Merge pull request #7685 from dotCooCoo/fix/warichu-line-height-block-lines

Type: a warichu line holds the ascent and descent of its outer block lines

crates/text/src/layout/warichu.rs

@@ -287,6 +287,10 @@ fn place_block(g: &mut [SGlyph], s: &WariStyle, (vertical, whole): (bool, bool))
     let rtl = !vertical && g.first().is_some_and(|gl| gl.level.is_rtl());
     let (inset, outset) = if rtl { (after, before) } else { (before, after) };
     let length = inset + block + outset;
+    // How far the glyphs reach above and below the line's baseline, each from its block line's
+    // baseline.
+    let above = g.iter().zip(&places).map(|(gl, p)| gl.ascent - p.1).fold(0.0, f64::max);
+    let below = g.iter().zip(&places).map(|(gl, p)| gl.descent + p.1).fold(0.0, f64::max);
     let glyphs = g.len();
     for (i, (gl, (along, across, advance))) in g.iter_mut().zip(places).enumerate() {
         let em = gl.face.units_per_em() * gl.sy / r;
@@ -300,9 +304,10 @@ fn place_block(g: &mut [SGlyph], s: &WariStyle, (vertical, whole): (bool, bool))
         if i + 1 < glyphs {
             gl.keeps_next = true;
         }
-        // The line keeps the height of the block's own size, and holds the whole stack.
-        gl.ascent = (ascent / r).max(-top);
-        gl.descent = (descent / r).max(bottom);
+        // The line keeps the height of the block's own size, and holds the whole stack with each
+        // block line's glyphs.
+        gl.ascent = (ascent / r).max(-top).max(above);
+        gl.descent = (descent / r).max(bottom).max(below);
         if s.auto_leading {
             gl.leading /= r;
         }

crates/text/src/tests/warichu.rs

@@ -626,6 +626,24 @@ fn a_block_of_several_fonts_keeps_the_tallest_of_them() {
     assert!(first_short.0 >= plain[pair.0].0 - 1e-6 && first_short.1 >= deepest - 1e-6, "{first_short:?} {plain:?}");
 }
 
+/// The line holds each block line's characters at their own height: with a wide Line Gap, the
+/// ascent of the top block line's characters and the descent of the bottom one's stay inside the
+/// line.
+#[test]
+fn a_wide_line_gap_keeps_the_outer_block_lines_inside_the_line() {
+    let small = layout(db(), &point("x", style(10.0)));
+    let (ascent, descent) = (small.lines[0].ascent, small.lines[0].descent);
+    for lines in [2, 3] {
+        let l = layout(db(), &with_block("cdefgh", CharStyle { warichu_lines: lines, warichu_gap: 20.0, ..marked(20.0) }));
+        let line = &l.lines[0];
+        let block = &l.glyphs[2..8];
+        let top = block.iter().map(|g| g.origin.y).fold(f64::INFINITY, f64::min);
+        let bottom = block.iter().map(|g| g.origin.y).fold(f64::NEG_INFINITY, f64::max);
+        assert!(line.baseline - line.ascent <= top - ascent + 1e-6, "{lines}: {} {} {top} {ascent}", line.baseline, line.ascent);
+        assert!(line.baseline + line.descent >= bottom + descent - 1e-6, "{lines}: {} {} {bottom} {descent}", line.baseline, line.descent);
+    }
+}
+
 /// Warichu Settings on characters not marked Warichu leave their shaping alone: "fi" keeps its
 /// ligature when only the f has other settings.
 #[test]

docs/mcp.md

@@ -9015,7 +9015,8 @@ Options). Warichu characters are set at `warichuScale` percent of their size (10
 `warichuLines` lines (a whole number from 1 to 6, default 2) inside their line: one above the other in horizontal type
 and side by side across the column in vertical type, the first line above or to the right. `warichuGap` is the space
 between the lines in points (0 to 100, default 0, document points as `baselineShift`). The stack is centered across the
-line on the center of the line's ideographic em box, and the line keeps the height of the characters' own size.
+line on the center of the line's ideographic em box, and the line keeps the height of the characters' own size, or
+more when the stack needs it: the line's ascent and descent take in the characters of the outer lines.
 A stretch of warichu characters is one block that takes the settings of its first character; a character with other
 settings, another size or the other kind of leading (Auto or a number) starts a new one, and a tab, a forced line break or a tate-chu-yoko character ends it. In
 vertical type a character marked `tateChuYoko` as well is set as tate-chu-yoko at its own size, and two or three digits