gfx: Implement font-stretch per CSS3-FONTS § 3.3 in the Core Text

font backend.

components/gfx/font.rs

@@ -10,7 +10,7 @@ use std::rc::Rc;
 use std::cell::RefCell;
 use servo_util::cache::HashCache;
 use servo_util::smallvec::{SmallVec, SmallVec8};
-use style::computed_values::{font_variant, font_weight};
+use style::computed_values::{font_stretch, font_variant, font_weight};
 use style::style_structs::Font as FontStyle;
 use std::sync::Arc;
 
@@ -37,6 +37,7 @@ pub trait FontHandleMethods {
     fn face_name(&self) -> String;
     fn is_italic(&self) -> bool;
     fn boldness(&self) -> font_weight::T;
+    fn stretchiness(&self) -> font_stretch::T;
 
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId>;
     fn glyph_h_advance(&self, GlyphId) -> Option<FractionalPixel>;

components/gfx/font_context.rs

@@ -140,7 +140,9 @@ impl FontContext {
         // so they will never be released. Find out a good time to drop them.
 
         let desc = FontTemplateDescriptor::new(style.font_weight,
-                                               style.font_style == font_style::T::italic || style.font_style == font_style::T::oblique);
+                                               style.font_stretch,
+                                               style.font_style == font_style::T::italic ||
+                                                style.font_style == font_style::T::oblique);
         let mut fonts = SmallVec8::new();
 
         for family in style.font_family.iter() {

components/gfx/font_template.rs

@@ -2,14 +2,14 @@
  * 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/. */
 
-use style::computed_values::font_weight;
+use font::FontHandleMethods;
 use platform::font_context::FontContextHandle;
 use platform::font::FontHandle;
 use platform::font_template::FontTemplateData;
 
 use std::borrow::ToOwned;
 use std::sync::{Arc, Weak};
-use font::FontHandleMethods;
+use style::computed_values::{font_stretch, font_weight};
 
 /// Describes how to select a font from a given family.
 /// This is very basic at the moment and needs to be
@@ -18,13 +18,17 @@ use font::FontHandleMethods;
 #[derive(Clone, Copy)]
 pub struct FontTemplateDescriptor {
     pub weight: font_weight::T,
+    pub stretch: font_stretch::T,
     pub italic: bool,
 }
 
 impl FontTemplateDescriptor {
-    pub fn new(weight: font_weight::T, italic: bool) -> FontTemplateDescriptor {
+    #[inline]
+    pub fn new(weight: font_weight::T, stretch: font_stretch::T, italic: bool)
+               -> FontTemplateDescriptor {
         FontTemplateDescriptor {
             weight: weight,
+            stretch: stretch,
             italic: italic,
         }
     }
@@ -33,6 +37,7 @@ impl FontTemplateDescriptor {
 impl PartialEq for FontTemplateDescriptor {
     fn eq(&self, other: &FontTemplateDescriptor) -> bool {
         self.weight.is_bold() == other.weight.is_bold() &&
+            self.stretch == other.stretch &&
             self.italic == other.italic
     }
 }
@@ -44,7 +49,8 @@ pub struct FontTemplate {
     identifier: String,
     descriptor: Option<FontTemplateDescriptor>,
     weak_ref: Option<Weak<FontTemplateData>>,
-    strong_ref: Option<Arc<FontTemplateData>>,      // GWTODO: Add code path to unset the strong_ref for web fonts!
+    // GWTODO: Add code path to unset the strong_ref for web fonts!
+    strong_ref: Option<Arc<FontTemplateData>>,
     is_valid: bool,
 }
 
@@ -82,8 +88,10 @@ impl FontTemplate {
     }
 
     /// Get the data for creating a font if it matches a given descriptor.
-    pub fn get_if_matches(&mut self, fctx: &FontContextHandle,
+    pub fn get_if_matches(&mut self,
-                            requested_desc: &FontTemplateDescriptor) -> Option<Arc<FontTemplateData>> {
+                          fctx: &FontContextHandle,
+                          requested_desc: &FontTemplateDescriptor)
+                          -> Option<Arc<FontTemplateData>> {
         // The font template data can be unloaded when nothing is referencing
         // it (via the Weak reference to the Arc above). However, if we have
         // already loaded a font, store the style information about it separately,
@@ -97,13 +105,14 @@ impl FontTemplate {
                     None
                 }
             },
-            None => {
+            None if self.is_valid => {
-                if self.is_valid {
                 let data = self.get_data();
-                    let handle: Result<FontHandle, ()> = FontHandleMethods::new_from_template(fctx, data.clone(), None);
+                let handle: Result<FontHandle, ()> =
+                    FontHandleMethods::new_from_template(fctx, data.clone(), None);
                 match handle {
                     Ok(handle) => {
                         let actual_desc = FontTemplateDescriptor::new(handle.boldness(),
+                                                                      handle.stretchiness(),
                                                                       handle.is_italic());
                         let desc_match = actual_desc == *requested_desc;
 
