268 lines
8.6 KiB
JavaScript
268 lines
8.6 KiB
JavaScript
import constant from "./constant.js";
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import {abs, acos, asin, atan2, cos, epsilon, halfPi, max, min, pi, sin, sqrt, tau} from "./math.js";
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import {withPath} from "./path.js";
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function arcInnerRadius(d) {
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return d.innerRadius;
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}
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function arcOuterRadius(d) {
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return d.outerRadius;
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}
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function arcStartAngle(d) {
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return d.startAngle;
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}
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function arcEndAngle(d) {
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return d.endAngle;
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}
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function arcPadAngle(d) {
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return d && d.padAngle; // Note: optional!
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}
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function intersect(x0, y0, x1, y1, x2, y2, x3, y3) {
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var x10 = x1 - x0, y10 = y1 - y0,
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x32 = x3 - x2, y32 = y3 - y2,
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t = y32 * x10 - x32 * y10;
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if (t * t < epsilon) return;
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t = (x32 * (y0 - y2) - y32 * (x0 - x2)) / t;
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return [x0 + t * x10, y0 + t * y10];
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}
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// Compute perpendicular offset line of length rc.
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// http://mathworld.wolfram.com/Circle-LineIntersection.html
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function cornerTangents(x0, y0, x1, y1, r1, rc, cw) {
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var x01 = x0 - x1,
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y01 = y0 - y1,
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lo = (cw ? rc : -rc) / sqrt(x01 * x01 + y01 * y01),
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ox = lo * y01,
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oy = -lo * x01,
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x11 = x0 + ox,
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y11 = y0 + oy,
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x10 = x1 + ox,
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y10 = y1 + oy,
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x00 = (x11 + x10) / 2,
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y00 = (y11 + y10) / 2,
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dx = x10 - x11,
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dy = y10 - y11,
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d2 = dx * dx + dy * dy,
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r = r1 - rc,
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D = x11 * y10 - x10 * y11,
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d = (dy < 0 ? -1 : 1) * sqrt(max(0, r * r * d2 - D * D)),
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cx0 = (D * dy - dx * d) / d2,
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cy0 = (-D * dx - dy * d) / d2,
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cx1 = (D * dy + dx * d) / d2,
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cy1 = (-D * dx + dy * d) / d2,
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dx0 = cx0 - x00,
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dy0 = cy0 - y00,
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dx1 = cx1 - x00,
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dy1 = cy1 - y00;
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// Pick the closer of the two intersection points.
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// TODO Is there a faster way to determine which intersection to use?
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if (dx0 * dx0 + dy0 * dy0 > dx1 * dx1 + dy1 * dy1) cx0 = cx1, cy0 = cy1;
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return {
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cx: cx0,
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cy: cy0,
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x01: -ox,
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y01: -oy,
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x11: cx0 * (r1 / r - 1),
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y11: cy0 * (r1 / r - 1)
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};
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}
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export default function() {
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var innerRadius = arcInnerRadius,
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outerRadius = arcOuterRadius,
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cornerRadius = constant(0),
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padRadius = null,
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startAngle = arcStartAngle,
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endAngle = arcEndAngle,
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padAngle = arcPadAngle,
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context = null,
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path = withPath(arc);
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function arc() {
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var buffer,
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r,
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r0 = +innerRadius.apply(this, arguments),
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r1 = +outerRadius.apply(this, arguments),
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a0 = startAngle.apply(this, arguments) - halfPi,
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a1 = endAngle.apply(this, arguments) - halfPi,
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da = abs(a1 - a0),
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cw = a1 > a0;
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if (!context) context = buffer = path();
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// Ensure that the outer radius is always larger than the inner radius.
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if (r1 < r0) r = r1, r1 = r0, r0 = r;
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// Is it a point?
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if (!(r1 > epsilon)) context.moveTo(0, 0);
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// Or is it a circle or annulus?
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else if (da > tau - epsilon) {
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context.moveTo(r1 * cos(a0), r1 * sin(a0));
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context.arc(0, 0, r1, a0, a1, !cw);
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if (r0 > epsilon) {
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context.moveTo(r0 * cos(a1), r0 * sin(a1));
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context.arc(0, 0, r0, a1, a0, cw);
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}
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}
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// Or is it a circular or annular sector?
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else {
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var a01 = a0,
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a11 = a1,
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a00 = a0,
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a10 = a1,
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da0 = da,
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da1 = da,
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ap = padAngle.apply(this, arguments) / 2,
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rp = (ap > epsilon) && (padRadius ? +padRadius.apply(this, arguments) : sqrt(r0 * r0 + r1 * r1)),
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rc = min(abs(r1 - r0) / 2, +cornerRadius.apply(this, arguments)),
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rc0 = rc,
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rc1 = rc,
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t0,
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t1;
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// Apply padding? Note that since r1 ≥ r0, da1 ≥ da0.
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if (rp > epsilon) {
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var p0 = asin(rp / r0 * sin(ap)),
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p1 = asin(rp / r1 * sin(ap));
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if ((da0 -= p0 * 2) > epsilon) p0 *= (cw ? 1 : -1), a00 += p0, a10 -= p0;
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else da0 = 0, a00 = a10 = (a0 + a1) / 2;
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if ((da1 -= p1 * 2) > epsilon) p1 *= (cw ? 1 : -1), a01 += p1, a11 -= p1;
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else da1 = 0, a01 = a11 = (a0 + a1) / 2;
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}
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var x01 = r1 * cos(a01),
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y01 = r1 * sin(a01),
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x10 = r0 * cos(a10),
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y10 = r0 * sin(a10);
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// Apply rounded corners?
