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layout: Simplify and improve the correctness of whitespace stripping in

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text layout, and unify the inline layout paths for pre- and
normally-formatted text.

This fixes a lot of "jumpiness" and removes the `new_line_pos` stuff.

Closes #2260.
This commit is contained in:
Patrick Walton 2015-03-30 14:09:37 -07:00
parent 88aa07b7e0
commit 6d61468160
12 changed files with 485 additions and 461 deletions
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369
components/layout/fragment.rs
View file

@ -27,16 +27,11 @@ use geom::{Point2D, Rect, Size2D};
use gfx::display_list::{BLUR_INFLATION_FACTOR, OpaqueNode};
use gfx::text::glyph::CharIndex;
use gfx::text::text_run::{TextRun, TextRunSlice};
use script_traits::UntrustedNodeAddress;
use rustc_serialize::{Encodable, Encoder};
use msg::constellation_msg::{ConstellationChan, Msg, PipelineId, SubpageId};
use net_traits::image::holder::ImageHolder;
use net_traits::local_image_cache::LocalImageCache;
use util::geometry::{self, Au, ZERO_POINT};
use util::logical_geometry::{LogicalRect, LogicalSize, LogicalMargin, WritingMode};
use util::range::*;
use util::smallvec::SmallVec;
use util::str::is_whitespace;
use rustc_serialize::{Encodable, Encoder};
use script_traits::UntrustedNodeAddress;
use std::borrow::ToOwned;
use std::cmp::{max, min};
use std::collections::LinkedList;
@ -56,6 +51,12 @@ use style::values::computed::{LengthOrPercentage, LengthOrPercentageOrAuto};
use style::values::computed::{LengthOrPercentageOrNone};
use text::TextRunScanner;
use url::Url;
use util::geometry::{self, Au, ZERO_POINT};
use util::logical_geometry::{LogicalRect, LogicalSize, LogicalMargin, WritingMode};
use util::range::*;
use util::smallvec::SmallVec;
use util::str::is_whitespace;
use util;
/// Fragments (`struct Fragment`) are the leaves of the layout tree. They cannot position
/// themselves. In general, fragments do not have a simple correspondence with CSS fragments in the
@ -580,36 +581,27 @@ pub struct ScannedTextFragmentInfo {
/// The text run that this represents.
pub run: Arc<Box<TextRun>>,
/// The intrinsic size of the text fragment.
pub content_size: LogicalSize<Au>,
/// The range within the above text run that this represents.
pub range: Range<CharIndex>,
/// The positions of newlines within this scanned text fragment.
///
/// FIXME(#2260, pcwalton): Can't this go somewhere else, like in the text run or something?
/// Or can we just remove it?
pub new_line_pos: Vec<CharIndex>,
/// The new_line_pos is eaten during line breaking. If we need to re-merge
/// fragments, it will have to be restored.
pub original_new_line_pos: Option<Vec<CharIndex>>,
/// The intrinsic size of the text fragment.
pub content_size: LogicalSize<Au>,
/// The endpoint of the above range, including whitespace that was stripped out. This exists
/// so that we can restore the range to its original value (before line breaking occurred) when
/// performing incremental reflow.
pub range_end_including_stripped_whitespace: CharIndex,
}
impl ScannedTextFragmentInfo {
/// Creates the information specific to a scanned text fragment from a range and a text run.
pub fn new(run: Arc<Box<TextRun>>,
range: Range<CharIndex>,
new_line_positions: Vec<CharIndex>,
content_size: LogicalSize<Au>)
pub fn new(run: Arc<Box<TextRun>>, range: Range<CharIndex>, content_size: LogicalSize<Au>)
-> ScannedTextFragmentInfo {
ScannedTextFragmentInfo {
run: run,
range: range,
new_line_pos: new_line_positions,
original_new_line_pos: None,
content_size: content_size,
range_end_including_stripped_whitespace: range.end(),
}
}
}
@ -769,32 +761,6 @@ impl Fragment {
self.margin = LogicalMargin::zero(self.style.writing_mode);
}
/// Saves the new_line_pos vector into a `SpecificFragmentInfo::ScannedText`. This will fail
/// if called on any other type of fragment.
pub fn save_new_line_pos(&mut self) {
match &mut self.specific {
&mut SpecificFragmentInfo::ScannedText(ref mut info) => {
if !info.new_line_pos.is_empty() {
info.original_new_line_pos = Some(info.new_line_pos.clone());
}
}
_ => {}
}
}
pub fn restore_new_line_pos(&mut self) {
match &mut self.specific {
&mut SpecificFragmentInfo::ScannedText(ref mut info) => {
match info.original_new_line_pos.take() {
None => {}
Some(new_line_pos) => info.new_line_pos = new_line_pos,
}
return
}
_ => {}
}
}
/// Returns a debug ID of this fragment. This ID should not be considered stable across
/// multiple layouts or fragment manipulations.
pub fn debug_id(&self) -> u16 {
@ -823,14 +789,12 @@ impl Fragment {
}
/// Transforms this fragment using the given `SplitInfo`, preserving all the other data.
pub fn transform_with_split_info(&self,
split: &SplitInfo,
text_run: Arc<Box<TextRun>>)
pub fn transform_with_split_info(&self, split: &SplitInfo, text_run: Arc<Box<TextRun>>)
-> Fragment {
let size = LogicalSize::new(self.style.writing_mode,
split.inline_size,
self.border_box.size.block);
let info = box ScannedTextFragmentInfo::new(text_run, split.range, Vec::new(), size);
let info = box ScannedTextFragmentInfo::new(text_run, split.range, size);
self.transform(size, SpecificFragmentInfo::ScannedText(info))
}
@ -857,7 +821,6 @@ impl Fragment {
style: Arc<ComputedValues>,
first_frag: bool,
last_frag: bool) {
if self.inline_context.is_none() {
self.inline_context = Some(InlineFragmentContext::new());
}
@ -1179,25 +1142,11 @@ impl Fragment {
}
}
/// Returns true if this element can be split. This is true for text fragments.
