3 * Copyright 2011 Dan Vanderkam (danvdk@gmail.com)
4 * MIT-licensed (http://opensource.org/licenses/MIT)
8 * @fileoverview Description of this file.
9 * @author danvk@google.com (Dan Vanderkam)
11 * A ticker is a function with the following interface:
13 * function(a, b, pixels, options_view, dygraph, forced_values);
14 * -> [ { v: tick1_v, label: tick1_label[, label_v: label_v1] },
15 * { v: tick2_v, label: tick2_label[, label_v: label_v2] },
19 * The returned value is called a "tick list".
24 * [a, b] is the range of the axis for which ticks are being generated. For a
25 * numeric axis, these will simply be numbers. For a date axis, these will be
26 * millis since epoch (convertable to Date objects using "new Date(a)" and "new
29 * opts provides access to chart- and axis-specific options. It can be used to
30 * access number/date formatting code/options, check for a log scale, etc.
32 * pixels is the length of the axis in pixels. opts('pixelsPerLabel') is the
33 * minimum amount of space to be allotted to each label. For instance, if
34 * pixels=400 and opts('pixelsPerLabel')=40 then the ticker should return
35 * between zero and ten (400/40) ticks.
37 * dygraph is the Dygraph object for which an axis is being constructed.
39 * forced_values is used for secondary y-axes. The tick positions are typically
40 * set by the primary y-axis, so the secondary y-axis has no choice in where to
41 * put these. It simply has to generate labels for these data values.
45 * Typically a tick will have both a grid/tick line and a label at one end of
46 * that line (at the bottom for an x-axis, at left or right for the y-axis).
48 * A tick may be missing one of these two components:
49 * - If "label_v" is specified instead of "v", then there will be no tick or
50 * gridline, just a label.
51 * - Similarly, if "label" is not specified, then there will be a gridline
54 * This flexibility is useful in a few situations:
55 * - For log scales, some of the tick lines may be too close to all have labels.
56 * - For date scales where years are being displayed, it is desirable to display
57 * tick marks at the beginnings of years but labels (e.g. "2006") in the
58 * middle of the years.
61 /*jshint globalstrict:true, sub:true */
62 /*global Dygraph:false */
65 /** @typedef {Array.<{v:number, label:string, label_v:(string|undefined)}>} */
66 Dygraph
.TickList
= undefined
; // the ' = undefined' keeps jshint happy.
68 /** @typedef {function(
75 * ): Dygraph.TickList}
77 Dygraph
.Ticker
= undefined
; // the ' = undefined' keeps jshint happy.
79 /** @type {Dygraph.Ticker} */
80 Dygraph
.numericLinearTicks
= function(a
, b
, pixels
, opts
, dygraph
, vals
) {
81 var nonLogscaleOpts
= function(opt
) {
82 if (opt
=== 'logscale') return false;
85 return Dygraph
.numericTicks(a
, b
, pixels
, nonLogscaleOpts
, dygraph
, vals
);
88 /** @type {Dygraph.Ticker} */
89 Dygraph
.numericTicks
= function(a
, b
, pixels
, opts
, dygraph
, vals
) {
90 var pixels_per_tick
= /** @type{number} */(opts('pixelsPerLabel'));
92 var i
, j
, tickV
, nTicks
;
94 for (i
= 0; i
< vals
.length
; i
++) {
95 ticks
.push({v
: vals
[i
]});
98 // TODO(danvk): factor this log-scale block out into a separate function.
99 if (opts("logscale")) {
100 nTicks
= Math
.floor(pixels
/ pixels_per_tick
);
101 var minIdx
= Dygraph
.binarySearch(a
, Dygraph
.PREFERRED_LOG_TICK_VALUES
, 1);
102 var maxIdx
= Dygraph
.binarySearch(b
, Dygraph
.PREFERRED_LOG_TICK_VALUES
, -1);
107 maxIdx
= Dygraph
.PREFERRED_LOG_TICK_VALUES
.length
- 1;
109 // Count the number of tick values would appear, if we can get at least
110 // nTicks / 4 accept them
.
