Use line_gap as top padding

Fixes #143

layout/CHANGELOG.md

@@ -1,3 +1,6 @@
+# Unreleased
+* Use font line_gap as top-padding for layouts to address issues with glyphs taller than the font ascent.
+
 # 0.2.3
 * Default layouts: Keep word trailing space width if ending in a hard break or end of all glyphs _e.g. `"Foo \n"`_ _(This particularly changes the layout of right & centre aligned text ending in spaces)_. 
 

layout/src/builtin.rs

@@ -723,11 +723,12 @@ mod layout_test {
  ],
  );
 
+ let sfont = A_FONT.as_scaled(40.0);
  for g in glyphs {
  println!("{:?}", (g.glyph.scale, g.glyph.position));
  // all glyphs should have the same ascent drawing position
  let y_pos = g.glyph.position.y;
- assert_relative_eq!(y_pos, A_FONT.as_scaled(40.0).ascent());
+ assert_relative_eq!(y_pos, sfont.ascent() + sfont.line_gap());
  }
  }
 

layout/src/lines.rs

@@ -28,6 +28,10 @@ impl Line {
  return Vec::new();
  }
 
+ // use line_gap as top-padding for all lines
+ // fixes issues with glyphs taller than the ascent
+ let screen_y = screen_y + self.max_v_metrics.line_gap;
+
  // implement v-aligns when they're are supported
  let screen_left = match h_align {
  HorizontalAlign::Left => point(screen_x, screen_y),