/// Returns true if this element can be split. This is true for text fragments, unless
/// `white-space: pre` is set.
pub fn can_split(&self) -> bool {
self.is_scanned_text_fragment()
}
/// Returns the newline positions of this fragment, if it's a scanned text fragment.
pub fn newline_positions(&self) -> Option<&Vec<CharIndex>> {
match self.specific {
SpecificFragmentInfo::ScannedText(ref info) => Some(&info.new_line_pos),
_ => None,
}
}
/// Returns the newline positions of this fragment, if it's a scanned text fragment.
pub fn newline_positions_mut(&mut self) -> Option<&mut Vec<CharIndex>> {
match self.specific {
SpecificFragmentInfo::ScannedText(ref mut info) => Some(&mut info.new_line_pos),
_ => None,
}
self.is_scanned_text_fragment() &&
self.style.get_inheritedtext().white_space != white_space::T::pre
}
/// Returns true if and only if this fragment is a generated content fragment.
@ -1359,64 +1308,6 @@ impl Fragment {
self.border_box - self.border_padding
}
/// Find the split of a fragment that includes a new-line character.
///
/// A return value of `None` indicates that the fragment is not splittable.
/// Otherwise the split information is returned. The right information is
/// optional due to the possibility of it being whitespace.
//
// TODO(bjz): The text run should be removed in the future, but it is currently needed for
// the current method of fragment splitting in the `inline::try_append_*` functions.
pub fn find_split_info_by_new_line(&self)
-> Option<(SplitInfo, Option<SplitInfo>, Arc<Box<TextRun>> /* TODO(bjz): remove */)> {
match self.specific {
SpecificFragmentInfo::Canvas(_) |
SpecificFragmentInfo::Generic |
SpecificFragmentInfo::GeneratedContent(_) |
SpecificFragmentInfo::Iframe(_) |
SpecificFragmentInfo::Image(_) |
SpecificFragmentInfo::Table |
SpecificFragmentInfo::TableCell |
SpecificFragmentInfo::TableRow |
SpecificFragmentInfo::TableWrapper => {
None
}
SpecificFragmentInfo::TableColumn(_) => {
panic!("Table column fragments do not need to split")
}
SpecificFragmentInfo::UnscannedText(_) => {
panic!("Unscanned text fragments should have been scanned by now!")
}
SpecificFragmentInfo::InlineBlock(_) |
SpecificFragmentInfo::InlineAbsoluteHypothetical(_) => {
panic!("Inline blocks or inline absolute hypothetical fragments do not get split")
}
SpecificFragmentInfo::ScannedText(ref text_fragment_info) => {
let mut new_line_pos = text_fragment_info.new_line_pos.clone();
let cur_new_line_pos = new_line_pos.remove(0);
let inline_start_range = Range::new(text_fragment_info.range.begin(),
cur_new_line_pos);
let inline_end_range = Range::new(
text_fragment_info.range.begin() + cur_new_line_pos + CharIndex(1),
text_fragment_info.range.length() - (cur_new_line_pos + CharIndex(1)));
// Left fragment is for inline-start text of first founded new-line character.
let inline_start_fragment = SplitInfo::new(inline_start_range,
&**text_fragment_info);
// Right fragment is for inline-end text of first founded new-line character.
let inline_end_fragment = if inline_end_range.length() > CharIndex(0) {
Some(SplitInfo::new(inline_end_range, &**text_fragment_info))
} else {
None
};
Some((inline_start_fragment, inline_end_fragment, text_fragment_info.run.clone()))
}
}
}
/// Attempts to find the split positions of a text fragment so that its inline-size is no more
/// than `max_inline_size`.
///
@ -1495,13 +1386,13 @@ impl Fragment {
/// A helper method that uses the breaking strategy described by `slice_iterator` (at present,
/// either natural word breaking or character breaking) to split this fragment.
fn calculate_split_position_using_breaking_strategy<'a,I>(&self,
slice_iterator: I,
max_inline_size: Au,
flags: SplitOptions)
-> Option<SplitResult>
where I: Iterator<Item=
TextRunSlice<'a>> {
fn calculate_split_position_using_breaking_strategy<'a,I>(
&self,
slice_iterator: I,
max_inline_size: Au,
flags: SplitOptions)
-> Option<SplitResult>
where I: Iterator<Item=TextRunSlice<'a>> {
let text_fragment_info =
if let SpecificFragmentInfo::ScannedText(ref text_fragment_info) = self.specific {
text_fragment_info
@ -1515,31 +1406,35 @@ impl Fragment {
let mut inline_end_range = None;
let mut overflowing = false;
debug!("calculate_split_position: splitting text fragment (strlen={}, range={:?}, \
max_inline_size={:?})",
debug!("calculate_split_position_using_breaking_strategy: splitting text fragment \
(strlen={}, range={:?}, max_inline_size={:?})",
text_fragment_info.run.text.len(),
text_fragment_info.range,
max_inline_size);
for slice in slice_iterator {
debug!("calculate_split_position: considering slice (offset={:?}, slice range={:?}, \
remaining_inline_size={:?})",
debug!("calculate_split_position_using_breaking_strategy: considering slice \
(offset={:?}, slice range={:?}, remaining_inline_size={:?})",
slice.offset,
slice.range,
remaining_inline_size);
// Use the `remaining_inline_size` to find a split point if possible. If not, go around
// the loop again with the next slice.
