Add delim-size parameter to mat, vec, and cases

Takes either a function or a relative length, just like with `lr`,
`stretch`, and `accent` which was changed in the previous two commits.
The short fall was changed in the first commit, so no test updates here.
The default is now much clearer to the user: `x => x * 1.1 - 0.1em`.

crates/typst-layout/src/math/frac.rs

@@ -1,14 +1,13 @@
 use typst_library::diag::SourceResult;
 use typst_library::foundations::{Content, Packed, Resolve, StyleChain, SymbolElem};
 use typst_library::layout::{Em, Frame, FrameItem, Point, Size};
-use typst_library::math::{BinomElem, FracElem};
+use typst_library::math::{BinomElem, FracElem, DELIM_SHORT_FALL};
 use typst_library::text::TextElem;
 use typst_library::visualize::{FixedStroke, Geometry};
 use typst_syntax::Span;
 
 use super::{
-    style_for_denominator, style_for_numerator, FrameFragment, GlyphFragment,
+    style_for_denominator, style_for_numerator, FrameFragment, GlyphFragment, MathContext,
-    MathContext, DELIM_SHORT_FALL,
 };
 
 const FRAC_AROUND: Em = Em::new(0.1);
@@ -49,7 +48,7 @@ fn layout_frac_like(
     binom: bool,
     span: Span,
 ) -> SourceResult<()> {
-    let short_fall = DELIM_SHORT_FALL.resolve(styles);
+    let short_fall = DELIM_SHORT_FALL.abs().resolve(styles);
     let axis = scaled!(ctx, styles, axis_height);
     let thickness = scaled!(ctx, styles, fraction_rule_thickness);
     let shift_up = scaled!(

crates/typst-layout/src/math/mat.rs

@@ -1,19 +1,20 @@
 use typst_library::diag::{bail, warning, SourceResult};
 use typst_library::foundations::{Content, Packed, Resolve, StyleChain};
 use typst_library::layout::{
-    Abs, Axes, Em, FixedAlignment, Frame, FrameItem, Point, Ratio, Rel, Size,
+    Abs, Axes, Em, FixedAlignment, Frame, FrameItem, Point, Rel, Size,
+};
+use typst_library::math::{
+    Augment, AugmentOffsets, CasesElem, MatElem, StretchSize, VecElem,
 };
-use typst_library::math::{Augment, AugmentOffsets, CasesElem, MatElem, VecElem};
 use typst_library::text::TextElem;
 use typst_library::visualize::{FillRule, FixedStroke, Geometry, LineCap, Shape};
 use typst_syntax::Span;
 
 use super::{
     alignments, delimiter_alignment, style_for_denominator, AlignmentResult,
-    FrameFragment, GlyphFragment, LeftRightAlternator, MathContext, DELIM_SHORT_FALL,
+    FrameFragment, GlyphFragment, LeftRightAlternator, MathContext,
 };
 
-const VERTICAL_PADDING: Ratio = Ratio::new(0.1);
 const DEFAULT_STROKE_THICKNESS: Em = Em::new(0.05);
 
 /// Lays out a [`VecElem`].
@@ -39,7 +40,15 @@ pub fn layout_vec(
     )?;
 
     let delim = elem.delim(styles);
-    layout_delimiters(ctx, styles, frame, delim.open(), delim.close(), span)
+    layout_delimiters(
+        ctx,
+        styles,
+        frame,
+        elem.delim_size(styles),
+        delim.open(),
+        delim.close(),
+        span,
+    )
 }
 
 /// Lays out a [`CasesElem`].
@@ -67,7 +76,7 @@ pub fn layout_cases(
     let delim = elem.delim(styles);
     let (open, close) =
         if elem.reverse(styles) { (None, delim.close()) } else { (delim.open(), None) };
-    layout_delimiters(ctx, styles, frame, open, close, span)
+    layout_delimiters(ctx, styles, frame, elem.delim_size(styles), open, close, span)
 }
 
 /// Lays out a [`MatElem`].
@@ -125,7 +134,15 @@ pub fn layout_mat(
     )?;
 
     let delim = elem.delim(styles);
-    layout_delimiters(ctx, styles, frame, delim.open(), delim.close(), span)
+    layout_delimiters(
+        ctx,
+        styles,
+        frame,
+        elem.delim_size(styles),
+        delim.open(),
+        delim.close(),
+        span,
+    )
 }
 
