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DirectWrite font backend for Windows
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| Original file line number | Diff line number | Diff line change |
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| /* This Source Code Form is subject to the terms of the Mozilla Public | ||
| * License, v. 2.0. If a copy of the MPL was not distributed with this | ||
| * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | ||
|
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| // NOTE: https://www.chromium.org/directwrite-font-proxy has useful | ||
| // information for an approach that we'll likely need to take when the | ||
| // renderer moves to a sandboxed process. | ||
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| use app_units::Au; | ||
| use font::{FontHandleMethods, FontMetrics, FontTableMethods}; | ||
| use font::{FontTableTag, FractionalPixel}; | ||
| use platform::font_template::{FontTemplateData}; | ||
| use platform::windows::font_list::{font_from_atom}; | ||
| use platform::windows::font_context::{FontContextHandle}; | ||
| use std::sync::Arc; | ||
| use style::computed_values::{font_stretch, font_weight}; | ||
| use text::glyph::GlyphId; | ||
| use dwrote::{Font, FontFace}; | ||
| use dwrote::{FontWeight, FontStretch, FontStyle}; | ||
|
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| // 1em = 12pt = 16px, assuming 72 points per inch and 96 px per inch | ||
| fn pt_to_px(pt: f64) -> f64 { pt / 72. * 96. } | ||
| fn em_to_px(em: f64) -> f64 { em * 16. } | ||
| fn au_from_em(em: f64) -> Au { Au::from_f64_px(em_to_px(em)) } | ||
| fn au_from_pt(pt: f64) -> Au { Au::from_f64_px(pt_to_px(pt)) } | ||
|
|
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| pub struct FontTable { | ||
| data: Vec<u8>, | ||
| } | ||
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| impl FontTable { | ||
| pub fn wrap(data: &[u8]) -> FontTable { | ||
| FontTable { data: data.to_vec() } | ||
| } | ||
| } | ||
|
|
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| impl FontTableMethods for FontTable { | ||
| fn buffer(&self) -> &[u8] { | ||
| &self.data | ||
| } | ||
| } | ||
|
|
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| #[derive(Debug)] | ||
| pub struct FontHandle { | ||
| font_data: Arc<FontTemplateData>, | ||
| font: Font, | ||
| face: FontFace, | ||
| em_size: f32, | ||
| du_per_em: f32, | ||
| du_to_px: f32, | ||
| scaled_du_to_px: f32, | ||
| } | ||
|
|
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| impl FontHandle { | ||
| } | ||
|
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| impl FontHandleMethods for FontHandle { | ||
| fn new_from_template(_: &FontContextHandle, template: Arc<FontTemplateData>, pt_size: Option<Au>) | ||
| -> Result<Self, ()> | ||
| { | ||
| if let Some(_) = template.bytes { | ||
| // FIXME we should load from template.bytes | ||
| Err(()) | ||
| } else { | ||
| let font = font_from_atom(&template.identifier); | ||
| let face = font.create_font_face(); | ||
|
|
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| let pt_size = pt_size.unwrap_or(au_from_pt(12.)); | ||
| let du_per_em = face.metrics().designUnitsPerEm as f32; | ||
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| let em_size = pt_size.to_f32_px() / 16.; | ||
| let design_units_per_pixel = du_per_em / 16.; | ||
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| let design_units_to_pixels = 1. / design_units_per_pixel; | ||
| let scaled_design_units_to_pixels = em_size / design_units_per_pixel; | ||
|
|
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| Ok(FontHandle { | ||
| font_data: template.clone(), | ||
| font: font, | ||
| face: face, | ||
| em_size: em_size, | ||
| du_per_em: du_per_em, | ||
| du_to_px: design_units_to_pixels, | ||
| scaled_du_to_px: scaled_design_units_to_pixels, | ||
| }) | ||
| } | ||
| } | ||
|
|
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| fn template(&self) -> Arc<FontTemplateData> { | ||
| self.font_data.clone() | ||
| } | ||
|
|
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| fn family_name(&self) -> String { | ||
| self.font.family_name() | ||
| } | ||
|
|
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| fn face_name(&self) -> String { | ||
| self.font.face_name() | ||
| } | ||
|
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| fn is_italic(&self) -> bool { | ||
| match self.font.style() { | ||
| FontStyle::Normal => false, | ||
| FontStyle::Oblique | FontStyle::Italic => true, | ||
| } | ||
| } | ||
|
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| fn boldness(&self) -> font_weight::T { | ||
| match self.font.weight() { | ||
| FontWeight::Thin => font_weight::T::Weight100, | ||
| FontWeight::ExtraLight => font_weight::T::Weight200, | ||
| FontWeight::Light => font_weight::T::Weight300, | ||
| // slightly lighter gray | ||
| FontWeight::SemiLight => font_weight::T::Weight300, | ||
| FontWeight::Regular => font_weight::T::Weight400, | ||
| FontWeight::Medium => font_weight::T::Weight500, | ||