@@ -121,18 +130,17 @@ impl FontTemplate {
                         None
                     }
                 }
-                } else {
-                    None
-                }
             }
+            None => None,
         }
     }
 
     /// Get the data for creating a font.
     pub fn get(&mut self) -> Option<Arc<FontTemplateData>> {
-        match self.is_valid {
+        if self.is_valid {
-            true => Some(self.get_data()),
+            Some(self.get_data())
-            false => None
+        } else {
+            None
         }
     }
 
@@ -145,14 +153,13 @@ impl FontTemplate {
             None => None,
         };
 
-        match maybe_data {
+        if let Some(data) = maybe_data {
-            Some(data) => data,
+            return data
-            None => {
+        }
+
         assert!(self.strong_ref.is_none());
         let template_data = Arc::new(FontTemplateData::new(self.identifier.as_slice(), None));
         self.weak_ref = Some(template_data.downgrade());
         template_data
     }
 }
-    }
-}

components/gfx/platform/freetype/font.rs

@@ -12,7 +12,7 @@ use servo_util::str::c_str_to_string;
 use platform::font_context::FontContextHandle;
 use text::glyph::GlyphId;
 use text::util::{float_to_fixed, fixed_to_float};
-use style::computed_values::font_weight;
+use style::computed_values::{font_stretch, font_weight};
 use platform::font_template::FontTemplateData;
 
 use freetype::freetype::{FT_Get_Char_Index, FT_Get_Postscript_Name};
@@ -161,6 +161,10 @@ impl FontHandleMethods for FontHandle {
             }
         }
     }
+    fn stretchiness(&self) -> font_stretch::T {
+        // TODO(pcwalton): Implement this.
+        font_stretch::T::normal
+    }
 
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {
         assert!(!self.face.is_null());

components/gfx/platform/macos/font.rs

@@ -15,7 +15,7 @@ use servo_util::geometry::{Au, px_to_pt};
 use servo_util::geometry;
 use platform::macos::font_context::FontContextHandle;
 use text::glyph::GlyphId;
-use style::computed_values::font_weight;
+use style::computed_values::{font_stretch, font_weight};
 use platform::font_template::FontTemplateData;
 
 use core_foundation::base::CFIndex;
@@ -111,6 +111,21 @@ impl FontHandleMethods for FontHandle {
         return font_weight::T::Weight900;
     }
 
+    fn stretchiness(&self) -> font_stretch::T {
+        let normalized = self.ctfont.all_traits().normalized_width();   // [-1.0, 1.0]
+        match (normalized + 1.0) / 2.0 * 9.0 {  // [0.0, 9.0]
+            v if v < 1.0 => font_stretch::T::ultra_condensed,
+            v if v < 2.0 => font_stretch::T::extra_condensed,
+            v if v < 3.0 => font_stretch::T::condensed,
+            v if v < 4.0 => font_stretch::T::semi_condensed,
+            v if v < 5.0 => font_stretch::T::normal,
+            v if v < 6.0 => font_stretch::T::semi_expanded,
+            v if v < 7.0 => font_stretch::T::expanded,
+            v if v < 8.0 => font_stretch::T::extra_expanded,
+            _ => font_stretch::T::ultra_expanded,
+        }
+    }
+
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {
         let characters: [UniChar; 1] = [codepoint as UniChar];
         let mut glyphs: [CGGlyph; 1] = [0 as CGGlyph];

components/script/dom/webidls/CSSStyleDeclaration.webidl

@@ -127,6 +127,7 @@ partial interface CSSStyleDeclaration {
   [TreatNullAs=EmptyString] attribute DOMString font;
   [TreatNullAs=EmptyString] attribute DOMString fontFamily;
   [TreatNullAs=EmptyString] attribute DOMString fontSize;
+  [TreatNullAs=EmptyString] attribute DOMString fontStretch;
   [TreatNullAs=EmptyString] attribute DOMString fontStyle;
   [TreatNullAs=EmptyString] attribute DOMString fontVariant;
   [TreatNullAs=EmptyString] attribute DOMString fontWeight;

components/style/properties/mod.rs.mako

@@ -1149,6 +1149,9 @@ pub mod longhands {
         }
     </%self:longhand>
 
+    ${single_keyword("font-stretch",
+                     "normal ultra-condensed extra-condensed condensed semi-condensed semi-expanded expanded extra-expanded ultra-expanded")}
+
     // CSS 2.1, Section 16 - Text
 
     ${new_style_struct("InheritedText", is_inherited=True)}

tests/html/font_stretch.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+<head>
+<style>
+body {
+    font-size: 36pt;
+    font-family: "Helvetica Neue";
+    font-weight: bold;
+    font-style: normal;
+}
+#a {
+    font-stretch: normal;
+}
+#b {
+    font-stretch: condensed;
+}
+</style>
+</head>
+<body>
+<div id=a>Felis silvestris catus</div>
+<div id=b>Felis silvestris catus</div>
+</body>
+</html>
+