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, 3 insertions, 12 deletions

diff --git a/src/exec/mod.rs b/src/exec/mod.rs
index 45abca02..35ffa2b6 100644
--- a/src/exec/mod.rs
+++ b/src/exec/mod.rs
@@ -35,15 +35,6 @@ pub fn exec(
     ctx.finish()
 }
 
-/// Defines how an item interacts with surrounding items.
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
-pub enum Softness {
-    /// A soft item can be skipped in some circumstances.
-    Soft,
-    /// A hard item is always retained.
-    Hard,
-}
-
 /// Execute a node.
 ///
 /// This manipulates active styling and document state and produces layout
@@ -106,15 +97,15 @@ impl Exec for NodeRaw {
         ctx.set_monospace();
 
         let em = ctx.state.font.font_size();
-        let line_spacing = ctx.state.par.line_spacing.resolve(em);
+        let leading = ctx.state.par.leading.resolve(em);
 
         let mut children = vec![];
         let mut newline = false;
         for line in &self.lines {
             if newline {
                 children.push(layout::Node::Spacing(NodeSpacing {
-                    amount: line_spacing,
-                    softness: Softness::Soft,
+                    amount: leading,
+                    softness: 2,
                 }));
             }