111 var lastDisplayed
= null;
112 if (maxIdx
- minIdx
>= nTicks
/ 4) {
113 for (var idx
= maxIdx
; idx
>= minIdx
; idx
--) {
114 var tickValue
= Dygraph
.PREFERRED_LOG_TICK_VALUES
[idx
];
115 var pixel_coord
= Math
.log(tickValue
/ a) / Math
.log(b
/ a
) * pixels
;
116 var tick
= { v
: tickValue
};
117 if (lastDisplayed
=== null) {
119 tickValue
: tickValue
,
120 pixel_coord
: pixel_coord
123 if (Math
.abs(pixel_coord
- lastDisplayed
.pixel_coord
) >= pixels_per_tick
) {
125 tickValue
: tickValue
,
126 pixel_coord
: pixel_coord
134 // Since we went in backwards order.
139 // ticks.length won't be 0 if the log scale function finds values to insert.
140 if (ticks
.length
=== 0) {
142 // Try labels every 1, 2, 5, 10, 20, 50, 100, etc.
143 // Calculate the resulting tick spacing (i.e. this.height_ / nTicks
).
144 // The first spacing greater than pixelsPerYLabel is what we use.
145 // TODO(danvk): version that works on a log scale.
146 var kmg2
= opts("labelsKMG2");
149 mults
= [1, 2, 4, 8, 16, 32, 64, 128, 256];
152 mults
= [1, 2, 5, 10, 20, 50, 100];
156 // Get the maximum number of permitted ticks based on the
157 // graph's pixel size and pixels_per_tick setting.
158 var max_ticks
= Math
.ceil(pixels
/ pixels_per_tick
);
160 // Now calculate the data unit equivalent of this tick spacing.
161 // Use abs() since graphs may have a reversed Y axis.
162 var units_per_tick
= Math
.abs(b
- a
) / max_ticks
;
164 // Based on this, get a starting scale which is the largest
165 // integer power of the chosen base (10 or 16) that still remains
166 // below the requested pixels_per_tick spacing.
167 var base_power
= Math
.floor(Math
.log(units_per_tick
) / Math
.log(base
));
168 var base_scale
= Math
.pow(base
, base_power
);
170 // Now try multiples of the starting scale until we find one
171 // that results in tick marks spaced sufficiently far apart.
172 // The "mults" array should cover the range 1 .. base^2 to
173 // adjust for rounding and edge effects.
174 var scale
, low_val
, high_val
, spacing
;
175 for (j
= 0; j
< mults
.length
; j
++) {
176 scale
= base_scale
* mults
[j
];
177 low_val
= Math
.floor(a
/ scale
) * scale
;
178 high_val
= Math
.ceil(b
/ scale
) * scale
;
179 nTicks
= Math
.abs(high_val
- low_val
) / scale
;
180 spacing
= pixels
/ nTicks
;
181 if (spacing
> pixels_per_tick
) break;
184 // Construct the set of ticks.
185 // Allow reverse y-axis if it's explicitly requested.
186 if (low_val
> high_val
) scale
*= -1;
187 for (i
= 0; i
< nTicks
; i
++) {
188 tickV
= low_val
+ i
* scale
;
189 ticks
.push( {v
: tickV
} );
194 var formatter
= /**@type{AxisLabelFormatter}*/(opts('axisLabelFormatter'));
196 // Add labels to the ticks.
197 for (i
= 0; i
< ticks
.length
; i
++) {
198 if (ticks
[i
].label
!== undefined
) continue; // Use current label.
199 // TODO(danvk): set granularity to something appropriate here.
200 ticks
[i
].label
= formatter(ticks
[i
].v
, 0, opts
, dygraph
);
207 /** @type {Dygraph.Ticker} */
208 Dygraph
.dateTicker
= function(a
, b
, pixels
, opts
, dygraph
, vals
) {
209 var chosen
= Dygraph
.pickDateTickGranularity(a
, b
, pixels
, opts
);
212 return Dygraph
.getDateAxis(a
, b
, chosen
, opts
, dygraph
);
214 // this can happen if self.width_ is zero.
