Mirrors/servo
1
0
Fork 0
mirror of https://github.com/servo/servo.git synced 2025-08-06 06:00:15 +01:00
Code Issues Projects Releases Packages Wiki Activity

layout: Implement text-align: justify and text-justify per

Browse source 
CSS-TEXT-3 § 7.3.

`text-justify: distribute` is not supported.

The behavior of `text-justify: none` does not seem to match what Firefox
and Chrome do, but it seems to match the spec.

Closes #213.
This commit is contained in:
Patrick Walton 2015-01-09 11:45:38 -08:00
parent f58a129251
commit 5fdaba05a6
17 changed files with 528 additions and 63 deletions
Download patch file Download diff file Expand all files Collapse all files

150
components/layout/inline.rs
View file

@ -34,7 +34,8 @@ use std::mem;
use std::num::ToPrimitive;
use std::ops::{Add, Sub, Mul, Div, Rem, Neg, Shl, Shr, Not, BitOr, BitAnd, BitXor};
use std::u16;
use style::computed_values::{overflow, text_align, text_overflow, vertical_align, white_space};
use style::computed_values::{overflow, text_align, text_justify, text_overflow, vertical_align};
use style::computed_values::{white_space};
use style::ComputedValues;
use std::sync::Arc;
@ -301,6 +302,18 @@ impl LineBreaker {
self.lines.len());
self.flush_current_line()
}
// Strip trailing whitespace from the last line if necessary.
if let Some(ref mut last_line) = self.lines.last_mut() {
if let Some(ref mut last_fragment) = self.new_fragments.last_mut() {
let previous_inline_size = last_line.bounds.size.inline -
last_fragment.border_box.size.inline;
if last_fragment.strip_trailing_whitespace_if_necessary() {
last_line.bounds.size.inline = previous_inline_size +
last_fragment.border_box.size.inline;
}
}
}
}
/// Acquires a new fragment to lay out from the work list or fragment list as appropriate.
@ -534,7 +547,7 @@ impl LineBreaker {
/// Tries to append the given fragment to the line, splitting it if necessary. Returns true if
/// we successfully pushed the fragment to the line or false if we couldn't.
fn append_fragment_to_line_if_possible(&mut self,
fragment: Fragment,
mut fragment: Fragment,
flow: &InlineFlow,
layout_context: &LayoutContext,
flags: InlineReflowFlags)
@ -546,7 +559,8 @@ impl LineBreaker {
self.pending_line.green_zone = line_bounds.size;
}
debug!("LineBreaker: trying to append to line {} (fragment size: {:?}, green zone: {:?}): {:?}",
debug!("LineBreaker: trying to append to line {} (fragment size: {:?}, green zone: {:?}): \
{:?}",
self.lines.len(),
fragment.border_box.size,
self.pending_line.green_zone,
@ -581,7 +595,7 @@ impl LineBreaker {
debug!("LineBreaker: fragment can't split and line {} is empty, so overflowing",
self.lines.len());
self.push_fragment_to_line(layout_context, fragment);
return true
return false
}
// Split it up!
@ -609,13 +623,15 @@ impl LineBreaker {
// 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(inline_start_fragment), Some(inline_end_fragment)) => {
(Some(inline_start_fragment), Some(mut inline_end_fragment)) => {
self.push_fragment_to_line(layout_context, inline_start_fragment);
self.flush_current_line();
self.work_list.push_front(inline_end_fragment)
},
(Some(fragment), None) | (None, Some(fragment)) => {
self.push_fragment_to_line(layout_context, fragment)
(Some(mut fragment), None) => {
self.push_fragment_to_line(layout_context, fragment);
}
(None, Some(_)) => debug_assert!(false, "un-normalized split result"),
(None, None) => {}
}
@ -856,25 +872,40 @@ impl InlineFlow {
}
}
/// Sets fragment positions in the inline direction based on alignment for one line.
/// 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: text_align::T,
indentation: Au) {
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);
// Set the fragment inline positions based on that alignment.
let mut inline_start_position_for_fragment = line.bounds.start.i + indentation +
match line_align {
// So sorry, but justified text is more complicated than shuffling line
// coordinates.
//
// TODO(burg, issue #213): Implement `text-align: justify`.
text_align::T::left | text_align::T::justify => Au(0),
text_align::T::center => slack_inline_size.scale_by(0.5),
text_align::T::right => slack_inline_size,
};
// Compute the value we're going to use for `text-justify`.
let text_justify = if fragments.fragments.is_empty() {
return
} else {
fragments.fragments[0].style().get_inheritedtext().text_justify
};
// 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 {
text_align::T::justify if !is_last_line && text_justify != text_justify::T::none => {
InlineFlow::justify_inline_fragments(fragments, line, slack_inline_size)
}
text_align::T::left | text_align::T::justify => {}
text_align::T::center => {
inline_start_position_for_fragment = inline_start_position_for_fragment +
slack_inline_size.scale_by(0.5)
}
text_align::T::right => {
inline_start_position_for_fragment = inline_start_position_for_fragment +
slack_inline_size
}
}
for fragment_index in range(line.range.begin(), line.range.end()) {
let fragment = fragments.get_mut(fragment_index.to_uint());
@ -889,6 +920,75 @@ impl InlineFlow {
}
}
/// 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 = 0i32;
for fragment_index in line.range.each_index() {
let fragment = fragments.get(fragment_index.to_uint());
let scanned_text_fragment_info =
if let SpecificFragmentInfo::ScannedText(ref info) = fragment.specific {
info
} else {
continue
};
for slice in scanned_text_fragment_info.run.character_slices_in_range(
&scanned_text_fragment_info.range) {
expansion_opportunities += slice.glyphs.space_count_in_range(&slice.range) as i32
}
}
// Then distribute all the space across the expansion opportunities.
let space_per_expansion_opportunity = slack_inline_size.to_subpx() /
(expansion_opportunities as f64);
for fragment_index in line.range.each_index() {
let fragment = fragments.get_mut(fragment_index.to_uint());
let mut scanned_text_fragment_info =
if let SpecificFragmentInfo::ScannedText(ref mut info) = fragment.specific {
info
} else {
continue
};
let fragment_range = scanned_text_fragment_info.range;
// FIXME(pcwalton): This is an awful lot of uniqueness making. I don't see any easy way
// to get rid of it without regressing the performance of the non-justified case,
// though.
let run = scanned_text_fragment_info.run.make_unique();
{
let glyph_runs = run.glyphs.make_unique();
for mut glyph_run in glyph_runs.iter_mut() {
let mut range = glyph_run.range.intersect(&fragment_range);
if range.is_empty() {
continue
}
range.shift_by(-glyph_run.range.begin());
let glyph_store = glyph_run.glyph_store.make_unique();
glyph_store.distribute_extra_space_in_range(&range,
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. Assumes that the
/// fragment positions were initially set to the distance from the baseline first.
fn set_block_fragment_positions(fragments: &mut InlineFragments,
@ -1083,12 +1183,16 @@ impl Flow for InlineFlow {
// Now, go through each line and lay out the fragments inside.
let mut line_distance_from_flow_block_start = Au(0);
for line in self.lines.iter_mut() {
// Lay out fragments in the inline direction.
let line_count = self.lines.len();
for line_index in range(0, line_count) {
let line = &mut self.lines[line_index];
// 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);
indentation,
line_index + 1 == line_count);
// Set the block-start position of the current line.
// `line_height_offset` is updated at the end of the previous loop.