 /// Layout the inner contents of a matrix, vector, or cases.
@@ -302,19 +319,23 @@ fn layout_delimiters(
     ctx: &mut MathContext,
     styles: StyleChain,
     mut frame: Frame,
+    size: StretchSize,
     left: Option<char>,
     right: Option<char>,
     span: Span,
 ) -> SourceResult<()> {
-    let short_fall = DELIM_SHORT_FALL.resolve(styles);
     let axis = scaled!(ctx, styles, axis_height);
     let height = frame.height();
-    let target = height + VERTICAL_PADDING.of(height);
     frame.set_baseline(height / 2.0 + axis);
 
+    let target = size.resolve(ctx.engine, styles, height)?;
+
     if let Some(left) = left {
-        let mut left = GlyphFragment::new(ctx, styles, left, span)
+        let mut left = GlyphFragment::new(ctx, styles, left, span).stretch_vertical(
-            .stretch_vertical(ctx, target, short_fall);
+            ctx,
+            target,
+            Abs::zero(),
+        );
         left.align_on_axis(ctx, delimiter_alignment(left.c));
         ctx.push(left);
     }
@@ -322,8 +343,11 @@ fn layout_delimiters(
     ctx.push(FrameFragment::new(styles, frame));
 
     if let Some(right) = right {
-        let mut right = GlyphFragment::new(ctx, styles, right, span)
+        let mut right = GlyphFragment::new(ctx, styles, right, span).stretch_vertical(
-            .stretch_vertical(ctx, target, short_fall);
+            ctx,
+            target,
+            Abs::zero(),
+        );
         right.align_on_axis(ctx, delimiter_alignment(right.c));
         ctx.push(right);
     }

crates/typst-layout/src/math/shared.rs

@@ -1,6 +1,6 @@
 use ttf_parser::math::MathValue;
 use typst_library::foundations::{Style, StyleChain};
-use typst_library::layout::{Abs, Em, FixedAlignment, Frame, Point, Size, VAlignment};
+use typst_library::layout::{Abs, FixedAlignment, Frame, Point, Size, VAlignment};
 use typst_library::math::{EquationElem, MathSize};
 use typst_utils::LazyHash;
 
@@ -28,9 +28,6 @@ macro_rules! percent {
     };
 }
 
-/// How much less high scaled delimiters can be than what they wrap.
-pub const DELIM_SHORT_FALL: Em = Em::new(0.1);
-
 /// Converts some unit to an absolute length with the current font & font size.
 pub trait Scaled {
     fn scaled(self, ctx: &MathContext, font_size: Abs) -> Abs;

crates/typst-library/src/math/lr.rs

@@ -2,7 +2,7 @@ use crate::foundations::{elem, func, Content, NativeElement, NativeFunc, SymbolE
 use crate::layout::{Em, Length, Ratio, Rel};
 use crate::math::{Mathy, StretchSize};
 
-const DELIM_SHORT_FALL: Em = Em::new(-0.1);
+pub const DELIM_SHORT_FALL: Em = Em::new(-0.1);
 
 #[func(name = "x => x - 0.1em")]
 pub const fn default_lr_size(base: Length) -> Rel {

crates/typst-library/src/math/matrix.rs

@@ -5,15 +5,27 @@ use unicode_math_class::MathClass;
 
 use crate::diag::{bail, At, HintedStrResult, StrResult};
 use crate::foundations::{
-    array, cast, dict, elem, Array, Content, Dict, Fold, NoneValue, Resolve, Smart,
+    array, cast, dict, elem, func, Array, Content, Dict, Fold, NativeFunc, NoneValue,
-    StyleChain, Symbol, Value,
+    Resolve, Smart, StyleChain, Symbol, Value,
 };
-use crate::layout::{Abs, Em, HAlignment, Length, Rel};
+use crate::layout::{Abs, Em, HAlignment, Length, Ratio, Rel};
-use crate::math::Mathy;
+use crate::math::{Mathy, StretchSize, DELIM_SHORT_FALL};
 use crate::visualize::Stroke;
 
 const DEFAULT_ROW_GAP: Em = Em::new(0.2);
 const DEFAULT_COL_GAP: Em = Em::new(0.5);
+const VERTICAL_PADDING: Ratio = Ratio::new(1.1);
+
+#[func(name = "x => x * 1.1 - 0.1em")]
+const fn default_mat_size(base: Length) -> Rel {
+    Rel {
+        rel: Ratio::zero(),
+        abs: Length {
+            abs: Abs::raw(base.abs.to_raw() * VERTICAL_PADDING.get()),
+            em: DELIM_SHORT_FALL,
+        },
+    }
+}
 
