      1 /**
      2  * @license
      3  * Copyright 2011 Dan Vanderkam (danvdk@gmail.com)
      4  * MIT-licenced: https://opensource.org/licenses/MIT
      5  */
      6
      7 /**
      8  * @fileoverview Description of this file.
      9  * @author danvk@google.com (Dan Vanderkam)
     10  */
     11
     12 /*
     13  * A ticker is a function with the following interface:
     14  *
     15  * function(a, b, pixels, options_view, dygraph, forced_values);
     16  * -> [ { v: tick1_v, label: tick1_label[, label_v: label_v1] },
     17  *      { v: tick2_v, label: tick2_label[, label_v: label_v2] },
     18  *      ...
     19  *    ]
     20  *
     21  * The returned value is called a "tick list".
     22  *
     23  * Arguments
     24  * ---------
     25  *
     26  * [a, b] is the range of the axis for which ticks are being generated. For a
     27  * numeric axis, these will simply be numbers. For a date axis, these will be
     28  * millis since epoch (convertable to Date objects using "new Date(a)" and "new
     29  * Date(b)").
     30  *
     31  * opts provides access to chart- and axis-specific options. It can be used to
     32  * access number/date formatting code/options, check for a log scale, etc.
     33  *
     34  * pixels is the length of the axis in pixels. opts('pixelsPerLabel') is the
     35  * minimum amount of space to be allotted to each label. For instance, if
     36  * pixels=400 and opts('pixelsPerLabel')=40 then the ticker should return
     37  * between zero and ten (400/40) ticks.
     38  *
     39  * dygraph is the Dygraph object for which an axis is being constructed.
     40  *
     41  * forced_values is used for secondary y-axes. The tick positions are typically
     42  * set by the primary y-axis, so the secondary y-axis has no choice in where to
     43  * put these. It simply has to generate labels for these data values.
     44  *
     45  * Tick lists
     46  * ----------
     47  * Typically a tick will have both a grid/tick line and a label at one end of
     48  * that line (at the bottom for an x-axis, at left or right for the y-axis).
     49  *
     50  * A tick may be missing one of these two components:
     51  * - If "label_v" is specified instead of "v", then there will be no tick or
     52  *   gridline, just a label.
     53  * - Similarly, if "label" is not specified, then there will be a gridline
     54  *   without a label.
     55  *
     56  * This flexibility is useful in a few situations:
     57  * - For log scales, some of the tick lines may be too close to all have labels.
     58  * - For date scales where years are being displayed, it is desirable to display
     59  *   tick marks at the beginnings of years but labels (e.g. "2006") in the
     60  *   middle of the years.
     61  */
     62
     63 /*jshint sub:true */
     64 /*global Dygraph:false */
     65 "use strict";
     66
     67 import * as utils from './dygraph-utils';
     68
     69 /** @typedef {Array.<{v:number, label:string, label_v:(string|undefined)}>} */
     70 var TickList = undefined;  // the ' = undefined' keeps jshint happy.
     71
     72 /** @typedef {function(
     73  *    number,
     74  *    number,
     75  *    number,
     76  *    function(string):*,
     77  *    Dygraph=,
     78  *    Array.<number>=
     79  *  ): TickList}
     80  */
     81 var Ticker = undefined;  // the ' = undefined' keeps jshint happy.
     82
     83 /** @type {Ticker} */
     84 export var numericLinearTicks = function(a, b, pixels, opts, dygraph, vals) {
     85   var nonLogscaleOpts = function(opt) {
     86     if (opt === 'logscale') return false;
     87     return opts(opt);
     88   };
     89   return numericTicks(a, b, pixels, nonLogscaleOpts, dygraph, vals);
     90 };
     91
     92 /** @type {Ticker} */
     93 export var numericTicks = function(a, b, pixels, opts, dygraph, vals) {
     94   var pixels_per_tick = /** @type{number} */(opts('pixelsPerLabel'));
     95   var ticks = [];
     96   var i, j, tickV, nTicks;
     97   if (vals) {
     98     for (i = 0; i < vals.length; i++) {
     99       ticks.push({v: vals[i]});
    100     }
    101   } else {
    102     // TODO(danvk): factor this log-scale block out into a separate function.