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if (rc > epsilon) {
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var x11 = r1 * cos(a11),
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y11 = r1 * sin(a11),
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x00 = r0 * cos(a00),
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y00 = r0 * sin(a00),
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oc;
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// Restrict the corner radius according to the sector angle. If this
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// intersection fails, it’s probably because the arc is too small, so
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// disable the corner radius entirely.
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if (da < pi) {
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if (oc = intersect(x01, y01, x00, y00, x11, y11, x10, y10)) {
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var ax = x01 - oc[0],
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ay = y01 - oc[1],
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bx = x11 - oc[0],
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by = y11 - oc[1],
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kc = 1 / sin(acos((ax * bx + ay * by) / (sqrt(ax * ax + ay * ay) * sqrt(bx * bx + by * by))) / 2),
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lc = sqrt(oc[0] * oc[0] + oc[1] * oc[1]);
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rc0 = min(rc, (r0 - lc) / (kc - 1));
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rc1 = min(rc, (r1 - lc) / (kc + 1));
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} else {
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rc0 = rc1 = 0;
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}
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}
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}
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// Is the sector collapsed to a line?
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if (!(da1 > epsilon)) context.moveTo(x01, y01);
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// Does the sector’s outer ring have rounded corners?
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else if (rc1 > epsilon) {
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t0 = cornerTangents(x00, y00, x01, y01, r1, rc1, cw);
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t1 = cornerTangents(x11, y11, x10, y10, r1, rc1, cw);
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context.moveTo(t0.cx + t0.x01, t0.cy + t0.y01);
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// Have the corners merged?
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if (rc1 < rc) context.arc(t0.cx, t0.cy, rc1, atan2(t0.y01, t0.x01), atan2(t1.y01, t1.x01), !cw);
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// Otherwise, draw the two corners and the ring.
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else {
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context.arc(t0.cx, t0.cy, rc1, atan2(t0.y01, t0.x01), atan2(t0.y11, t0.x11), !cw);
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context.arc(0, 0, r1, atan2(t0.cy + t0.y11, t0.cx + t0.x11), atan2(t1.cy + t1.y11, t1.cx + t1.x11), !cw);
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context.arc(t1.cx, t1.cy, rc1, atan2(t1.y11, t1.x11), atan2(t1.y01, t1.x01), !cw);
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}
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}
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// Or is the outer ring just a circular arc?
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else context.moveTo(x01, y01), context.arc(0, 0, r1, a01, a11, !cw);
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// Is there no inner ring, and it’s a circular sector?
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// Or perhaps it’s an annular sector collapsed due to padding?
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if (!(r0 > epsilon) || !(da0 > epsilon)) context.lineTo(x10, y10);
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// Does the sector’s inner ring (or point) have rounded corners?
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else if (rc0 > epsilon) {
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t0 = cornerTangents(x10, y10, x11, y11, r0, -rc0, cw);
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t1 = cornerTangents(x01, y01, x00, y00, r0, -rc0, cw);
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context.lineTo(t0.cx + t0.x01, t0.cy + t0.y01);
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// Have the corners merged?
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if (rc0 < rc) context.arc(t0.cx, t0.cy, rc0, atan2(t0.y01, t0.x01), atan2(t1.y01, t1.x01), !cw);
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// Otherwise, draw the two corners and the ring.
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else {
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context.arc(t0.cx, t0.cy, rc0, atan2(t0.y01, t0.x01), atan2(t0.y11, t0.x11), !cw);
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context.arc(0, 0, r0, atan2(t0.cy + t0.y11, t0.cx + t0.x11), atan2(t1.cy + t1.y11, t1.cx + t1.x11), cw);
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context.arc(t1.cx, t1.cy, rc0, atan2(t1.y11, t1.x11), atan2(t1.y01, t1.x01), !cw);
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}
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}
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// Or is the inner ring just a circular arc?
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else context.arc(0, 0, r0, a10, a00, cw);
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}
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context.closePath();
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if (buffer) return context = null, buffer + "" || null;
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}
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arc.centroid = function() {
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var r = (+innerRadius.apply(this, arguments) + +outerRadius.apply(this, arguments)) / 2,
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a = (+startAngle.apply(this, arguments) + +endAngle.apply(this, arguments)) / 2 - pi / 2;
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return [cos(a) * r, sin(a) * r];
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};
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arc.innerRadius = function(_) {
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return arguments.length ? (innerRadius = typeof _ === "function" ? _ : constant(+_), arc) : innerRadius;
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};
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arc.outerRadius = function(_) {
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return arguments.length ? (outerRadius = typeof _ === "function" ? _ : constant(+_), arc) : outerRadius;
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};
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arc.cornerRadius = function(_) {
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return arguments.length ? (cornerRadius = typeof _ === "function" ? _ : constant(+_), arc) : cornerRadius;
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};
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arc.padRadius = function(_) {
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return arguments.length ? (padRadius = _ == null ? null : typeof _ === "function" ? _ : constant(+_), arc) : padRadius;
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};
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arc.startAngle = function(_) {
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return arguments.length ? (startAngle = typeof _ === "function" ? _ : constant(+_), arc) : startAngle;
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};
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arc.endAngle = function(_) {
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return arguments.length ? (endAngle = typeof _ === "function" ? _ : constant(+_), arc) : endAngle;
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};
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arc.padAngle = function(_) {
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return arguments.length ? (padAngle = typeof _ === "function" ? _ : constant(+_), arc) : padAngle;
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};
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arc.context = function(_) {
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return arguments.length ? ((context = _ == null ? null : _), arc) : context;
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};
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return arc;
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}
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