/* 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/. */
#![deny(unsafe_code)]
use ServoArc;
use app_units::{Au, MIN_AU};
use block::AbsoluteAssignBSizesTraversal;
use context::{LayoutContext, LayoutFontContext};
use display_list::{DisplayListBuildState, InlineFlowDisplayListBuilding};
use display_list::StackingContextCollectionState;
use euclid::{Point2D, Size2D};
use floats::{FloatKind, Floats, PlacementInfo};
use flow::{BaseFlow, Flow, FlowClass, ForceNonfloatedFlag};
use flow::{FlowFlags, EarlyAbsolutePositionInfo, GetBaseFlow, OpaqueFlow};
use flow_ref::FlowRef;
use fragment::{CoordinateSystem, Fragment, FragmentBorderBoxIterator, Overflow};
use fragment::FragmentFlags;
use fragment::SpecificFragmentInfo;
use gfx::display_list::OpaqueNode;
use gfx::font::FontMetrics;
use gfx_traits::print_tree::PrintTree;
use layout_debug;
use model::IntrinsicISizesContribution;
use range::{Range, RangeIndex};
use script_layout_interface::wrapper_traits::PseudoElementType;
use std::{fmt, i32, isize, mem};
use std::cmp::max;
use std::collections::VecDeque;
use std::sync::Arc;
use style::computed_values::display::T as Display;
use style::computed_values::overflow_x::T as StyleOverflow;
use style::computed_values::position::T as Position;
use style::computed_values::text_align::T as TextAlign;
use style::computed_values::text_justify::T as TextJustify;
use style::computed_values::white_space::T as WhiteSpace;
use style::logical_geometry::{LogicalRect, LogicalSize, WritingMode};
use style::properties::ComputedValues;
use style::servo::restyle_damage::ServoRestyleDamage;
use style::values::computed::box_::VerticalAlign;
use style::values::generics::box_::VerticalAlign as GenericVerticalAlign;
use style::values::specified::text::TextOverflowSide;
use text;
use traversal::PreorderFlowTraversal;
use unicode_bidi as bidi;
/// `Line`s are represented as offsets into the child list, rather than
/// as an object that "owns" fragments. Choosing a different set of line
/// breaks requires a new list of offsets, and possibly some splitting and
/// merging of TextFragments.
///
/// A similar list will keep track of the mapping between CSS fragments and
/// the corresponding fragments in the inline flow.
///
/// After line breaks are determined, render fragments in the inline flow may
/// overlap visually. For example, in the case of nested inline CSS fragments,
/// outer inlines must be at least as large as the inner inlines, for
/// purposes of drawing noninherited things like backgrounds, borders,
/// outlines.
///
/// N.B. roc has an alternative design where the list instead consists of
/// things like "start outer fragment, text, start inner fragment, text, end inner
/// fragment, text, end outer fragment, text". This seems a little complicated to
/// serve as the starting point, but the current design doesn't make it
/// hard to try out that alternative.
///
/// Line fragments also contain some metadata used during line breaking. The
/// green zone is the area that the line can expand to before it collides
/// with a float or a horizontal wall of the containing block. The block-start
/// inline-start corner of the green zone is the same as that of the line, but
/// the green zone can be taller and wider than the line itself.
#[derive(Clone, Debug, Serialize)]
pub struct Line {
/// A range of line indices that describe line breaks.
///
/// For example, consider the following HTML and rendered element with
/// linebreaks:
///
/// ~~~html
/// <span>I <span>like truffles, <img></span> yes I do.</span>
/// ~~~
///
/// ~~~text
/// +------------+
/// | I like |
/// | truffles, |
/// | +----+ |
/// | | | |
/// | +----+ yes |
/// | I do. |
/// +------------+
/// ~~~
///
/// The ranges that describe these lines would be:
///
/// | [0, 2) | [2, 3) | [3, 5) | [5, 6) |
/// |----------|-------------|-------------|----------|
/// | 'I like' | 'truffles,' | '<img> yes' | 'I do.' |
pub range: Range<FragmentIndex>,
/// The bidirectional embedding level runs for this line, in visual order.
///
/// Can be set to `None` if the line is 100% left-to-right.
pub visual_runs: Option<Vec<(Range<FragmentIndex>, bidi::Level)>>,
/// The bounds are the exact position and extents of the line with respect
/// to the parent box.
///
/// For example, for the HTML below...
///
/// ~~~html
/// <div><span>I like truffles, <img></span></div>
/// ~~~
///
/// ...the bounds would be:
///
/// ~~~text
/// +-----------------------------------------------------------+
/// | ^ |
/// | | |
/// | origin.y |
/// | | |
/// | v |
/// |< - origin.x ->+ - - - - - - - - +---------+---- |
/// | | | | ^ |
/// | | | <img> | size.block |
/// | I like truffles, | | v |
/// | + - - - - - - - - +---------+---- |
/// | | | |
/// | |<------ size.inline ------>| |
/// | |
/// | |
/// +-----------------------------------------------------------+
/// ~~~
pub bounds: LogicalRect<Au>,
/// The green zone is the greatest extent from which a line can extend to
/// before it collides with a float.
///
/// ~~~text
/// +-----------------------+
/// |::::::::::::::::: |
/// |:::::::::::::::::FFFFFF|
/// |============:::::FFFFFF|
/// |:::::::::::::::::FFFFFF|
/// |:::::::::::::::::FFFFFF|
/// |::::::::::::::::: |
/// | FFFFFFFFF |
/// | FFFFFFFFF |
/// | FFFFFFFFF |
/// | |
/// +-----------------------+
///
/// === line
/// ::: green zone
/// FFF float
/// ~~~
pub green_zone: LogicalSize<Au>,
/// The minimum metrics for this line, as specified by the style.
pub minimum_metrics: LineMetrics,
/// The actual metrics for this line.
pub metrics: LineMetrics,
}
impl Line {
fn new(writing_mode: WritingMode, minimum_metrics: &LineMetrics) -> Line {
Line {
range: Range::empty(),
visual_runs: None,
bounds: LogicalRect::zero(writing_mode),
green_zone: LogicalSize::zero(writing_mode),
minimum_metrics: *minimum_metrics,
metrics: *minimum_metrics,
}
}
/// Returns the new metrics that this line would have if `new_fragment` were added to it.
///
/// FIXME(pcwalton): this assumes that the tallest fragment in the line determines the line
/// block-size. This might not be the case with some weird text fonts.
fn new_metrics_for_fragment(&self, new_fragment: &Fragment, layout_context: &LayoutContext)
-> LineMetrics {
if !new_fragment.is_vertically_aligned_to_top_or_bottom() {
let fragment_inline_metrics =
new_fragment.aligned_inline_metrics(layout_context, &self.minimum_metrics, None);
self.metrics.new_metrics_for_fragment(&fragment_inline_metrics)
} else {
self.metrics
}
}
/// Returns the new block size that this line would have if `new_fragment` were added to it.
/// `new_inline_metrics` represents the new inline metrics that this line would have; it can
/// be computed with `new_inline_metrics()`.
fn new_block_size_for_fragment(&self,
new_fragment: &Fragment,
new_line_metrics: &LineMetrics,
layout_context: &LayoutContext)
-> Au {
let new_block_size = if new_fragment.is_vertically_aligned_to_top_or_bottom() {
max(new_fragment.aligned_inline_metrics(layout_context, &self.minimum_metrics, None)
.space_needed(),
self.minimum_metrics.space_needed())
} else {
new_line_metrics.space_needed()
};
max(self.bounds.size.block, new_block_size)
}
}
int_range_index! {
#[derive(Serialize)]
#[doc = "The index of a fragment in a flattened vector of DOM elements."]
struct FragmentIndex(isize)
}
/// Arranges fragments into lines, splitting them up as necessary.
struct LineBreaker {
/// The floats we need to flow around.
floats: Floats,
/// The resulting fragment list for the flow, consisting of possibly-broken fragments.
new_fragments: Vec<Fragment>,
/// The next fragment or fragments that we need to work on.
work_list: VecDeque<Fragment>,
/// The line we're currently working on.
pending_line: Line,
/// The lines we've already committed.
lines: Vec<Line>,
/// The index of the last known good line breaking opportunity. The opportunity will either
/// be inside this fragment (if it is splittable) or immediately prior to it.
last_known_line_breaking_opportunity: Option<FragmentIndex>,
/// The current position in the block direction.
cur_b: Au,
/// The computed value of the indentation for the first line (`text-indent`, CSS 2.1 § 16.1).
first_line_indentation: Au,
/// The minimum metrics for each line, as specified by the line height and font style.
minimum_metrics: LineMetrics,
}
impl LineBreaker {
/// Creates a new `LineBreaker` with a set of floats and the indentation of the first line.
