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Fix shaping of tab characters with Harfbuzz 1.0

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Harfbuzz now renders tabs with a "missing character" glyph by default, so we
need to filter them out ourselves after computing an advance.
This commit is contained in:
Matt Brubeck 2015-09-29 10:44:38 -07:00
parent 6304186f4f
commit 569b434023
1 changed files with 17 additions and 5 deletions
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22
components/gfx/text/shaping/harfbuzz.rs
View file

@ -442,6 +442,21 @@ impl Shaper {
let character = text.char_at(char_byte_span.begin());
if is_bidi_control(character) {
glyphs.add_nonglyph_for_char_index(char_idx, false, false);
} else if character == '\t' {
// Treat tabs in pre-formatted text as a fixed number of spaces.
//
// TODO: Proper tab stops.
const TAB_COLS: i32 = 8;
let font = self.font_and_shaping_options.font;
let (space_glyph_id, space_advance) = glyph_space_advance(font);
let advance = Au::from_f64_px(space_advance) * TAB_COLS;
let data = GlyphData::new(space_glyph_id,
advance,
Default::default(),
false,
true,
true);
glyphs.add_glyph_for_char_index(char_idx, Some(character), &data);
} else {
let shape = glyph_data.entry_for_glyph(glyph_span.begin(), &mut y_pos);
let advance = self.advance_for_shaped_glyph(shape.advance, character, options);
@ -508,9 +523,6 @@ impl Shaper {
// We elect to only space the two required code points.
if character == ' ' || character == '\u{a0}' {
advance = advance + options.word_spacing
} else if character == '\t' {
let tab_size = 8f64;
advance = Au::from_f64_px(tab_size * glyph_space_advance(self.font_and_shaping_options.font));
}
advance
@ -566,7 +578,7 @@ extern fn glyph_h_advance_func(_: *mut hb_font_t,
}
}
fn glyph_space_advance(font: *mut Font) -> f64 {
fn glyph_space_advance(font: *mut Font) -> (hb_codepoint_t, f64) {
let space_unicode = ' ';
let space_glyph: hb_codepoint_t;
match unsafe { (*font).glyph_index(space_unicode) } {
@ -576,7 +588,7 @@ fn glyph_space_advance(font: *mut Font) -> f64 {
None => panic!("No space info")
}
let space_advance = unsafe { (*font).glyph_h_advance(space_glyph as GlyphId) };
space_advance
(space_glyph, space_advance)
}
extern fn glyph_h_kerning_func(_: *mut hb_font_t,