From eabb8d4f2918ff3f8f992f369c7a6779a6461e8b Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 22 Sep 2014 17:00:00 +0100
Subject: [PATCH] Add support for font-size relative size keywords. Fix #3423

---
 components/style/properties/mod.rs.mako | 27 ++++++++++++++-----------
 tests/ref/font_size.html                |  2 ++
 tests/ref/font_size_ref.html            |  2 ++
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/components/style/properties/mod.rs.mako b/components/style/properties/mod.rs.mako
index a38c7568ca0..5f457dfcd49 100644
--- a/components/style/properties/mod.rs.mako
+++ b/components/style/properties/mod.rs.mako
@@ -908,8 +908,7 @@ pub mod longhands {
             // We already computed this element's font size; no need to compute it again.
             return context.font_size
         }
-        /// <length> | <percentage> | <absolute-size>
-        /// TODO: support <relative-size>
+        /// <length> | <percentage> | <absolute-size> | <relative-size>
         pub fn from_component_value(input: &ComponentValue, _base_url: &Url)
                                     -> Result<SpecifiedValue, ()> {
             match specified::LengthOrPercentage::parse_non_negative(input) {
@@ -917,17 +916,21 @@ pub mod longhands {
                 Ok(specified::LP_Percentage(value)) => return Ok(specified::Em(value)),
                 Err(()) => (),
             }
-            let au = match try!(get_ident_lower(input)).as_slice() {
-                "xx-small" => Au::from_px(MEDIUM_PX) * 3 / 5,
-                "x-small" => Au::from_px(MEDIUM_PX) * 3 / 4,
-                "small" => Au::from_px(MEDIUM_PX) * 8 / 9,
-                "medium" => Au::from_px(MEDIUM_PX),
-                "large" => Au::from_px(MEDIUM_PX) * 6 / 5,
-                "x-large" => Au::from_px(MEDIUM_PX) * 3 / 2,
-                "xx-large" => Au::from_px(MEDIUM_PX) * 2,
+            match try!(get_ident_lower(input)).as_slice() {
+                "xx-small" => Ok(specified::Au_(Au::from_px(MEDIUM_PX) * 3 / 5)),
+                "x-small" => Ok(specified::Au_(Au::from_px(MEDIUM_PX) * 3 / 4)),
+                "small" => Ok(specified::Au_(Au::from_px(MEDIUM_PX) * 8 / 9)),
+                "medium" => Ok(specified::Au_(Au::from_px(MEDIUM_PX))),
+                "large" => Ok(specified::Au_(Au::from_px(MEDIUM_PX) * 6 / 5)),
+                "x-large" => Ok(specified::Au_(Au::from_px(MEDIUM_PX) * 3 / 2)),
+                "xx-large" => Ok(specified::Au_(Au::from_px(MEDIUM_PX) * 2)),
+
+                // https://github.com/servo/servo/issues/3423#issuecomment-56321664
+                "smaller" => Ok(specified::Em(0.85)),
+                "larger" => Ok(specified::Em(1.2)),
+
                 _ => return Err(())
-            };
-            Ok(specified::Au_(au))
+            }
         }
     </%self:single_component_value>
 
diff --git a/tests/ref/font_size.html b/tests/ref/font_size.html
index 868a6f4b3d3..6d534378724 100644
--- a/tests/ref/font_size.html
+++ b/tests/ref/font_size.html
@@ -4,6 +4,8 @@
 <p style="font-size: 24pt">24pt is 32px.
 <p style="font-size: 2em">2em is 40px.
 <p style="font-size: 200%">200% is 40px.
+<p style="font-size: smaller">smaller is 17px.
+<p style="font-size: larger">larger is 24px.
 <p style="font-size: xx-small">xx-small is 9.6px.
 <p style="font-size: x-small">x-small is 12px.
 <p style="font-size: small">small is 14.2222…px.
diff --git a/tests/ref/font_size_ref.html b/tests/ref/font_size_ref.html
index d85c120b822..0c5d50fb8b7 100644
--- a/tests/ref/font_size_ref.html
+++ b/tests/ref/font_size_ref.html
@@ -4,6 +4,8 @@
 <p style="font-size: 32px">24pt is 32px.
 <p style="font-size: 40px">2em is 40px.
 <p style="font-size: 40px">200% is 40px.
+<p style="font-size: 17px">smaller is 17px.
+<p style="font-size: 24px">larger is 24px.
 <p style="font-size: 9.6px">xx-small is 9.6px.
 <p style="font-size: 12px">x-small is 12px.
 <p style="font-size: 14.2222222222222222222222222222px">small is 14.2222…px.