fn new(float_context: Floats, first_line_indentation: Au, minimum_line_metrics: &LineMetrics)
-> LineBreaker {
LineBreaker {
new_fragments: Vec::new(),
work_list: VecDeque::new(),
pending_line: Line::new(float_context.writing_mode, minimum_line_metrics),
floats: float_context,
lines: Vec::new(),
cur_b: Au(0),
last_known_line_breaking_opportunity: None,
first_line_indentation: first_line_indentation,
minimum_metrics: *minimum_line_metrics,
}
}
/// Resets the `LineBreaker` to the initial state it had after a call to `new`.
fn reset_scanner(&mut self) {
self.lines = Vec::new();
self.new_fragments = Vec::new();
self.cur_b = Au(0);
self.reset_line();
}
/// Reinitializes the pending line to blank data.
fn reset_line(&mut self) -> Line {
self.last_known_line_breaking_opportunity = None;
mem::replace(&mut self.pending_line,
Line::new(self.floats.writing_mode, &self.minimum_metrics))
}
/// Reflows fragments for the given inline flow.
fn scan_for_lines(&mut self,
flow: &mut InlineFlow,
layout_context: &LayoutContext) {
self.reset_scanner();
// Create our fragment iterator.
debug!("LineBreaker: scanning for lines, {} fragments", flow.fragments.len());
let mut old_fragments = mem::replace(&mut flow.fragments, InlineFragments::new());
let old_fragment_iter = old_fragments.fragments.into_iter();
// TODO(pcwalton): This would likely be better as a list of dirty line
// indices. That way we could resynchronize if we discover during reflow
// that all subsequent fragments must have the same position as they had
// in the previous reflow. I don't know how common this case really is
// in practice, but it's probably worth handling.
self.lines = Vec::new();
// Do the reflow.
self.reflow_fragments(old_fragment_iter, flow, layout_context);
// Perform unicode bidirectional layout.
let para_level = flow.base.writing_mode.to_bidi_level();
// The text within a fragment is at a single bidi embedding level
// (because we split fragments on level run boundaries during flow
// construction), so we can build a level array with just one entry per
// fragment.
let levels: Vec<bidi::Level> = self.new_fragments.iter().map(
|fragment| match fragment.specific {
SpecificFragmentInfo::ScannedText(ref info) => info.run.bidi_level,
_ => para_level
}
).collect();
let mut lines = mem::replace(&mut self.lines, Vec::new());
// If everything is LTR, don't bother with reordering.
if bidi::level::has_rtl(&levels) {
// Compute and store the visual ordering of the fragments within the
// line.
for line in &mut lines {
let range = line.range.begin().to_usize()..line.range.end().to_usize();
// FIXME: Update to use BidiInfo::visual_runs, as this algorithm needs access to
// the original text and original BidiClass of its characters.
#[allow(deprecated)]
let runs = bidi::deprecated::visual_runs(range, &levels);
line.visual_runs = Some(runs.iter().map(|run| {
let start = FragmentIndex(run.start as isize);
let len = FragmentIndex(run.len() as isize);
(Range::new(start, len), levels[run.start])
}).collect());
}
}
// Place the fragments back into the flow.
old_fragments.fragments = mem::replace(&mut self.new_fragments, vec![]);
flow.fragments = old_fragments;
flow.lines = lines;
}
/// Reflows the given fragments, which have been plucked out of the inline flow.
fn reflow_fragments<'a, I>(&mut self,
mut old_fragment_iter: I,
flow: &'a InlineFlow,
layout_context: &LayoutContext)
where I: Iterator<Item=Fragment>,
{
loop {
// Acquire the next fragment to lay out from the work list or fragment list, as
// appropriate.
let fragment = match self.next_unbroken_fragment(&mut old_fragment_iter) {
None => break,
Some(fragment) => fragment,
};
// Do not reflow truncated fragments. Reflow the original fragment only.
let fragment = if fragment.flags.contains(FragmentFlags::IS_ELLIPSIS) {
continue
} else if let SpecificFragmentInfo::TruncatedFragment(info) = fragment.specific {
info.full
} else {
fragment
};
// Try to append the fragment.
self.reflow_fragment(fragment, flow, layout_context);
}
if !self.pending_line_is_empty() {
debug!("LineBreaker: partially full line {} at end of scanning; committing it",
self.lines.len());
self.flush_current_line()
}
}
/// Acquires a new fragment to lay out from the work list or fragment list as appropriate.
/// Note that you probably don't want to call this method directly in order to be incremental-
/// reflow-safe; try `next_unbroken_fragment` instead.
fn next_fragment<I>(&mut self,
old_fragment_iter: &mut I)
-> Option<Fragment>
where I: Iterator<Item=Fragment>,
{
self.work_list.pop_front().or_else(|| old_fragment_iter.next())
}
/// Acquires a new fragment to lay out from the work list or fragment list,
/// merging it with any subsequent fragments as appropriate. In effect, what
/// this method does is to return the next fragment to lay out, undoing line
/// break operations that any previous reflows may have performed. You
/// probably want to be using this method instead of `next_fragment`.
fn next_unbroken_fragment<I>(&mut self,
old_fragment_iter: &mut I)
-> Option<Fragment>
where I: Iterator<Item=Fragment>,
{
let mut result = self.next_fragment(old_fragment_iter)?;
loop {
let candidate = match self.next_fragment(old_fragment_iter) {
None => return Some(result),
Some(fragment) => fragment,
};
let need_to_merge = match (&mut result.specific, &candidate.specific) {
(&mut SpecificFragmentInfo::ScannedText(ref mut result_info),
&SpecificFragmentInfo::ScannedText(ref candidate_info)) => {
result.margin.inline_end == Au(0) &&
candidate.margin.inline_start == Au(0) &&
result.border_padding.inline_end == Au(0) &&
candidate.border_padding.inline_start == Au(0) &&
result_info.selected() == candidate_info.selected() &&
Arc::ptr_eq(&result_info.run, &candidate_info.run) &&
inline_contexts_are_equal(&result.inline_context,
&candidate.inline_context)
}
_ => false,
};
if need_to_merge {
result.merge_with(candidate);
continue
}
self.work_list.push_front(candidate);
return Some(result)
}
}
/// Commits a line to the list.
fn flush_current_line(&mut self) {
debug!("LineBreaker: flushing line {}: {:?}", self.lines.len(), self.pending_line);
self.strip_trailing_whitespace_from_pending_line_if_necessary();
self.lines.push(self.pending_line.clone());
self.cur_b = self.pending_line.bounds.start.b + self.pending_line.bounds.size.block;
self.reset_line();
}
/// Removes trailing whitespace from the pending line if necessary. This is done right before
/// flushing it.
fn strip_trailing_whitespace_from_pending_line_if_necessary(&mut self) {
if self.pending_line.range.is_empty() {
return
}
let last_fragment_index = self.pending_line.range.end() - FragmentIndex(1);
let fragment = &mut self.new_fragments[last_fragment_index.get() as usize];
let old_fragment_inline_size = fragment.border_box.size.inline;
fragment.strip_trailing_whitespace_if_necessary();
self.pending_line.bounds.size.inline +=
fragment.border_box.size.inline - old_fragment_inline_size;
}
/// Computes the position of a line that has only the provided fragment. Returns the bounding
/// rect of the line's green zone (whose origin coincides with the line's origin) and the
/// actual inline-size of the first fragment after splitting.
fn initial_line_placement(&self,
flow: &InlineFlow,
first_fragment: &Fragment,
ceiling: Au)
-> (LogicalRect<Au>, Au) {
debug!("LineBreaker: trying to place first fragment of line {}; fragment size: {:?}, \
splittable: {}",
self.lines.len(),
first_fragment.border_box.size,
first_fragment.can_split());
// Initially, pretend a splittable fragment has zero inline-size. We will move it later if
// it has nonzero inline-size and that causes problems.
let placement_inline_size = if first_fragment.can_split() {
first_fragment.minimum_splittable_inline_size()
} else {
first_fragment.margin_box_inline_size() + self.indentation_for_pending_fragment()
};
// Try to place the fragment between floats.
let line_bounds = self.floats.place_between_floats(&PlacementInfo {
size: LogicalSize::new(self.floats.writing_mode,
placement_inline_size,
first_fragment.border_box.size.block),
ceiling: ceiling,
max_inline_size: flow.base.position.size.inline,
kind: FloatKind::Left,
});
let fragment_margin_box_inline_size = first_fragment.margin_box_inline_size();
// Simple case: if the fragment fits, then we can stop here.
if line_bounds.size.inline > fragment_margin_box_inline_size {
debug!("LineBreaker: fragment fits on line {}", self.lines.len());
return (line_bounds, fragment_margin_box_inline_size);
}
// If not, but we can't split the fragment, then we'll place the line here and it will
// overflow.
if !first_fragment.can_split() {
debug!("LineBreaker: line doesn't fit, but is unsplittable");
}
(line_bounds, fragment_margin_box_inline_size)
}
/// Performs float collision avoidance. This is called when adding a fragment is going to
/// increase the block-size, and because of that we will collide with some floats.
