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 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,
-    MathContext, DELIM_SHORT_FALL,
+    style_for_denominator, style_for_numerator, FrameFragment, GlyphFragment, MathContext,
 };
 
 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, style_for_denominator, AlignmentResult, FrameFragment, GlyphFragment,
-    LeftRightAlternator, MathContext, DELIM_SHORT_FALL,
+    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.get(styles);
-    layout_delimiters(ctx, styles, frame, delim.open(), delim.close(), span)
+    layout_delimiters(
+        ctx,
+        styles,
+        frame,
+        elem.delim_size.get_ref(styles),
+        delim.open(),
+        delim.close(),
+        span,
+    )
 }
 
 /// Lays out a [`CasesElem`].
@@ -70,7 +79,15 @@ pub fn layout_cases(
     } else {
         (delim.open(), None)
     };
-    layout_delimiters(ctx, styles, frame, open, close, span)
+    layout_delimiters(
+        ctx,
+        styles,
+        frame,
+        elem.delim_size.get_ref(styles),
+        open,
+        close,
+        span,
+    )
 }
 
 /// Lays out a [`MatElem`].
@@ -128,7 +145,15 @@ pub fn layout_mat(
     )?;
 
     let delim = elem.delim.get(styles);
-    layout_delimiters(ctx, styles, frame, delim.open(), delim.close(), span)
+    layout_delimiters(
+        ctx,
+        styles,
+        frame,
+        elem.delim_size.get_ref(styles),
+        delim.open(),
+        delim.close(),
+        span,
+    )
 }
 
 /// Layout the inner contents of a matrix, vector, or cases.
@@ -309,19 +334,20 @@ 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_c) = left {
         let mut left = GlyphFragment::new_char(ctx.font, styles, left_c, span)?;
-        left.stretch_vertical(ctx, target - short_fall);
+        left.stretch_vertical(ctx, target);
         left.center_on_axis();
         ctx.push(left);
     }
@@ -330,7 +356,7 @@ fn layout_delimiters(
 
     if let Some(right_c) = right {
         let mut right = GlyphFragment::new_char(ctx.font, styles, right_c, span)?;
-        right.stretch_vertical(ctx, target - short_fall);
+        right.stretch_vertical(ctx, target);
         right.center_on_axis();
         ctx.push(right);
     }

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

@@ -1,7 +1,7 @@
 use ttf_parser::math::MathValue;
 use ttf_parser::Tag;
 use typst_library::foundations::{Style, StyleChain};
-use typst_library::layout::{Abs, Em, FixedAlignment, Frame, Point, Size};
+use typst_library::layout::{Abs, FixedAlignment, Frame, Point, Size};
 use typst_library::math::{EquationElem, MathSize};
 use typst_library::text::{FontFeatures, TextElem};
 use typst_utils::LazyHash;
@@ -30,9 +30,6 @@ 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,
-    StyleChain, Symbol, Value,
+    array, cast, dict, elem, func, Array, Content, Dict, Fold, NativeFunc, NoneValue,
+    Resolve, Smart, StyleChain, Symbol, Value,
 };
-use crate::layout::{Abs, Em, HAlignment, Length, Rel};
-use crate::math::Mathy;
+use crate::layout::{Abs, Em, HAlignment, Length, Ratio, Rel};
+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
@@ -99,6 +118,13 @@ 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
@@ -238,6 +264,13 @@ 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