Function calcAxisExpansion

src/traces/scatter/calc.js:159–221

(gd, trace, xa, ya, x, y, ppad)

}

function calcAxisExpansion(gd, trace, xa, ya, x, y, ppad) {
    var serieslen = trace._length;
    var fullLayout = gd._fullLayout;
    var xId = xa._id;
    var yId = ya._id;
    var firstScatter = fullLayout._firstScatter[firstScatterGroup(trace)] === trace.uid;
    var stackOrientation = (getStackOpts(trace, fullLayout, xa, ya) || {}).orientation;
    var fill = trace.fill;

    // cancel minimum tick spacings (only applies to bars and boxes)
    xa._minDtick = 0;
    ya._minDtick = 0;

    // check whether bounds should be tight, padded, extended to zero...
    // most cases both should be padded on both ends, so start with that.
    var xOptions = {padded: true};
    var yOptions = {padded: true};

    if(ppad) {
        xOptions.ppad = yOptions.ppad = ppad;
    }

    // TODO: text size

    var openEnded = serieslen < 2 || (x[0] !== x[serieslen - 1]) || (y[0] !== y[serieslen - 1]);

    if(openEnded && (
        (fill === 'tozerox') ||
        ((fill === 'tonextx') && (firstScatter || stackOrientation === 'h'))
    )) {
        // include zero (tight) and extremes (padded) if fill to zero
        // (unless the shape is closed, then it's just filling the shape regardless)

        xOptions.tozero = true;
    } else if(!(trace.error_y || {}).visible && (
        // if no error bars, markers or text, or fill to y=0 remove x padding

            (fill === 'tonexty' || fill === 'tozeroy') ||
            (!subTypes.hasMarkers(trace) && !subTypes.hasText(trace))
        )) {
        xOptions.padded = false;
        xOptions.ppad = 0;
    }

    if(openEnded && (
        (fill === 'tozeroy') ||
        ((fill === 'tonexty') && (firstScatter || stackOrientation === 'v'))
    )) {
        // now check for y - rather different logic, though still mostly padded both ends
        // include zero (tight) and extremes (padded) if fill to zero
        // (unless the shape is closed, then it's just filling the shape regardless)

        yOptions.tozero = true;
    } else if(fill === 'tonextx' || fill === 'tozerox') {
        // tight y: any x fill

        yOptions.padded = false;
    }