///
/// We have two options here:
/// 1) Move the entire line so that it doesn't collide any more.
/// 2) Break the line and put the new fragment on the next line.
///
/// The problem with option 1 is that we might move the line and then wind up breaking anyway,
/// which violates the standard. But option 2 is going to look weird sometimes.
///
/// So we'll try to move the line whenever we can, but break if we have to.
///
/// Returns false if and only if we should break the line.
fn avoid_floats(&mut self,
flow: &InlineFlow,
in_fragment: Fragment,
new_block_size: Au)
-> bool {
debug!("LineBreaker: entering float collision avoider!");
// First predict where the next line is going to be.
let (next_line, first_fragment_inline_size) =
self.initial_line_placement(flow,
&in_fragment,
self.pending_line.bounds.start.b);
let next_green_zone = next_line.size;
let new_inline_size = self.pending_line.bounds.size.inline + first_fragment_inline_size;
// Now, see if everything can fit at the new location.
if next_green_zone.inline >= new_inline_size && next_green_zone.block >= new_block_size {
debug!("LineBreaker: case=adding fragment collides vertically with floats: moving \
line");
self.pending_line.bounds.start = next_line.start;
self.pending_line.green_zone = next_green_zone;
debug_assert!(!self.pending_line_is_empty(), "Non-terminating line breaking");
self.work_list.push_front(in_fragment);
return true
}
debug!("LineBreaker: case=adding fragment collides vertically with floats: breaking line");
self.work_list.push_front(in_fragment);
false
}
/// Tries to append the given fragment to the line, splitting it if necessary. Commits the
/// current line if needed.
fn reflow_fragment(&mut self,
mut fragment: Fragment,
flow: &InlineFlow,
layout_context: &LayoutContext) {
// Undo any whitespace stripping from previous reflows.
fragment.reset_text_range_and_inline_size();
// Determine initial placement for the fragment if we need to.
//
// Also, determine whether we can legally break the line before, or
// inside, this fragment.
let fragment_is_line_break_opportunity = if self.pending_line_is_empty() {
fragment.strip_leading_whitespace_if_necessary();
let (line_bounds, _) = self.initial_line_placement(flow, &fragment, self.cur_b);
self.pending_line.bounds.start = line_bounds.start;
self.pending_line.green_zone = line_bounds.size;
false
} else {
// In case of Foo<span style="...">bar</span>, the line breaker will
// set the "suppress line break before" flag for the second fragment.
//
// In case of Foo<span>bar</span> the second fragment ("bar") will
// start _within_ a glyph run, so we also avoid breaking there
//
// is_on_glyph_run_boundary does a binary search, but this is ok
// because the result will be cached and reused in
// `calculate_split_position` later
if fragment.suppress_line_break_before() ||
!fragment.is_on_glyph_run_boundary() {
false
} else {
fragment.white_space().allow_wrap()
}
};
debug!("LineBreaker: trying to append to line {} \
(fragment size: {:?}, green zone: {:?}): {:?}",
self.lines.len(),
fragment.border_box.size,
self.pending_line.green_zone,
fragment);
// NB: At this point, if `green_zone.inline <
// self.pending_line.bounds.size.inline` or `green_zone.block <
// self.pending_line.bounds.size.block`, then we committed a line that
// overlaps with floats.
let green_zone = self.pending_line.green_zone;
let new_line_metrics = self.pending_line.new_metrics_for_fragment(&fragment,
layout_context);
let new_block_size = self.pending_line.new_block_size_for_fragment(&fragment,
&new_line_metrics,
layout_context);
if new_block_size > green_zone.block {
// Uh-oh. Float collision imminent. Enter the float collision avoider!
if !self.avoid_floats(flow, fragment, new_block_size) {
self.flush_current_line();
}
return
}
// Record the last known good line break opportunity if this is one.
if fragment_is_line_break_opportunity {
self.last_known_line_breaking_opportunity = Some(self.pending_line.range.end())
}
// If we must flush the line after finishing this fragment due to `white-space: pre`,
// detect that.
let line_flush_mode = if fragment.white_space().preserve_newlines() {
if fragment.requires_line_break_afterward_if_wrapping_on_newlines() {
LineFlushMode::Flush
} else {
LineFlushMode::No
}
} else {
LineFlushMode::No
};
// If we're not going to overflow the green zone vertically, we might still do so
// horizontally. We'll try to place the whole fragment on this line and break somewhere if
// it doesn't fit.
let indentation = self.indentation_for_pending_fragment();
let new_inline_size = self.pending_line.bounds.size.inline +
fragment.margin_box_inline_size() + indentation;
if new_inline_size <= green_zone.inline {
debug!("LineBreaker: fragment fits without splitting");
self.push_fragment_to_line(layout_context, fragment, line_flush_mode);
return
}
// If the wrapping mode prevents us from splitting, then back up and split at the last
// known good split point.
if !fragment.white_space().allow_wrap() {
debug!("LineBreaker: fragment can't split; falling back to last known good split point");
self.split_line_at_last_known_good_position(layout_context, fragment, line_flush_mode);
return;
}
// Split it up!
let available_inline_size = green_zone.inline -
self.pending_line.bounds.size.inline -
indentation;
let inline_start_fragment;
let inline_end_fragment;
let split_result = match fragment.calculate_split_position(available_inline_size,
self.pending_line_is_empty()) {
None => {
// We failed to split. Defer to the next line if we're allowed to; otherwise,
// rewind to the last line breaking opportunity.
if fragment_is_line_break_opportunity {
debug!("LineBreaker: fragment was unsplittable; deferring to next line");
self.work_list.push_front(fragment);
self.flush_current_line();
} else {
self.split_line_at_last_known_good_position(layout_context,
fragment,
LineFlushMode::No);
}
return
}
Some(split_result) => split_result,
};
inline_start_fragment = split_result.inline_start.as_ref().map(|x| {
fragment.transform_with_split_info(x, split_result.text_run.clone(), true)
});
inline_end_fragment = split_result.inline_end.as_ref().map(|x| {
fragment.transform_with_split_info(x, split_result.text_run.clone(), false)
});
// Push the first fragment onto the line we're working on and start off the next line with
// the second fragment. If there's no second fragment, the next line will start off empty.
match (inline_start_fragment, inline_end_fragment) {
(Some(mut inline_start_fragment), Some(mut inline_end_fragment)) => {
inline_start_fragment.border_padding.inline_end = Au(0);
if let Some(ref mut inline_context) = inline_start_fragment.inline_context {
for node in &mut inline_context.nodes {
node.flags.remove(InlineFragmentNodeFlags::LAST_FRAGMENT_OF_ELEMENT);
}
}
inline_start_fragment.border_box.size.inline += inline_start_fragment.border_padding.inline_start;
inline_end_fragment.border_padding.inline_start = Au(0);
if let Some(ref mut inline_context) = inline_end_fragment.inline_context {
for node in &mut inline_context.nodes {
node.flags.remove(InlineFragmentNodeFlags::FIRST_FRAGMENT_OF_ELEMENT);
}
}
inline_end_fragment.border_box.size.inline += inline_end_fragment.border_padding.inline_end;
self.push_fragment_to_line(layout_context,
inline_start_fragment,
LineFlushMode::Flush);
self.work_list.push_front(inline_end_fragment)
},
(Some(fragment), None) => {
self.push_fragment_to_line(layout_context, fragment, line_flush_mode);
}
(None, Some(fragment)) => {
// Yes, this can happen!
self.flush_current_line();
self.work_list.push_front(fragment)
}
(None, None) => {}
}
}
/// Pushes a fragment to the current line unconditionally, possibly truncating it and placing
/// an ellipsis based on the value of `text-overflow`. If `flush_line` is `Flush`, then flushes
/// the line afterward;
fn push_fragment_to_line(&mut self,
layout_context: &LayoutContext,
fragment: Fragment,
line_flush_mode: LineFlushMode) {
let indentation = self.indentation_for_pending_fragment();
if self.pending_line_is_empty() {
debug_assert!(self.new_fragments.len() <= (isize::MAX as usize));
self.pending_line.range.reset(FragmentIndex(self.new_fragments.len() as isize),
FragmentIndex(0));
}
// Determine if an ellipsis will be necessary to account for `text-overflow`.
