feat: Add u-shape wire-style

Reviewed-on: HEL/circuiteria#25

README.md

@@ -3,7 +3,7 @@
 Circuiteria is a [Typst](https://typst.app) package for drawing block circuit diagrams using the [CeTZ](https://typst.app/universe/package/cetz) package.
 
 <p align="center">
-  <img src="./gallery/platypus.png" alt="Perry the platypus" alt="A platypus / Perry the Platypus meme made with colored rounded rectangles">
+  <img src="./gallery/platypus.png" alt="A platypus / Perry the Platypus meme made with colored rounded rectangles">
 </p>
 
 ## Examples

doc/examples.typ

@@ -56,7 +56,7 @@ for i in range(3) {
 ```)
 
 #let wires = example(```
-for i in range(4) {
+for i in range(5) {
   draw.circle((i * 3, 0), radius: .1, name: "p" + str(i * 2))
   draw.circle((i * 3 + 2, 1), radius: .1, name: "p" + str(i * 2 + 1))
   draw.content((i * 3 + 1, -1), raw(wire.wire-styles.at(i)))
@@ -68,6 +68,8 @@ wire.wire("w3", ("p4", "p5"), style: "dodge",
 wire.wire("w4", ("p6","p7"), style: "guided",
           guided-center:(20%, 40%), guided-margins: (90%,87%),
           guided-sides: ("north","south"))
+wire.wire("w5", ("p8", "p9"), style: "u-shape",
+          u-side: "east", u-depth: 0.5)
 
 ```, vertical: true)
 
