Vector and case layout

library/src/math/matrix.rs

@@ -1,5 +1,8 @@
 use super::*;
 
+const ROW_GAP: Em = Em::new(0.5);
+const VERTICAL_PADDING: Ratio = Ratio::new(0.1);
+
 /// # Vector
 /// A column vector.
 ///
@@ -18,7 +21,7 @@ use super::*;
 /// ## Category
 /// math
 #[func]
-#[capable(Texify)]
+#[capable(LayoutMath)]
 #[derive(Debug, Hash)]
 pub struct VecNode(Vec<Content>);
 
@@ -47,52 +50,13 @@ impl VecNode {
     }
 }
 
-impl Texify for VecNode {
-    fn texify(&self, t: &mut Texifier) -> SourceResult<()> {
-        let kind = match t.styles.get(Self::DELIM) {
-            Delimiter::Paren => "pmatrix",
-            Delimiter::Bracket => "bmatrix",
-            Delimiter::Brace => "Bmatrix",
-            Delimiter::Bar => "vmatrix",
-        };
-
-        t.push_str("\\begin{");
-        t.push_str(kind);
-        t.push_str("}");
-
-        for component in &self.0 {
-            component.texify(t)?;
-            t.push_str("\\\\");
-        }
-        t.push_str("\\end{");
-        t.push_str(kind);
-        t.push_str("}");
-
-        Ok(())
+impl LayoutMath for VecNode {
+    fn layout_math(&self, ctx: &mut MathContext) -> SourceResult<()> {
+        let delim = ctx.outer.get(Self::DELIM);
+        layout(ctx, &self.0, Align::Center, Some(delim.open()), Some(delim.close()))
     }
 }
 
-/// A vector / matrix delimiter.
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
-pub enum Delimiter {
-    Paren,
-    Bracket,
-    Brace,
-    Bar,
-}
-
-castable! {
-    Delimiter,
-    /// Delimit the vector with parentheses.
-    "(" => Self::Paren,
-    /// Delimit the vector with brackets.
-    "[" => Self::Bracket,
-    /// Delimit the vector with curly braces.
-    "{" => Self::Brace,
-    /// Delimit the vector with vertical bars.
-    "|" => Self::Bar,
-}
-
 /// # Cases
 /// A case distinction.
 ///
@@ -113,7 +77,7 @@ castable! {
 /// ## Category
 /// math
 #[func]
-#[capable(Texify)]
+#[capable(LayoutMath)]
 #[derive(Debug, Hash)]
 pub struct CasesNode(Vec<Content>);
 
@@ -133,14 +97,132 @@ impl CasesNode {
     }
 }
 
-impl Texify for CasesNode {
-    fn texify(&self, t: &mut Texifier) -> SourceResult<()> {
-        t.push_str("\\begin{cases}");
-        for component in &self.0 {
-            component.texify(t)?;
-            t.push_str("\\\\");
-        }
-        t.push_str("\\end{cases}");
-        Ok(())
+impl LayoutMath for CasesNode {
+    fn layout_math(&self, ctx: &mut MathContext) -> SourceResult<()> {
+        layout(ctx, &self.0, Align::Left, Some('{'), None)
     }
 }
+
+/// A vector / matrix delimiter.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum Delimiter {
+    Paren,
+    Bracket,
+    Brace,
+    Bar,
+    DoubleBar,
+}
+
+impl Delimiter {
+    /// The delimiter's opening character.
+    fn open(self) -> char {
+        match self {
+            Self::Paren => '(',
+            Self::Bracket => '[',
+            Self::Brace => '{',
+            Self::Bar => '|',
+            Self::DoubleBar => '‖',
+        }
+    }
+
+    /// The delimiter's closing character.
+    fn close(self) -> char {
+        match self {
+            Self::Paren => ')',
+            Self::Bracket => ']',
+            Self::Brace => '}',
+            Self::Bar => '|',
+            Self::DoubleBar => '‖',
+        }
+    }
+}
+
+castable! {
+    Delimiter,
+    /// Delimit the vector with parentheses.
+    "(" => Self::Paren,
+    /// Delimit the vector with brackets.
+    "[" => Self::Bracket,
+    /// Delimit the vector with curly braces.
+    "{" => Self::Brace,
+    /// Delimit the vector with vertical bars.
+    "|" => Self::Bar,
+    /// Delimit the vector with double vertical bars.
+    "||" => Self::DoubleBar,
+}
+
+/// Layout a matrix.
+fn layout(
+    ctx: &mut MathContext,
+    elements: &[Content],
+    align: Align,
+    left: Option<char>,
+    right: Option<char>,
+) -> SourceResult<()> {
+    let axis = scaled!(ctx, axis_height);
+    let gap = ROW_GAP.scaled(ctx);
+
+    ctx.style(ctx.style.for_denominator());
+    let mut rows = vec![];
+    for element in elements {
+        rows.push(ctx.layout_row(element)?);
+    }
+    ctx.unstyle();
+
+    if let Some(left) = left {
+        ctx.push(GlyphFragment::new(ctx, left));
+    }
+
+    let mut frame = stack(ctx, rows, align, gap, 0);
+    frame.set_baseline(frame.height() / 2.0 + axis);
+
+    ctx.push(frame);
+
+    if let Some(right) = right {
+        ctx.push(GlyphFragment::new(ctx, right));
+    }
+
+    Ok(())
+}
+
+/// Stack rows on top of each other.
+///
+/// Add a `gap` between each row and uses the baseline of the `baseline`th
+/// row for the whole frame.
+pub(super) fn stack(
+    ctx: &MathContext,
+    rows: Vec<MathRow>,
+    align: Align,
+    gap: Abs,
+    baseline: usize,
+) -> Frame {
+    let mut width = Abs::zero();
+    let mut height = rows.len().saturating_sub(1) as f64 * gap;
+
+    let points = alignments(&rows);
+    let rows: Vec<_> =
+        rows.into_iter().map(|row| row.to_line_frame(ctx, &points)).collect();
+
+    for row in &rows {
+        height += row.height();
+        width.set_max(row.width());
+    }
+
+    let extra = VERTICAL_PADDING.of(height);
+    height += extra;
+
+    let mut y = extra / 2.0;
+    let mut frame = Frame::new(Size::new(width, height));
+
+    for (i, row) in rows.into_iter().enumerate() {
+        let x = align.position(width - row.width());
+        let pos = Point::new(x, y);
+        if i == baseline {
+            frame.set_baseline(y + row.baseline());
+        }
+        y += row.height() + gap;
+        frame.push_frame(pos, row);
+    }
+
+    frame
+}