Function getProjection

src/plots/geo/geo.js:710–768

(geoLayout)

//
// This wrapper alleviates subsequent code of (many) annoying if-statements.
function getProjection(geoLayout) {
    var projLayout = geoLayout.projection;
    var projType = projLayout.type;

    var projName = constants.projNames[projType];
    // uppercase the first letter and add geo to the start of method name
    projName = 'geo' + Lib.titleCase(projName);
    var projFn = geo[projName] || geoProjection[projName];
    var projection = projFn();

    var clipAngle =
        geoLayout._isSatellite ? Math.acos(1 / projLayout.distance) * 180 / Math.PI :
        geoLayout._isClipped ? constants.lonaxisSpan[projType] / 2 : null;

    var methods = ['center', 'rotate', 'parallels', 'clipExtent'];
    var dummyFn = function(_) { return _ ? projection : []; };

    for(var i = 0; i < methods.length; i++) {
        var m = methods[i];
        if(typeof projection[m] !== 'function') {
            projection[m] = dummyFn;
        }
    }

    projection.isLonLatOverEdges = function(lonlat) {
        if(projection(lonlat) === null) {
            return true;
        }

        if(clipAngle) {
            var r = projection.rotate();
            var angle = geoDistance(lonlat, [-r[0], -r[1]]);
            var maxAngle = clipAngle * Math.PI / 180;
            return angle > maxAngle;
        } else {
            return false;
        }
    };

    projection.getPath = function() {
        return geoPath().projection(projection);
    };

    projection.getBounds = function(object) {
        return projection.getPath().bounds(object);
    };

    projection.precision(constants.precision);

    if(geoLayout._isSatellite) {
        projection.tilt(projLayout.tilt).distance(projLayout.distance);
    }

    if(clipAngle) {
        projection.clipAngle(clipAngle - constants.clipPad);
    }

    return projection;