curveBumpX, curveBumpY

README.md

@@ -659,6 +659,18 @@ Produces a closed cubic [basis spline](https://en.wikipedia.org/wiki/B-spline) u
 
 Produces a cubic [basis spline](https://en.wikipedia.org/wiki/B-spline) using the specified control points. Unlike [basis](#basis), the first and last points are not repeated, and thus the curve typically does not intersect these points.
 
+<a name="curveBumpX" href="#curveBumpX">#</a> d3.<b>curveBumpX</b>(<i>context</i>) · [Source](https://github.com/d3/d3-shape/blob/master/src/curve/bump.js)
+
+<img src="https://raw.githubusercontent.com/d3/d3-shape/master/img/bumpX.png" width="888" height="240" alt="bumpX">
+
+Produces a Bézier curve between each pair of points, with horizontal tangents at each point.
+
+<a name="curveBumpY" href="#curveBumpY">#</a> d3.<b>curveBumpY</b>(<i>context</i>) · [Source](https://github.com/d3/d3-shape/blob/master/src/curve/bump.js)
+
+<img src="https://raw.githubusercontent.com/d3/d3-shape/master/img/bumpY.png" width="888" height="240" alt="bumpY">
+
+Produces a Bézier curve between each pair of points, with vertical tangents at each point.
+
 <a name="curveBundle" href="#curveBundle">#</a> d3.<b>curveBundle</b>(<i>context</i>) · [Source](https://github.com/d3/d3-shape/blob/master/src/curve/bundle.js)
 
 <img src="https://raw.githubusercontent.com/d3/d3-shape/master/img/bundle.png" width="888" height="240" alt="bundle">

src/curve/bump.js

@@ -0,0 +1,45 @@
+class Bump {
+  constructor(context, x) {
+    this._context = context;
+    this._x = x;
+  }
+  areaStart() {
+    this._line = 0;
+  }
+  areaEnd() {
+    this._line = NaN;
+  }
+  lineStart() {
+    this._point = 0;
+  }
+  lineEnd() {
+    if (this._line || (this._line !== 0 && this._point === 1)) this._context.closePath();
+    this._line = 1 - this._line;
+  }
+  point(x, y) {
+    x = +x, y = +y;
+    switch (this._point) {
+      case 0: {
+        this._point = 1;
+        if (this._line) this._context.lineTo(x, y);
+        else this._context.moveTo(x, y);
+        break;
+      }
+      case 1: this._point = 2; // proceed
+      default: {
+        if (this._x) this._context.bezierCurveTo(this._x0 = (this._x0 + x) / 2, this._y0, this._x0, y, x, y);
+        else this._context.bezierCurveTo(this._x0, this._y0 = (this._y0 + y) / 2, x, this._y0, x, y);
+        break;
+      }
+    }
+    this._x0 = x, this._y0 = y;
+  }
+}
+
+export function bumpX(context) {
+  return new Bump(context, true);
+}
+
+export function bumpY(context) {
+  return new Bump(context, false);
+}

src/index.js

@@ -19,6 +19,7 @@ export {default as symbolWye} from "./symbol/wye.js";
 export {default as curveBasisClosed} from "./curve/basisClosed.js";
 export {default as curveBasisOpen} from "./curve/basisOpen.js";
 export {default as curveBasis} from "./curve/basis.js";
+export {bumpX as curveBumpX, bumpY as curveBumpY} from "./curve/bump.js";
 export {default as curveBundle} from "./curve/bundle.js";
 export {default as curveCardinalClosed} from "./curve/cardinalClosed.js";
 export {default as curveCardinalOpen} from "./curve/cardinalOpen.js";

test/curve/bumpX-test.js

@@ -0,0 +1,22 @@
+var tape = require("tape"),
+    shape = require("../../");
+
+require("../pathEqual");
+
+tape("line.curve(curveBumpX)(data) generates the expected path", function(test) {
+  var l = shape.line().curve(shape.curveBumpX);
+  test.equal(l([]), null);
+  test.pathEqual(l([[0, 1]]), "M0,1Z");
+  test.pathEqual(l([[0, 1], [1, 3]]), "M0,1C0.500000,1,0.500000,3,1,3");
+  test.pathEqual(l([[0, 1], [1, 3], [2, 1]]), "M0,1C0.500000,1,0.500000,3,1,3C1.500000,3,1.500000,1,2,1");
+  test.end();
+});
+
+tape("area.curve(curveBumpX)(data) generates the expected path", function(test) {
+  var a = shape.area().curve(shape.curveBumpX);
+  test.equal(a([]), null);
+  test.pathEqual(a([[0, 1]]), "M0,1L0,0Z");
+  test.pathEqual(a([[0, 1], [1, 3]]), "M0,1C0.500000,1,0.500000,3,1,3L1,0C0.500000,0,0.500000,0,0,0Z");
+  test.pathEqual(a([[0, 1], [1, 3], [2, 1]]), "M0,1C0.500000,1,0.500000,3,1,3C1.500000,3,1.500000,1,2,1L2,0C1.500000,0,1.500000,0,1,0C0.500000,0,0.500000,0,0,0Z");
+  test.end();
+});

test/curve/bumpY-test.js

@@ -0,0 +1,22 @@
+var tape = require("tape"),
+    shape = require("../../");
+
+require("../pathEqual");
+
+tape("line.curve(curveBumpY)(data) generates the expected path", function(test) {
+  var l = shape.line().curve(shape.curveBumpY);
+  test.equal(l([]), null);
+  test.pathEqual(l([[0, 1]]), "M0,1Z");
+  test.pathEqual(l([[0, 1], [1, 3]]), "M0,1C0,2,1,2,1,3");
+  test.pathEqual(l([[0, 1], [1, 3], [2, 1]]), "M0,1C0,2,1,2,1,3C1,2,2,2,2,1");
+  test.end();
+});
+
+tape("area.curve(curveBumpY)(data) generates the expected path", function(test) {
+  var a = shape.area().curve(shape.curveBumpY);
+  test.equal(a([]), null);
+  test.pathEqual(a([[0, 1]]), "M0,1L0,0Z");
+  test.pathEqual(a([[0, 1], [1, 3]]), "M0,1C0,2,1,2,1,3L1,0C1,0,0,0,0,0Z");
+  test.pathEqual(a([[0, 1], [1, 3], [2, 1]]), "M0,1C0,2,1,2,1,3C1,2,2,2,2,1L2,0C2,0,1,0,1,0C1,0,0,0,0,0Z");
+  test.end();
+});