Add alignment parameter to matrices and vectors (#4998)

crates/typst/src/math/matrix.rs

@@ -7,7 +7,8 @@ use crate::foundations::{
     Smart, StyleChain, Value,
 };
 use crate::layout::{
-    Abs, Axes, Em, FixedAlignment, Frame, FrameItem, Length, Point, Ratio, Rel, Size,
+    Abs, Axes, Em, FixedAlignment, Frame, FrameItem, HAlignment, Length, Point, Ratio,
+    Rel, Size,
 };
 use crate::math::{
     alignments, scaled_font_size, stack, style_for_denominator, AlignmentResult,
@@ -29,7 +30,8 @@ const DEFAULT_STROKE_THICKNESS: Em = Em::new(0.05);
 
 /// A column vector.
 ///
-/// Content in the vector's elements can be aligned with the `&` symbol.
+/// Content in the vector's elements can be aligned with the
+/// [`align`]($math.vec.align) parameter, or the `&` symbol.
 ///
 /// # Example
 /// ```example
@@ -47,6 +49,16 @@ pub struct VecElem {
     #[default(DelimiterPair::PAREN)]
     pub delim: DelimiterPair,
 
+    /// The horizontal alignment that each element should have.
+    ///
+    /// ```example
+    /// #set math.vec(align: right)
+    /// $ vec(-1, 1, -1) $
+    /// ```
+    #[resolve]
+    #[default(HAlignment::Center)]
+    pub align: HAlignment,
+
     /// The gap between elements.
     ///
     /// ```example
@@ -70,7 +82,7 @@ impl LayoutMath for Packed<VecElem> {
             ctx,
             styles,
             self.children(),
-            FixedAlignment::Center,
+            self.align(styles),
             self.gap(styles),
             LeftRightAlternator::Right,
         )?;
@@ -87,7 +99,9 @@ impl LayoutMath for Packed<VecElem> {
 /// special syntax of math function calls to define custom functions that take
 /// 2D data.
 ///
-/// Content in cells that are in the same row can be aligned with the `&` symbol.
+/// Content in cells can be aligned with the [`align`]($math.mat.align)
+/// parameter, or content in cells that are in the same row can be aligned with
+/// the `&` symbol.
 ///
 /// # Example
 /// ```example
@@ -109,6 +123,16 @@ pub struct MatElem {
     #[default(DelimiterPair::PAREN)]
     pub delim: DelimiterPair,
 
+    /// The horizontal alignment that each cell should have.
+    ///
+    /// ```example
+    /// #set math.mat(align: right)
+    /// $ mat(-1, 1, 1; 1, -1, 1; 1, 1, -1) $
+    /// ```
+    #[resolve]
+    #[default(HAlignment::Center)]
+    pub align: HAlignment,
+
     /// Draws augmentation lines in a matrix.
     ///
     /// - `{none}`: No lines are drawn.
@@ -249,6 +273,7 @@ impl LayoutMath for Packed<MatElem> {
             ctx,
             styles,
             rows,
+            self.align(styles),
             augment,
             Axes::new(self.column_gap(styles), self.row_gap(styles)),
             self.span(),
@@ -454,6 +479,7 @@ fn layout_mat_body(
     ctx: &mut MathContext,
     styles: StyleChain,
     rows: &[Vec<Content>],
+    align: FixedAlignment,
     augment: Option<Augment<Abs>>,
     gap: Axes<Rel<Abs>>,
     span: Span,
@@ -538,7 +564,11 @@ fn layout_mat_body(
         for (cell, &(ascent, descent)) in col.into_iter().zip(&heights) {
             let cell = cell.into_line_frame(&points, LeftRightAlternator::Right);
             let pos = Point::new(
-                if points.is_empty() { x + (rcol - cell.width()) / 2.0 } else { x },
+                if points.is_empty() {
+                    x + align.position(rcol - cell.width())
+                } else {
+                    x
+                },
                 y + ascent - cell.ascent(),
             );
 

crates/typst/src/math/underover.rs

@@ -476,7 +476,11 @@ pub(super) fn stack(
 
     let mut y = Abs::zero();
     for (i, row) in rows.into_iter().enumerate() {
-        let x = align.position(width - row.width());
+        let x = if points.is_empty() {
+            align.position(width - row.width())
+        } else {
+            Abs::zero()
+        };
         let ascent_padded_part = minimum_ascent_descent
             .map_or(Abs::zero(), |(a, _)| (a - row.ascent()))
             .max(Abs::zero());

tests/suite/math/mat.typ

@@ -92,7 +92,12 @@ $ mat(1, 0, 0, 0; 0, 1, 0, 0; 0, 0, 1, 1) $
 // Error: 3-37 cannot draw a vertical line after column 3 of a matrix with 3 columns
 $ mat(1, 0, 0; 0, 1, 1; augment: #3) $,
 
---- math-mat-align-explicit--alternating ---
+--- math-mat-align ---
+$ mat(-1, 1, 1; 1, -1, 1; 1, 1, -1; align: #left) $
+$ mat(-1, 1, 1; 1, -1, 1; 1, 1, -1; align: #center) $
+$ mat(-1, 1, 1; 1, -1, 1; 1, 1, -1; align: #right) $
+
+--- math-mat-align-explicit-alternating ---
 // Test alternating explicit alignment in a matrix.
 $ mat(
   "a" & "a a a" & "a a";
@@ -124,6 +129,17 @@ $ mat(
   "a a a"&, "a"&, "a a a"&;
 ) $
 
+--- math-mat-align-explicit-mixed ---
+// Test explicit alignment in some columns with align parameter in a matrix.
+#let data = (
+  ($&18&&.02$, $1$, $+1$),
+  ($-&9&&.3$, $-1$, $-&21$),
+  ($&&&.011$, $1$, $&0$)
+)
+$ #math.mat(align: left, ..data) $
+$ #math.mat(align: center, ..data) $
+$ #math.mat(align: right, ..data) $
+
 --- math-mat-align-complex ---
 // Test #460 equations.
 #let stop = {

tests/suite/math/vec.typ

@@ -4,6 +4,10 @@
 #set math.vec(gap: 1em)
 $ vec(1, 2) $
 
+--- math-vec-align ---
+$ vec(-1, 1, -1, align: #left)
+  vec(-1, 1, -1, align: #center)
+  vec(-1, 1, -1, align: #right) $
 
 --- math-vec-align-explicit-alternating ---
 // Test alternating alignment in a vector.