219 // Time granularity enumeration
220 // TODO(danvk): make this an @enum
221 Dygraph
.SECONDLY
= 0;
222 Dygraph
.TWO_SECONDLY
= 1;
223 Dygraph
.FIVE_SECONDLY
= 2;
224 Dygraph
.TEN_SECONDLY
= 3;
225 Dygraph
.THIRTY_SECONDLY
= 4;
226 Dygraph
.MINUTELY
= 5;
227 Dygraph
.TWO_MINUTELY
= 6;
228 Dygraph
.FIVE_MINUTELY
= 7;
229 Dygraph
.TEN_MINUTELY
= 8;
230 Dygraph
.THIRTY_MINUTELY
= 9;
232 Dygraph
.TWO_HOURLY
= 11;
233 Dygraph
.SIX_HOURLY
= 12;
236 Dygraph
.MONTHLY
= 15;
237 Dygraph
.QUARTERLY
= 16;
238 Dygraph
.BIANNUAL
= 17;
240 Dygraph
.DECADAL
= 19;
241 Dygraph
.CENTENNIAL
= 20;
242 Dygraph
.NUM_GRANULARITIES
= 21;
244 /** @type {Array.<number>} */
245 Dygraph
.SHORT_SPACINGS
= [];
246 Dygraph
.SHORT_SPACINGS
[Dygraph
.SECONDLY
] = 1000 * 1;
247 Dygraph
.SHORT_SPACINGS
[Dygraph
.TWO_SECONDLY
] = 1000 * 2;
248 Dygraph
.SHORT_SPACINGS
[Dygraph
.FIVE_SECONDLY
] = 1000 * 5;
249 Dygraph
.SHORT_SPACINGS
[Dygraph
.TEN_SECONDLY
] = 1000 * 10;
250 Dygraph
.SHORT_SPACINGS
[Dygraph
.THIRTY_SECONDLY
] = 1000 * 30;
251 Dygraph
.SHORT_SPACINGS
[Dygraph
.MINUTELY
] = 1000 * 60;
252 Dygraph
.SHORT_SPACINGS
[Dygraph
.TWO_MINUTELY
] = 1000 * 60 * 2;
253 Dygraph
.SHORT_SPACINGS
[Dygraph
.FIVE_MINUTELY
] = 1000 * 60 * 5;
254 Dygraph
.SHORT_SPACINGS
[Dygraph
.TEN_MINUTELY
] = 1000 * 60 * 10;
255 Dygraph
.SHORT_SPACINGS
[Dygraph
.THIRTY_MINUTELY
] = 1000 * 60 * 30;
256 Dygraph
.SHORT_SPACINGS
[Dygraph
.HOURLY
] = 1000 * 3600;
257 Dygraph
.SHORT_SPACINGS
[Dygraph
.TWO_HOURLY
] = 1000 * 3600 * 2;
258 Dygraph
.SHORT_SPACINGS
[Dygraph
.SIX_HOURLY
] = 1000 * 3600 * 6;
259 Dygraph
.SHORT_SPACINGS
[Dygraph
.DAILY
] = 1000 * 86400;
260 Dygraph
.SHORT_SPACINGS
[Dygraph
.WEEKLY
] = 1000 * 604800;
262 /** @type {Array.<Object>} */
263 Dygraph
.LONG_TICK_PLACEMENTS
= [];
264 Dygraph
.LONG_TICK_PLACEMENTS
[Dygraph
.MONTHLY
] = {
265 months
: [0,1,2,3,4,5,6,7,8,9,10,11],
268 Dygraph
.LONG_TICK_PLACEMENTS
[Dygraph
.QUARTERLY
] = {
272 Dygraph
.LONG_TICK_PLACEMENTS
[Dygraph
.BIANNUAL
] = {
276 Dygraph
.LONG_TICK_PLACEMENTS
[Dygraph
.ANNUAL
] = {
280 Dygraph
.LONG_TICK_PLACEMENTS
[Dygraph
.DECADAL
] = {
284 Dygraph
.LONG_TICK_PLACEMENTS
[Dygraph
.CENTENNIAL
] = {
290 * This is a list of human-friendly values at which to show tick marks on a log
291 * scale. It is k * 10^n, where k=1..9 and n=-39..+39, so:
292 * ..., 1, 2, 3, 4, 5, ..., 9, 10, 20, 30, ..., 90, 100, 200, 300, ...
293 * NOTE: this assumes that Dygraph.LOG_SCALE = 10.
