Document the Au struct and add similar font metrics debug as mac

servo · Dec 9, 2013 · 00e3a21 · 00e3a21
1 parent 76e3b34
commit 00e3a21
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Showing 3 changed files with 18 additions and 4 deletions.
diff --git a/src/components/gfx/platform/android/font.rs b/src/components/gfx/platform/android/font.rs
@@ -244,7 +244,7 @@ impl FontHandleMethods for FontHandle {
             }
         }
 
-        return FontMetrics {
+        let metrics = FontMetrics {
             underline_size:   underline_size,
             underline_offset: underline_offset,
             strikeout_size:   strikeout_size,
@@ -255,7 +255,10 @@ impl FontHandleMethods for FontHandle {
             ascent:           ascent,
             descent:          -descent, // linux font's seem to use the opposite sign from mac
             max_advance:      max_advance
-        }
+        };
+
+        debug!("Font metrics (@{:f} pt): {:?}", geometry::to_pt(em_size), metrics);
+        return metrics;
     }
 
     fn get_table_for_tag(&self, _: FontTableTag) -> Option<FontTable> {

diff --git a/src/components/gfx/platform/linux/font.rs b/src/components/gfx/platform/linux/font.rs
@@ -243,7 +243,7 @@ impl FontHandleMethods for FontHandle {
             }
         }
 
-        return FontMetrics {
+        let metrics = FontMetrics {
             underline_size:   underline_size,
             underline_offset: underline_offset,
             strikeout_size:   strikeout_size,
@@ -254,7 +254,10 @@ impl FontHandleMethods for FontHandle {
             ascent:           ascent,
             descent:          -descent, // linux font's seem to use the opposite sign from mac
             max_advance:      max_advance
-        }
+        };
+
+        debug!("Font metrics (@{:f} pt): {:?}", geometry::to_pt(em_size), metrics);
+        return metrics;
     }
 
     fn get_table_for_tag(&self, _: FontTableTag) -> Option<FontTable> {

diff --git a/src/components/util/geometry.rs b/src/components/util/geometry.rs
@@ -9,6 +9,9 @@ use geom::size::Size2D;
 use std::num::{NumCast, One, Zero};
 use std::fmt;
 
+// An Au is an "App Unit" and represents 1/60th of a CSS pixel.  It was
+// originally proposed in 2002 as a standard unit of measure in Gecko.
+// See https://bugzilla.mozilla.org/show_bug.cgi?id=177805 for more info.
 pub struct Au(i32);
 
 // We don't use #[deriving] here for inlining.
@@ -225,3 +228,8 @@ pub fn from_pt(pt: f64) -> Au {
     from_px((pt / 72f64 * 96f64) as int)
 }
 
+// assumes 72 points per inch, and 96 px per inch
+pub fn to_pt(au: Au) -> f64 {
+    (*au as f64) / 60f64 * 72f64 / 96f64
+}
+