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Don't create HarfBuzz shaper if it isn't used

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Move the fast shaping code out of the HarfBuzz shaper, and initialize the
shaper lazily to avoid creating any HarfBuzz objects.
This commit is contained in:
Matt Brubeck 2016-05-23 10:11:35 -07:00
parent 7bf6a41553
commit 43e12f7eba
2 changed files with 67 additions and 79 deletions
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62
components/gfx/text/shaping/harfbuzz.rs
View file

@ -4,7 +4,7 @@
use app_units::Au;
use euclid::Point2D;
use font::{DISABLE_KERNING_SHAPING_FLAG, Font, FontHandleMethods, FontTableMethods, FontTableTag};
use font::{DISABLE_KERNING_SHAPING_FLAG, Font, FontTableMethods, FontTableTag};
use font::{IGNORE_LIGATURES_SHAPING_FLAG, KERN, RTL_FLAG, ShapingOptions};
use harfbuzz::{HB_DIRECTION_LTR, HB_DIRECTION_RTL, HB_MEMORY_MODE_READONLY};
use harfbuzz::{hb_blob_create, hb_face_create_for_tables};
@ -34,12 +34,10 @@ use harfbuzz::{hb_glyph_position_t};
use harfbuzz::{hb_position_t, hb_tag_t};
use libc::{c_char, c_int, c_uint, c_void};
use platform::font::FontTable;
use std::ascii::AsciiExt;
use std::{char, cmp, ptr};
use text::glyph::{ByteIndex, GlyphData, GlyphId, GlyphStore};
use text::shaping::ShaperMethods;
use text::util::{fixed_to_float, float_to_fixed, is_bidi_control};
use unicode_script::Script;
const NO_GLYPH: i32 = -1;
const LIGA: u32 = ot_tag!('l', 'i', 'g', 'a');
@ -130,7 +128,7 @@ impl ShapedGlyphData {
pub struct Shaper {
hb_face: *mut hb_face_t,
hb_font: *mut hb_font_t,
font: *mut Font,
font: *const Font,
}
impl Drop for Shaper {
@ -146,16 +144,16 @@ impl Drop for Shaper {
}
impl Shaper {
pub fn new(font: &mut Font) -> Shaper {
pub fn new(font: *const Font) -> Shaper {
unsafe {
let hb_face: *mut hb_face_t =
hb_face_create_for_tables(Some(font_table_func),
font as *mut _ as *mut c_void,
font as *const c_void as *mut c_void,
None);
let hb_font: *mut hb_font_t = hb_font_create(hb_face);
// Set points-per-em. if zero, performs no hinting in that direction.
let pt_size = font.actual_pt_size.to_f64_px();
let pt_size = (*font).actual_pt_size.to_f64_px();
hb_font_set_ppem(hb_font, pt_size as c_uint, pt_size as c_uint);
// Set scaling. Note that this takes 16.16 fixed point.
@ -187,14 +185,7 @@ impl ShaperMethods for Shaper {
/// Calculate the layout metrics associated with the given text when painted in a specific
/// font.
fn shape_text(&self, text: &str, options: &ShapingOptions, glyphs: &mut GlyphStore) {
if self.can_use_fast_path(text, options) {
debug!("shape_text: Using ASCII fast path.");
self.shape_text_fast(text, options, glyphs);
return;
}
unsafe {
debug!("shape_text: Using Harfbuzz.");
let hb_buffer: *mut hb_buffer_t = hb_buffer_create();
hb_buffer_set_direction(hb_buffer, if options.flags.contains(RTL_FLAG) {
HB_DIRECTION_RTL
@ -236,47 +227,6 @@ impl ShaperMethods for Shaper {
}
impl Shaper {
fn can_use_fast_path(&self, text: &str, options: &ShapingOptions) -> bool {
let font = self.font_and_shaping_options.font;
options.script == Script::Latin &&
!options.flags.contains(RTL_FLAG) &&
unsafe { (*font).handle.can_do_fast_shaping() } &&
text.is_ascii()
}
/// Fast path for ASCII text that only needs simple horizontal LTR kerning.
fn shape_text_fast(&self, text: &str, options: &ShapingOptions, glyphs: &mut GlyphStore) {
let font = unsafe { &mut *self.font_and_shaping_options.font };
let mut prev_glyph_id = None;
for (i, byte) in text.bytes().enumerate() {
let character = byte as char;
let glyph_id = match font.glyph_index(character) {
Some(id) => id,
None => continue,
};
let mut advance = Au::from_f64_px(font.glyph_h_advance(glyph_id));
if character == ' ' {
advance += options.word_spacing;
}
if let Some(letter_spacing) = options.letter_spacing {
advance += letter_spacing;
}
let offset = prev_glyph_id.map(|prev| {
let h_kerning = Au::from_f64_px(font.glyph_h_kerning(prev, glyph_id));
advance += h_kerning;
Point2D::new(h_kerning, Au(0))
});
let glyph = GlyphData::new(glyph_id, advance, offset, true, true);
glyphs.add_glyph_for_byte_index(ByteIndex(i as isize), character, &glyph);
prev_glyph_id = Some(glyph_id);
}
glyphs.finalize_changes();
}
fn save_glyph_results(&self,
text: &str,
options: &ShapingOptions,
@ -507,7 +457,7 @@ extern fn glyph_h_advance_func(_: *mut hb_font_t,
}
}
fn glyph_space_advance(font: *mut Font) -> (hb_codepoint_t, f64) {
fn glyph_space_advance(font: *const Font) -> (hb_codepoint_t, f64) {
let space_unicode = ' ';
let space_glyph: hb_codepoint_t;
match unsafe { (*font).glyph_index(space_unicode) } {