| FontWeight::SemiBold => font_weight::T::Weight600, | ||
| FontWeight::Bold => font_weight::T::Weight700, | ||
| FontWeight::ExtraBold => font_weight::T::Weight800, | ||
| FontWeight::Black => font_weight::T::Weight900, | ||
| // slightly blacker black | ||
| FontWeight::ExtraBlack => font_weight::T::Weight900, | ||
| } | ||
| } | ||
|
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| fn stretchiness(&self) -> font_stretch::T { | ||
| match self.font.stretch() { | ||
| FontStretch::Undefined => font_stretch::T::normal, | ||
| FontStretch::UltraCondensed => font_stretch::T::ultra_condensed, | ||
| FontStretch::ExtraCondensed => font_stretch::T::extra_condensed, | ||
| FontStretch::Condensed => font_stretch::T::condensed, | ||
| FontStretch::SemiCondensed => font_stretch::T::semi_condensed, | ||
| FontStretch::Normal => font_stretch::T::normal, | ||
| FontStretch::SemiExpanded => font_stretch::T::semi_expanded, | ||
| FontStretch::Expanded => font_stretch::T::expanded, | ||
| FontStretch::ExtraExpanded => font_stretch::T::extra_expanded, | ||
| FontStretch::UltraExpanded => font_stretch::T::ultra_expanded, | ||
| } | ||
| } | ||
|
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| fn glyph_index(&self, codepoint: char) -> Option<GlyphId> { | ||
| let glyph = self.face.get_glyph_indices(&[codepoint as u32])[0]; | ||
| if glyph == 0 { | ||
| return None; | ||
| } | ||
| Some(glyph as GlyphId) | ||
| } | ||
|
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| fn glyph_h_advance(&self, glyph: GlyphId) -> Option<FractionalPixel> { | ||
| if glyph == 0 { | ||
| return None; | ||
| } | ||
|
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| let gm = self.face.get_design_glyph_metrics(&[glyph as u16], false)[0]; | ||
| let f = (gm.advanceWidth as f32 * self.scaled_du_to_px) as FractionalPixel; | ||
|
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| Some(f) | ||
| } | ||
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| /// Can this font do basic horizontal LTR shaping without Harfbuzz? | ||
| fn can_do_fast_shaping(&self) -> bool { | ||
| // TODO copy CachedKernTable from the MacOS X implementation to | ||
| // somehwere global and use it here. We could also implement the | ||
| // IDirectWriteFontFace1 interface and use the glyph kerning pair | ||
| // methods there. | ||
| false | ||
| } | ||
|
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| fn glyph_h_kerning(&self, _: GlyphId, _: GlyphId) -> FractionalPixel { | ||
| 0.0 | ||
| } | ||
|
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| fn metrics(&self) -> FontMetrics { | ||
| let dm = self.face.metrics(); | ||
|
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| let au_from_du = |du| -> Au { Au::from_f32_px(du as f32 * self.du_to_px) }; | ||
| let au_from_du_s = |du| -> Au { Au:: from_f32_px(du as f32 * self.scaled_du_to_px) }; | ||
|
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| // anything that we calculate and don't just pull out of self.face.metrics | ||
| // is pulled out here for clarity | ||
| let leading = dm.ascent - dm.capHeight; | ||
|
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| let metrics = FontMetrics { | ||
| underline_size: au_from_du(dm.underlineThickness as i32), | ||
| underline_offset: au_from_du_s(dm.underlinePosition as i32), | ||
| strikeout_size: au_from_du(dm.strikethroughThickness as i32), | ||
| strikeout_offset: au_from_du_s(dm.strikethroughPosition as i32), | ||
| leading: au_from_du_s(leading as i32), | ||
| x_height: au_from_du_s(dm.xHeight as i32), | ||
| em_size: au_from_em(self.em_size as f64), | ||
| ascent: au_from_du_s(dm.ascent as i32), | ||
| descent: au_from_du_s(dm.descent as i32), | ||
| max_advance: au_from_pt(0.0), // FIXME | ||
| average_advance: au_from_pt(0.0), // FIXME | ||
| line_gap: au_from_du(dm.lineGap as i32), | ||
| }; | ||
| debug!("Font metrics (@{} pt): {:?}", self.em_size * 12., metrics); | ||
| metrics | ||
| } | ||
|
|
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| fn table_for_tag(&self, tag: FontTableTag) -> Option<FontTable> { | ||
| self.face.get_font_table(tag).map(|bytes| FontTable { data: bytes }) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,21 @@ | ||
| /* This Source Code Form is subject to the terms of the Mozilla Public | ||
| * License, v. 2.0. If a copy of the MPL was not distributed with this | ||
| * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | ||
|
|
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| use heapsize::HeapSizeOf; | ||
|
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| #[derive(Clone, Debug)] | ||
| pub struct FontContextHandle; | ||
|
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| impl FontContextHandle { | ||
| // *shrug* | ||
| pub fn new() -> FontContextHandle { | ||
| FontContextHandle {} | ||
| } | ||
| } | ||
|
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| impl HeapSizeOf for FontContextHandle { | ||
| fn heap_size_of_children(&self) -> usize { | ||
| 0 | ||
| } | ||
| } |
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