let metrics = text_fragment_info.run.metrics_for_slice(slice.glyphs, &slice.range);
let advance = metrics.advance_width;
// Have we found the split point?
if advance <= remaining_inline_size || slice.glyphs.is_whitespace() {
// Keep going; we haven't found the split point yet.
if flags.contains(STARTS_LINE) && pieces_processed_count == 0 &&
if flags.contains(STARTS_LINE) &&
pieces_processed_count == 0 &&
slice.glyphs.is_whitespace() {
debug!("calculate_split_position: skipping leading trimmable whitespace");
debug!("calculate_split_position_using_breaking_strategy: skipping \
leading trimmable whitespace");
inline_start_range.shift_by(slice.range.length());
} else {
debug!("split_to_inline_size: enlarging span");
debug!("calculate_split_position_using_breaking_strategy: enlarging span");
remaining_inline_size = remaining_inline_size - advance;
inline_start_range.extend_by(slice.range.length());
}
@ -1570,60 +1465,31 @@ impl Fragment {
inline_end);
}
break
}
// If we failed to find a suitable split point, we're on the verge of overflowing the
// line.
if inline_start_range.is_empty() || overflowing {
// If we've been instructed to retry at character boundaries (probably via
// `overflow-wrap: break-word`), do so.
if flags.contains(RETRY_AT_CHARACTER_BOUNDARIES) {
let character_breaking_strategy =
text_fragment_info.run
.character_slices_in_range(&text_fragment_info.range);
let mut flags = flags;
flags.remove(RETRY_AT_CHARACTER_BOUNDARIES);
return self.calculate_split_position_using_breaking_strategy(
character_breaking_strategy,
max_inline_size,
flags)
}
// If we failed to find a suitable split point, we're on the verge of overflowing the line.
if inline_start_range.is_empty() || overflowing {
// If we've been instructed to retry at character boundaries (probably via
// `overflow-wrap: break-word`), do so.
if flags.contains(RETRY_AT_CHARACTER_BOUNDARIES) {
let character_breaking_strategy =
text_fragment_info.run.character_slices_in_range(&text_fragment_info.range);
let mut flags = flags;
flags.remove(RETRY_AT_CHARACTER_BOUNDARIES);
return self.calculate_split_position_using_breaking_strategy(
character_breaking_strategy,
max_inline_size,
flags)
}
// We aren't at the start of the line, so don't overflow. Let inline layout wrap to the
// next line instead.
if !flags.contains(STARTS_LINE) {
return None
}
}
// Remove trailing whitespace from the inline-start split, if necessary.
//
// FIXME(pcwalton): Is there a more clever (i.e. faster) way to do this?
strip_trailing_whitespace(&**text_fragment_info.run, &mut inline_start_range);
// Remove leading whitespace from the inline-end split, if necessary.
//
// FIXME(pcwalton): Is there a more clever (i.e. faster) way to do this?
if let Some(ref mut inline_end_range) = inline_end_range {
let inline_end_fragment_text =
text_fragment_info.run.text.slice_chars(inline_end_range.begin().to_usize(),
inline_end_range.end().to_usize());
let mut leading_whitespace_character_count = 0;
for ch in inline_end_fragment_text.chars() {
if ch.is_whitespace() {
leading_whitespace_character_count += 1
} else {
break
// We aren't at the start of the line, so don't overflow. Let inline layout wrap to
// the next line instead.
if !flags.contains(STARTS_LINE) {
return None
}
}
inline_end_range.adjust_by(CharIndex(leading_whitespace_character_count),
-CharIndex(leading_whitespace_character_count));
}
// Normalize our split so that the inline-end fragment will never be `Some` while the
// inline-start fragment is `None`.
if inline_start_range.is_empty() && inline_end_range.is_some() {
inline_start_range = inline_end_range.unwrap();
inline_end_range = None
break
}
let inline_start = if !inline_start_range.is_empty() {
@ -1642,22 +1508,21 @@ impl Fragment {
})
}
/// Attempts to strip trailing whitespace from this fragment by adjusting the text run range.
/// Returns true if any modifications were made.
pub fn strip_trailing_whitespace_if_necessary(&mut self) -> bool {
let text_fragment_info =
if let SpecificFragmentInfo::ScannedText(ref mut text_fragment_info) = self.specific {
text_fragment_info
} else {
return false
};
let run = text_fragment_info.run.clone();
if strip_trailing_whitespace(&**run, &mut text_fragment_info.range) {
self.border_box.size.inline = run.advance_for_range(&text_fragment_info.range);
return true
/// The opposite of `calculate_split_position_using_breaking_strategy`: merges this fragment
/// with the next one.
pub fn merge_with(&mut self, next_fragment: Fragment) {
match (&mut self.specific, &next_fragment.specific) {
(&mut SpecificFragmentInfo::ScannedText(ref mut this_info),
&SpecificFragmentInfo::ScannedText(ref other_info)) => {
debug_assert!(util::arc_ptr_eq(&this_info.run, &other_info.run));
this_info.range.extend_to(other_info.range_end_including_stripped_whitespace);
this_info.content_size.inline =
this_info.run.metrics_for_range(&this_info.range).advance_width;
self.border_box.size.inline = this_info.content_size.inline +
self.border_padding.inline_start_end();
}
_ => panic!("Can only merge two scanned-text fragments!"),
}
false
}
/// Returns true if this fragment is an unscanned text fragment that consists entirely of
@ -1669,7 +1534,7 @@ impl Fragment {
}
match self.specific {
SpecificFragmentInfo::UnscannedText(ref text_fragment_info) => {
is_whitespace(text_fragment_info.text.as_slice())
util::str::is_whitespace(text_fragment_info.text.as_slice())
}
_ => false,
}
@ -1890,11 +1755,14 @@ impl Fragment {
/// Returns true if this fragment can merge with another adjacent fragment or false otherwise.
