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Don't perform font matching for control characters

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We can encounter control characters here, for example when processing a
<pre> element which contains newlines. Control characters are inherently
non-printing, therefore if we try to call find_by_codepoint for these
characters we will end up triggering an unnecessary font fallback
search.
This commit is contained in:
Jon Leighton 2018-04-06 10:54:13 +10:00
parent 691c6c6f1a
commit 4403bcddfe
1 changed files with 52 additions and 50 deletions
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102
components/layout/text.rs
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@ -215,61 +215,63 @@ impl TextRunScanner {
let (mut start_position, mut end_position) = (0, 0);
for (byte_index, character) in text.char_indices() {
let font = font_group.borrow_mut().find_by_codepoint(&mut font_context, character);
if !character.is_control() {
let font = font_group.borrow_mut().find_by_codepoint(&mut font_context, character);
let bidi_level = match bidi_levels {
Some(levels) => levels[*paragraph_bytes_processed],
None => bidi::Level::ltr(),
};
let bidi_level = match bidi_levels {
Some(levels) => levels[*paragraph_bytes_processed],
None => bidi::Level::ltr(),
};
// Break the run if the new character has a different explicit script than the
// previous characters.
//
// TODO: Special handling of paired punctuation characters.
// http://www.unicode.org/reports/tr24/#Common
let script = get_script(character);
let compatible_script = is_compatible(script, run_info.script);
if compatible_script && !is_specific(run_info.script) && is_specific(script) {
run_info.script = script;
}
let selected = match selection {
Some(range) => range.contains(ByteIndex(byte_index as isize)),
None => false
};
// Now, if necessary, flush the mapping we were building up.
let flush_run = !run_info.has_font(&font) ||
run_info.bidi_level != bidi_level ||
!compatible_script;
let new_mapping_needed = flush_run || mapping.selected != selected;
if new_mapping_needed {
// We ignore empty mappings at the very start of a fragment.
// The run info values are uninitialized at this point so
// flushing an empty mapping is pointless.
if end_position > 0 {
mapping.flush(&mut mappings,
&mut run_info,
&**text,
compression,
text_transform,
&mut last_whitespace,
&mut start_position,
end_position);
// Break the run if the new character has a different explicit script than the
// previous characters.
//
// TODO: Special handling of paired punctuation characters.
// http://www.unicode.org/reports/tr24/#Common
let script = get_script(character);
let compatible_script = is_compatible(script, run_info.script);
if compatible_script && !is_specific(run_info.script) && is_specific(script) {
run_info.script = script;
}
if run_info.text.len() > 0 {
if flush_run {
run_info.flush(&mut run_info_list, &mut insertion_point);
run_info = RunInfo::new();
let selected = match selection {
Some(range) => range.contains(ByteIndex(byte_index as isize)),
None => false
};
// Now, if necessary, flush the mapping we were building up.
let flush_run = !run_info.has_font(&font) ||
run_info.bidi_level != bidi_level ||
!compatible_script;
let new_mapping_needed = flush_run || mapping.selected != selected;
if new_mapping_needed {
// We ignore empty mappings at the very start of a fragment.
// The run info values are uninitialized at this point so
// flushing an empty mapping is pointless.
if end_position > 0 {
mapping.flush(&mut mappings,
&mut run_info,
&**text,
compression,
text_transform,
&mut last_whitespace,
&mut start_position,
end_position);
}
mapping = RunMapping::new(&run_info_list[..],
fragment_index);
if run_info.text.len() > 0 {
if flush_run {
run_info.flush(&mut run_info_list, &mut insertion_point);
run_info = RunInfo::new();
}
mapping = RunMapping::new(&run_info_list[..],
fragment_index);
}
run_info.font = font;
run_info.bidi_level = bidi_level;
run_info.script = script;
mapping.selected = selected;
}
run_info.font = font;
run_info.bidi_level = bidi_level;
run_info.script = script;
mapping.selected = selected;
}
// Consume this character.