@@ -192,3 +194,45 @@ wire.wire("w2", ((0, 0), (1, -.5)),
           style: "zigzag", zigzag-ratio: 80%)
 wire.intersection("w1.zig")
 ```)
+
+#let u-shape-wire = example(```
+// east <-> east (u-side auto-detected)
+element.block(x: 0,   y: 0,    w: 1.5, h: 1.5, id: "eA",
+  fill: util.colors.orange,
+  ports: (east: ((id: "out"),)))
+element.block(x: 0.5, y: -2.5, w: 1.5, h: 1.5, id: "eB",
+  fill: util.colors.orange,
+  ports: (east: ((id: "out"),)))
+wire.wire("uEE", ("eA-port-out", "eB-port-out"),
+          style: "u-shape", u-depth: 0.5)
+
+// west <-> west (auto-detected)
+element.block(x: 6,   y: 0,    w: 1.5, h: 1.5, id: "wA",
+  fill: util.colors.yellow,
+  ports: (west: ((id: "in"),)))
+element.block(x: 6.5, y: -2.5, w: 1.5, h: 1.5, id: "wB",
+  fill: util.colors.yellow,
+  ports: (west: ((id: "in"),)))
+wire.wire("uWW", ("wA-port-in", "wB-port-in"),
+          style: "u-shape", u-depth: 0.5)
+
+// north <-> north (auto-detected)
+element.block(x: 10,   y: -3,   w: 1.5, h: 1.5, id: "nA",
+  fill: util.colors.green,
+  ports: (north: ((id: "out"),)))
+element.block(x: 12.5, y: -2.5, w: 1.5, h: 1.5, id: "nB",
+  fill: util.colors.green,
+  ports: (north: ((id: "out"),)))
+wire.wire("uNN", ("nA-port-out", "nB-port-out"),
+          style: "u-shape", u-depth: 0.5)
+
+// south <-> south with explicit u-side override
+element.block(x: 16,   y: -3,   w: 1.5, h: 1.5, id: "sA",
+  fill: util.colors.pink,
+  ports: (south: ((id: "out"),)))
+element.block(x: 18.5, y: -3.5, w: 1.5, h: 1.5, id: "sB",
+  fill: util.colors.pink,
+  ports: (south: ((id: "out"),)))
+wire.wire("uSS", ("sA-port-out", "sB-port-out"),
+          style: "u-shape", u-side: "south", u-depth: 0.5)
+```, vertical: true)

gallery/test_ushape.typ

@@ -0,0 +1,53 @@
+// Demonstrates the u-shape wire style.
+// The u-side is auto-detected from the port anchors when both endpoints
+// belong to elements (deduced from the port position vs the element's
+// center anchor). It can also be set explicitly with u-side.
+#import "/src/lib.typ": circuit, element, util, wire
+
+#set page(width: auto, height: auto, margin: .5cm)
+
+#circuit({
+  // ---- east <-> east (auto-detected) ----
+  element.block(x: 0,   y: 0,    w: 1.5, h: 1.5, id: "eA",
+    fill: util.colors.orange,
+    ports: (east: ((id: "out"),)))
+  element.block(x: 0.5, y: -2.5, w: 1.5, h: 1.5, id: "eB",
+    fill: util.colors.orange,
+    ports: (east: ((id: "out"),)))
+  wire.wire("uEE", ("eA-port-out", "eB-port-out"),
+            style: "u-shape", u-depth: 0.6,
+            name: "E-E")
+
+  // ---- west <-> west (auto-detected) ----
+  element.block(x: 6,   y: 0,    w: 1.5, h: 1.5, id: "wA",
+    fill: util.colors.yellow,
+    ports: (west: ((id: "in"),)))
+  element.block(x: 6.5, y: -2.5, w: 1.5, h: 1.5, id: "wB",
+    fill: util.colors.yellow,
+    ports: (west: ((id: "in"),)))
+  wire.wire("uWW", ("wA-port-in", "wB-port-in"),
+            style: "u-shape", u-depth: 0.6,
+            name: "W-W")
+
+  // ---- north <-> north (auto-detected) ----
+  element.block(x: 10,   y: -3,   w: 1.5, h: 1.5, id: "nA",
+    fill: util.colors.green,
+    ports: (north: ((id: "out"),)))
+  element.block(x: 12.5, y: -2.5, w: 1.5, h: 1.5, id: "nB",
+    fill: util.colors.green,
+    ports: (north: ((id: "out"),)))
+  wire.wire("uNN", ("nA-port-out", "nB-port-out"),
+            style: "u-shape", u-depth: 0.6,
+            name: "N-N")
+
+  // ---- south <-> south (explicit u-side override) ----
+  element.block(x: 16,   y: 0,    w: 1.5, h: 1.5, id: "sA",
+    fill: util.colors.pink,
+    ports: (south: ((id: "out"),)))
+  element.block(x: 18.5, y: -0.5, w: 1.5, h: 1.5, id: "sB",
+    fill: util.colors.pink,
+    ports: (south: ((id: "out"),)))
+  wire.wire("uSS", ("sA-port-out", "sB-port-out"),
+            style: "u-shape", u-side: "south", u-depth: 0.6,
+            name: "S-S")
+})

gallery/test_yrel.typ

@@ -0,0 +1,46 @@
+// Demonstrates the `(rel: <number>, to: <anchor>)` shorthand for the `y`
+// parameter (analogous to the existing shorthand for `x`).
+#import "/src/lib.typ": circuit, element, util, wire
+
+#set page(width: auto, height: auto, margin: .5cm)
+
+#circuit({
+  // Anchor block: absolute placement.
+  element.block(
+    x: 0, y: 0, w: 2, h: 1.5,
+    id: "A",
+    fill: util.colors.orange,
+    ports: (east: ((id: "out"),))
+  )
+
+  // X relative, Y absolute (existing feature).
+  element.block(
+    x: (rel: 1, to: "A.east"), y: 0, w: 2, h: 1.5,
+    id: "B",
+    fill: util.colors.yellow,
+    ports: (west: ((id: "in"),), east: ((id: "out"),))
+  )
+
+  // Both X and Y relative to another element's anchor (new feature).
