Configurable font edges ⚙

Adds top-edge and bottom-edge parameters to the font function. These define how
the box around a word is computed. The possible values are:
- ascender
- cap-height (default top edge)
- x-height
- baseline (default bottom edge)
- descender

The defaults are chosen so that it's easy to create good-looking designs with
vertical alignment. Since they are much tighter than what most other software
uses by default, the default leading had to be increased to 50% of the font size
and paragraph spacing to 100% of the font size.

The values cap-height and x-height fall back to ascender in case they are zero
because this value may occur in fonts that don't have glyphs with cap- or
x-height (like Twitter Color Emoji). Since cap-height is the default top edge,
doing no fallback would break things badly.

Removes softness in favor of a simple boolean for pages and a more finegread u8
for spacing. This is needed to make paragraph spacing consume line spacing
created by hard line breaks.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/library/mod.rs b/src/library/mod.rs
index 09fda20f..453eab26 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -26,9 +26,9 @@ use std::fmt::{self, Display, Formatter};
 use fontdock::{FontStyle, FontWeight};
 
 use crate::eval::{Scope, ValueAny, ValueFunc};
-use crate::exec::Softness;
 use crate::layout::*;
 use crate::prelude::*;
+use crate::shaping::VerticalFontMetric;
 
 /// Construct a scope containing all standard library definitions.
 pub fn new() -> Scope {
@@ -81,6 +81,11 @@ pub fn new() -> Scope {
     set!(any: "bold", FontWeight::BOLD);
     set!(any: "extrabold", FontWeight::EXTRABOLD);
     set!(any: "black", FontWeight::BLACK);
+    set!(any: "ascender", VerticalFontMetric::Ascender);
+    set!(any: "cap-height", VerticalFontMetric::CapHeight);
+    set!(any: "x-height", VerticalFontMetric::XHeight);
+    set!(any: "baseline", VerticalFontMetric::Baseline);
+    set!(any: "descender", VerticalFontMetric::Descender);
 
     std
 }