vertical writing attribute (#9)

* add v_advance, v_side_bearing

* update message

* Update changelog

Co-authored-by: Alex Butler <alexheretic@gmail.com>

glyph/CHANGELOG.md

@@ -1,3 +1,6 @@
+# Unreleased
+* Add `v_advance` & `v_side_bearing` methods to `ScaleFont` + `_unscaled` variants to `Font`.
+
 # 0.2.2
 * Add `Font::glyph_bounds` method, similar to glyph_brush's `glyph_bounds` but for a single glyph.
 * Rename `OutlinedGlyph::bounds` to `OutlinedGlyph::px_bounds` for clarity.

glyph/src/font.rs

@@ -43,6 +43,16 @@ pub trait Font {
     /// Scaling can be done with [as_scaled](trait.Font.html#method.as_scaled).
     fn h_side_bearing_unscaled(&self, id: GlyphId) -> f32;
 
+    /// Unscaled vertical advance for a given glyph id.
+    ///
+    /// Scaling can be done with [as_scaled](trait.Font.html#method.as_scaled).
+    fn v_advance_unscaled(&self, id: GlyphId) -> f32;
+
+    /// Unscaled vertical side bearing for a given glyph id.
+    ///
+    /// Scaling can be done with [as_scaled](trait.Font.html#method.as_scaled).
+    fn v_side_bearing_unscaled(&self, id: GlyphId) -> f32;
+
     /// Returns additional unscaled kerning to apply for a particular pair of glyph ids.
     ///
     /// Scaling can be done with [as_scaled](trait.Font.html#method.as_scaled).
@@ -154,6 +164,16 @@ impl<F: Font> Font for &F {
         (*self).h_side_bearing_unscaled(id)
     }
 
+    #[inline]
+    fn v_advance_unscaled(&self, id: GlyphId) -> f32 {
+        (*self).v_advance_unscaled(id)
+    }
+
+    #[inline]
+    fn v_side_bearing_unscaled(&self, id: GlyphId) -> f32 {
+        (*self).v_side_bearing_unscaled(id)
+    }
+
     #[inline]
     fn kern_unscaled(&self, first: GlyphId, second: GlyphId) -> f32 {
         (*self).kern_unscaled(first, second)

glyph/src/font_arc.rs

@@ -101,6 +101,16 @@ impl Font for FontArc {
         self.0.h_side_bearing_unscaled(id)
     }
 
+    #[inline]
+    fn v_advance_unscaled(&self, id: GlyphId) -> f32 {
+        self.0.v_advance_unscaled(id)
+    }
+
+    #[inline]
+    fn v_side_bearing_unscaled(&self, id: GlyphId) -> f32 {
+        self.0.v_side_bearing_unscaled(id)
+    }
+
     #[inline]
     fn kern_unscaled(&self, first: GlyphId, second: GlyphId) -> f32 {
         self.0.kern_unscaled(first, second)

glyph/src/scale.rs

@@ -144,6 +144,18 @@ pub trait ScaleFont<F: Font> {
         self.h_scale_factor() * self.font().h_side_bearing_unscaled(id)
     }
 
+    /// Pixel scaled vertical advance for a given glyph.
+    #[inline]
+    fn v_advance(&self, id: GlyphId) -> f32 {
+        self.v_scale_factor() * self.font().v_advance_unscaled(id)
+    }
+
+    /// Pixel scaled vertical side bearing for a given glyph.
+    #[inline]
+    fn v_side_bearing(&self, id: GlyphId) -> f32 {
+        self.v_scale_factor() * self.font().v_side_bearing_unscaled(id)
+    }
+
     /// Returns additional pixel scaled kerning to apply for a particular pair of glyphs.
     #[inline]
     fn kern(&self, first: GlyphId, second: GlyphId) -> f32 {

glyph/src/ttfp.rs

@@ -186,6 +186,26 @@ macro_rules! impl_font {
                 f32::from(advance)
             }
 
+            #[inline]
+            fn v_advance_unscaled(&self, id: GlyphId) -> f32 {
+                let advance = self
+                    .0
+                    .as_font()
+                    .glyph_ver_advance(id.into())
+                    .expect("Invalid glyph_ver_advance");
+                f32::from(advance)
+            }
+
+            #[inline]
+            fn v_side_bearing_unscaled(&self, id: GlyphId) -> f32 {
+                let advance = self
+                    .0
+                    .as_font()
+                    .glyph_ver_side_bearing(id.into())
+                    .expect("Invalid glyph_ver_side_bearing");
+                f32::from(advance)
+            }
+
             #[inline]
             fn kern_unscaled(&self, first: GlyphId, second: GlyphId) -> f32 {
                 self.0