let available_inline_size = self.pending_line.green_zone.inline -
self.pending_line.bounds.size.inline - indentation;
let ellipsis = match (&fragment.style().get_text().text_overflow.second,
fragment.style().get_box().overflow_x) {
(&TextOverflowSide::Clip, _) | (_, StyleOverflow::Visible) => None,
(&TextOverflowSide::Ellipsis, _) => {
if fragment.margin_box_inline_size() > available_inline_size {
Some("…".to_string())
} else {
None
}
},
(&TextOverflowSide::String(ref string), _) => {
if fragment.margin_box_inline_size() > available_inline_size {
Some(string.to_string())
} else {
None
}
}
};
if let Some(string) = ellipsis {
let ellipsis = fragment.transform_into_ellipsis(layout_context, string);
let truncated = fragment.truncate_to_inline_size(available_inline_size -
ellipsis.margin_box_inline_size());
self.push_fragment_to_line_ignoring_text_overflow(truncated, layout_context);
self.push_fragment_to_line_ignoring_text_overflow(ellipsis, layout_context);
} else {
self.push_fragment_to_line_ignoring_text_overflow(fragment, layout_context);
}
if line_flush_mode == LineFlushMode::Flush {
self.flush_current_line()
}
}
/// Pushes a fragment to the current line unconditionally, without placing an ellipsis in the
/// case of `text-overflow: ellipsis`.
fn push_fragment_to_line_ignoring_text_overflow(&mut self,
fragment: Fragment,
layout_context: &LayoutContext) {
let indentation = self.indentation_for_pending_fragment();
self.pending_line.range.extend_by(FragmentIndex(1));
if !fragment.is_inline_absolute() && !fragment.is_hypothetical() {
self.pending_line.bounds.size.inline = self.pending_line.bounds.size.inline +
fragment.margin_box_inline_size() + indentation;
self.pending_line.metrics = self.pending_line.new_metrics_for_fragment(&fragment,
layout_context);
self.pending_line.bounds.size.block =
self.pending_line.new_block_size_for_fragment(&fragment,
&self.pending_line.metrics,
layout_context);
}
self.new_fragments.push(fragment);
}
fn split_line_at_last_known_good_position(&mut self,
layout_context: &LayoutContext,
cur_fragment: Fragment,
line_flush_mode: LineFlushMode) {
let last_known_line_breaking_opportunity =
match self.last_known_line_breaking_opportunity {
None => {
// No line breaking opportunity exists at all for this line. Overflow.
self.push_fragment_to_line(layout_context, cur_fragment, line_flush_mode);
return;
}
Some(last_known_line_breaking_opportunity) => last_known_line_breaking_opportunity,
};
self.work_list.push_front(cur_fragment);
for fragment_index in (last_known_line_breaking_opportunity.get()..
self.pending_line.range.end().get()).rev() {
debug_assert_eq!(fragment_index, (self.new_fragments.len() as isize) - 1);
self.work_list.push_front(self.new_fragments.pop().unwrap());
}
// FIXME(pcwalton): This should actually attempt to split the last fragment if
// possible to do so, to handle cases like:
//
// (available width)
// +-------------+
// The alphabet
// (<em>abcdefghijklmnopqrstuvwxyz</em>)
//
// Here, the last known-good split point is inside the fragment containing
// "The alphabet (", which has already been committed by the time we get to this
// point. Unfortunately, the existing splitting API (`calculate_split_position`)
// has no concept of "split right before the last non-whitespace position". We'll
// need to add that feature to the API to handle this case correctly.
self.pending_line.range.extend_to(last_known_line_breaking_opportunity);
self.flush_current_line();
}
/// Returns the indentation that needs to be applied before the fragment we're reflowing.
fn indentation_for_pending_fragment(&self) -> Au {
if self.pending_line_is_empty() && self.lines.is_empty() {
self.first_line_indentation
} else {
Au(0)
}
}
/// Returns true if the pending line is empty and false otherwise.
fn pending_line_is_empty(&self) -> bool {
self.pending_line.range.length() == FragmentIndex(0)
}
}
/// Represents a list of inline fragments, including element ranges.
#[derive(Clone, Serialize)]
pub struct InlineFragments {
/// The fragments themselves.
pub fragments: Vec<Fragment>,
}
impl InlineFragments {
/// Creates an empty set of inline fragments.
pub fn new() -> InlineFragments {
InlineFragments {
fragments: vec![],
}
}
/// Returns the number of inline fragments.
pub fn len(&self) -> usize {
self.fragments.len()
}
/// Returns true if this list contains no fragments and false if it contains at least one
/// fragment.
pub fn is_empty(&self) -> bool {
self.fragments.is_empty()
}
/// A convenience function to return the fragment at a given index.
pub fn get(&self, index: usize) -> &Fragment {
&self.fragments[index]
}
/// A convenience function to return a mutable reference to the fragment at a given index.
pub fn get_mut(&mut self, index: usize) -> &mut Fragment {
&mut self.fragments[index]
}
}
#[allow(unsafe_code)]
unsafe impl ::flow::HasBaseFlow for InlineFlow {}
/// Flows for inline layout.
#[derive(Serialize)]
#[repr(C)]
pub struct InlineFlow {
/// Data common to all flows.
pub base: BaseFlow,
/// A vector of all inline fragments. Several fragments may correspond to one node/element.
pub fragments: InlineFragments,
/// A vector of ranges into fragments that represents line positions. These ranges are disjoint
/// and are the result of inline layout. This also includes some metadata used for positioning
/// lines.
pub lines: Vec<Line>,
/// The minimum metrics for each line, as specified by the line height and font style.
pub minimum_line_metrics: LineMetrics,
/// The amount of indentation to use on the first line. This is determined by our block parent
/// (because percentages are relative to the containing block, and we aren't in a position to
/// compute things relative to our parent's containing block).
pub first_line_indentation: Au,
}
impl InlineFlow {
pub fn from_fragments(fragments: InlineFragments, writing_mode: WritingMode) -> InlineFlow {
let mut flow = InlineFlow {
base: BaseFlow::new(None, writing_mode, ForceNonfloatedFlag::ForceNonfloated),
fragments: fragments,
lines: Vec::new(),
minimum_line_metrics: LineMetrics::new(Au(0), Au(0)),
first_line_indentation: Au(0),
};
if flow.fragments.fragments.iter().any(Fragment::is_unscanned_generated_content) {
flow.base.restyle_damage.insert(ServoRestyleDamage::RESOLVE_GENERATED_CONTENT);
}
flow
}
/// Sets fragment positions in the inline direction based on alignment for one line. This
/// performs text justification if mandated by the style.
fn set_inline_fragment_positions(fragments: &mut InlineFragments,
line: &Line,
line_align: TextAlign,
indentation: Au,
is_last_line: bool) {
// Figure out how much inline-size we have.
let slack_inline_size = max(Au(0), line.green_zone.inline - line.bounds.size.inline);
// Compute the value we're going to use for `text-justify`.
if fragments.fragments.is_empty() {
return
}
let text_justify = fragments.fragments[0].style().get_inheritedtext().text_justify;
// Translate `left` and `right` to logical directions.
let is_ltr = fragments.fragments[0].style().writing_mode.is_bidi_ltr();
let line_align = match (line_align, is_ltr) {
(TextAlign::Left, true) |
(TextAlign::ServoLeft, true) |
(TextAlign::Right, false) |
(TextAlign::ServoRight, false) => TextAlign::Start,
(TextAlign::Left, false) |
(TextAlign::ServoLeft, false) |
(TextAlign::Right, true) |
(TextAlign::ServoRight, true) => TextAlign::End,
_ => line_align
};
// Set the fragment inline positions based on that alignment, and justify the text if
// necessary.
let mut inline_start_position_for_fragment = line.bounds.start.i + indentation;
match line_align {
TextAlign::Justify if !is_last_line && text_justify != TextJustify::None => {
InlineFlow::justify_inline_fragments(fragments, line, slack_inline_size)
}
TextAlign::Justify | TextAlign::Start => {}
TextAlign::Center | TextAlign::ServoCenter => {
inline_start_position_for_fragment = inline_start_position_for_fragment +
slack_inline_size.scale_by(0.5)
}
TextAlign::End => {
inline_start_position_for_fragment = inline_start_position_for_fragment +
slack_inline_size
}
TextAlign::Left |
TextAlign::ServoLeft |
TextAlign::Right |
TextAlign::ServoRight => unreachable!()
}
// Lay out the fragments in visual order.
let run_count = match line.visual_runs {
Some(ref runs) => runs.len(),
None => 1
};
for run_idx in 0..run_count {
let (range, level) = match line.visual_runs {
Some(ref runs) if is_ltr => runs[run_idx],
Some(ref runs) => runs[run_count - run_idx - 1], // reverse order for RTL runs
None => (line.range, bidi::Level::ltr())
};
struct MaybeReverse<I> {
iter: I,
reverse: bool,
}
impl<I: DoubleEndedIterator> Iterator for MaybeReverse<I> {
type Item = I::Item;
fn next(&mut self) -> Option<I::Item> {
if self.reverse {
self.iter.next_back()
} else {
self.iter.next()
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
// If the bidi embedding direction is opposite the layout direction, lay out this
// run in reverse order.
