2025-03-28 17:33:16 +00:00

597 lines
19 KiB
Rust

use kurbo::ParamCurveExtrema;
use typst_macros::{scope, Cast};
use typst_utils::Numeric;
use crate::diag::{bail, HintedStrResult, HintedString, SourceResult};
use crate::engine::Engine;
use crate::foundations::{
cast, elem, Content, NativeElement, Packed, Show, Smart, StyleChain,
};
use crate::layout::{Abs, Axes, BlockElem, Length, Point, Rel, Size};
use crate::visualize::{FillRule, Paint, Stroke};
use super::FixedStroke;
/// A curve consisting of movements, lines, and Bézier segments.
///
/// At any point in time, there is a conceptual pen or cursor.
/// - Move elements move the cursor without drawing.
/// - Line/Quadratic/Cubic elements draw a segment from the cursor to a new
/// position, potentially with control point for a Bézier curve.
/// - Close elements draw a straight or smooth line back to the start of the
/// curve or the latest preceding move segment.
///
/// For layout purposes, the bounding box of the curve is a tight rectangle
/// containing all segments as well as the point `{(0pt, 0pt)}`.
///
/// Positions may be specified absolutely (i.e. relatively to `{(0pt, 0pt)}`),
/// or relative to the current pen/cursor position, that is, the position where
/// the previous segment ended.
///
/// Bézier curve control points can be skipped by passing `{none}` or
/// automatically mirrored from the preceding segment by passing `{auto}`.
///
/// # Example
/// ```example
/// #curve(
/// fill: blue.lighten(80%),
/// stroke: blue,
/// curve.move((0pt, 50pt)),
/// curve.line((100pt, 50pt)),
/// curve.cubic(none, (90pt, 0pt), (50pt, 0pt)),
/// curve.close(),
/// )
/// ```
#[elem(scope, Show)]
pub struct CurveElem {
/// How to fill the curve.
///
/// When setting a fill, the default stroke disappears. To create a
/// rectangle with both fill and stroke, you have to configure both.
pub fill: Option<Paint>,
/// The drawing rule used to fill the curve.
///
/// ```example
/// // We use `.with` to get a new
/// // function that has the common
/// // arguments pre-applied.
/// #let star = curve.with(
/// fill: red,
/// curve.move((25pt, 0pt)),
/// curve.line((10pt, 50pt)),
/// curve.line((50pt, 20pt)),
/// curve.line((0pt, 20pt)),
/// curve.line((40pt, 50pt)),
/// curve.close(),
/// )
///
/// #star(fill-rule: "non-zero")
/// #star(fill-rule: "even-odd")
/// ```
#[default]
pub fill_rule: FillRule,
/// How to [stroke] the curve. This can be:
///
/// Can be set to `{none}` to disable the stroke or to `{auto}` for a
/// stroke of `{1pt}` black if and if only if no fill is given.
///
/// ```example
/// #let down = curve.line((40pt, 40pt), relative: true)
/// #let up = curve.line((40pt, -40pt), relative: true)
///
/// #curve(
/// stroke: 4pt + gradient.linear(red, blue),
/// down, up, down, up, down,
/// )
/// ```
#[resolve]
#[fold]
pub stroke: Smart<Option<Stroke>>,
/// The components of the curve, in the form of moves, line and Bézier
/// segment, and closes.
#[variadic]
pub components: Vec<CurveComponent>,
}
impl Show for Packed<CurveElem> {
fn show(&self, engine: &mut Engine, _: StyleChain) -> SourceResult<Content> {
Ok(BlockElem::single_layouter(self.clone(), engine.routines.layout_curve)
.pack()
.spanned(self.span()))
}
}
#[scope]
impl CurveElem {
#[elem]
type CurveMove;
#[elem]
type CurveLine;
#[elem]
type CurveQuad;
#[elem]
type CurveCubic;
#[elem]
type CurveClose;
}
/// A component used for curve creation.
