shapes: Add svg-path element

Author: johannes-wolf

CHANGES.md

@@ -14,6 +14,8 @@
   leaks elements (like `scope` does) (#1004)
 - Fixed a bug that prevented the leakage of elements of `scope` elements inside
   a `group` (#930)
+- Added a new element `svg-path` that accepts a list of a subset of SVG
+  commands to construct paths
 
 # 0.4.2
 - The `tree` element now has a `anchor:` argument to position the tree (#929)
@@ -65,6 +67,7 @@
 - Added support for user-defined coordinate systems. See `register-coordinate-resolver(<callback>)`
 - The default style value for `mark.transform-shape` changed to `false`
 - Harpoon marks changed sides (on a line from (0, 0) to (1, 0), the end mark now appears on the left side/top)
+- Brace styling changed, see the documention of `decorations.brace`
 
 # 0.3.4
 - Fixed a bug with rendering curves with Typst 0.13.1

src/draw.typ

@@ -1,6 +1,6 @@
 #import "draw/grouping.typ": intersections, group, scope, anchor, copy-anchors, set-ctx, get-ctx, for-each-anchor, on-layer, hide, floating
 #import "draw/transformations.typ": set-transform, rotate, translate, scale, set-origin, move-to, set-viewport
 #import "draw/styling.typ": set-style, fill, stroke, register-mark
-#import "draw/shapes.typ": circle, circle-through, arc, arc-through, mark, line, grid, content, rect, bezier, bezier-through, catmull, hobby, merge-path, polygon, compound-path, n-star, rect-around
+#import "draw/shapes.typ": circle, circle-through, arc, arc-through, mark, line, grid, content, rect, bezier, bezier-through, catmull, hobby, merge-path, polygon, compound-path, n-star, rect-around, svg-path
 #import "draw/projection.typ": ortho, on-xy, on-xz, on-yz
 #import "draw/util.typ": assert-version, register-coordinate-resolver

src/draw/shapes.typ

@@ -917,7 +917,7 @@
 
     let (from-x, from-y, ..) = from
     let (to-x, to-y, ..) = to
-    
+
     // Resolve shift parameter
     let shift = style.at("shift", default: 0)
     if type(shift) == dictionary {
@@ -2022,3 +2022,124 @@
   })
   return ctx
 }
+
+/// Create a new path from a SVG-like list of commands.
+///
+/// The following commands are supported (uppercase command names use absolute coordinates, lowercase use relative coordinates)
+/// - `("l", coordinate)` line to `coordinate`
+/// - `("h", number)` Horizontal line
+/// - `("v", number)` Vertical line
+/// - `("m", coordinate)` Move to `coordinate`
+/// - `("c", ctrl-coordinate-a, ctrl-coordinate-b, coordinate)` Cubic bezier curve to `coordinate` with two control points a and b
+/// - `("q", ctrl-coordinate, coordinate)` Quadratic bezier curve
+/// - `("z",)` Close the current path
+///
+/// ```example
+/// svg-path(("h", 2),
+///          ("c", (0, 1), (0, 0), (-1, 0)),
+///          ("v", -0.5),
+///          ("h", -1),
+///          ("z",))
+/// ```
+#let svg-path(name: none, anchor: none, ..commands-style) = {
+  let style = commands-style.named()
+  let commands = commands-style.pos().map(cmd => {
+    if type(cmd) == str {
+      (cmd,)
+    } else {
+      cmd
+    }
+  })
+  return (ctx => {
+    let paths = ()
+
+    let origin = (0, 0, 0)
+    let current = ()
+
+    for ((cmd, ..args)) in commands {
+      assert(cmd in ("m", "M", "l", "L", "c", "C", "h", "H", "v", "V", "z", "Z", "q", "Q"),
+        message: "Unknown svg-path command: " + repr(cmd))
+
+      let is-relative = cmd in ("m", "l", "c", "h", "v", "q")
+      let wrap-coordinate = if is-relative {
+        x => (rel: x)
+      } else {
+        x => x
+      }
+
+      if cmd in ("h", "H") {
+        assert.eq(args.len(), 1)
+        let (x, ..rest) = args
+        args = ((x, 0.0, 0.0),)
+        cmd = if cmd == "h" { "l" } else { "L" }
+      } else if cmd in ("v", "V") {
+        assert.eq(args.len(), 1)
+        let (y, ..rest) = args
+        args = ((0.0, y, 0.0),)
+        cmd = if cmd == "v" { "l" } else { "L" }
+      }
+
+      (ctx, ..args) = coordinate.resolve(ctx, ..args.map(wrap-coordinate))
+
+      if cmd in ("z", "Z") {
+        assert.eq(args.len(), 0)
+        if current != () {
+          paths.push(path-util.make-subpath(origin, current, closed: cmd == "z"))
+        }
+
+        current = ()
+      }
+
+      if cmd in ("m", "M", "l", "L") {
+        if cmd in ("m", "M") {
+          assert.eq(args.len(), 1)
+          origin = args.at(0, default: (0, 0, 0))
+          args.pop()
+        }
+
+        current += args.map(pt => ("l", pt))
+      } else if cmd in ("c", "C") {
+        assert.eq(args.len(), 3)
+        let (c1, c2, pt) = args
+        current.push(("c", c1, c2, pt))
+      } else if cmd in ("q", "Q") {
+        assert.eq(args.len(), 2)
+        let (c1, pt) = args
+        let (_, pt, c1, c2) = bezier_.quadratic-to-cubic(ctx.prev.pt, pt, c1)
+        current.push(("c", c1, c2, pt))
+      }
+    }
+
+    if current != () {
+      paths.push(path-util.make-subpath(origin, current, closed: false))
+    }
+
+    let style = styles.resolve(ctx.style, merge: style)
+    let drawables = drawable.path(paths, stroke: style.stroke, fill: style.fill, fill-rule: style.fill-rule)
+
+    let (transform, anchors) = anchor_.setup(
+      (_) => none,
+      (),
+      default: none,
+      name: name,
+      offset-anchor: anchor,
+      transform: ctx.transform,
+      //border-anchors: true,
+      path-anchors: true,
+      path: drawables,
+    )
+
+    if mark_.check-mark(style.mark) {
+      drawables = mark_.place-marks-along-path(ctx, style.mark, transform, drawables)
+    } else {
+      drawables = drawable.apply-transform(transform, drawables)
+    }
+
+    return (
+      ctx: ctx,
+      name: name,
+      anchors: anchors,
+      drawables: drawables,
+    )
+  },)
+}