    103     if (opts("logscale")) {
    104       nTicks  = Math.floor(pixels / pixels_per_tick);
    105       var minIdx = utils.binarySearch(a, PREFERRED_LOG_TICK_VALUES, 1);
    106       var maxIdx = utils.binarySearch(b, PREFERRED_LOG_TICK_VALUES, -1);
    107       if (minIdx == -1) {
    108         minIdx = 0;
    109       }
    110       if (maxIdx == -1) {
    111         maxIdx = PREFERRED_LOG_TICK_VALUES.length - 1;
    112       }
    113       // Count the number of tick values would appear, if we can get at least
    114       // nTicks / 4 accept them.
    115       var lastDisplayed = null;
    116       if (maxIdx - minIdx >= nTicks / 4) {
    117         for (var idx = maxIdx; idx >= minIdx; idx--) {
    118           var tickValue = PREFERRED_LOG_TICK_VALUES[idx];
    119           var pixel_coord = Math.log(tickValue / a) / Math.log(b / a) * pixels;
    120           var tick = { v: tickValue };
    121           if (lastDisplayed === null) {
    122             lastDisplayed = {
    123               tickValue : tickValue,
    124               pixel_coord : pixel_coord
    125             };
    126           } else {
    127             if (Math.abs(pixel_coord - lastDisplayed.pixel_coord) >= pixels_per_tick) {
    128               lastDisplayed = {
    129                 tickValue : tickValue,
    130                 pixel_coord : pixel_coord
    131               };
    132             } else {
    133               tick.label = "";
    134             }
    135           }
    136           ticks.push(tick);
    137         }
    138         // Since we went in backwards order.
    139         ticks.reverse();
    140       }
    141     }
    142
    143     // ticks.length won't be 0 if the log scale function finds values to insert.
    144     if (ticks.length === 0) {
    145       // Basic idea:
    146       // Try labels every 1, 2, 5, 10, 20, 50, 100, etc.
    147       // Calculate the resulting tick spacing (i.e. this.height_ / nTicks).
    148       // The first spacing greater than pixelsPerYLabel is what we use.
    149       // TODO(danvk): version that works on a log scale.
    150       var kmg2 = opts("labelsKMG2");
    151       var mults, base;
    152       if (kmg2) {
    153         mults = [1, 2, 4, 8, 16, 32, 64, 128, 256];
    154         base = 16;
    155       } else {
    156         mults = [1, 2, 5, 10, 20, 50, 100];
    157         base = 10;
    158       }
    159
    160       // Get the maximum number of permitted ticks based on the
    161       // graph's pixel size and pixels_per_tick setting.
    162       var max_ticks = Math.ceil(pixels / pixels_per_tick);
    163
    164       // Now calculate the data unit equivalent of this tick spacing.
    165       // Use abs() since graphs may have a reversed Y axis.
    166       var units_per_tick = Math.abs(b - a) / max_ticks;
    167
    168       // Based on this, get a starting scale which is the largest
    169       // integer power of the chosen base (10 or 16) that still remains
    170       // below the requested pixels_per_tick spacing.
    171       var base_power = Math.floor(Math.log(units_per_tick) / Math.log(base));
    172       var base_scale = Math.pow(base, base_power);
    173
    174       // Now try multiples of the starting scale until we find one
    175       // that results in tick marks spaced sufficiently far apart.
    176       // The "mults" array should cover the range 1 .. base^2 to
    177       // adjust for rounding and edge effects.
    178       var scale, low_val, high_val, spacing;
    179       for (j = 0; j < mults.length; j++) {
    180         scale = base_scale * mults[j];
    181         low_val = Math.floor(a / scale) * scale;
    182         high_val = Math.ceil(b / scale) * scale;
    183         nTicks = Math.abs(high_val - low_val) / scale;
    184         spacing = pixels / nTicks;
    185         if (spacing > pixels_per_tick) break;
    186       }
    187
    188       // Construct the set of ticks.