#[derive(Debug, Clone, PartialEq, Hash)]
pub enum CurveComponent {
Move(Packed<CurveMove>),
Line(Packed<CurveLine>),
Quad(Packed<CurveQuad>),
Cubic(Packed<CurveCubic>),
Close(Packed<CurveClose>),
}
cast! {
CurveComponent,
self => match self {
Self::Move(element) => element.into_value(),
Self::Line(element) => element.into_value(),
Self::Quad(element) => element.into_value(),
Self::Cubic(element) => element.into_value(),
Self::Close(element) => element.into_value(),
},
v: Content => {
v.try_into()?
}
}
impl TryFrom<Content> for CurveComponent {
type Error = HintedString;
fn try_from(value: Content) -> HintedStrResult<Self> {
value
.into_packed::<CurveMove>()
.map(Self::Move)
.or_else(|value| value.into_packed::<CurveLine>().map(Self::Line))
.or_else(|value| value.into_packed::<CurveQuad>().map(Self::Quad))
.or_else(|value| value.into_packed::<CurveCubic>().map(Self::Cubic))
.or_else(|value| value.into_packed::<CurveClose>().map(Self::Close))
.or_else(|_| bail!("expecting a curve element"))
}
}
/// Starts a new curve component.
///
/// If no `curve.move` element is passed, the curve will start at
/// `{(0pt, 0pt)}`.
///
/// ```example
/// #curve(
/// fill: blue.lighten(80%),
/// fill-rule: "even-odd",
/// stroke: blue,
/// curve.line((50pt, 0pt)),
/// curve.line((50pt, 50pt)),
/// curve.line((0pt, 50pt)),
/// curve.close(),
/// curve.move((10pt, 10pt)),
/// curve.line((40pt, 10pt)),
/// curve.line((40pt, 40pt)),
/// curve.line((10pt, 40pt)),
/// curve.close(),
/// )
/// ```
#[elem(name = "move", title = "Curve Move")]
pub struct CurveMove {
/// The starting point for the new component.
#[required]
pub start: Axes<Rel<Length>>,
/// Whether the coordinates are relative to the previous point.
#[default(false)]
pub relative: bool,
}
/// Adds a straight line from the current point to a following one.
///
/// ```example
/// #curve(
/// stroke: blue,
/// curve.line((50pt, 0pt)),
/// curve.line((50pt, 50pt)),
/// curve.line((100pt, 50pt)),
/// curve.line((100pt, 0pt)),
/// curve.line((150pt, 0pt)),
/// )
/// ```
#[elem(name = "line", title = "Curve Line")]
pub struct CurveLine {
/// The point at which the line shall end.
#[required]
pub end: Axes<Rel<Length>>,
/// Whether the coordinates are relative to the previous point.
///
/// ```example
/// #curve(
/// stroke: blue,
/// curve.line((50pt, 0pt), relative: true),
/// curve.line((0pt, 50pt), relative: true),
/// curve.line((50pt, 0pt), relative: true),
/// curve.line((0pt, -50pt), relative: true),
/// curve.line((50pt, 0pt), relative: true),
/// )
/// ```
#[default(false)]
pub relative: bool,
}
/// Adds a quadratic Bézier curve segment from the last point to `end`, using
/// `control` as the control point.
///
/// ```example
/// // Function to illustrate where the control point is.
/// #let mark((x, y)) = place(
/// dx: x - 1pt, dy: y - 1pt,
/// circle(fill: aqua, radius: 2pt),
/// )
///
/// #mark((20pt, 20pt))
///
/// #curve(
/// stroke: blue,
/// curve.move((0pt, 100pt)),
/// curve.quad((20pt, 20pt), (100pt, 0pt)),
/// )
/// ```
#[elem(name = "quad", title = "Curve Quadratic Segment")]
pub struct CurveQuad {
/// The control point of the quadratic Bézier curve.
///
/// - If `{auto}` and this segment follows another quadratic Bézier curve,
/// the previous control point will be mirrored.