let fragment_indices = MaybeReverse {
iter: range.begin().get()..range.end().get(),
reverse: level.is_ltr() != is_ltr,
};
for fragment_index in fragment_indices {
let fragment = fragments.get_mut(fragment_index as usize);
inline_start_position_for_fragment = inline_start_position_for_fragment +
fragment.margin.inline_start;
let border_start = if fragment.style.writing_mode.is_bidi_ltr() == is_ltr {
inline_start_position_for_fragment
} else {
line.green_zone.inline - inline_start_position_for_fragment
- fragment.margin.inline_end
- fragment.border_box.size.inline
};
fragment.border_box = LogicalRect::new(fragment.style.writing_mode,
border_start,
fragment.border_box.start.b,
fragment.border_box.size.inline,
fragment.border_box.size.block);
fragment.update_late_computed_inline_position_if_necessary();
if !fragment.is_inline_absolute() {
inline_start_position_for_fragment = inline_start_position_for_fragment +
fragment.border_box.size.inline + fragment.margin.inline_end;
}
}
}
}
/// Justifies the given set of inline fragments, distributing the `slack_inline_size` among all
/// of them according to the value of `text-justify`.
fn justify_inline_fragments(fragments: &mut InlineFragments,
line: &Line,
slack_inline_size: Au) {
// Fast path.
if slack_inline_size == Au(0) {
return
}
// First, calculate the number of expansion opportunities (spaces, normally).
let mut expansion_opportunities = 0;
for fragment_index in line.range.each_index() {
let fragment = fragments.get(fragment_index.to_usize());
let scanned_text_fragment_info = match fragment.specific {
SpecificFragmentInfo::ScannedText(ref info) if !info.range.is_empty() => info,
_ => continue
};
let fragment_range = scanned_text_fragment_info.range;
for slice in scanned_text_fragment_info.run.character_slices_in_range(&fragment_range) {
expansion_opportunities += slice.glyphs.space_count_in_range(&slice.range)
}
}
if expansion_opportunities == 0 {
return
}
// Then distribute all the space across the expansion opportunities.
let space_per_expansion_opportunity = slack_inline_size / expansion_opportunities as i32;
for fragment_index in line.range.each_index() {
let fragment = fragments.get_mut(fragment_index.to_usize());
let scanned_text_fragment_info = match fragment.specific {
SpecificFragmentInfo::ScannedText(ref mut info) if !info.range.is_empty() => info,
_ => continue
};
let fragment_range = scanned_text_fragment_info.range;
let run = Arc::make_mut(&mut scanned_text_fragment_info.run);
run.extra_word_spacing = space_per_expansion_opportunity;
// Recompute the fragment's border box size.
let new_inline_size = run.advance_for_range(&fragment_range);
let new_size = LogicalSize::new(fragment.style.writing_mode,
new_inline_size,
fragment.border_box.size.block);
fragment.border_box = LogicalRect::from_point_size(fragment.style.writing_mode,
fragment.border_box.start,
new_size);
}
}
/// Sets final fragment positions in the block direction for one line.
fn set_block_fragment_positions(fragments: &mut InlineFragments,
line: &Line,
minimum_line_metrics: &LineMetrics,
layout_context: &LayoutContext) {
for fragment_index in line.range.each_index() {
let fragment = fragments.get_mut(fragment_index.to_usize());
let line_metrics = LineMetrics::for_line_and_fragment(line, fragment, layout_context);
let inline_metrics = fragment.aligned_inline_metrics(layout_context,
minimum_line_metrics,
Some(&line_metrics));
// Align the top of the fragment's border box with its ascent above the baseline.
fragment.border_box.start.b = line.bounds.start.b + line_metrics.space_above_baseline -
inline_metrics.ascent;
// CSS 2.1 § 10.8: "The height of each inline-level box in the line box is
// calculated. For replaced elements, inline-block elements, and inline-table
// elements, this is the height of their margin box; for inline boxes, this is their
// 'line-height'."
//
// CSS 2.1 § 10.8.1: "Although margins, borders, and padding of non-replaced elements
// do not enter into the line box calculation, they are still rendered around inline
// boxes."
//
// Effectively, if the fragment is a non-replaced element (excluding inline-block), we
// need to align its ascent above the baseline with the top of the *content box*, not
// the border box. Since the code above has already aligned it to the border box, we
// simply need to adjust it in this case.
if !fragment.is_replaced_or_inline_block() {
fragment.border_box.start.b -= fragment.border_padding.block_start
}
fragment.update_late_computed_block_position_if_necessary();
}
}
/// Computes the minimum metrics for each line. This is done during flow construction.
///
/// `style` is the style of the block.
pub fn minimum_line_metrics(&self, font_context: &mut LayoutFontContext, style: &ComputedValues)
-> LineMetrics {
InlineFlow::minimum_line_metrics_for_fragments(&self.fragments.fragments,
font_context,
style)
}
/// Computes the minimum line metrics for the given fragments. This is typically done during
/// flow construction.
///
/// `style` is the style of the block that these fragments belong to.
pub fn minimum_line_metrics_for_fragments(fragments: &[Fragment],
font_context: &mut LayoutFontContext,
style: &ComputedValues)
-> LineMetrics {
// As a special case, if this flow contains only hypothetical fragments, then the entire
// flow is hypothetical and takes up no space. See CSS 2.1 § 10.3.7.
if fragments.iter().all(Fragment::is_hypothetical) {
return LineMetrics::new(Au(0), Au(0))
}
let font_style = style.clone_font();
let font_metrics = text::font_metrics_for_style(font_context, font_style);
let line_height = text::line_height_from_style(style, &font_metrics);
let inline_metrics = if fragments.iter().any(Fragment::is_text_or_replaced) {
InlineMetrics::from_font_metrics(&font_metrics, line_height)
} else {
InlineMetrics::new(Au(0), Au(0), Au(0))
};
let mut line_metrics = LineMetrics::new(Au(0), MIN_AU);
let mut largest_block_size_for_top_fragments = Au(0);
let mut largest_block_size_for_bottom_fragments = Au(0);
// We use `VerticalAlign::Baseline` here because `vertical-align` must
// not apply to the inside of inline blocks.
update_line_metrics_for_fragment(&mut line_metrics,
&inline_metrics,
style.get_box().display,
GenericVerticalAlign::Baseline,
&mut largest_block_size_for_top_fragments,
&mut largest_block_size_for_bottom_fragments);
// According to CSS 2.1 § 10.8, `line-height` of any inline element specifies the minimal
// height of line boxes within the element.
