Function clampAndSetR0R1

src/plots/polar/polar.js:948–974

(rr0, rr1)

    // N.B. this sets scoped 'r0' and 'r1'
    // return true if 'valid' zoom distance, false otherwise
    function clampAndSetR0R1(rr0, rr1) {
        rr1 = Math.max(Math.min(rr1, radius), innerRadius);

        // starting or ending drag near center (outer edge),
        // clamps radial distance at origin (at r=radius)
        if(rr0 < OFFEDGE) rr0 = 0;
        else if((radius - rr0) < OFFEDGE) rr0 = radius;
        else if(rr1 < OFFEDGE) rr1 = 0;
        else if((radius - rr1) < OFFEDGE) rr1 = radius;

        // make sure r0 < r1,
        // to get correct fill pattern in path1 below
        if(Math.abs(rr1 - rr0) > MINZOOM) {
            if(rr0 < rr1) {
                r0 = rr0;
                r1 = rr1;
            } else {
                r0 = rr1;
                r1 = rr0;
            }
            return true;
        } else {
            r0 = null;
            r1 = null;
            return false;
        }
    }

    function applyZoomMove(path1, cpath) {
        path1 = path1 || path0;