pub fn can_merge_with_fragment(&self, other: &Fragment) -> bool {
match (&self.specific, &other.specific) {
(&SpecificFragmentInfo::UnscannedText(_), &SpecificFragmentInfo::UnscannedText(_)) => {
(&SpecificFragmentInfo::UnscannedText(ref first_unscanned_text),
&SpecificFragmentInfo::UnscannedText(_)) => {
// FIXME: Should probably use a whitelist of styles that can safely differ (#3165)
let length = first_unscanned_text.text.len();
self.style().get_font() == other.style().get_font() &&
self.text_decoration() == other.text_decoration() &&
self.white_space() == other.white_space()
self.white_space() == other.white_space() &&
(length == 0 || first_unscanned_text.text.char_at_reverse(length) != '\n')
}
_ => false,
}
@ -2076,14 +1944,57 @@ impl Fragment {
_ => {}
}
}
pub fn requires_line_break_afterward_if_wrapping_on_newlines(&self) -> bool {
match self.specific {
SpecificFragmentInfo::ScannedText(ref scanned_text) => {
!scanned_text.range.is_empty() &&
scanned_text.run.text.char_at_reverse(scanned_text.range
.end()
.get() as usize) == '\n'
}
_ => false,
}
}
pub fn strip_leading_whitespace_if_necessary(&mut self) {
let mut scanned_text_fragment_info = match self.specific {
SpecificFragmentInfo::ScannedText(ref mut scanned_text_fragment_info) => {
scanned_text_fragment_info
}
_ => return,
};
if self.style.get_inheritedtext().white_space == white_space::T::pre {
return
}
let mut leading_whitespace_character_count = 0;
{
let text = scanned_text_fragment_info.run.text.slice_chars(
scanned_text_fragment_info.range.begin().to_usize(),
scanned_text_fragment_info.range.end().to_usize());
for character in text.chars() {
if util::str::char_is_whitespace(character) {
leading_whitespace_character_count += 1
} else {
break
}
}
}
scanned_text_fragment_info.range.adjust_by(CharIndex(leading_whitespace_character_count),
-CharIndex(leading_whitespace_character_count));
}
}
impl fmt::Debug for Fragment {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
try!(write!(f, "({} {} ", self.debug_id(), self.specific.get_type()));
try!(write!(f, "bp {:?}", self.border_padding));
try!(write!(f, " "));
try!(write!(f, "m {:?}", self.margin));
try!(write!(f, "bb {:?} bp {:?} m {:?}",
self.border_box,
self.border_padding,
self.margin));
write!(f, ")")
}
}
@ -2105,7 +2016,7 @@ bitflags! {
const STARTS_LINE = 0x01,
#[doc="True if we should attempt to split at character boundaries if this split fails. \
This is used to implement `overflow-wrap: break-word`."]
const RETRY_AT_CHARACTER_BOUNDARIES = 0x02
const RETRY_AT_CHARACTER_BOUNDARIES = 0x02,
}
}
@ -2129,25 +2040,3 @@ pub enum CoordinateSystem {
Own,
}
/// Given a range and a text run, adjusts the range to eliminate trailing whitespace. Returns true
/// if any modifications were made.
fn strip_trailing_whitespace(text_run: &TextRun, range: &mut Range<CharIndex>) -> bool {
// FIXME(pcwalton): Is there a more clever (i.e. faster) way to do this?
let text = text_run.text.slice_chars(range.begin().to_usize(), range.end().to_usize());
let mut trailing_whitespace_character_count = 0;
for ch in text.chars().rev() {
if ch.is_whitespace() {
trailing_whitespace_character_count += 1
} else {
break
}
}
if trailing_whitespace_character_count == 0 {
return false
}
range.extend_by(-CharIndex(trailing_whitespace_character_count));
return true
}

356
components/layout/inline.rs
View file

@ -8,11 +8,9 @@ use css::node_style::StyledNode;
use context::LayoutContext;
use display_list_builder::{FragmentDisplayListBuilding, InlineFlowDisplayListBuilding};
use floats::{FloatKind, Floats, PlacementInfo};
use flow::{BaseFlow, FlowClass, Flow, MutableFlowUtils, ForceNonfloatedFlag};
use flow::{self, BaseFlow, FlowClass, Flow, MutableFlowUtils, ForceNonfloatedFlag};
use flow::{IS_ABSOLUTELY_POSITIONED};
use flow;
use fragment::{CoordinateSystem, Fragment, FragmentBorderBoxIterator, ScannedTextFragmentInfo};
use fragment::{SpecificFragmentInfo, SplitInfo};
use fragment::{CoordinateSystem, Fragment, FragmentBorderBoxIterator, SpecificFragmentInfo};
use incremental::{REFLOW, REFLOW_OUT_OF_FLOW, RESOLVE_GENERATED_CONTENT};
use layout_debug;
use model::IntrinsicISizesContribution;
@ -23,20 +21,21 @@ use geom::{Point2D, Rect};
use gfx::font::FontMetrics;
use gfx::font_context::FontContext;
use gfx::text::glyph::CharIndex;
use util::arc_ptr_eq;
use util::geometry::{Au, ZERO_RECT};
use util::logical_geometry::{LogicalRect, LogicalSize, WritingMode};
use util::range::{Range, RangeIndex};
use gfx::text::text_run::TextRun;
use std::cmp::max;
use std::fmt;
use std::mem;
use std::num::ToPrimitive;
use std::ops::{Add, Sub, Mul, Div, Rem, Neg, Shl, Shr, Not, BitOr, BitAnd, BitXor};
use std::sync::Arc;
use std::u16;
use style::computed_values::{overflow_x, text_align, text_justify, text_overflow, vertical_align};
use style::computed_values::{white_space};
use style::properties::ComputedValues;
use std::sync::Arc;
use util::geometry::{Au, MAX_AU, ZERO_RECT};
use util::logical_geometry::{LogicalRect, LogicalSize, WritingMode};
use util::range::{Range, RangeIndex};
use util;
// From gfxFontConstants.h in Firefox
static FONT_SUBSCRIPT_OFFSET_RATIO: f64 = 0.20;
@ -160,7 +159,9 @@ int_range_index! {
bitflags! {
flags InlineReflowFlags: u8 {
#[doc="The `white-space: nowrap` property from CSS 2.1 § 16.6 is in effect."]
