hover.js

/**
* Copyright 2012-2017, Plotly, Inc.
* All rights reserved.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/


'use strict';

var Lib = require('../../lib');
var Fx = require('../../components/fx');
var ErrorBars = require('../../components/errorbars');
var getTraceColor = require('./get_trace_color');
var Color = require('../../components/color');

var MAXDIST = Fx.constants.MAXDIST;

module.exports = function hoverPoints(pointData, xval, yval, hovermode) {
    var cd = pointData.cd,
        trace = cd[0].trace,
        xa = pointData.xa,
        ya = pointData.ya,
        xpx = xa.c2p(xval),
        ypx = ya.c2p(yval),
        pt = [xpx, ypx],
        hoveron = trace.hoveron || '';

    // look for points to hover on first, then take fills only if we
    // didn't find a point
    if(hoveron.indexOf('points') !== -1) {
        var dx = function(di) {
                // scatter points: d.mrc is the calculated marker radius
                // adjust the distance so if you're inside the marker it
                // always will show up regardless of point size, but
                // prioritize smaller points
                var rad = Math.max(3, di.mrc || 0);
                return Math.max(Math.abs(xa.c2p(di.x) - xpx) - rad, 1 - 3 / rad);
            },
            dy = function(di) {
                var rad = Math.max(3, di.mrc || 0);
                return Math.max(Math.abs(ya.c2p(di.y) - ypx) - rad, 1 - 3 / rad);
            },
            dxy = function(di) {
                var rad = Math.max(3, di.mrc || 0),
                    dx = xa.c2p(di.x) - xpx,
                    dy = ya.c2p(di.y) - ypx;
                return Math.max(Math.sqrt(dx * dx + dy * dy) - rad, 1 - 3 / rad);
            },
            distfn = Fx.getDistanceFunction(hovermode, dx, dy, dxy);

        Fx.getClosest(cd, distfn, pointData);

        // skip the rest (for this trace) if we didn't find a close point
        if(pointData.index !== false) {

            // the closest data point
            var di = cd[pointData.index],
                xc = xa.c2p(di.x, true),
                yc = ya.c2p(di.y, true),
                rad = di.mrc || 1;

            Lib.extendFlat(pointData, {
                color: getTraceColor(trace, di),

                x0: xc - rad,
                x1: xc + rad,
                xLabelVal: di.x,

                y0: yc - rad,
                y1: yc + rad,
                yLabelVal: di.y
            });

            if(di.htx) pointData.text = di.htx;
            else if(trace.hovertext) pointData.text = trace.hovertext;
            else if(di.tx) pointData.text = di.tx;
            else if(trace.text) pointData.text = trace.text;

            ErrorBars.hoverInfo(di, trace, pointData);

            return [pointData];
        }
    }

    // even if hoveron is 'fills', only use it if we have polygons too
    if(hoveron.indexOf('fills') !== -1 && trace._polygons) {
        var polygons = trace._polygons,
            polygonsIn = [],
            inside = false,
            xmin = Infinity,
            xmax = -Infinity,
            ymin = Infinity,
            ymax = -Infinity,
            i, j, polygon, pts, xCross, x0, x1, y0, y1;

        for(i = 0; i < polygons.length; i++) {
            polygon = polygons[i];
            // TODO: this is not going to work right for curved edges, it will
            // act as though they're straight. That's probably going to need
            // the elements themselves to capture the events. Worth it?
            if(polygon.contains(pt)) {
                inside = !inside;
                // TODO: need better than just the overall bounding box
                polygonsIn.push(polygon);
                ymin = Math.min(ymin, polygon.ymin);
                ymax = Math.max(ymax, polygon.ymax);
            }
        }

        if(inside) {
            // constrain ymin/max to the visible plot, so the label goes
            // at the middle of the piece you can see
            ymin = Math.max(ymin, 0);
            ymax = Math.min(ymax, ya._length);

            // find the overall left-most and right-most points of the
            // polygon(s) we're inside at their combined vertical midpoint.
            // This is where we will draw the hover label.
            // Note that this might not be the vertical midpoint of the
            // whole trace, if it's disjoint.
            var yAvg = (ymin + ymax) / 2;
            for(i = 0; i < polygonsIn.length; i++) {
                pts = polygonsIn[i].pts;
                for(j = 1; j < pts.length; j++) {
                    y0 = pts[j - 1][1];
                    y1 = pts[j][1];
                    if((y0 > yAvg) !== (y1 >= yAvg)) {
                        x0 = pts[j - 1][0];
                        x1 = pts[j][0];
                        xCross = x0 + (x1 - x0) * (yAvg - y0) / (y1 - y0);
                        xmin = Math.min(xmin, xCross);
                        xmax = Math.max(xmax, xCross);
                    }
                }
            }

            // constrain xmin/max to the visible plot now too
            xmin = Math.max(xmin, 0);
            xmax = Math.min(xmax, xa._length);

            // get only fill or line color for the hover color
            var color = Color.defaultLine;
            if(Color.opacity(trace.fillcolor)) color = trace.fillcolor;
            else if(Color.opacity((trace.line || {}).color)) {
                color = trace.line.color;
            }

            Lib.extendFlat(pointData, {
                // never let a 2D override 1D type as closest point
                distance: MAXDIST + 10,
                x0: xmin,
                x1: xmax,
                y0: yAvg,
                y1: yAvg,
                color: color
            });

            delete pointData.index;

            if(trace.text && !Array.isArray(trace.text)) {
                pointData.text = String(trace.text);
            }
            else pointData.text = trace.name;

            return [pointData];
        }
    }
};