Function _path

src/lib/angles.js:106–175

(r0, r1, a0, a1, cx, cy, isClosed)

// common to pathArc, pathSector and pathAnnulus
function _path(r0, r1, a0, a1, cx, cy, isClosed) {
    cx = cx || 0;
    cy = cy || 0;

    var isCircle = isFullCircle([a0, a1]);
    var aStart, aMid, aEnd;
    var rStart, rEnd;

    if(isCircle) {
        aStart = 0;
        aMid = PI;
        aEnd = twoPI;
    } else {
        if(a0 < a1) {
            aStart = a0;
            aEnd = a1;
        } else {
            aStart = a1;
            aEnd = a0;
        }
    }

    if(r0 < r1) {
        rStart = r0;
        rEnd = r1;
    } else {
        rStart = r1;
        rEnd = r0;
    }

    // N.B. svg coordinates here, where y increases downward
    function pt(r, a) {
        return [r * Math.cos(a) + cx, cy - r * Math.sin(a)];
    }

    var largeArc = Math.abs(aEnd - aStart) <= PI ? 0 : 1;
    function arc(r, a, cw) {
        return 'A' + [r, r] + ' ' + [0, largeArc, cw] + ' ' + pt(r, a);
    }

    var p;

    if(isCircle) {
        if(rStart === null) {
            p = 'M' + pt(rEnd, aStart) +
                arc(rEnd, aMid, 0) +
                arc(rEnd, aEnd, 0) + 'Z';
        } else {
            p = 'M' + pt(rStart, aStart) +
                arc(rStart, aMid, 0) +
                arc(rStart, aEnd, 0) + 'Z' +
                'M' + pt(rEnd, aStart) +
                arc(rEnd, aMid, 1) +
                arc(rEnd, aEnd, 1) + 'Z';
        }
    } else {
        if(rStart === null) {
            p = 'M' + pt(rEnd, aStart) + arc(rEnd, aEnd, 0);