const NO_WRAP_INLINE_REFLOW_FLAG = 0x01
const NO_WRAP_INLINE_REFLOW_FLAG = 0x01,
#[doc="The `white-space: pre` property from CSS 2.1 § 16.6 is in effect."]
const WRAP_ON_NEWLINE_INLINE_REFLOW_FLAG = 0x02
}
}
@ -191,7 +192,7 @@ impl LineBreaker {
pending_line: Line {
range: Range::empty(),
bounds: LogicalRect::zero(float_context.writing_mode),
green_zone: LogicalSize::zero(float_context.writing_mode)
green_zone: LogicalSize::zero(float_context.writing_mode),
},
floats: float_context,
lines: Vec::new(),
@ -216,7 +217,7 @@ impl LineBreaker {
self.cur_b,
Au(0),
Au(0));
self.pending_line.green_zone = LogicalSize::zero(self.floats.writing_mode)
self.pending_line.green_zone = LogicalSize::zero(self.floats.writing_mode);
}
/// Reflows fragments for the given inline flow.
@ -226,23 +227,13 @@ impl LineBreaker {
// 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 mut old_fragment_iter = old_fragments.fragments.into_iter();
let old_fragment_iter = old_fragments.fragments.into_iter();
// Set up our initial line state with the clean lines from a previous reflow.
//
// 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 = mem::replace(&mut flow.lines, Vec::new());
match self.lines.as_slice().last() {
None => {}
Some(last_line) => {
for _ in range(FragmentIndex(0), last_line.range.end()) {
self.new_fragments.push(old_fragment_iter.next().unwrap())
}
}
}
self.lines = Vec::new();
// Do the reflow.
self.reflow_fragments(old_fragment_iter, flow, layout_context);
@ -270,30 +261,14 @@ impl LineBreaker {
// Set up our reflow flags.
let flags = match fragment.style().get_inheritedtext().white_space {
white_space::T::normal => InlineReflowFlags::empty(),
white_space::T::pre | white_space::T::nowrap => NO_WRAP_INLINE_REFLOW_FLAG,
white_space::T::nowrap => NO_WRAP_INLINE_REFLOW_FLAG,
white_space::T::pre => {
WRAP_ON_NEWLINE_INLINE_REFLOW_FLAG | NO_WRAP_INLINE_REFLOW_FLAG
}
};
// Try to append the fragment, and commit the line (so we can try again with the next
// line) if we couldn't.
match fragment.style().get_inheritedtext().white_space {
white_space::T::normal | white_space::T::nowrap => {
if !self.append_fragment_to_line_if_possible(fragment,
flow,
layout_context,
flags) {
self.flush_current_line()
}
}
white_space::T::pre => {
// FIXME(pcwalton): Surely we can unify
// `append_fragment_to_line_if_possible` and
// `try_append_to_line_by_new_line` by adding another bit in the reflow
// flags.
if !self.try_append_to_line_by_new_line(layout_context, fragment) {
self.flush_current_line()
}
}
}
// Try to append the fragment.
self.reflow_fragment(fragment, flow, layout_context, flags);
}
if !self.pending_line_is_empty() {
@ -301,37 +276,25 @@ 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.
/// Note that you probably don't want to call this method directly in order to be
/// incremental-reflow-safe; try `next_unbroken_fragment` instead.
/// If the fragment was at the end of an old line, undoes the line break for that fragment.
/// 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> {
let mut fragment;
if self.work_list.is_empty() {
return match old_fragment_iter.next() {
None => None,
Some(fragment) => {
debug!("LineBreaker: working with fragment from flow: {:?}", fragment);
Some(fragment)
}
match old_fragment_iter.next() {
None => return None,
Some(this_fragment) => fragment = this_fragment,
}
} else {
return self.work_list.pop_front()
}
debug!("LineBreaker: working with fragment from work list: {:?}", self.work_list.front());
self.work_list.pop_front()
Some(fragment)
}
/// Acquires a new fragment to lay out from the work list or fragment list, merging it with any
@ -346,10 +309,6 @@ impl LineBreaker {
};
loop {
// FIXME(pcwalton): Yuck! I hate this `new_line_pos` stuff. Can we avoid having to do
// this?
