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layout: Rewrite whitespace stripping.

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This patch makes Servo unconditionally strip whitespace before text run
scanning (assuming that the `white-space` property allows it). Whitespace
stripping during reflow is now only used for handling whitespace at the ends of
lines; reflow now never attempts to handle ignorable whitespace.

Many CSS tests pass now. There are some new failures, however.

The following reference tests now fail due to a pre-existing bug whereby
whitespace is used to calculate the position of inline hypothetical boxes for
elements with `display: inline; position: absolute`:

* `absolute-replaced-height-036.htm`
* `vertical-align-sub-001.htm`
* `vertical-align-super-001.htm`

The following reference tests fail due to a pre-existing bug whereby we don't
handle `font-size: 0` properly in inline reflow:

* `font-size-zero-1.htm`
* `font-size-zero-2.htm`

The following reference test fails due to the fact that it relied on our
incorrect insertion of whitespace to make room for the black background:

* `inline-formatting-context-007.htm`
This commit is contained in:
Patrick Walton 2015-08-05 09:28:39 -07:00
parent 9c528c6382
commit ae378a8c3e
34 changed files with 216 additions and 181 deletions
Download patch file Download diff file Expand all files Collapse all files

176
components/layout/fragment.rs
View file

@ -23,6 +23,7 @@ use euclid::{Point2D, Rect, Size2D};
use gfx::display_list::{BLUR_INFLATION_FACTOR, OpaqueNode};
use gfx::text::glyph::CharIndex;
use gfx::text::text_run::{TextRun, TextRunSlice};
use gfx;
use ipc_channel::ipc::IpcSender;
use msg::constellation_msg::{ConstellationChan, Msg, PipelineId, SubpageId};
use net_traits::image::base::Image;
@ -210,6 +211,9 @@ impl fmt::Debug for SpecificFragmentInfo {
write!(f, " \"{}\"", slice_chars(&*info.run.text, info.range.begin().get() as usize,
info.range.end().get() as usize))
}
SpecificFragmentInfo::UnscannedText(ref info) => {
write!(f, " \"{}\"", info.text)
}
_ => Ok(())
}
}
@ -2102,35 +2106,144 @@ impl Fragment {
}
}
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,
};
pub fn strip_leading_whitespace_if_necessary(&mut self) -> WhitespaceStrippingResult {
if self.style.get_inheritedtext().white_space == white_space::T::pre {
return
return WhitespaceStrippingResult::RetainFragment
}
let mut leading_whitespace_character_count = 0;
{
let text = slice_chars(
&*scanned_text_fragment_info.run.text,
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 {
match self.specific {
SpecificFragmentInfo::ScannedText(ref mut scanned_text_fragment_info) => {
let mut leading_whitespace_character_count = 0;
{
let text = slice_chars(
&*scanned_text_fragment_info.run.text,
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
}
}
}
let whitespace_range = Range::new(scanned_text_fragment_info.range.begin(),
CharIndex(leading_whitespace_character_count));
let text_bounds =
scanned_text_fragment_info.run.metrics_for_range(&whitespace_range).bounding_box;
self.border_box.size.inline = self.border_box.size.inline - text_bounds.size.width;
scanned_text_fragment_info.content_size.inline =
scanned_text_fragment_info.content_size.inline - text_bounds.size.width;
scanned_text_fragment_info.range.adjust_by(
CharIndex(leading_whitespace_character_count),
-CharIndex(leading_whitespace_character_count));
return WhitespaceStrippingResult::RetainFragment
}
SpecificFragmentInfo::UnscannedText(ref mut unscanned_text_fragment_info) => {
let mut new_text_string = String::new();
let mut modified = false;
for (i, character) in unscanned_text_fragment_info.text.char_indices() {
if gfx::text::util::is_bidi_control(character) {
new_text_string.push(character);
continue
}