    189       // Allow reverse y-axis if it's explicitly requested.
    190       if (low_val > high_val) scale *= -1;
    191       for (i = 0; i <= nTicks; i++) {
    192         tickV = low_val + i * scale;
    193         ticks.push( {v: tickV} );
    194       }
    195     }
    196   }
    197
    198   var formatter = /**@type{AxisLabelFormatter}*/(opts('axisLabelFormatter'));
    199
    200   // Add labels to the ticks.
    201   for (i = 0; i < ticks.length; i++) {
    202     if (ticks[i].label !== undefined) continue;  // Use current label.
    203     // TODO(danvk): set granularity to something appropriate here.
    204     ticks[i].label = formatter.call(dygraph, ticks[i].v, 0, opts, dygraph);
    205   }
    206
    207   return ticks;
    208 };
    209
    210 /** @type {Ticker} */
    211 export var dateTicker = function(a, b, pixels, opts, dygraph, vals) {
    212   var chosen = pickDateTickGranularity(a, b, pixels, opts);
    213
    214   if (chosen >= 0) {
    215     return getDateAxis(a, b, chosen, opts, dygraph);
    216   } else {
    217     // this can happen if self.width_ is zero.
    218     return [];
    219   }
    220 };
    221
    222 // Time granularity enumeration
    223 export var Granularity = {
    224   MILLISECONDLY: 0,
    225   TWO_MILLISECONDLY: 1,
    226   FIVE_MILLISECONDLY: 2,
    227   TEN_MILLISECONDLY: 3,
    228   FIFTY_MILLISECONDLY: 4,
    229   HUNDRED_MILLISECONDLY: 5,
    230   FIVE_HUNDRED_MILLISECONDLY: 6,
    231   SECONDLY: 7,
    232   TWO_SECONDLY: 8,
    233   FIVE_SECONDLY: 9,
    234   TEN_SECONDLY: 10,
    235   THIRTY_SECONDLY: 11,
    236   MINUTELY: 12,
    237   TWO_MINUTELY: 13,
    238   FIVE_MINUTELY: 14,
    239   TEN_MINUTELY: 15,
    240   THIRTY_MINUTELY: 16,
    241   HOURLY: 17,
    242   TWO_HOURLY: 18,
    243   SIX_HOURLY: 19,
    244   DAILY: 20,
    245   TWO_DAILY: 21,
    246   WEEKLY: 22,
    247   MONTHLY: 23,
    248   QUARTERLY: 24,
    249   BIANNUAL: 25,
    250   ANNUAL: 26,
    251   DECADAL: 27,
    252   CENTENNIAL: 28,
    253   NUM_GRANULARITIES: 29
    254 }
    255
    256 // Date components enumeration (in the order of the arguments in Date)
    257 // TODO: make this an @enum
    258 var DateField = {
    259   DATEFIELD_Y: 0,
    260   DATEFIELD_M: 1,
    261   DATEFIELD_D: 2,
    262   DATEFIELD_HH: 3,
    263   DATEFIELD_MM: 4,
    264   DATEFIELD_SS: 5,
    265   DATEFIELD_MS: 6,
    266   NUM_DATEFIELDS: 7
    267 };
    268
    269 /**
    270  * The value of datefield will start at an even multiple of "step", i.e.
    271  *   if datefield=SS and step=5 then the first tick will be on a multiple of 5s.
    272  *
    273  * For granularities <= HOURLY, ticks are generated every `spacing` ms.
    274  *
    275  * At coarser granularities, ticks are generated by incrementing `datefield` by
    276  *   `step`. In this case, the `spacing` value is only used to estimate the
    277  *   number of ticks. It should roughly correspond to the spacing between
    278  *   adjacent ticks.
