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Add most font metrics for FreeType

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This commit is contained in:
Brian Anderson 2012-10-15 18:14:01 -07:00
parent 952d0ce2f1
commit fdf7dc1a02
1 changed files with 44 additions and 10 deletions
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54
src/servo/text/native_font/ft_native_font.rs
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@ -3,7 +3,8 @@ export FreeTypeNativeFont, with_test_native_font, create;
use font::{FontMetrics, FractionalPixel}; use font::{FontMetrics, FractionalPixel};
use au = gfx::geometry; use gfx::geometry;
use gfx::geometry::au;
use util::*; use util::*;
use vec_as_buf = vec::as_imm_buf; use vec_as_buf = vec::as_imm_buf;
use ptr::{addr_of, null}; use ptr::{addr_of, null};
@ -11,7 +12,8 @@ use cast::reinterpret_cast;
use glyph::GlyphIndex; use glyph::GlyphIndex;
use font::FontMetrics; use font::FontMetrics;
use azure::freetype; use azure::freetype;
use freetype::{ FT_Error, FT_Library, FT_Face, FT_Long, FT_ULong, FT_UInt, FT_GlyphSlot }; use freetype::{ FT_Error, FT_Library, FT_Face, FT_Long, FT_ULong, FT_Size, FT_SizeRec,
FT_UInt, FT_GlyphSlot, FT_Size_Metrics, FT_FaceRec };
use freetype::bindgen::{ use freetype::bindgen::{
FT_Init_FreeType, FT_Init_FreeType,
FT_Done_FreeType, FT_Done_FreeType,
@ -84,17 +86,49 @@ impl FreeTypeNativeFont {
fn get_metrics() -> FontMetrics { fn get_metrics() -> FontMetrics {
/* TODO: complete me (Issue #76) */ /* TODO: complete me (Issue #76) */
let face = self.get_face_rec();
let underline_size = self.font_units_to_au(face.underline_thickness as float);
let underline_offset = self.font_units_to_au(face.underline_position as float);
let em_size = self.font_units_to_au(face.units_per_EM as float);
let ascent = self.font_units_to_au(face.ascender as float);
let descent = self.font_units_to_au(face.descender as float);
let max_advance = self.font_units_to_au(face.max_advance_width as float);
return FontMetrics { return FontMetrics {
underline_size: au::from_pt(0.0), underline_size: underline_size,
underline_offset: au::from_pt(0.0), underline_offset: underline_offset,
leading: au::from_pt(0.0), leading: geometry::from_pt(0.0), //FIXME
x_height: au::from_pt(0.0), x_height: geometry::from_pt(0.0), //FIXME
em_size: au::from_pt(0.0), em_size: em_size,
ascent: au::from_pt(0.0), ascent: ascent,
descent: au::from_pt(0.0), descent: descent,
max_advance: au::from_pt(0.0) max_advance: max_advance
} }
} }
priv fn get_face_rec() -> &self/FT_FaceRec unsafe {
&(*self.face)
}
priv fn font_units_to_au(value: float) -> au {
let face = self.get_face_rec();
// face.size is a *c_void in the bindings, presumably to avoid
// recursive structural types
let size: &FT_SizeRec = unsafe { cast::transmute(&(*face.size)) };
let metrics: &FT_Size_Metrics = unsafe { &((*size).metrics) };
let em_size = face.units_per_EM as float;
let x_scale = (metrics.x_ppem as float) / em_size as float;
// If this isn't true then we're scaling one of the axes wrong
assert metrics.x_ppem == metrics.y_ppem;
return geometry::from_frac_px(value * x_scale);
}
} }
pub fn create(lib: &FT_Library, buf: @~[u8]) -> Result<FreeTypeNativeFont, ()> { pub fn create(lib: &FT_Library, buf: @~[u8]) -> Result<FreeTypeNativeFont, ()> {