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Increase performance with bidi text

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This commit is contained in:
Jeremy Soller 2022-10-07 19:44:41 -06:00
parent 92c20fd6e1
commit 71d5beda5c
2 changed files with 24 additions and 75 deletions
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98
examples/text/src/font/matches.rs
View file

@ -5,12 +5,17 @@ pub struct FontMatches<'a> {
}
impl<'a> FontMatches<'a> {
fn shape_word(&self, font_i: usize, line: &str, start_word: usize, end_word: usize) -> FontShapeWord {
fn shape_word(&self, font_i: usize, line: &str, start_word: usize, end_word: usize, span_rtl: bool) -> FontShapeWord {
let word = &line[start_word..end_word];
let font_scale = self.fonts[font_i].rustybuzz.units_per_em() as f32;
let mut buffer = rustybuzz::UnicodeBuffer::new();
buffer.set_direction(if span_rtl {
rustybuzz::Direction::RightToLeft
} else {
rustybuzz::Direction::LeftToRight
});
buffer.push_str(word);
buffer.guess_segment_properties();
@ -19,6 +24,7 @@ impl<'a> FontMatches<'a> {
//TODO: other directions?
_ => false,
};
assert_eq!(rtl, span_rtl);
if font_i == 0 {
println!(" Word {}: '{}'", if rtl { "RTL" } else { "LTR" }, word);
@ -132,7 +138,7 @@ impl<'a> FontMatches<'a> {
}
}
let mut fb_word = self.shape_word(font_i + 1, line, start_glyph, end_glyph);
let mut fb_word = self.shape_word(font_i + 1, line, start_glyph, end_glyph, span_rtl);
// Insert all matching glyphs
// println!("Locate fallback for {},{} '{}' from font {} to font {}", start_glyph, end_glyph, &line[start_glyph..end_glyph], font_i + 1, font_i);
@ -155,88 +161,32 @@ impl<'a> FontMatches<'a> {
}
*/
FontShapeWord {
rtl,
glyphs
}
FontShapeWord { glyphs }
}
fn shape_span(&self, line: &str, start_span: usize, end_span: usize, para_rtl: bool, span_rtl: bool) -> FontShapeSpan {
use unicode_script::{Script, UnicodeScript};
fn shape_span(&self, line: &str, start_span: usize, end_span: usize, line_rtl: bool, span_rtl: bool) -> FontShapeSpan {
let span = &line[start_span..end_span];
println!(" Span {}: '{}'", if span_rtl { "RTL" } else { "LTR" }, span);
let mut words = Vec::new();
let script_splitting = false;
if script_splitting {
let mut start = 0;
let mut word_script = Script::Unknown;
for (i, c) in span.char_indices() {
let next_script = c.script();
if word_script != next_script && word_script != Script::Unknown {
// No combination, start new span
words.push(self.shape_word(0, line, start_span + start, start_span + i));
start = i;
word_script = Script::Unknown;
} else {
word_script = next_script;
}
}
words.push(self.shape_word(0, line, start_span + start, end_span));
} else {
words.push(self.shape_word(0, line, start_span, end_span));
}
if span_rtl {
for word in words.iter_mut() {
word.glyphs.reverse();
}
}
//TODO: improve performance
let mut start = 0;
for (linebreak, _) in unicode_linebreak::linebreaks(span) {
let mut word_opt = None;
'words: for word_i in 0..words.len() {
for glyph_i in 0..words[word_i].glyphs.len() {
if words[word_i].glyphs[glyph_i].start == start_span + linebreak {
word_opt = Some((
word_i + 1,
FontShapeWord {
rtl: words[word_i].rtl,
glyphs: words[word_i].glyphs.split_off(glyph_i)
}
));
break 'words;
}
}
}
if let Some((word_i, word)) = word_opt {
words.insert(word_i, word);
}
words.push(self.shape_word(0, line, start_span + start, start_span + linebreak, span_rtl));
start = linebreak;
}
words.push(self.shape_word(0, line, start_span + start, end_span, span_rtl));
if span_rtl {
for word in words.iter_mut() {
word.glyphs.reverse();
}
} else {
for word in words.iter_mut() {
if word.rtl {
word.glyphs.reverse();
}
}
}
if para_rtl {
// Reverse glyphs in RTL lines
if line_rtl {
for word in words.iter_mut() {
word.glyphs.reverse();
}
}
if para_rtl != span_rtl {
// Reverse words in spans that do not match line direction
if line_rtl != span_rtl {
words.reverse();
}
@ -255,25 +205,25 @@ impl<'a> FontMatches<'a> {
} else {
assert_eq!(bidi.paragraphs.len(), 1);
let para_info = &bidi.paragraphs[0];
let para_rtl = para_info.level.is_rtl();
let line_rtl = para_info.level.is_rtl();
println!("Line {}: '{}'", if para_rtl { "RTL" } else { "LTR" }, line);
println!("Line {}: '{}'", if line_rtl { "RTL" } else { "LTR" }, line);
let paragraph = unicode_bidi::Paragraph::new(&bidi, &para_info);
let mut start = 0;
let mut span_rtl = para_rtl;
let mut span_rtl = line_rtl;
for i in paragraph.para.range.clone() {
let next_rtl = paragraph.info.levels[i].is_rtl();
if span_rtl != next_rtl {
spans.push(self.shape_span(line, start, i, para_rtl, span_rtl));
spans.push(self.shape_span(line, start, i, line_rtl, span_rtl));
span_rtl = next_rtl;
start = i;
}
}
spans.push(self.shape_span(line, start, line.len(), para_rtl, span_rtl));
spans.push(self.shape_span(line, start, line.len(), line_rtl, span_rtl));
para_rtl
line_rtl
};
FontShapeLine {

1
examples/text/src/font/shape.rs
View file

@ -103,7 +103,6 @@ impl<'a> FontShapeGlyph<'a> {
}
pub struct FontShapeWord<'a> {
pub rtl: bool,
pub glyphs: Vec<FontShapeGlyph<'a>>,
}