result.restore_new_line_pos();
let candidate = match self.next_fragment(old_fragment_iter) {
None => return Some(result),
Some(fragment) => fragment,
@ -357,31 +316,58 @@ impl LineBreaker {
let need_to_merge = match (&mut result.specific, &candidate.specific) {
(&mut SpecificFragmentInfo::ScannedText(ref mut result_info),
&SpecificFragmentInfo::ScannedText(ref candidate_info))
if arc_ptr_eq(&result_info.run, &candidate_info.run) &&
result_info.range.end() + CharIndex(1) == candidate_info.range.begin() => {
// We found a previously-broken fragment. Merge it up.
result_info.range.extend_by(candidate_info.range.length() + CharIndex(1));
true
&SpecificFragmentInfo::ScannedText(ref candidate_info)) => {
util::arc_ptr_eq(&result_info.run, &candidate_info.run) &&
inline_contexts_are_equal(&result.inline_context,
&candidate.inline_context)
}
_ => false,
};
if !need_to_merge {
self.work_list.push_front(candidate);
return Some(result)
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);
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 mut fragment = &mut self.new_fragments[last_fragment_index.get() as usize];
if let SpecificFragmentInfo::ScannedText(ref mut scanned_text_fragment_info) =
fragment.specific {
let scanned_text_fragment_info = &mut **scanned_text_fragment_info;
let mut range = &mut scanned_text_fragment_info.range;
strip_trailing_whitespace_if_necessary(&**scanned_text_fragment_info.run, range);
let old_fragment_inline_size = fragment.border_box.size.inline;
scanned_text_fragment_info.content_size.inline =
scanned_text_fragment_info.run.metrics_for_range(range).advance_width;
fragment.border_box.size.inline = scanned_text_fragment_info.content_size.inline +
fragment.border_padding.inline_start_end();
self.pending_line.bounds.size.inline = self.pending_line.bounds.size.inline -
(old_fragment_inline_size - fragment.border_box.size.inline)
}
}
// FIXME(eatkinson): 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_block_size_for_line(&self, new_fragment: &Fragment, layout_context: &LayoutContext)
@ -488,71 +474,16 @@ impl LineBreaker {
false
}
/// Tries to append the given fragment to the line for `pre`-formatted text, splitting it if
/// necessary. Returns true if we successfully pushed the fragment to the line or false if we
/// couldn't.
fn try_append_to_line_by_new_line(&mut self,
layout_context: &LayoutContext,
in_fragment: Fragment)
-> bool {
let should_push = match in_fragment.newline_positions() {
None => true,
Some(ref positions) => positions.is_empty(),
};
if should_push {
debug!("LineBreaker: did not find a newline character; pushing the fragment to \
the line without splitting");
self.push_fragment_to_line(layout_context, in_fragment);
return true
}
debug!("LineBreaker: Found a new-line character, so splitting the line.");
let (inline_start, inline_end, run) =
in_fragment.find_split_info_by_new_line()
.expect("LineBreaker: this split case makes no sense!");
let writing_mode = self.floats.writing_mode;
let split_fragment = |split: SplitInfo| {
let size = LogicalSize::new(writing_mode,
split.inline_size,
in_fragment.border_box.size.block);
let info = box ScannedTextFragmentInfo::new(run.clone(),
split.range,
(*in_fragment.newline_positions()
.unwrap()).clone(),
size);
in_fragment.transform(size, SpecificFragmentInfo::ScannedText(info))
};
debug!("LineBreaker: Pushing the fragment to the inline_start of the new-line character \
to the line.");
let mut inline_start = split_fragment(inline_start);
inline_start.save_new_line_pos();
*inline_start.newline_positions_mut().unwrap() = vec![];
self.push_fragment_to_line(layout_context, inline_start);
for inline_end in inline_end.into_iter() {
debug!("LineBreaker: Deferring the fragment to the inline_end of the new-line \
character to the line.");
let mut inline_end = split_fragment(inline_end);
inline_end.newline_positions_mut().unwrap().remove(0);
self.work_list.push_front(inline_end);
}
false
}
/// 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,
flow: &InlineFlow,
layout_context: &LayoutContext,
flags: InlineReflowFlags)
-> bool {
/// 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,
flags: InlineReflowFlags) {
// Determine initial placement for the fragment if we need to.
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;
@ -572,9 +503,22 @@ impl LineBreaker {
let new_block_size = self.new_block_size_for_line(&fragment, layout_context);
if new_block_size > green_zone.block {
// Uh-oh. Float collision imminent. Enter the float collision avoider!
return self.avoid_floats(flow, fragment, new_block_size)
if !self.avoid_floats(flow, fragment, new_block_size) {
self.flush_current_line();
}
return
}
// If we must flush the line after finishing this fragment due to `white-space: pre`,
// detect that.
let line_flush_mode =
if flags.contains(WRAP_ON_NEWLINE_INLINE_REFLOW_FLAG) &&
fragment.requires_line_break_afterward_if_wrapping_on_newlines() {
LineFlushMode::Flush
} 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.