+  element.block(
+    x: (rel: 1, to: "B.east"),
+    y: (rel: 2, to: "B.south-west"),
+    w: 2, h: 1.5,
+    id: "C",
+    fill: util.colors.green,
+    ports: (west: ((id: "in"),))
+  )
+
+  // Y relative only, X absolute.
+  element.block(
+    x: 0,
+    y: (rel: -2.5, to: "A.south-west"),
+    w: 2, h: 1.5,
+    id: "D",
+    fill: util.colors.blue,
+    ports: (east: ((id: "out"),))
+  )
+
+  wire.wire("wAB", ("A-port-out", "B-port-in"))
+  wire.wire("wBC", ("B-port-out", "C-port-in"), style: "zigzag")
+})

src/elements/element.typ

@@ -24,7 +24,9 @@
 ///   If it is a dictionary, it should be in the format `(rel: number, to: str)`, where `rel` is the offset and `to` the base anchor
 /// - y (number, dictionary): The y position (bottom-left corner).
 ///
-///   If it is a dictionary, it should be in the format `(from: str, to: str)`, where `from` is the base anchor and `to` is the id of the port to align with the anchor
+///   If it is a dictionary, it can take one of two forms:
+///     - `(rel: number, to: str)`: `rel` is the y offset and `to` the base anchor (analogous to `x`)
+///     - `(from: str, to: str)`: `from` is the base anchor and `to` is the id of the port to align with the anchor
 /// - w (number): Width of the element
 /// - h (number): Height of the element
 /// - name (none, str): Optional name of the block
@@ -74,13 +76,12 @@
   if h == none { panic("Parameter h must be set") }
 
   if (type(x) == dictionary) {
-    let offset = x.rel
+    x = util.resolve-rel-coord(ctx, x, 0)
-    let to = x.to
-    let (ctx, to-pos) = coordinate.resolve(ctx, (rel: (offset, 0), to: to))
-    x = to-pos.at(0)
   }
   
-  if (type(y) == dictionary) {
+  if (type(y) == dictionary and "rel" in y) {
+    y = util.resolve-rel-coord(ctx, y, 1)
+  } else if (type(y) == dictionary) {
     let from = y.from
     let to = y.to
     let (to-side, i) = find-port(ports, to)

src/elements/logic/gate.typ

@@ -1,4 +1,5 @@
 #import "/src/cetz.typ": draw, coordinate
+#import "/src/util.typ"
 #import "../ports.typ": add-ports, add-port
 #import "../element.typ"
 
@@ -49,13 +50,12 @@
   if h == none { panic("Parameter h must be set") }
 
   if (type(x) == dictionary) {
-    let offset = x.rel
+    x = util.resolve-rel-coord(ctx, x, 0)
-    let to = x.to
-    let (ctx, to-pos) = coordinate.resolve(ctx, (rel: (offset, 0), to: to))
-    x = to-pos.at(0)
   }
   
-  if (type(y) == dictionary) {
+  if (type(y) == dictionary and "rel" in y) {
+    y = util.resolve-rel-coord(ctx, y, 1)
+  } else if (type(y) == dictionary) {
     let from = y.from
     let to = y.to
     

src/elements/logic/iec_gate.typ

@@ -1,4 +1,5 @@
 #import "/src/cetz.typ": draw, coordinate
+#import "/src/util.typ"
 #import "../ports.typ": add-ports, add-port
 #import "../element.typ"
 
@@ -60,13 +61,12 @@
   if h == none { panic("Parameter h must be set") }
 
   if (type(x) == dictionary) {
-    let offset = x.rel
+    x = util.resolve-rel-coord(ctx, x, 0)
-    let to = x.to
-    let (ctx, to-pos) = coordinate.resolve(ctx, (rel: (offset, 0), to: to))
-    x = to-pos.at(0)
   }
   
-  if (type(y) == dictionary) {
+  if (type(y) == dictionary and "rel" in y) {
+    y = util.resolve-rel-coord(ctx, y, 1)
+  } else if (type(y) == dictionary) {
     let from = y.from
     let to = y.to
     

src/util.typ

@@ -1,3 +1,23 @@
+#import "cetz.typ": coordinate
+
+/// Resolves a relative coordinate shorthand of the form `(rel: <number>, to: <anchor>)`
+/// to a single scalar along the requested axis.
+///
+/// Used to implement the shared `(rel:, to:)` shorthand accepted by the `x` and
+/// `y` parameters of `elmt`, `gate` and `iec-gate`.
+///
+/// - ctx (dictionary): The current CeTZ context
+/// - val (dictionary): A dictionary with fields `rel` (number) and `to` (anchor)
+/// - axis (int): `0` for x, `1` for y
+/// -> number
+#let resolve-rel-coord(ctx, val, axis) = {
+  let offset = val.rel
+  let to = val.to
+  let delta = if axis == 0 { (offset, 0) } else { (0, offset) }
+  let (_, to-pos) = coordinate.resolve(ctx, (rel: delta, to: to))
+  return to-pos.at(axis)
+}
+
 /// Predefined color palette
 /// #let w = 4
 /// #box(width: 100%, align(center)[

src/wire.typ

@@ -3,7 +3,10 @@
 
 /// List of valid wire styles
 /// #examples.wires
-#let wire-styles = ("direct", "zigzag", "dodge", "guided")
+///
+/// The `"u-shape"` style connects two ports that face the same cardinal side.
+/// #examples.u-shape-wire
+#let wire-styles = ("direct", "zigzag", "dodge", "guided", "u-shape")
 #let signal-width = 1pt
 #let bus-width = 1.5pt
 
@@ -109,6 +112,100 @@
   return (points, anchors)
 }
 