for inline_context in fragments.iter()
.filter_map(|fragment| fragment.inline_context.as_ref()) {
for node in &inline_context.nodes {
let font_style = node.style.clone_font();
let font_metrics = text::font_metrics_for_style(font_context, font_style);
let line_height = text::line_height_from_style(&*node.style, &font_metrics);
let inline_metrics = InlineMetrics::from_font_metrics(&font_metrics, line_height);
update_line_metrics_for_fragment(&mut line_metrics,
&inline_metrics,
node.style.get_box().display,
node.style.get_box().vertical_align,
&mut largest_block_size_for_top_fragments,
&mut largest_block_size_for_bottom_fragments);
}
}
line_metrics.space_above_baseline =
max(line_metrics.space_above_baseline,
largest_block_size_for_bottom_fragments - max(line_metrics.space_below_baseline,
Au(0)));
line_metrics.space_below_baseline =
max(line_metrics.space_below_baseline,
largest_block_size_for_top_fragments - line_metrics.space_above_baseline);
return line_metrics;
fn update_line_metrics_for_fragment(line_metrics: &mut LineMetrics,
inline_metrics: &InlineMetrics,
display_value: Display,
vertical_align_value: VerticalAlign,
largest_block_size_for_top_fragments: &mut Au,
largest_block_size_for_bottom_fragments: &mut Au) {
match (display_value, vertical_align_value) {
(Display::Inline, GenericVerticalAlign::Top) |
(Display::Block, GenericVerticalAlign::Top) |
(Display::InlineFlex, GenericVerticalAlign::Top) |
(Display::InlineBlock, GenericVerticalAlign::Top) if
inline_metrics.space_above_baseline >= Au(0) => {
*largest_block_size_for_top_fragments = max(
*largest_block_size_for_top_fragments,
inline_metrics.space_above_baseline + inline_metrics.space_below_baseline)
}
(Display::Inline, GenericVerticalAlign::Bottom) |
(Display::Block, GenericVerticalAlign::Bottom) |
(Display::InlineFlex, GenericVerticalAlign::Bottom) |
(Display::InlineBlock, GenericVerticalAlign::Bottom) if
inline_metrics.space_below_baseline >= Au(0) => {
*largest_block_size_for_bottom_fragments = max(
*largest_block_size_for_bottom_fragments,
inline_metrics.space_above_baseline + inline_metrics.space_below_baseline)
}
_ => *line_metrics = line_metrics.new_metrics_for_fragment(inline_metrics),
}
}
}
fn update_restyle_damage(&mut self) {
let mut damage = self.base.restyle_damage;
for frag in &self.fragments.fragments {
damage.insert(frag.restyle_damage());
}
self.base.restyle_damage = damage;
}
fn containing_block_range_for_flow_surrounding_fragment_at_index(&self,
fragment_index: FragmentIndex)
-> Range<FragmentIndex> {
let mut start_index = fragment_index;
while start_index > FragmentIndex(0) &&
self.fragments
.fragments[(start_index - FragmentIndex(1)).get() as usize]
.is_positioned() {
start_index = start_index - FragmentIndex(1)
}
let mut end_index = fragment_index + FragmentIndex(1);
while end_index < FragmentIndex(self.fragments.fragments.len() as isize) &&
self.fragments.fragments[end_index.get() as usize].is_positioned() {
end_index = end_index + FragmentIndex(1)
}
Range::new(start_index, end_index - start_index)
}
fn containing_block_range_for_flow(&self, opaque_flow: OpaqueFlow) -> Range<FragmentIndex> {
match self.fragments.fragments.iter().position(|fragment| {
match fragment.specific {
SpecificFragmentInfo::InlineAbsolute(ref inline_absolute) => {
OpaqueFlow::from_flow(&*inline_absolute.flow_ref) == opaque_flow
}
SpecificFragmentInfo::InlineAbsoluteHypothetical(
ref inline_absolute_hypothetical) => {
OpaqueFlow::from_flow(&*inline_absolute_hypothetical.flow_ref) == opaque_flow
}
_ => false,
}
}) {
Some(index) => {
let index = FragmentIndex(index as isize);
self.containing_block_range_for_flow_surrounding_fragment_at_index(index)
}
None => {
// FIXME(pcwalton): This is quite wrong. We should only return the range
// surrounding the inline fragments that constitute the containing block. But this
// suffices to get Google looking right.
Range::new(FragmentIndex(0),
FragmentIndex(self.fragments.fragments.len() as isize))
}
}
}
pub fn baseline_offset_of_last_line(&self) -> Option<Au> {
self.last_line_containing_real_fragments().map(|line| {
line.bounds.start.b + line.bounds.size.block - line.metrics.space_below_baseline
})
}
// Returns the last line that doesn't consist entirely of hypothetical boxes.
fn last_line_containing_real_fragments(&self) -> Option<&Line> {
for line in self.lines.iter().rev() {
if (line.range.begin().get()..line.range.end().get()).any(|index| {
!self.fragments.fragments[index as usize].is_hypothetical()
}) {
return Some(line)
}
}
None
}
}
impl Flow for InlineFlow {
fn class(&self) -> FlowClass {
FlowClass::Inline
}
fn as_inline(&self) -> &InlineFlow {
self
}
fn as_mut_inline(&mut self) -> &mut InlineFlow {
self
}
fn bubble_inline_sizes(&mut self) {
self.update_restyle_damage();
let _scope = layout_debug_scope!("inline::bubble_inline_sizes {:x}",
self.base.debug_id());
let writing_mode = self.base.writing_mode;
for kid in self.base.child_iter_mut() {
kid.mut_base().floats = Floats::new(writing_mode);
}
self.base.flags.remove(FlowFlags::CONTAINS_TEXT_OR_REPLACED_FRAGMENTS);
let mut intrinsic_sizes_for_flow = IntrinsicISizesContribution::new();
let mut intrinsic_sizes_for_inline_run = IntrinsicISizesContribution::new();
let mut intrinsic_sizes_for_nonbroken_run = IntrinsicISizesContribution::new();
for fragment in &mut self.fragments.fragments {
let intrinsic_sizes_for_fragment = fragment.compute_intrinsic_inline_sizes().finish();
match fragment.style.get_inheritedtext().white_space {
WhiteSpace::Nowrap => {
intrinsic_sizes_for_nonbroken_run.union_nonbreaking_inline(
&intrinsic_sizes_for_fragment)
}
WhiteSpace::Pre => {
intrinsic_sizes_for_nonbroken_run.union_nonbreaking_inline(
&intrinsic_sizes_for_fragment);
// Flush the intrinsic sizes we've been gathering up in order to handle the
// line break, if necessary.
if fragment.requires_line_break_afterward_if_wrapping_on_newlines() {
intrinsic_sizes_for_inline_run.union_inline(
&intrinsic_sizes_for_nonbroken_run.finish());
intrinsic_sizes_for_nonbroken_run = IntrinsicISizesContribution::new();
intrinsic_sizes_for_flow.union_block(
&intrinsic_sizes_for_inline_run.finish());
intrinsic_sizes_for_inline_run = IntrinsicISizesContribution::new();
}
}
WhiteSpace::PreWrap |
WhiteSpace::PreLine => {
// Flush the intrinsic sizes we were gathering up for the nonbroken run, if
// necessary.
intrinsic_sizes_for_inline_run.union_inline(
&intrinsic_sizes_for_nonbroken_run.finish());
intrinsic_sizes_for_nonbroken_run = IntrinsicISizesContribution::new();
intrinsic_sizes_for_nonbroken_run.union_inline(&intrinsic_sizes_for_fragment);
// Flush the intrinsic sizes we've been gathering up in order to handle the
// line break, if necessary.
if fragment.requires_line_break_afterward_if_wrapping_on_newlines() {
intrinsic_sizes_for_inline_run.union_inline(
&intrinsic_sizes_for_nonbroken_run.finish());
intrinsic_sizes_for_nonbroken_run = IntrinsicISizesContribution::new();
intrinsic_sizes_for_flow.union_block(
&intrinsic_sizes_for_inline_run.finish());
intrinsic_sizes_for_inline_run = IntrinsicISizesContribution::new();
}
}
WhiteSpace::Normal => {
// Flush the intrinsic sizes we were gathering up for the nonbroken run, if
// necessary.
intrinsic_sizes_for_inline_run.union_inline(
&intrinsic_sizes_for_nonbroken_run.finish());
intrinsic_sizes_for_nonbroken_run = IntrinsicISizesContribution::new();
intrinsic_sizes_for_nonbroken_run.union_inline(&intrinsic_sizes_for_fragment);
}
}
fragment.restyle_damage.remove(ServoRestyleDamage::BUBBLE_ISIZES);
if fragment.is_text_or_replaced() {
self.base.flags.insert(FlowFlags::CONTAINS_TEXT_OR_REPLACED_FRAGMENTS);
}
}
// Flush any remaining nonbroken-run and inline-run intrinsic sizes.
intrinsic_sizes_for_inline_run.union_inline(&intrinsic_sizes_for_nonbroken_run.finish());
intrinsic_sizes_for_flow.union_block(&intrinsic_sizes_for_inline_run.finish());
// Finish up the computation.
self.base.intrinsic_inline_sizes = intrinsic_sizes_for_flow.finish()
}
/// Recursively (top-down) determines the actual inline-size of child contexts and fragments.
/// When called on this context, the context has had its inline-size set by the parent context.
fn assign_inline_sizes(&mut self, _: &LayoutContext) {
let _scope = layout_debug_scope!("inline::assign_inline_sizes {:x}", self.base.debug_id());
// Initialize content fragment inline-sizes if they haven't been initialized already.
//
// TODO: Combine this with `LineBreaker`'s walk in the fragment list, or put this into
// `Fragment`.
debug!("InlineFlow::assign_inline_sizes: floats in: {:?}", self.base.floats);
let inline_size = self.base.block_container_inline_size;
let container_mode = self.base.block_container_writing_mode;
let container_block_size = self.base.block_container_explicit_block_size;
self.base.position.size.inline = inline_size;
{
let this = &mut *self;
for fragment in this.fragments.fragments.iter_mut() {
fragment.compute_border_and_padding(inline_size);
fragment.compute_block_direction_margins(inline_size);
fragment.compute_inline_direction_margins(inline_size);
fragment.assign_replaced_inline_size_if_necessary(inline_size, container_block_size);
}
}
// If there are any inline-block kids, propagate explicit block and inline
// sizes down to them.
let block_container_explicit_block_size = self.base.block_container_explicit_block_size;
for kid in self.base.child_iter_mut() {
let kid_base = kid.mut_base();
kid_base.block_container_inline_size = inline_size;
kid_base.block_container_writing_mode = container_mode;
kid_base.block_container_explicit_block_size = block_container_explicit_block_size;
}
}
/// Calculate and set the block-size of this flow. See CSS 2.1 § 10.6.1.
