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      1 /* Flot plugin for stacking data sets rather than overlyaing them.
      2 
      3 Copyright (c) 2007-2014 IOLA and Ole Laursen.
      4 Licensed under the MIT license.
      5 
      6 The plugin assumes the data is sorted on x (or y if stacking horizontally).
      7 For line charts, it is assumed that if a line has an undefined gap (from a
      8 null point), then the line above it should have the same gap - insert zeros
      9 instead of "null" if you want another behaviour. This also holds for the start
     10 and end of the chart. Note that stacking a mix of positive and negative values
     11 in most instances doesn't make sense (so it looks weird).
     12 
     13 Two or more series are stacked when their "stack" attribute is set to the same
     14 key (which can be any number or string or just "true"). To specify the default
     15 stack, you can set the stack option like this:
     16 
     17 	series: {
     18 		stack: null/false, true, or a key (number/string)
     19 	}
     20 
     21 You can also specify it for a single series, like this:
     22 
     23 	$.plot( $("#placeholder"), [{
     24 		data: [ ... ],
     25 		stack: true
     26 	}])
     27 
     28 The stacking order is determined by the order of the data series in the array
     29 (later series end up on top of the previous).
     30 
     31 Internally, the plugin modifies the datapoints in each series, adding an
     32 offset to the y value. For line series, extra data points are inserted through
     33 interpolation. If there's a second y value, it's also adjusted (e.g for bar
     34 charts or filled areas).
     35 
     36 */
     37 
     38 (function ($) {
     39     var options = {
     40         series: { stack: null } // or number/string
     41     };
     42 
     43     function init(plot) {
     44         function findMatchingSeries(s, allseries) {
     45             var res = null;
     46             for (var i = 0; i < allseries.length; ++i) {
     47                 if (s == allseries[i])
     48                     break;
     49 
     50                 if (allseries[i].stack == s.stack)
     51                     res = allseries[i];
     52             }
     53 
     54             return res;
     55         }
     56 
     57         function stackData(plot, s, datapoints) {
     58             if (s.stack == null || s.stack === false)
     59                 return;
     60 
     61             var other = findMatchingSeries(s, plot.getData());
     62             if (!other)
     63                 return;
     64 
     65             var ps = datapoints.pointsize,
     66                 points = datapoints.points,
     67                 otherps = other.datapoints.pointsize,
     68                 otherpoints = other.datapoints.points,
     69                 newpoints = [],
     70                 px, py, intery, qx, qy, bottom,
     71                 withlines = s.lines.show,
     72                 horizontal = s.bars.horizontal,
     73                 withbottom = ps > 2 && (horizontal ? datapoints.format[2].x : datapoints.format[2].y),
     74                 withsteps = withlines && s.lines.steps,
     75                 fromgap = true,
     76                 keyOffset = horizontal ? 1 : 0,
     77                 accumulateOffset = horizontal ? 0 : 1,
     78                 i = 0, j = 0, l, m;
     79 
     80             while (true) {
     81                 if (i >= points.length)
     82                     break;
     83 
     84                 l = newpoints.length;
     85 
     86                 if (points[i] == null) {
     87                     // copy gaps
     88                     for (m = 0; m < ps; ++m)
     89                         newpoints.push(points[i + m]);
     90                     i += ps;
     91                 }
     92                 else if (j >= otherpoints.length) {
     93                     // for lines, we can't use the rest of the points
     94                     if (!withlines) {
     95                         for (m = 0; m < ps; ++m)
     96                             newpoints.push(points[i + m]);
     97                     }
     98                     i += ps;
     99                 }
    100                 else if (otherpoints[j] == null) {
    101                     // oops, got a gap
    102                     for (m = 0; m < ps; ++m)
    103                         newpoints.push(null);
    104                     fromgap = true;
    105                     j += otherps;
    106                 }
    107                 else {
    108                     // cases where we actually got two points
    109                     px = points[i + keyOffset];
    110                     py = points[i + accumulateOffset];
    111                     qx = otherpoints[j + keyOffset];
    112                     qy = otherpoints[j + accumulateOffset];
    113                     bottom = 0;
    114 
    115                     if (px == qx) {
    116                         for (m = 0; m < ps; ++m)
    117                             newpoints.push(points[i + m]);
    118 
    119                         newpoints[l + accumulateOffset] += qy;
    120                         bottom = qy;
    121 
    122                         i += ps;
    123                         j += otherps;
    124                     }
    125                     else if (px > qx) {
    126                         // we got past point below, might need to
    127                         // insert interpolated extra point
    128                         if (withlines && i > 0 && points[i - ps] != null) {
    129                             intery = py + (points[i - ps + accumulateOffset] - py) * (qx - px) / (points[i - ps + keyOffset] - px);
    130                             newpoints.push(qx);
    131                             newpoints.push(intery + qy);
    132                             for (m = 2; m < ps; ++m)
    133                                 newpoints.push(points[i + m]);
    134                             bottom = qy;
    135                         }
    136 
    137                         j += otherps;
    138                     }
    139                     else { // px < qx
    140                         if (fromgap && withlines) {
    141                             // if we come from a gap, we just skip this point
    142                             i += ps;
    143                             continue;
    144                         }
    145 
    146                         for (m = 0; m < ps; ++m)
    147                             newpoints.push(points[i + m]);
    148 
    149                         // we might be able to interpolate a point below,
    150                         // this can give us a better y
    151                         if (withlines && j > 0 && otherpoints[j - otherps] != null)
    152                             bottom = qy + (otherpoints[j - otherps + accumulateOffset] - qy) * (px - qx) / (otherpoints[j - otherps + keyOffset] - qx);
    153 
    154                         newpoints[l + accumulateOffset] += bottom;
    155 
    156                         i += ps;
    157                     }
    158 
    159                     fromgap = false;
    160 
    161                     if (l != newpoints.length && withbottom)
    162                         newpoints[l + 2] += bottom;
    163                 }
    164 
    165                 // maintain the line steps invariant
    166                 if (withsteps && l != newpoints.length && l > 0
    167                     && newpoints[l] != null
    168                     && newpoints[l] != newpoints[l - ps]
    169                     && newpoints[l + 1] != newpoints[l - ps + 1]) {
    170                     for (m = 0; m < ps; ++m)
    171                         newpoints[l + ps + m] = newpoints[l + m];
    172                     newpoints[l + 1] = newpoints[l - ps + 1];
    173                 }
    174             }
    175 
    176             datapoints.points = newpoints;
    177         }
    178 
    179         plot.hooks.processDatapoints.push(stackData);
    180     }
    181 
    182     $.plot.plugins.push({
    183         init: init,
    184         options: options,
    185         name: 'stack',
    186         version: '1.2'
    187     });
    188 })(jQuery);
    189