+#let _u-valid-sides = ("east", "west", "north", "south")
+
+// Try to deduce the cardinal side a port anchor faces by comparing its
+// position to the center of the element it belongs to. Returns none if the
+// anchor is not a port-style anchor (i.e. does not contain "-port-") or if
+// resolution fails.
+#let _u-detect-side(anchor, ctx) = {
+  if type(anchor) != str { return none }
+  let sep = "-port-"
+  if not anchor.contains(sep) { return none }
+  let elmt-id = anchor.split(sep).first()
+  let port-pos = none
+  let center-pos = none
+  // coordinate.resolve panics on unknown anchors; there is no try/catch in
+  // Typst, so we assume port anchors created by add-port always come with a
+  // matching group of the same name. If not, the user must set u-side
+  // explicitly.
+  let (_, p1) = coordinate.resolve(ctx, anchor)
+  let (_, p2) = coordinate.resolve(ctx, elmt-id + ".center")
+  port-pos = p1
+  center-pos = p2
+  let dx = port-pos.at(0) - center-pos.at(0)
+  let dy = port-pos.at(1) - center-pos.at(1)
+  if calc.abs(dx) >= calc.abs(dy) {
+    return if dx >= 0 { "east" } else { "west" }
+  } else {
+    return if dy >= 0 { "north" } else { "south" }
+  }
+}
+
+#let get-u-shape-wire(pts, u-depth, u-side, ctx) = {
+  let start = pts.first()
+  let end = pts.last()
+
+  // Resolve the (auto|explicit) side
+  let side = u-side
+  if side == auto {
+    let side-start = _u-detect-side(start, ctx)
+    let side-end = _u-detect-side(end, ctx)
+    if side-start != none and side-end != none and side-start != side-end {
+      panic(
+        "u-shape: start port faces '" + side-start
+        + "' but end port faces '" + side-end
+        + "'; both must face the same side, or set u-side explicitly"
+      )
+    }
+    if side-start != none { side = side-start }
+    else if side-end != none { side = side-end }
+    else {
+      panic(
+        "u-shape: could not auto-detect u-side (endpoints are not port anchors); "
+        + "please set u-side explicitly to one of " + repr(_u-valid-sides)
+      )
+    }
+  }
+  if not side in _u-valid-sides {
+    panic("u-shape: invalid u-side '" + repr(side) + "'; must be one of " + repr(_u-valid-sides))
+  }
+
+  let (ctx, s) = coordinate.resolve(ctx, start)
+  let (ctx, e) = coordinate.resolve(ctx, end)
+  let (sx, sy, ..) = s
+  let (ex, ey, ..) = e
+
+  let p1
+  let p2
+  if side == "east" {
+    let bx = calc.max(sx, ex) + u-depth
+    p1 = (bx, sy, 0)
+    p2 = (bx, ey, 0)
+  } else if side == "west" {
+    let bx = calc.min(sx, ex) - u-depth
+    p1 = (bx, sy, 0)
+    p2 = (bx, ey, 0)
+  } else if side == "north" {
+    let by = calc.max(sy, ey) + u-depth
+    p1 = (sx, by, 0)
+    p2 = (ex, by, 0)
+  } else if side == "south" {
+    let by = calc.min(sy, ey) - u-depth
+    p1 = (sx, by, 0)
+    p2 = (ex, by, 0)
+  }
+
+  let points = (start, p1, p2, end)
+  let anchors = (
+    "start": start,
+    "u-start": p1,
+    "u-end": p2,
+    "end": end
+  )
+  return (points, anchors)
+}
+
 #let get-guided-wire(pts, margins, sides, center-guides, ctx) = {
   let start = pts.first()
   let end = pts.last()
@@ -212,6 +309,8 @@
 /// - guided-center (array): the horizontal and vertical guides of the center guides (only with style "guided")
 /// - guided-margins (array): the start and end of guided margins of the wire (only with style "guided")
 /// - guided-sides (array): the side of start and end array (must be either "north", "south", "west", "east") (only work with style "guided")
+/// - u-side (auto, str): The cardinal side both endpoints face (one of "east", "west", "north", "south"). If `auto`, it is deduced from the endpoints when they are port anchors of the form `<elmt-id>-port-<port-id>` by comparing each port's position with its element's `.center` anchor. Auto-detection panics if the two endpoints resolve to different sides, or if neither endpoint is a port anchor (only with style "u-shape")
+/// - u-depth (number): Distance between the outermost endpoint (in the `u-side` direction) and the U-bend line (only with style "u-shape")
 #let wire(
   id, pts,
   bus: false,
@@ -231,7 +330,9 @@
   zigzag-dir: "vertical",
   dodge-y: 0,
   dodge-sides: ("east", "west"),
-  dodge-margins: (5%, 5%)
+  dodge-margins: (5%, 5%),
+  u-side: auto,
+  u-depth: 0.5,
 ) = draw.get-ctx(ctx => {
   if not style in wire-styles {
     panic("Invalid wire style '" + style + "'")
@@ -277,6 +378,13 @@
       guided-center,
       ctx
     )
+  } else if style == "u-shape" {
+    (points, anchors) = get-u-shape-wire(
+      pts,
+      u-depth,
+      u-side,
+      ctx
+    )
   }
 
   let mark = (fill: color)