/// Note that we do not need to do in-order traversal because the children
/// are always block formatting context.
fn assign_block_size(&mut self, layout_context: &LayoutContext) {
let _scope = layout_debug_scope!("inline::assign_block_size {:x}",
self.base.debug_id());
// Divide the fragments into lines.
//
// TODO(pcwalton, #226): Get the CSS `line-height` property from the
// style of the containing block to determine the minimum line block
// size.
//
// TODO(pcwalton, #226): Get the CSS `line-height` property from each
// non-replaced inline element to determine its block-size for computing
// the line's own block-size.
//
// TODO(pcwalton): Cache the line scanner?
debug!("assign_block_size_inline: floats in: {:?}", self.base.floats);
// Assign the block-size and late-computed inline-sizes for the inline fragments.
for fragment in &mut self.fragments.fragments {
fragment.update_late_computed_replaced_inline_size_if_necessary();
fragment.assign_replaced_block_size_if_necessary();
}
// Reset our state, so that we handle incremental reflow correctly.
//
// TODO(pcwalton): Do something smarter, like Gecko and WebKit?
self.lines.clear();
// Determine how much indentation the first line wants.
let mut indentation = if self.fragments.is_empty() {
Au(0)
} else {
self.first_line_indentation
};
// Perform line breaking.
let mut scanner = LineBreaker::new(self.base.floats.clone(),
indentation,
&self.minimum_line_metrics);
scanner.scan_for_lines(self, layout_context);
// Now, go through each line and lay out the fragments inside.
let line_count = self.lines.len();
for (line_index, line) in self.lines.iter_mut().enumerate() {
// Lay out fragments in the inline direction, and justify them if
// necessary.
InlineFlow::set_inline_fragment_positions(&mut self.fragments,
line,
self.base.flags.text_align(),
indentation,
line_index + 1 == line_count);
// Compute the final positions in the block direction of each fragment.
InlineFlow::set_block_fragment_positions(&mut self.fragments,
line,
&self.minimum_line_metrics,
layout_context);
// This is used to set the block-start position of the next line in
// the next iteration of the loop. We're no longer on the first
// line, so set indentation to zero.
indentation = Au(0)
}
if self.is_absolute_containing_block() {
// Assign block-sizes for all flows in this absolute flow tree.
// This is preorder because the block-size of an absolute flow may depend on
// the block-size of its containing block, which may also be an absolute flow.
let assign_abs_b_sizes = AbsoluteAssignBSizesTraversal(layout_context.shared_context());
assign_abs_b_sizes.traverse_absolute_flows(&mut *self);
}
self.base.position.size.block = match self.last_line_containing_real_fragments() {
Some(last_line) => last_line.bounds.start.b + last_line.bounds.size.block,
None => Au(0),
};
self.base.floats = scanner.floats.clone();
let writing_mode = self.base.floats.writing_mode;
self.base.floats.translate(LogicalSize::new(writing_mode,
Au(0),
-self.base.position.size.block));
let containing_block_size = LogicalSize::new(writing_mode,
Au(0),
self.base.position.size.block);
self.mutate_fragments(&mut |f: &mut Fragment| {
match f.specific {
SpecificFragmentInfo::InlineBlock(ref mut info) => {
let block = FlowRef::deref_mut(&mut info.flow_ref);
block.mut_base().early_absolute_position_info = EarlyAbsolutePositionInfo {
relative_containing_block_size: containing_block_size,
relative_containing_block_mode: writing_mode,
};
}
SpecificFragmentInfo::InlineAbsolute(ref mut info) => {
let block = FlowRef::deref_mut(&mut info.flow_ref);
block.mut_base().early_absolute_position_info = EarlyAbsolutePositionInfo {
relative_containing_block_size: containing_block_size,
relative_containing_block_mode: writing_mode,
};
}
_ => (),
}
});
self.base.restyle_damage.remove(ServoRestyleDamage::REFLOW_OUT_OF_FLOW | ServoRestyleDamage::REFLOW);
for fragment in &mut self.fragments.fragments {
fragment.restyle_damage.remove(ServoRestyleDamage::REFLOW_OUT_OF_FLOW | ServoRestyleDamage::REFLOW);
}
}
fn compute_stacking_relative_position(&mut self, _: &LayoutContext) {
// First, gather up the positions of all the containing blocks (if any).
//
// FIXME(pcwalton): This will get the absolute containing blocks inside `...` wrong in the
// case of something like:
//
// <span style="position: relative">
// Foo
// <span style="display: inline-block">...</span>
// </span>
let mut containing_block_positions = Vec::new();
let container_size = Size2D::new(self.base.block_container_inline_size, Au(0));
for (fragment_index, fragment) in self.fragments.fragments.iter().enumerate() {
match fragment.specific {
SpecificFragmentInfo::InlineAbsolute(_) => {
let containing_block_range =
self.containing_block_range_for_flow_surrounding_fragment_at_index(
FragmentIndex(fragment_index as isize));
let first_fragment_index = containing_block_range.begin().get() as usize;
debug_assert!(first_fragment_index < self.fragments.fragments.len());
let first_fragment = &self.fragments.fragments[first_fragment_index];
let padding_box_origin = (first_fragment.border_box -
first_fragment.style.logical_border_width()).start;
containing_block_positions.push(
padding_box_origin.to_physical(self.base.writing_mode, container_size));
}
SpecificFragmentInfo::InlineBlock(_) if fragment.is_positioned() => {
let containing_block_range =
self.containing_block_range_for_flow_surrounding_fragment_at_index(
FragmentIndex(fragment_index as isize));
let first_fragment_index = containing_block_range.begin().get() as usize;
debug_assert!(first_fragment_index < self.fragments.fragments.len());
let first_fragment = &self.fragments.fragments[first_fragment_index];
let padding_box_origin = (first_fragment.border_box -
first_fragment.style.logical_border_width()).start;
containing_block_positions.push(
padding_box_origin.to_physical(self.base.writing_mode, container_size));
}
_ => {}
}
}
// Then compute the positions of all of our fragments.
let mut containing_block_positions = containing_block_positions.iter();
for fragment in &mut self.fragments.fragments {
let stacking_relative_border_box =
fragment.stacking_relative_border_box(&self.base.stacking_relative_position,
&self.base
.early_absolute_position_info
.relative_containing_block_size,
self.base
.early_absolute_position_info
.relative_containing_block_mode,
CoordinateSystem::Parent);
let stacking_relative_content_box =
fragment.stacking_relative_content_box(&stacking_relative_border_box);
let is_positioned = fragment.is_positioned();
match fragment.specific {
SpecificFragmentInfo::InlineBlock(ref mut info) => {
let flow = FlowRef::deref_mut(&mut info.flow_ref);
let block_flow = flow.as_mut_block();
block_flow.base.late_absolute_position_info =
self.base.late_absolute_position_info;
let stacking_relative_position = self.base.stacking_relative_position;
if is_positioned {
let padding_box_origin = containing_block_positions.next().unwrap();
block_flow.base
.late_absolute_position_info
.stacking_relative_position_of_absolute_containing_block =
*padding_box_origin + stacking_relative_position;
}
block_flow.base.stacking_relative_position =
stacking_relative_content_box.origin.to_vector();
// Write the clip in our coordinate system into the child flow. (The kid will
// fix it up to be in its own coordinate system if necessary.)
block_flow.base.clip = self.base.clip.clone()
}
SpecificFragmentInfo::InlineAbsoluteHypothetical(ref mut info) => {
let flow = FlowRef::deref_mut(&mut info.flow_ref);
let block_flow = flow.as_mut_block();
block_flow.base.late_absolute_position_info =
self.base.late_absolute_position_info;
block_flow.base.stacking_relative_position =
stacking_relative_border_box.origin.to_vector();
// As above, this is in our coordinate system for now.
block_flow.base.clip = self.base.clip.clone()
}
SpecificFragmentInfo::InlineAbsolute(ref mut info) => {
let flow = FlowRef::deref_mut(&mut info.flow_ref);
let block_flow = flow.as_mut_block();
block_flow.base.late_absolute_position_info =
self.base.late_absolute_position_info;
let stacking_relative_position = self.base.stacking_relative_position;
let padding_box_origin = containing_block_positions.next().unwrap();
block_flow.base
.late_absolute_position_info
.stacking_relative_position_of_absolute_containing_block =
*padding_box_origin + stacking_relative_position;
block_flow.base.stacking_relative_position =
stacking_relative_border_box.origin.to_vector();
// As above, this is in our coordinate system for now.