    279  *
    280  * @type {Array.<{datefield:number, step:number, spacing:number}>}
    281  */
    282 var TICK_PLACEMENT = [];
    283 TICK_PLACEMENT[Granularity.MILLISECONDLY]               = {datefield: DateField.DATEFIELD_MS, step:   1, spacing: 1};
    284 TICK_PLACEMENT[Granularity.TWO_MILLISECONDLY]           = {datefield: DateField.DATEFIELD_MS, step:   2, spacing: 2};
    285 TICK_PLACEMENT[Granularity.FIVE_MILLISECONDLY]          = {datefield: DateField.DATEFIELD_MS, step:   5, spacing: 5};
    286 TICK_PLACEMENT[Granularity.TEN_MILLISECONDLY]           = {datefield: DateField.DATEFIELD_MS, step:  10, spacing: 10};
    287 TICK_PLACEMENT[Granularity.FIFTY_MILLISECONDLY]         = {datefield: DateField.DATEFIELD_MS, step:  50, spacing: 50};
    288 TICK_PLACEMENT[Granularity.HUNDRED_MILLISECONDLY]       = {datefield: DateField.DATEFIELD_MS, step: 100, spacing: 100};
    289 TICK_PLACEMENT[Granularity.FIVE_HUNDRED_MILLISECONDLY]  = {datefield: DateField.DATEFIELD_MS, step: 500, spacing: 500};
    290 TICK_PLACEMENT[Granularity.SECONDLY]        = {datefield: DateField.DATEFIELD_SS, step:   1, spacing: 1000 * 1};
    291 TICK_PLACEMENT[Granularity.TWO_SECONDLY]    = {datefield: DateField.DATEFIELD_SS, step:   2, spacing: 1000 * 2};
    292 TICK_PLACEMENT[Granularity.FIVE_SECONDLY]   = {datefield: DateField.DATEFIELD_SS, step:   5, spacing: 1000 * 5};
    293 TICK_PLACEMENT[Granularity.TEN_SECONDLY]    = {datefield: DateField.DATEFIELD_SS, step:  10, spacing: 1000 * 10};
    294 TICK_PLACEMENT[Granularity.THIRTY_SECONDLY] = {datefield: DateField.DATEFIELD_SS, step:  30, spacing: 1000 * 30};
    295 TICK_PLACEMENT[Granularity.MINUTELY]        = {datefield: DateField.DATEFIELD_MM, step:   1, spacing: 1000 * 60};
    296 TICK_PLACEMENT[Granularity.TWO_MINUTELY]    = {datefield: DateField.DATEFIELD_MM, step:   2, spacing: 1000 * 60 * 2};
    297 TICK_PLACEMENT[Granularity.FIVE_MINUTELY]   = {datefield: DateField.DATEFIELD_MM, step:   5, spacing: 1000 * 60 * 5};
    298 TICK_PLACEMENT[Granularity.TEN_MINUTELY]    = {datefield: DateField.DATEFIELD_MM, step:  10, spacing: 1000 * 60 * 10};
    299 TICK_PLACEMENT[Granularity.THIRTY_MINUTELY] = {datefield: DateField.DATEFIELD_MM, step:  30, spacing: 1000 * 60 * 30};
    300 TICK_PLACEMENT[Granularity.HOURLY]          = {datefield: DateField.DATEFIELD_HH, step:   1, spacing: 1000 * 3600};
    301 TICK_PLACEMENT[Granularity.TWO_HOURLY]      = {datefield: DateField.DATEFIELD_HH, step:   2, spacing: 1000 * 3600 * 2};
    302 TICK_PLACEMENT[Granularity.SIX_HOURLY]      = {datefield: DateField.DATEFIELD_HH, step:   6, spacing: 1000 * 3600 * 6};
    303 TICK_PLACEMENT[Granularity.DAILY]           = {datefield: DateField.DATEFIELD_D,  step:   1, spacing: 1000 * 86400};
    304 TICK_PLACEMENT[Granularity.TWO_DAILY]       = {datefield: DateField.DATEFIELD_D,  step:   2, spacing: 1000 * 86400 * 2};
    305 TICK_PLACEMENT[Granularity.WEEKLY]          = {datefield: DateField.DATEFIELD_D,  step:   7, spacing: 1000 * 604800};
    306 TICK_PLACEMENT[Granularity.MONTHLY]         = {datefield: DateField.DATEFIELD_M,  step:   1, spacing: 1000 * 7200  * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 / 12
    307 TICK_PLACEMENT[Granularity.QUARTERLY]       = {datefield: DateField.DATEFIELD_M,  step:   3, spacing: 1000 * 21600 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 / 4
