Function selectMarkers

src/traces/scatter/plot.js:623–663

(gd, idx, plotinfo, cdscatter, cdscatterAll)

}

function selectMarkers(gd, idx, plotinfo, cdscatter, cdscatterAll) {
    var xa = plotinfo.xaxis;
    var ya = plotinfo.yaxis;
    var xr = d3.extent(Lib.simpleMap(xa.range, xa.r2c));
    var yr = d3.extent(Lib.simpleMap(ya.range, ya.r2c));

    var trace = cdscatter[0].trace;
    if(!subTypes.hasMarkers(trace)) return;
    // if marker.maxdisplayed is used, select a maximum of
    // mnum markers to show, from the set that are in the viewport
    var mnum = trace.marker.maxdisplayed;

    // TODO: remove some as we get away from the viewport?
    if(mnum === 0) return;

    var cd = cdscatter.filter(function(v) {
        return v.x >= xr[0] && v.x <= xr[1] && v.y >= yr[0] && v.y <= yr[1];
    });
    var inc = Math.ceil(cd.length / mnum);
    var tnum = 0;
    cdscatterAll.forEach(function(cdj, j) {
        var tracei = cdj[0].trace;
        if(subTypes.hasMarkers(tracei) &&
                tracei.marker.maxdisplayed > 0 && j < idx) {
            tnum++;
        }
    });

    // if multiple traces use maxdisplayed, stagger which markers we
    // display this formula offsets successive traces by 1/3 of the
    // increment, adding an extra small amount after each triplet so
    // it's not quite periodic
    var i0 = Math.round(tnum * inc / 3 + Math.floor(tnum / 3) * inc / 7.1);

    // for error bars: save in cd which markers to show
    // so we don't have to repeat this
    cdscatter.forEach(function(v) { delete v.vis; });
    cd.forEach(function(v, i) {
        if(Math.round((i + i0) % inc) === 0) v.vis = true;
    });
}