Combine FontOffset and GlyphOffset structs into Delta struct

The two structs are very similar, so there is no reason for them to be
separate. Instead combine them into a single Delta struct, which can be
used to shift a point in a two dimensional plane.

src/config.rs

@@ -1163,54 +1163,18 @@ impl Dpi {
     }
 }
 
-/// Modifications to font spacing
-///
-/// The way Alacritty calculates vertical and horizontal cell sizes may not be
-/// ideal for all fonts. This gives the user a way to tweak those values.
-#[derive(Debug, Deserialize)]
-pub struct FontOffset {
-    /// Extra horizontal spacing between letters
-    x: f32,
-    /// Extra vertical spacing between lines
-    y: f32,
-}
-
-impl FontOffset {
-    /// Get letter spacing
-    #[inline]
-    pub fn x(&self) -> f32 {
-        self.x
-    }
-
-    /// Get line spacing
-    #[inline]
-    pub fn y(&self) -> f32 {
-        self.y
-    }
-}
-
-impl Default for FontOffset {
-    fn default() -> FontOffset {
-        FontOffset { x: 0.0, y: 0.0 }
-    }
-}
-
-/// Modifications to glyph positions within their cells
-///
-/// By default the glyphs are located at the bottom of the cell which can be
-/// undesirable. This gives the user a way to shift where the glyphs are
-/// displayed in their cells.
+/// A delta for a point in a 2 dimensional plane
 #[derive(Clone, Copy, Debug, Deserialize)]
-pub struct GlyphOffset {
-    /// Horizontal position
+pub struct Delta {
+    /// Horizontal change
     pub x: f32,
-    /// Vertical position
+    /// Vertical change
     pub y: f32,
 }
 
-impl Default for GlyphOffset {
-    fn default() -> GlyphOffset {
-        GlyphOffset { x: 0.0, y: 0.0 }
+impl Default for Delta {
+    fn default() -> Delta {
+        Delta { x: 0.0, y: 0.0 }
     }
 }
 
@@ -1273,11 +1237,11 @@ pub struct Font {
     size: Size,
 
     /// Extra spacing per character
-    offset: FontOffset,
+    offset: Delta,
 
     /// Glyph offset within character cell
     #[serde(default)]
-    glyph_offset: GlyphOffset,
+    glyph_offset: Delta,
 
     #[serde(default="true_bool")]
     use_thin_strokes: bool
@@ -1316,13 +1280,13 @@ impl Font {
 
     /// Get offsets to font metrics
     #[inline]
-    pub fn offset(&self) -> &FontOffset {
+    pub fn offset(&self) -> &Delta {
         &self.offset
     }
 
     /// Get cell offsets for glyphs
     #[inline]
-    pub fn glyph_offset(&self) -> &GlyphOffset {
+    pub fn glyph_offset(&self) -> &Delta {
         &self.glyph_offset
     }
 }

src/display.rs

@@ -171,8 +171,8 @@ impl Display {
         // font metrics should be computed before creating the window in the first
         // place so that a resize is not needed.
         let metrics = glyph_cache.font_metrics();
-        let cell_width = (metrics.average_advance + font.offset().x() as f64) as u32;
-        let cell_height = (metrics.line_height + font.offset().y() as f64) as u32;
+        let cell_width = (metrics.average_advance + font.offset().x as f64) as u32;
+        let cell_height = (metrics.line_height + font.offset().y as f64) as u32;
 
         // Resize window to specified dimensions
         let dimensions = options.dimensions()

src/renderer/mod.rs

@@ -28,7 +28,7 @@ use gl;
 use index::{Line, Column, RangeInclusive};
 use notify::{Watcher as WatcherApi, RecommendedWatcher as Watcher, op};
 
-use config::{Config, GlyphOffset};
+use config::{Config, Delta};
 use term::{self, cell, RenderableCell};
 use window::{Size, Pixels};
 
@@ -156,7 +156,7 @@ pub struct GlyphCache {
     font_size: font::Size,
 
     /// glyph offset
-    glyph_offset: GlyphOffset,
+    glyph_offset: Delta,
 }
 
 impl GlyphCache {