    308 TICK_PLACEMENT[Granularity.BIANNUAL]        = {datefield: DateField.DATEFIELD_M,  step:   6, spacing: 1000 * 43200 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 / 2
    309 TICK_PLACEMENT[Granularity.ANNUAL]          = {datefield: DateField.DATEFIELD_Y,  step:   1, spacing: 1000 * 86400   * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 * 1
    310 TICK_PLACEMENT[Granularity.DECADAL]         = {datefield: DateField.DATEFIELD_Y,  step:  10, spacing: 1000 * 864000  * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 * 10
    311 TICK_PLACEMENT[Granularity.CENTENNIAL]      = {datefield: DateField.DATEFIELD_Y,  step: 100, spacing: 1000 * 8640000 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 * 100
    312
    313 /**
    314  * This is a list of human-friendly values at which to show tick marks on a log
    315  * scale. It is k * 10^n, where k=1..9 and n=-39..+39, so:
    316  * ..., 1, 2, 3, 4, 5, ..., 9, 10, 20, 30, ..., 90, 100, 200, 300, ...
    317  * NOTE: this assumes that utils.LOG_SCALE = 10.
    318  * @type {Array.<number>}
    319  */
    320 var PREFERRED_LOG_TICK_VALUES = (function() {
    321   var vals = [];
    322   for (var power = -39; power <= 39; power++) {
    323     var range = Math.pow(10, power);
    324     for (var mult = 1; mult <= 9; mult++) {
    325       var val = range * mult;
    326       vals.push(val);
    327     }
    328   }
    329   return vals;
    330 })();
    331
    332 /**
    333  * Determine the correct granularity of ticks on a date axis.
    334  *
    335  * @param {number} a Left edge of the chart (ms)
    336  * @param {number} b Right edge of the chart (ms)
    337  * @param {number} pixels Size of the chart in the relevant dimension (width).
    338  * @param {function(string):*} opts Function mapping from option name -> value.
    339  * @return {number} The appropriate axis granularity for this chart. See the
    340  *     enumeration of possible values in dygraph-tickers.js.
    341  */
    342 var pickDateTickGranularity = function(a, b, pixels, opts) {
    343   var pixels_per_tick = /** @type{number} */(opts('pixelsPerLabel'));
    344   for (var i = 0; i < Granularity.NUM_GRANULARITIES; i++) {
    345     var num_ticks = numDateTicks(a, b, i);
    346     if (pixels / num_ticks >= pixels_per_tick) {
    347       return i;
    348     }
    349   }
    350   return -1;
    351 };
    352
    353 /**
    354  * Compute the number of ticks on a date axis for a given granularity.
    355  * @param {number} start_time
    356  * @param {number} end_time
    357  * @param {number} granularity (one of the granularities enumerated above)
    358  * @return {number} (Approximate) number of ticks that would result.
    359  */
    360 var numDateTicks = function(start_time, end_time, granularity) {
    361   var spacing = TICK_PLACEMENT[granularity].spacing;
    362   return Math.round(1.0 * (end_time - start_time) / spacing);
    363 };
    364
    365 /**
    366  * Compute the positions and labels of ticks on a date axis for a given granularity.
    367  * @param {number} start_time
    368  * @param {number} end_time
    369  * @param {number} granularity (one of the granularities enumerated above)
    370  * @param {function(string):*} opts Function mapping from option name -> value.