block_flow.base.clip = self.base.clip.clone()
}
_ => {}
}
}
}
fn update_late_computed_inline_position_if_necessary(&mut self, _: Au) {}
fn update_late_computed_block_position_if_necessary(&mut self, _: Au) {}
fn collect_stacking_contexts(&mut self, state: &mut StackingContextCollectionState) {
self.collect_stacking_contexts_for_inline(state);
}
fn build_display_list(&mut self, state: &mut DisplayListBuildState) {
self.build_display_list_for_inline(state);
}
fn repair_style(&mut self, _: &ServoArc<ComputedValues>) {}
fn compute_overflow(&self) -> Overflow {
let mut overflow = Overflow::new();
let flow_size = self.base.position.size.to_physical(self.base.writing_mode);
let relative_containing_block_size =
&self.base.early_absolute_position_info.relative_containing_block_size;
for fragment in &self.fragments.fragments {
overflow.union(&fragment.compute_overflow(&flow_size, &relative_containing_block_size))
}
overflow
}
fn iterate_through_fragment_border_boxes(&self,
iterator: &mut FragmentBorderBoxIterator,
level: i32,
stacking_context_position: &Point2D<Au>) {
// FIXME(#2795): Get the real container size.
for fragment in &self.fragments.fragments {
if !iterator.should_process(fragment) {
continue
}
let stacking_relative_position = &self.base.stacking_relative_position;
let relative_containing_block_size =
&self.base.early_absolute_position_info.relative_containing_block_size;
let relative_containing_block_mode =
self.base.early_absolute_position_info.relative_containing_block_mode;
iterator.process(fragment,
level,
&fragment.stacking_relative_border_box(stacking_relative_position,
relative_containing_block_size,
relative_containing_block_mode,
CoordinateSystem::Own)
.translate(&stacking_context_position.to_vector()))
}
}
fn mutate_fragments(&mut self, mutator: &mut FnMut(&mut Fragment)) {
for fragment in &mut self.fragments.fragments {
(*mutator)(fragment)
}
}
fn contains_positioned_fragments(&self) -> bool {
self.fragments.fragments.iter().any(|fragment| fragment.is_positioned())
}
fn contains_relatively_positioned_fragments(&self) -> bool {
self.fragments.fragments.iter().any(|fragment| {
fragment.style.get_box().position == Position::Relative
})
}
fn generated_containing_block_size(&self, for_flow: OpaqueFlow) -> LogicalSize<Au> {
let mut containing_block_size = LogicalSize::new(self.base.writing_mode, Au(0), Au(0));
for index in self.containing_block_range_for_flow(for_flow).each_index() {
let fragment = &self.fragments.fragments[index.get() as usize];
if fragment.is_absolutely_positioned() {
continue
}
containing_block_size.inline = containing_block_size.inline +
fragment.border_box.size.inline;
containing_block_size.block = max(containing_block_size.block,
fragment.border_box.size.block);
}
containing_block_size
}
fn print_extra_flow_children(&self, print_tree: &mut PrintTree) {
for fragment in &self.fragments.fragments {
print_tree.add_item(format!("{:?}", fragment));
}
}
}
impl fmt::Debug for InlineFlow {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f,
"{:?}({:x}) {:?}",
self.class(),
self.base.debug_id(),
self.base())
}
}
#[derive(Clone)]
pub struct InlineFragmentNodeInfo {
pub address: OpaqueNode,
pub style: ServoArc<ComputedValues>,
pub selected_style: ServoArc<ComputedValues>,
pub pseudo: PseudoElementType,
pub flags: InlineFragmentNodeFlags,
}
bitflags! {
pub struct InlineFragmentNodeFlags: u8 {
const FIRST_FRAGMENT_OF_ELEMENT = 0x01;
const LAST_FRAGMENT_OF_ELEMENT = 0x02;
}
}
impl fmt::Debug for InlineFragmentNodeInfo {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{:?}", self.flags.bits())
}
}
#[derive(Clone)]
pub struct InlineFragmentContext {
/// The list of nodes that this fragment will be inheriting styles from,
/// from the most deeply-nested node out.
pub nodes: Vec<InlineFragmentNodeInfo>,
}
impl InlineFragmentContext {
pub fn new() -> InlineFragmentContext {
InlineFragmentContext {
nodes: vec!(),
}
}
#[inline]
pub fn contains_node(&self, node_address: OpaqueNode) -> bool {
self.nodes.iter().position(|node| node.address == node_address).is_some()
}
fn ptr_eq(&self, other: &InlineFragmentContext) -> bool {
if self.nodes.len() != other.nodes.len() {
return false
}
for (this_node, other_node) in self.nodes.iter().zip(&other.nodes) {
if this_node.address != other_node.address {
return false
}
}
true
}
}
fn inline_contexts_are_equal(inline_context_a: &Option<InlineFragmentContext>,
inline_context_b: &Option<InlineFragmentContext>)
-> bool {
match (inline_context_a, inline_context_b) {
(&Some(ref inline_context_a), &Some(ref inline_context_b)) => {
inline_context_a.ptr_eq(inline_context_b)
}
(&None, &None) => true,
(&Some(_), &None) | (&None, &Some(_)) => false,
}
}
/// Ascent and space needed above and below the baseline for a fragment. See CSS 2.1 § 10.8.1.
///
/// Descent is not included in this structure because it can be computed from the fragment's
/// border/content box and the ascent.
#[derive(Clone, Copy, Debug, Serialize)]
pub struct InlineMetrics {
/// The amount of space above the baseline needed for this fragment.
pub space_above_baseline: Au,
/// The amount of space below the baseline needed for this fragment.
pub space_below_baseline: Au,
/// The distance from the baseline to the top of this fragment. This can differ from
/// `block_size_above_baseline` if the fragment needs some empty space above it due to
/// line-height, etc.
pub ascent: Au,
}
impl InlineMetrics {
/// Creates a new set of inline metrics.
pub fn new(space_above_baseline: Au, space_below_baseline: Au, ascent: Au) -> InlineMetrics {
InlineMetrics {
space_above_baseline: space_above_baseline,
space_below_baseline: space_below_baseline,
ascent: ascent,
}
}
/// Calculates inline metrics from font metrics and line block-size per CSS 2.1 § 10.8.1.
#[inline]
pub fn from_font_metrics(font_metrics: &FontMetrics, line_height: Au) -> InlineMetrics {
let leading = line_height - (font_metrics.ascent + font_metrics.descent);
// Calculating the half leading here and then using leading - half_leading
// below ensure that we don't introduce any rounding accuracy issues here.
// The invariant is that the resulting total line height must exactly
// equal the requested line_height.
let half_leading = leading.scale_by(0.5);
InlineMetrics {
space_above_baseline: font_metrics.ascent + half_leading,
space_below_baseline: font_metrics.descent + leading - half_leading,
ascent: font_metrics.ascent,
}
}
/// Returns the sum of the space needed above and below the baseline.
fn space_needed(&self) -> Au {
self.space_above_baseline + self.space_below_baseline
}
}
#[derive(Clone, Copy, PartialEq)]
enum LineFlushMode {
No,
Flush,
}
#[derive(Clone, Copy, Debug, Serialize)]
pub struct LineMetrics {
pub space_above_baseline: Au,
pub space_below_baseline: Au,
}
impl LineMetrics {
pub fn new(space_above_baseline: Au, space_below_baseline: Au) -> LineMetrics {
LineMetrics {
space_above_baseline: space_above_baseline,
space_below_baseline: space_below_baseline,
}
}
/// Returns the line metrics that result from combining the line that these metrics represent
/// with a fragment with the given metrics.
fn new_metrics_for_fragment(&self, fragment_inline_metrics: &InlineMetrics) -> LineMetrics {
LineMetrics {
space_above_baseline: max(self.space_above_baseline,
fragment_inline_metrics.space_above_baseline),
space_below_baseline: max(self.space_below_baseline,
fragment_inline_metrics.space_below_baseline),
}
}
fn for_line_and_fragment(line: &Line, fragment: &Fragment, layout_context: &LayoutContext)
-> LineMetrics {
if !fragment.is_hypothetical() {
let space_above_baseline = line.metrics.space_above_baseline;
return LineMetrics {
space_above_baseline: space_above_baseline,
space_below_baseline: line.bounds.size.block - space_above_baseline,
}
}
let hypothetical_line_metrics = line.new_metrics_for_fragment(fragment, layout_context);
let hypothetical_block_size = line.new_block_size_for_fragment(fragment,
&hypothetical_line_metrics,
layout_context);
let hypothetical_space_above_baseline = hypothetical_line_metrics.space_above_baseline;
LineMetrics {
space_above_baseline: hypothetical_space_above_baseline,
space_below_baseline: hypothetical_block_size - hypothetical_space_above_baseline,
}
}
/// Returns the sum of the space needed above and below the baseline.
pub fn space_needed(&self) -> Au {
self.space_above_baseline + self.space_below_baseline
}
}