/// - If `{none}`, the control point defaults to `end`, and the curve will
/// be a straight line.
///
/// ```example
/// #curve(
/// stroke: 2pt,
/// curve.quad((20pt, 40pt), (40pt, 40pt), relative: true),
/// curve.quad(auto, (40pt, -40pt), relative: true),
/// )
/// ```
#[required]
pub control: Smart<Option<Axes<Rel<Length>>>>,
/// The point at which the segment shall end.
#[required]
pub end: Axes<Rel<Length>>,
/// Whether the `control` and `end` coordinates are relative to the previous
/// point.
#[default(false)]
pub relative: bool,
}
/// Adds a cubic Bézier curve segment from the last point to `end`, using
/// `control-start` and `control-end` as the control points.
///
/// ```example
/// // Function to illustrate where the control points are.
/// #let handle(start, end) = place(
/// line(stroke: red, start: start, end: end)
/// )
///
/// #handle((0pt, 80pt), (10pt, 20pt))
/// #handle((90pt, 60pt), (100pt, 0pt))
///
/// #curve(
/// stroke: blue,
/// curve.move((0pt, 80pt)),
/// curve.cubic((10pt, 20pt), (90pt, 60pt), (100pt, 0pt)),
/// )
/// ```
#[elem(name = "cubic", title = "Curve Cubic Segment")]
pub struct CurveCubic {
/// The control point going out from the start of the curve segment.
///
/// - If `{auto}` and this element follows another `curve.cubic` element,
/// the last control point will be mirrored. In SVG terms, this makes
/// `curve.cubic` behave like the `S` operator instead of the `C` operator.
///
/// - If `{none}`, the curve has no first control point, or equivalently,
/// the control point defaults to the curve's starting point.
///
/// ```example
/// #curve(
/// stroke: blue,
/// curve.move((0pt, 50pt)),
/// // - No start control point
/// // - End control point at `(20pt, 0pt)`
/// // - End point at `(50pt, 0pt)`
/// curve.cubic(none, (20pt, 0pt), (50pt, 0pt)),
/// // - No start control point
/// // - No end control point
/// // - End point at `(50pt, 0pt)`
/// curve.cubic(none, none, (100pt, 50pt)),
/// )
///
/// #curve(
/// stroke: blue,
/// curve.move((0pt, 50pt)),
/// curve.cubic(none, (20pt, 0pt), (50pt, 0pt)),
/// // Passing `auto` instead of `none` means the start control point
/// // mirrors the end control point of the previous curve. Mirror of
/// // `(20pt, 0pt)` w.r.t `(50pt, 0pt)` is `(80pt, 0pt)`.
/// curve.cubic(auto, none, (100pt, 50pt)),
/// )
///
/// #curve(
/// stroke: blue,
/// curve.move((0pt, 50pt)),
/// curve.cubic(none, (20pt, 0pt), (50pt, 0pt)),
/// // `(80pt, 0pt)` is the same as `auto` in this case.
/// curve.cubic((80pt, 0pt), none, (100pt, 50pt)),
/// )
/// ```
#[required]
pub control_start: Option<Smart<Axes<Rel<Length>>>>,
/// The control point going into the end point of the curve segment.
///
/// If set to `{none}`, the curve has no end control point, or equivalently,
/// the control point defaults to the curve's end point.
#[required]
pub control_end: Option<Axes<Rel<Length>>>,
/// The point at which the curve segment shall end.
#[required]
pub end: Axes<Rel<Length>>,
/// Whether the `control-start`, `control-end`, and `end` coordinates are
/// relative to the previous point.
#[default(false)]
pub relative: bool,
}
/// Closes the curve by adding a segment from the last point to the start of the
/// curve (or the last preceding `curve.move` point).
///
/// ```example
/// // We define a function to show the same shape with
/// // both closing modes.