    371  * @param {Dygraph=} dg
    372  * @return {!TickList}
    373  */
    374 export var getDateAxis = function(start_time, end_time, granularity, opts, dg) {
    375   var formatter = /** @type{AxisLabelFormatter} */(
    376       opts("axisLabelFormatter"));
    377   var utc = opts("labelsUTC");
    378   var accessors = utc ? utils.DateAccessorsUTC : utils.DateAccessorsLocal;
    379
    380   var datefield = TICK_PLACEMENT[granularity].datefield;
    381   var step = TICK_PLACEMENT[granularity].step;
    382   var spacing = TICK_PLACEMENT[granularity].spacing;
    383
    384   // Choose a nice tick position before the initial instant.
    385   // Currently, this code deals properly with the existent daily granularities:
    386   // DAILY (with step of 1) and WEEKLY (with step of 7 but specially handled).
    387   // Other daily granularities (say TWO_DAILY) should also be handled specially
    388   // by setting the start_date_offset to 0.
    389   var start_date = new Date(start_time);
    390   var date_array = [];
    391   date_array[DateField.DATEFIELD_Y]  = accessors.getFullYear(start_date);
    392   date_array[DateField.DATEFIELD_M]  = accessors.getMonth(start_date);
    393   date_array[DateField.DATEFIELD_D]  = accessors.getDate(start_date);
    394   date_array[DateField.DATEFIELD_HH] = accessors.getHours(start_date);
    395   date_array[DateField.DATEFIELD_MM] = accessors.getMinutes(start_date);
    396   date_array[DateField.DATEFIELD_SS] = accessors.getSeconds(start_date);
    397   date_array[DateField.DATEFIELD_MS] = accessors.getMilliseconds(start_date);
    398
    399   var start_date_offset = date_array[datefield] % step;
    400   if (granularity == Granularity.WEEKLY) {
    401     // This will put the ticks on Sundays.
    402     start_date_offset = accessors.getDay(start_date);
    403   }
    404
    405   date_array[datefield] -= start_date_offset;
    406   for (var df = datefield + 1; df < DateField.NUM_DATEFIELDS; df++) {
    407     // The minimum value is 1 for the day of month, and 0 for all other fields.
    408     date_array[df] = (df === DateField.DATEFIELD_D) ? 1 : 0;
    409   }
    410
    411   // Generate the ticks.
    412   // For granularities not coarser than HOURLY we use the fact that:
    413   //   the number of milliseconds between ticks is constant
    414   //   and equal to the defined spacing.
    415   // Otherwise we rely on the 'roll over' property of the Date functions:
    416   //   when some date field is set to a value outside of its logical range,
    417   //   the excess 'rolls over' the next (more significant) field.
    418   // However, when using local time with DST transitions,
    419   // there are dates that do not represent any time value at all
    420   // (those in the hour skipped at the 'spring forward'),
    421   // and the JavaScript engines usually return an equivalent value.
    422   // Hence we have to check that the date is properly increased at each step,
    423   // returning a date at a nice tick position.
    424   var ticks = [];
    425   var tick_date = accessors.makeDate.apply(null, date_array);
    426   var tick_time = tick_date.getTime();
    427   if (granularity <= Granularity.HOURLY) {
    428     if (tick_time < start_time) {
    429       tick_time += spacing;
    430       tick_date = new Date(tick_time);
    431     }
    432     while (tick_time <= end_time) {
    433       ticks.push({ v: tick_time,
    434                    label: formatter.call(dg, tick_date, granularity, opts, dg)
    435                  });
    436       tick_time += spacing;
    437       tick_date = new Date(tick_time);
    438     }
    439   } else {
    440     if (tick_time < start_time) {
    441       date_array[datefield] += step;
    442       tick_date = accessors.makeDate.apply(null, date_array);
    443       tick_time = tick_date.getTime();
    444     }
    445     while (tick_time <= end_time) {
    446       if (granularity >= Granularity.DAILY ||
    447           accessors.getHours(tick_date) % step === 0) {
    448         ticks.push({ v: tick_time,
    449                      label: formatter.call(dg, tick_date, granularity, opts, dg)
    450                    });
    451       }
    452       date_array[datefield] += step;
    453       tick_date = accessors.makeDate.apply(null, date_array);
    454       tick_time = tick_date.getTime();
    455     }
    456   }
    457   return ticks;
    458 };
    459