,
whitespace_style,
node.selected_style(self.style_context()).clone(),
whitespace_damage,
fragment_info);
fragment_accumulator.fragments.fragments.push_back(fragment)
}
ConstructionResult::ConstructionItem(ConstructionItem::TableColumnFragment(_)) => {
// TODO: Implement anonymous table objects for missing parents
// CSS 2.1 § 17.2.1, step 3-2
}
}
}
let node_style = node.style(self.style_context());
if is_empty && node_style.has_padding_or_border() {
// An empty inline box needs at least one fragment to draw its background and borders.
let info = SpecificFragmentInfo::UnscannedText(
box UnscannedTextFragmentInfo::new(String::new(), None));
let mut modified_style = node_style.clone();
properties::modify_style_for_replaced_content(&mut modified_style);
properties::modify_style_for_text(&mut modified_style);
let fragment = Fragment::from_opaque_node_and_style(node.opaque(),
node.get_pseudo_element_type().strip(),
modified_style,
node.selected_style(self.style_context()).clone(),
node.restyle_damage(),
info);
fragment_accumulator.fragments.fragments.push_back(fragment)
}
// Finally, make a new construction result.
if opt_inline_block_splits.len() > 0 || !fragment_accumulator.fragments.is_empty()
|| abs_descendants.len() > 0 {
fragment_accumulator.fragments.absolute_descendants.push_descendants(abs_descendants);
// If the node is positioned, then it's the containing block for all absolutely-
// positioned descendants.
if node_style.get_box().position != position::T::static_ {
fragment_accumulator.fragments
.absolute_descendants
.mark_as_having_reached_containing_block();
}
let construction_item = ConstructionItem::InlineFragments(
InlineFragmentsConstructionResult {
splits: opt_inline_block_splits,
fragments: fragment_accumulator.to_intermediate_inline_fragments(),
});
ConstructionResult::ConstructionItem(construction_item)
} else {
ConstructionResult::None
}
}
/// Creates an `InlineFragmentsConstructionResult` for replaced content. Replaced content
/// doesn't render its children, so this just nukes a child's fragments and creates a
/// `Fragment`.
fn build_fragments_for_replaced_inline_content(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
for kid in node.children() {
self.set_flow_construction_result(&kid, ConstructionResult::None)
}
// If this node is ignorable whitespace, bail out now.
if node.is_ignorable_whitespace(self.style_context()) {
return ConstructionResult::ConstructionItem(ConstructionItem::Whitespace(
node.opaque(),
node.get_pseudo_element_type().strip(),
node.style(self.style_context()).clone(),
node.restyle_damage()))
}
// Modify the style as necessary. (See the comment in
// `properties::modify_style_for_replaced_content()`.)
let mut style = node.style(self.style_context()).clone();
match node.get_pseudo_element_type() {
PseudoElementType::Before(_) |
PseudoElementType::After(_) => {}
_ => properties::modify_style_for_replaced_content(&mut style)
}
// If this is generated content, then we need to initialize the accumulator with the
// fragment corresponding to that content. Otherwise, just initialize with the ordinary
// fragment that needs to be generated for this inline node.
let mut fragments = IntermediateInlineFragments::new();
match (node.get_pseudo_element_type(), node.type_id()) {
(_, Some(LayoutNodeType::Text)) => {
self.create_fragments_for_node_text_content(&mut fragments, node, &style)
}
(PseudoElementType::Normal, _) => {
fragments.fragments.push_back(self.build_fragment_for_block(node));
}
(_, _) => self.create_fragments_for_node_text_content(&mut fragments, node, &style),
}
let construction_item =
ConstructionItem::InlineFragments(InlineFragmentsConstructionResult {
splits: LinkedList::new(),
fragments: fragments,
});
ConstructionResult::ConstructionItem(construction_item)
}
fn build_fragment_for_inline_block(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let block_flow_result = self.build_flow_for_block(node, None);
let (block_flow, abs_descendants) = match block_flow_result {
ConstructionResult::Flow(block_flow, abs_descendants) => (block_flow, abs_descendants),
_ => unreachable!()
};
let style_context = self.style_context();
let mut modified_style = (*node.style(self.style_context())).clone();
properties::modify_style_for_outer_inline_block_fragment(&mut modified_style);
let fragment_info = SpecificFragmentInfo::InlineBlock(InlineBlockFragmentInfo::new(
block_flow));
let fragment = Fragment::from_opaque_node_and_style(node.opaque(),