 /// A column vector.
 ///
@@ -40,6 +52,13 @@ pub struct VecElem {
     #[default(DelimiterPair::PAREN)]
     pub delim: DelimiterPair,
 
+    /// The size of the delimiters, relative to the elements' total height.
+    ///
+    /// See the [stretch documentation]($math.stretch.size) for more
+    /// information on sizes.
+    #[default(<default_mat_size>::data().into())]
+    pub delim_size: StretchSize,
+
     /// The horizontal alignment that each element should have.
     ///
     /// ```example
@@ -101,6 +120,13 @@ pub struct MatElem {
     #[default(DelimiterPair::PAREN)]
     pub delim: DelimiterPair,
 
+    /// The size of the delimiters, relative to the cells' total height.
+    ///
+    /// See the [stretch documentation]($math.stretch.size) for more
+    /// information on sizes.
+    #[default(<default_mat_size>::data().into())]
+    pub delim_size: StretchSize,
+
     /// The horizontal alignment that each cell should have.
     ///
     /// ```example
@@ -244,6 +270,13 @@ pub struct CasesElem {
     #[default(DelimiterPair::BRACE)]
     pub delim: DelimiterPair,
 
+    /// The size of the delimiters, relative to the branches' total height.
+    ///
+    /// See the [stretch documentation]($math.stretch.size) for more
+    /// information on sizes.
+    #[default(<default_mat_size>::data().into())]
+    pub delim_size: StretchSize,
+
     /// Whether the direction of cases should be reversed.
     ///
     /// ```example

tests/suite/math/cases.typ

@@ -16,6 +16,12 @@ $ x = cases(1, 2) $
 #set math.cases(delim: sym.angle.l)
 $ cases(a, b, c) $
 
+--- math-cases-delim-size ---
+// Test setting delimiter size.
+$ cases(reverse: #true, 1, 2, 3) cases(delim-size: #100%, 1, 2, 3) $
+#set math.cases(delim-size: x => calc.max(x - 5pt, x * 0.901))
+$ cases(1, 2) cases(1, 2, 3, 4) $
+
 --- math-cases-linebreaks ---
 // Warning: 40-49 linebreaks are ignored in branches
 // Hint: 40-49 use commas instead to separate each line

tests/suite/math/mat.typ

@@ -54,6 +54,12 @@ $ a + mat(delim: #none, 1, 2; 3, 4) + b $
   $ mat(1, 2; 3, 4; delim: "[") $,
 )
 
+--- math-mat-delim-size ---
+// Test setting delimiter size.
+$ mat(c; c; c) mat(delim-size: #100%, c; c; c) $
+#set math.mat(delim-size: x => calc.max(x - 5pt, x * 0.901))
+$ mat(delim: "[", f; f; f; f) mat(delim: ||, x; x; x; x) $
+
 --- math-mat-spread ---
 // Test argument spreading in matrix.
 $ mat(..#range(1, 5).chunks(2))
@@ -263,7 +269,7 @@ $ mat(a; b; c) mat(a \ b \ c) $
 --- math-mat-vec-cases-unity ---
 // Test that matrices, vectors, and cases are all laid out the same.
 $ mat(z_(n_p); a^2)
-  vec(z_(n_p), a^2) 
+  vec(z_(n_p), a^2)
   cases(reverse: #true, delim: \(, z_(n_p), a^2)
   cases(delim: \(, z_(n_p), a^2) $
 

tests/suite/math/vec.typ

@@ -50,6 +50,12 @@ $ vec(1, 2) $
 // Error: 22-33 invalid delimiter: "%"
 #set math.vec(delim: (none, "%"))
 
+--- math-vec-delim-size ---
+// Test setting delimiter size.
+$ vec(1, 2, 3) vec(delim-size: #100%, 1, 2, 3) $
+#set math.vec(delim-size: x => calc.max(x - 5pt, x * 0.901))
+$ vec(delim: "{", 1, 2, 3) vec(delim: "[", 1, 2, 3) $
+
 --- math-vec-linebreaks ---
 // Warning: 20-29 linebreaks are ignored in elements
 // Hint: 20-29 use commas instead to separate each line