if util::str::char_is_whitespace(character) {
modified = true;
continue
}
new_text_string.push_str(&unscanned_text_fragment_info.text[i..]);
break
}
if modified {
unscanned_text_fragment_info.text = new_text_string.into_boxed_slice();
}
WhitespaceStrippingResult::from_unscanned_text_fragment_info(
&unscanned_text_fragment_info)
}
_ => WhitespaceStrippingResult::RetainFragment,
}
}
/// Returns true if the entire fragment was stripped.
pub fn strip_trailing_whitespace_if_necessary(&mut self) -> WhitespaceStrippingResult {
if self.style.get_inheritedtext().white_space == white_space::T::pre {
return WhitespaceStrippingResult::RetainFragment
}
scanned_text_fragment_info.range.adjust_by(CharIndex(leading_whitespace_character_count),
-CharIndex(leading_whitespace_character_count));
match self.specific {
SpecificFragmentInfo::ScannedText(ref mut scanned_text_fragment_info) => {
// FIXME(pcwalton): Is there a more clever (i.e. faster) way to do this?
debug!("stripping trailing whitespace: range={:?}, len={}",
scanned_text_fragment_info.range,
scanned_text_fragment_info.run.text.chars().count());
let mut trailing_whitespace_character_count = 0;
let text_bounds;
{
let text = slice_chars(&*scanned_text_fragment_info.run.text,
scanned_text_fragment_info.range.begin().to_usize(),
scanned_text_fragment_info.range.end().to_usize());
for ch in text.chars().rev() {
if util::str::char_is_whitespace(ch) {
trailing_whitespace_character_count += 1
} else {
break
}
}
let whitespace_range =
Range::new(scanned_text_fragment_info.range.end() -
CharIndex(trailing_whitespace_character_count),
CharIndex(trailing_whitespace_character_count));
text_bounds = scanned_text_fragment_info.run
.metrics_for_range(&whitespace_range)
.bounding_box;
self.border_box.size.inline = self.border_box.size.inline -
text_bounds.size.width;
}
scanned_text_fragment_info.content_size.inline =
scanned_text_fragment_info.content_size.inline - text_bounds.size.width;
if trailing_whitespace_character_count != 0 {
scanned_text_fragment_info.range.extend_by(
CharIndex(-trailing_whitespace_character_count));
}
WhitespaceStrippingResult::RetainFragment
}
SpecificFragmentInfo::UnscannedText(ref mut unscanned_text_fragment_info) => {
let mut trailing_bidi_control_characters_to_retain = Vec::new();
let (mut modified, mut last_character_index) = (true, 0);
for (i, character) in unscanned_text_fragment_info.text.char_indices().rev() {
if gfx::text::util::is_bidi_control(character) {
trailing_bidi_control_characters_to_retain.push(character);
continue
}
if util::str::char_is_whitespace(character) {
modified = true;
continue
}
last_character_index = i + character.len_utf8();
break
}
if modified {
let mut text = unscanned_text_fragment_info.text.to_string();
text.truncate(last_character_index);
for character in trailing_bidi_control_characters_to_retain.iter().rev() {
text.push(*character);
}
unscanned_text_fragment_info.text = text.into_boxed_slice();
}
WhitespaceStrippingResult::from_unscanned_text_fragment_info(
&unscanned_text_fragment_info)
}
_ => WhitespaceStrippingResult::RetainFragment,
}
}
pub fn inline_styles<'a>(&'a self) -> InlineStyleIterator<'a> {
@ -2232,3 +2345,24 @@ impl<'a> InlineStyleIterator<'a> {
}
}
}
#[derive(Copy, Clone, Debug)]
pub enum WhitespaceStrippingResult {
RetainFragment,
FragmentContainedOnlyBidiControlCharacters,
FragmentContainedOnlyWhitespace,
}
impl WhitespaceStrippingResult {
fn from_unscanned_text_fragment_info(info: &UnscannedTextFragmentInfo)
-> WhitespaceStrippingResult {
if info.text.is_empty() {
WhitespaceStrippingResult::FragmentContainedOnlyWhitespace
} else if info.text.chars().all(gfx::text::util::is_bidi_control) {
WhitespaceStrippingResult::FragmentContainedOnlyBidiControlCharacters
} else {
WhitespaceStrippingResult::RetainFragment
}
}
}