@ -583,23 +527,27 @@ impl LineBreaker {
fragment.border_box.size.inline + indentation;
if new_inline_size <= green_zone.inline {
debug!("LineBreaker: fragment fits without splitting");
self.push_fragment_to_line(layout_context, fragment);
return true
self.push_fragment_to_line(layout_context, fragment, line_flush_mode);
return
}
// If we can't split the fragment or aren't allowed to because of the wrapping mode, then
// just overflow.
if (!fragment.can_split() && self.pending_line_is_empty()) ||
flags.contains(NO_WRAP_INLINE_REFLOW_FLAG) {
(flags.contains(NO_WRAP_INLINE_REFLOW_FLAG) &&
!flags.contains(WRAP_ON_NEWLINE_INLINE_REFLOW_FLAG)) {
debug!("LineBreaker: fragment can't split and line {} is empty, so overflowing",
self.lines.len());
self.push_fragment_to_line(layout_context, fragment);
return false
self.push_fragment_to_line(layout_context, fragment, LineFlushMode::No);
return
}
// Split it up!
let available_inline_size = green_zone.inline - self.pending_line.bounds.size.inline -
indentation;
let available_inline_size = if !flags.contains(NO_WRAP_INLINE_REFLOW_FLAG) {
green_zone.inline - self.pending_line.bounds.size.inline - indentation
} else {
MAX_AU
};
let inline_start_fragment;
let inline_end_fragment;
let split_result = match fragment.calculate_split_position(available_inline_size,
@ -607,7 +555,8 @@ impl LineBreaker {
None => {
debug!("LineBreaker: fragment was unsplittable; deferring to next line");
self.work_list.push_front(fragment);
return false
self.flush_current_line();
return
}
Some(split_result) => split_result,
};
@ -623,23 +572,30 @@ impl LineBreaker {
// 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)) => {
self.push_fragment_to_line(layout_context, inline_start_fragment);
self.flush_current_line();
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);
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, Some(_)) => debug_assert!(false, "un-normalized split result"),
(None, None) => {}
}
true
}
/// Pushes a fragment to the current line unconditionally, possibly truncating it and placing
/// an ellipsis based on the value of `text-overflow`.
fn push_fragment_to_line(&mut self, layout_context: &LayoutContext, fragment: Fragment) {
/// 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() {
assert!(self.new_fragments.len() <= (u16::MAX as usize));
@ -661,25 +617,27 @@ impl LineBreaker {
if !need_ellipsis {
self.push_fragment_to_line_ignoring_text_overflow(fragment);
return
} else {
let ellipsis = fragment.transform_into_ellipsis(layout_context);
if let Some(truncation_info) =
fragment.truncate_to_inline_size(available_inline_size -
ellipsis.border_box.size.inline) {
let fragment = fragment.transform_with_split_info(&truncation_info.split,
truncation_info.text_run);
self.push_fragment_to_line_ignoring_text_overflow(fragment);
}
self.push_fragment_to_line_ignoring_text_overflow(ellipsis);
}
let ellipsis = fragment.transform_into_ellipsis(layout_context);
if let Some(truncation_info) =
fragment.truncate_to_inline_size(available_inline_size -
ellipsis.border_box.size.inline) {
let fragment = fragment.transform_with_split_info(&truncation_info.split,
truncation_info.text_run);
self.push_fragment_to_line_ignoring_text_overflow(fragment);
if line_flush_mode == LineFlushMode::Flush {
self.flush_current_line()
}
self.push_fragment_to_line_ignoring_text_overflow(ellipsis);
}
/// 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) {
let indentation = self.indentation_for_pending_fragment();
self.pending_line.range.extend_by(FragmentIndex(1));
self.pending_line.bounds.size.inline = self.pending_line.bounds.size.inline +
fragment.border_box.size.inline +
@ -813,7 +771,7 @@ impl InlineFlow {
///
/// The extra boolean is set if and only if `largest_block_size_for_top_fragments` and/or
/// `largest_block_size_for_bottom_fragments` were updated. That is, if the box has a `top` or
/// `bottom` value for `vertical-align, true is returned.
/// `bottom` value for `vertical-align`, true is returned.
fn distance_from_baseline(fragment: &Fragment,
ascent: Au,
parent_text_block_start: Au,
@ -1180,7 +1138,7 @@ impl Flow for InlineFlow {
// Reset our state, so that we handle incremental reflow correctly.
//
// TODO(pcwalton): Do something smarter, like Gecko and WebKit?
self.lines = Vec::new();
self.lines.clear();
// Determine how much indentation the first line wants.
let mut indentation = if self.fragments.is_empty() {
@ -1431,6 +1389,30 @@ impl InlineFragmentContext {
styles: vec!()
}
}
fn ptr_eq(&self, other: &InlineFragmentContext) -> bool {
if self.styles.len() != other.styles.len() {
return false
}
for (this_style, other_style) in self.styles.iter().zip(other.styles.iter()) {
if !util::arc_ptr_eq(this_style, other_style) {
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,
}
}
/// Block-size above the baseline, depth below the baseline, and ascent for a fragment. See CSS 2.1
@ -1464,3 +1446,31 @@ impl InlineMetrics {
}
}
}
#[derive(Copy, Clone, PartialEq)]
enum LineFlushMode {
No,
Flush,
}
/// Given a range and a text run, adjusts the range to eliminate trailing whitespace.
fn strip_trailing_whitespace_if_necessary(text_run: &TextRun, range: &mut Range<CharIndex>) {
// FIXME(pcwalton): Is there a more clever (i.e. faster) way to do this?
