Function ordinalScaleSnap

src/traces/parcoords/axisbrush.js:21–47

(isHigh, a, v, existingRanges)

// find the interval we're in, and snap to 1/4 the distance to the next
// these two could be unified at a slight loss of readability / perf
function ordinalScaleSnap(isHigh, a, v, existingRanges) {
    if(overlappingExisting(v, existingRanges)) return v;

    var dir = isHigh ? -1 : 1;

    var first = 0;
    var last = a.length - 1;
    if(dir < 0) {
        var tmp = first;
        first = last;
        last = tmp;
    }

    var aHere = a[first];
    var aPrev = aHere;
    for(var i = first; dir * i < dir * last; i += dir) {
        var nextI = i + dir;
        var aNext = a[nextI];

        // very close to the previous - snap down to it
        if(dir * v < dir * closeToCovering(aHere, aNext)) return snapOvershoot(aHere, aPrev);
        if(dir * v < dir * aNext || nextI === last) return snapOvershoot(aNext, aHere);

        aPrev = aHere;
        aHere = aNext;
    }
}

function overlappingExisting(v, existingRanges) {
    for(var i = 0; i < existingRanges.length; i++) {