/// #let shape(mode: "smooth") = curve(
/// fill: blue.lighten(80%),
/// stroke: blue,
/// curve.move((0pt, 50pt)),
/// curve.line((100pt, 50pt)),
/// curve.cubic(auto, (90pt, 0pt), (50pt, 0pt)),
/// curve.close(mode: mode),
/// )
///
/// #shape(mode: "smooth")
/// #shape(mode: "straight")
/// ```
#[elem(name = "close", title = "Curve Close")]
pub struct CurveClose {
/// How to close the curve.
pub mode: CloseMode,
}
/// How to close a curve.
#[derive(Debug, Copy, Clone, Default, Eq, PartialEq, Hash, Cast)]
pub enum CloseMode {
/// Closes the curve with a smooth segment that takes into account the
/// control point opposite the start point.
#[default]
Smooth,
/// Closes the curve with a straight line.
Straight,
}
/// A curve consisting of movements, lines, and Bézier segments.
#[derive(Debug, Default, Clone, Eq, PartialEq, Hash)]
pub struct Curve(pub Vec<CurveItem>);
/// An item in a curve.
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub enum CurveItem {
Move(Point),
Line(Point),
Cubic(Point, Point, Point),
Close,
}
impl Curve {
/// Creates an empty curve.
pub const fn new() -> Self {
Self(vec![])
}
/// Creates a curve that describes a rectangle.
pub fn rect(size: Size) -> Self {
let z = Abs::zero();
let point = Point::new;
let mut curve = Self::new();
curve.move_(point(z, z));
curve.line(point(size.x, z));
curve.line(point(size.x, size.y));
curve.line(point(z, size.y));
curve.close();
curve
}
/// Creates a curve that describes an axis-aligned ellipse.
pub fn ellipse(size: Size) -> Self {
// https://stackoverflow.com/a/2007782
let z = Abs::zero();
let rx = size.x / 2.0;
let ry = size.y / 2.0;
let m = 0.551784;
let mx = m * rx;
let my = m * ry;
let point = |x, y| Point::new(x + rx, y + ry);
let mut curve = Curve::new();
curve.move_(point(-rx, z));
curve.cubic(point(-rx, -my), point(-mx, -ry), point(z, -ry));
curve.cubic(point(mx, -ry), point(rx, -my), point(rx, z));
curve.cubic(point(rx, my), point(mx, ry), point(z, ry));
curve.cubic(point(-mx, ry), point(-rx, my), point(-rx, z));
curve
}
/// Push a [`Move`](CurveItem::Move) item.
pub fn move_(&mut self, p: Point) {
self.0.push(CurveItem::Move(p));
}
/// Push a [`Line`](CurveItem::Line) item.
pub fn line(&mut self, p: Point) {
self.0.push(CurveItem::Line(p));
}
/// Push a [`Cubic`](CurveItem::Cubic) item.
pub fn cubic(&mut self, p1: Point, p2: Point, p3: Point) {
self.0.push(CurveItem::Cubic(p1, p2, p3));
}
/// Push a [`Close`](CurveItem::Close) item.
pub fn close(&mut self) {
self.0.push(CurveItem::Close);
}
/// Check if the curve is empty.
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// Translate all points in this curve by the given offset.
pub fn translate(&mut self, offset: Point) {
if offset.is_zero() {
return;
}
for item in self.0.iter_mut() {
match item {
CurveItem::Move(p) => *p += offset,
CurveItem::Line(p) => *p += offset,
CurveItem::Cubic(p1, p2, p3) => {
*p1 += offset;
*p2 += offset;
*p3 += offset;
}
CurveItem::Close => (),
}
}
}
/// Computes the size of the bounding box of this curve.