debug!("stripping trailing whitespace: range={:?}, len={}",
range,
text_run.text.chars().count());
let text = text_run.text.slice_chars(range.begin().to_usize(), range.end().to_usize());
let mut trailing_whitespace_character_count = 0;
for ch in text.chars().rev() {
if util::str::char_is_whitespace(ch) {
trailing_whitespace_character_count += 1
} else {
break
}
}
if trailing_whitespace_character_count != 0 {
range.extend_by(CharIndex(-trailing_whitespace_character_count));
}
}

78
components/layout/text.rs
View file

@ -6,7 +6,7 @@
#![deny(unsafe_code)]
use fragment::{Fragment, SpecificFragmentInfo, ScannedTextFragmentInfo};
use fragment::{Fragment, SpecificFragmentInfo, ScannedTextFragmentInfo, UnscannedTextFragmentInfo};
use inline::InlineFragments;
use gfx::font::{DISABLE_KERNING_SHAPING_FLAG, FontMetrics, IGNORE_LIGATURES_SHAPING_FLAG};
@ -15,18 +15,19 @@ use gfx::font_context::FontContext;
use gfx::text::glyph::CharIndex;
use gfx::text::text_run::TextRun;
use gfx::text::util::{self, CompressionMode};
use util::linked_list::split_off_head;
use util::geometry::Au;
use util::logical_geometry::{LogicalSize, WritingMode};
use util::range::Range;
use util::smallvec::{SmallVec, SmallVec1};
use std::borrow::ToOwned;
use std::collections::LinkedList;
use std::mem;
use std::sync::Arc;
use style::computed_values::{line_height, text_orientation, text_rendering, text_transform};
use style::computed_values::{white_space};
use style::properties::ComputedValues;
use style::properties::style_structs::Font as FontStyle;
use std::sync::Arc;
use util::geometry::Au;
use util::linked_list::split_off_head;
use util::logical_geometry::{LogicalSize, WritingMode};
use util::range::Range;
use util::smallvec::{SmallVec, SmallVec1};
/// A stack-allocated object for scanning an inline flow into `TextRun`-containing `TextFragment`s.
pub struct TextRunScanner {
@ -40,7 +41,9 @@ impl TextRunScanner {
}
}
pub fn scan_for_runs(&mut self, font_context: &mut FontContext, mut fragments: LinkedList<Fragment>)
pub fn scan_for_runs(&mut self,
font_context: &mut FontContext,
mut fragments: LinkedList<Fragment>)
-> InlineFragments {
debug!("TextRunScanner: scanning {} fragments for text runs...", fragments.len());
@ -50,12 +53,14 @@ impl TextRunScanner {
let mut last_whitespace = true;
while !fragments.is_empty() {
// Create a clump.
split_first_fragment_at_newline_if_necessary(&mut fragments);
self.clump.append(&mut split_off_head(&mut fragments));
while !fragments.is_empty() && self.clump
.back()
.unwrap()
.can_merge_with_fragment(fragments.front()
.unwrap()) {
split_first_fragment_at_newline_if_necessary(&mut fragments);
self.clump.append(&mut split_off_head(&mut fragments));
}
@ -101,7 +106,6 @@ impl TextRunScanner {
//
// Concatenate all of the transformed strings together, saving the new character indices.
let mut new_ranges: SmallVec1<Range<CharIndex>> = SmallVec1::new();
let mut new_line_positions: SmallVec1<NewLinePositions> = SmallVec1::new();
let mut char_total = CharIndex(0);
let run = {
let fontgroup;
@ -137,14 +141,11 @@ impl TextRunScanner {
_ => panic!("Expected an unscanned text fragment!"),
};
let mut new_line_pos = Vec::new();
let old_length = CharIndex(run_text.chars().count() as isize);
last_whitespace = util::transform_text(in_fragment.as_slice(),
compression,
last_whitespace,
&mut run_text,
&mut new_line_pos);
new_line_positions.push(NewLinePositions(new_line_pos));
&mut run_text);
let added_chars = CharIndex(run_text.chars().count() as isize) - old_length;
new_ranges.push(Range::new(char_total, added_chars));
@ -200,13 +201,8 @@ impl TextRunScanner {
}
let text_size = old_fragment.border_box.size;
let &mut NewLinePositions(ref mut new_line_positions) =
new_line_positions.get_mut(logical_offset);
let mut new_text_fragment_info =
box ScannedTextFragmentInfo::new(run.clone(),
range,
mem::replace(new_line_positions, Vec::new()),
text_size);
box ScannedTextFragmentInfo::new(run.clone(), range, text_size);
let new_metrics = new_text_fragment_info.run.metrics_for_range(&range);
let bounding_box_size = bounding_box_for_run_metrics(&new_metrics,
old_fragment.style.writing_mode);
@ -270,8 +266,6 @@ impl TextRunScanner {
}
}
struct NewLinePositions(Vec<CharIndex>);
#[inline]
fn bounding_box_for_run_metrics(metrics: &RunMetrics, writing_mode: WritingMode)
-> LogicalSize<Au> {
@ -318,3 +312,45 @@ pub fn line_height_from_style(style: &ComputedValues, metrics: &FontMetrics) ->
line_height::T::Length(l) => l
}
}
fn split_first_fragment_at_newline_if_necessary(fragments: &mut LinkedList<Fragment>) {
if fragments.len() < 1 {
return
}
let new_fragment = {
let mut first_fragment = fragments.front_mut().unwrap();
let string_before;
{
let unscanned_text_fragment_info = match first_fragment.specific {
SpecificFragmentInfo::UnscannedText(ref mut unscanned_text_fragment_info) => {
unscanned_text_fragment_info
}
_ => return,
};
if first_fragment.style.get_inheritedtext().white_space != white_space::T::pre {
return
}
let position = match unscanned_text_fragment_info.text.find('\n') {
Some(position) if position < unscanned_text_fragment_info.text.len() - 1 => {
position
}
Some(_) | None => return,
};
string_before =
box unscanned_text_fragment_info.text[..(position + 1)].to_owned();
unscanned_text_fragment_info.text =
box unscanned_text_fragment_info.text[(position + 1)..].to_owned();
}
first_fragment.transform(first_fragment.border_box.size,
SpecificFragmentInfo::UnscannedText(UnscannedTextFragmentInfo {
text: string_before,
}))
};
fragments.push_front(new_fragment);
}