typst_library/math/
cancel.rs

1use crate::foundations::{Content, Func, Smart, cast, elem};
2use crate::layout::{Abs, Angle, Length, Ratio, Rel};
3use crate::math::Mathy;
4use crate::visualize::Stroke;
5
6/// Displays a diagonal line over a part of an equation.
7///
8/// This is commonly used to show the elimination of a term.
9///
10/// # Example
11/// ```example
12/// >>> #set page(width: 140pt)
13/// Here, we can simplify:
14/// $ (a dot b dot cancel(x)) /
15///     cancel(x) $
16/// ```
17#[elem(Mathy)]
18pub struct CancelElem {
19    /// The content over which the line should be placed.
20    #[required]
21    pub body: Content,
22
23    /// The length of the line, relative to the length of the diagonal spanning
24    /// the whole element being "cancelled". A value of `{100%}` would then have
25    /// the line span precisely the element's diagonal.
26    ///
27    /// ```example
28    /// >>> #set page(width: 140pt)
29    /// $ a + cancel(x, length: #200%)
30    ///     - cancel(x, length: #200%) $
31    /// ```
32    #[default(Rel::new(Ratio::one(), Abs::pt(3.0).into()))]
33    pub length: Rel<Length>,
34
35    /// Whether the cancel line should be inverted (flipped along the y-axis).
36    /// For the default angle setting, inverted means the cancel line
37    /// points to the top left instead of top right.
38    ///
39    /// ```example
40    /// >>> #set page(width: 140pt)
41    /// $ (a cancel((b + c), inverted: #true)) /
42    ///     cancel(b + c, inverted: #true) $
43    /// ```
44    #[default(false)]
45    pub inverted: bool,
46
47    /// Whether two opposing cancel lines should be drawn, forming a cross over
48    /// the element. Overrides `inverted`.
49    ///
50    /// ```example
51    /// >>> #set page(width: 140pt)
52    /// $ cancel(Pi, cross: #true) $
53    /// ```
54    #[default(false)]
55    pub cross: bool,
56
57    /// How much to rotate the cancel line.
58    ///
59    /// - If given an angle, the line is rotated by that angle clockwise with
60    ///   respect to the y-axis.
61    /// - If `{auto}`, the line assumes the default angle; that is, along the
62    ///   rising diagonal of the content box.
63    /// - If given a function `angle => angle`, the line is rotated, with
64    ///   respect to the y-axis, by the angle returned by that function. The
65    ///   function receives the default angle as its input.
66    ///
67    /// ```example
68    /// >>> #set page(width: 140pt)
69    /// $ cancel(Pi)
70    ///   cancel(Pi, angle: #0deg)
71    ///   cancel(Pi, angle: #45deg)
72    ///   cancel(Pi, angle: #90deg)
73    ///   cancel(1/(1+x), angle: #(a => a + 45deg))
74    ///   cancel(1/(1+x), angle: #(a => a + 90deg)) $
75    /// ```
76    pub angle: Smart<CancelAngle>,
77
78    /// How to [stroke]($stroke) the cancel line.
79    ///
80    /// ```example
81    /// >>> #set page(width: 140pt)
82    /// $ cancel(
83    ///   sum x,
84    ///   stroke: #(
85    ///     paint: red,
86    ///     thickness: 1.5pt,
87    ///     dash: "dashed",
88    ///   ),
89    /// ) $
90    /// ```
91    #[fold]
92    #[default(Stroke {
93        // Default stroke has 0.5pt for better visuals.
94        thickness: Smart::Custom(Abs::pt(0.5).into()),
95        ..Default::default()
96    })]
97    pub stroke: Stroke,
98}
99
100/// Defines the cancel line.
101#[derive(Debug, Clone, PartialEq, Hash)]
102pub enum CancelAngle {
103    Angle(Angle),
104    Func(Func),
105}
106
107cast! {
108    CancelAngle,
109    self => match self {
110        Self::Angle(v) => v.into_value(),
111        Self::Func(v) => v.into_value()
112    },
113    v: Angle => CancelAngle::Angle(v),
114    v: Func => CancelAngle::Func(v),
115}
typst_library/math/cancel.rs

typst_library/math/
cancel.rs