pub fn bbox_size(&self) -> Size {
let mut min_x = Abs::inf();
let mut min_y = Abs::inf();
let mut max_x = -Abs::inf();
let mut max_y = -Abs::inf();
let mut cursor = Point::zero();
for item in self.0.iter() {
match item {
CurveItem::Move(to) => {
min_x = min_x.min(cursor.x);
min_y = min_y.min(cursor.y);
max_x = max_x.max(cursor.x);
max_y = max_y.max(cursor.y);
cursor = *to;
}
CurveItem::Line(to) => {
min_x = min_x.min(cursor.x);
min_y = min_y.min(cursor.y);
max_x = max_x.max(cursor.x);
max_y = max_y.max(cursor.y);
cursor = *to;
}
CurveItem::Cubic(c0, c1, end) => {
let cubic = kurbo::CubicBez::new(
kurbo::Point::new(cursor.x.to_pt(), cursor.y.to_pt()),
kurbo::Point::new(c0.x.to_pt(), c0.y.to_pt()),
kurbo::Point::new(c1.x.to_pt(), c1.y.to_pt()),
kurbo::Point::new(end.x.to_pt(), end.y.to_pt()),
);
let bbox = cubic.bounding_box();
min_x = min_x.min(Abs::pt(bbox.x0)).min(Abs::pt(bbox.x1));
min_y = min_y.min(Abs::pt(bbox.y0)).min(Abs::pt(bbox.y1));
max_x = max_x.max(Abs::pt(bbox.x0)).max(Abs::pt(bbox.x1));
max_y = max_y.max(Abs::pt(bbox.y0)).max(Abs::pt(bbox.y1));
cursor = *end;
}
CurveItem::Close => (),
}
}
Size::new(max_x - min_x, max_y - min_y)
}
}
impl Curve {
fn to_kurbo(&self) -> impl Iterator<Item = kurbo::PathEl> + '_ {
use kurbo::PathEl;
self.0.iter().map(|item| match *item {
CurveItem::Move(point) => PathEl::MoveTo(point_to_kurbo(point)),
CurveItem::Line(point) => PathEl::LineTo(point_to_kurbo(point)),
CurveItem::Cubic(point, point1, point2) => PathEl::CurveTo(
point_to_kurbo(point),
point_to_kurbo(point1),
point_to_kurbo(point2),
),
CurveItem::Close => PathEl::ClosePath,
})
}
/// When this curve is interpreted as a clip mask, would it contain `point`?
pub fn contains(&self, fill_rule: FillRule, needle: Point) -> bool {
let kurbo = kurbo::BezPath::from_vec(self.to_kurbo().collect());
let windings = kurbo::Shape::winding(&kurbo, point_to_kurbo(needle));
match fill_rule {
FillRule::NonZero => windings != 0,
FillRule::EvenOdd => windings % 2 != 0,
}
}
/// When this curve is stroked with `stroke`, would the stroke contain
/// `point`?
pub fn stroke_contains(&self, stroke: &FixedStroke, needle: Point) -> bool {
let width = stroke.thickness.to_raw();
let cap = match stroke.cap {
super::LineCap::Butt => kurbo::Cap::Butt,
super::LineCap::Round => kurbo::Cap::Round,
super::LineCap::Square => kurbo::Cap::Square,
};
let join = match stroke.join {
super::LineJoin::Miter => kurbo::Join::Miter,
super::LineJoin::Round => kurbo::Join::Round,
super::LineJoin::Bevel => kurbo::Join::Bevel,
};
let miter_limit = stroke.miter_limit.get();
let mut style = kurbo::Stroke::new(width)
.with_caps(cap)
.with_join(join)
.with_miter_limit(miter_limit);
if let Some(dash) = &stroke.dash {
style = style.with_dashes(
dash.phase.to_raw(),
dash.array.iter().copied().map(Abs::to_raw),
);
}
let opts = kurbo::StrokeOpts::default();
let tolerance = 0.01;
let expanded = kurbo::stroke(self.to_kurbo(), &style, &opts, tolerance);
kurbo::Shape::contains(&expanded, point_to_kurbo(needle))
}
}
fn point_to_kurbo(point: Point) -> kurbo::Point {
kurbo::Point::new(point.x.to_raw(), point.y.to_raw())
}