294 * @type {Array.<number>}
296 Dygraph
.PREFERRED_LOG_TICK_VALUES
= function() {
298 for (var power
= -39; power
<= 39; power
++) {
299 var range
= Math
.pow(10, power
);
300 for (var mult
= 1; mult
<= 9; mult
++) {
301 var val
= range
* mult
;
309 * Determine the correct granularity of ticks on a date axis.
311 * @param {number} a Left edge of the chart (ms)
312 * @param {number} b Right edge of the chart (ms)
313 * @param {number} pixels Size of the chart in the relevant dimension (width).
314 * @param {function(string):*} opts Function mapping from option name ->
316 * @return {number} The appropriate axis granularity for this chart. See the
317 * enumeration of possible values in dygraph-tickers.js.
319 Dygraph
.pickDateTickGranularity
= function(a
, b
, pixels
, opts
) {
320 var pixels_per_tick
= /** @type{number} */(opts('pixelsPerLabel'));
321 for (var i
= 0; i
< Dygraph
.NUM_GRANULARITIES
; i
++) {
322 var num_ticks
= Dygraph
.numDateTicks(a
, b
, i
);
323 if (pixels
/ num_ticks
>= pixels_per_tick
) {
331 * @param {number} start_time
332 * @param {number} end_time
333 * @param {number} granularity (one of the granularities enumerated above)
334 * @return {number} Number of ticks that would result.
336 Dygraph
.numDateTicks
= function(start_time
, end_time
, granularity
) {
337 if (granularity
< Dygraph
.MONTHLY
) {
338 // Generate one tick mark for every fixed interval of time.
339 var spacing
= Dygraph
.SHORT_SPACINGS
[granularity
];
340 return Math
.floor(0.5 + 1.0 * (end_time
- start_time
) / spacing
);
342 var tickPlacement
= Dygraph
.LONG_TICK_PLACEMENTS
[granularity
];
344 var msInYear
= 365.2524 * 24 * 3600 * 1000;
345 var num_years
= 1.0 * (end_time
- start_time
) / msInYear
;
346 return Math
.floor(0.5 + 1.0 * num_years
* tickPlacement
.months
.length
/ tickPlacement
.year_mod
);
351 * @param {number} start_time
352 * @param {number} end_time
353 * @param {number} granularity (one of the granularities enumerated above)
354 * @param {function(string):*} opts Function mapping from option name -> value.
355 * @param {Dygraph=} dg
356 * @return {!Dygraph.TickList}
358 Dygraph
.getDateAxis
= function(start_time
, end_time
, granularity
, opts
, dg
) {
359 var formatter
= /** @type{AxisLabelFormatter} */(
360 opts("axisLabelFormatter"));
364 if (granularity
< Dygraph
.MONTHLY
) {
365 // Generate one tick mark for every fixed interval of time.
366 var spacing
= Dygraph
.SHORT_SPACINGS
[granularity
];
368 // Find a time less than start_time which occurs on a "nice" time boundary
369 // for this granularity.
370 var g
= spacing
/ 1000;
371 var d
= new Date(start_time
);
372 Dygraph
.setDateSameTZ(d
, {ms
: 0});
375 if (g
<= 60) { // seconds
377 Dygraph
.setDateSameTZ(d
, {s
: x
- x
% g
});
379 Dygraph
.setDateSameTZ(d
, {s
: 0});
381 if (g
<= 60) { // minutes
383 Dygraph
.setDateSameTZ(d
, {m
: x
- x
% g
});
385 Dygraph
.setDateSameTZ(d
, {m
: 0});
388 if (g
<= 24) { // days
390 d
.setHours(x
- x
% g
);
395 if (g
== 7) { // one week
396 d
.setDate(d
.getDate() - d
.getDay());
401 start_time
= d
.getTime();
403 // For spacings coarser than two-hourly, we want to ignore daylight
404 // savings transitions to get consistent ticks. For finer-grained ticks,
405 // it's essential to show the DST transition in all its messiness.
406 var start_offset_min
= new Date(start_time
).getTimezoneOffset();
407 var check_dst
= (spacing
>= Dygraph
.SHORT_SPACINGS
[Dygraph
.TWO_HOURLY
]);
409 for (t
= start_time
; t
<= end_time
; t
+= spacing
) {
412 // This ensures that we stay on the same hourly "rhythm" across
413 // daylight savings transitions. Without this, the ticks could get off
414 // by an hour. See tests/daylight-savings
.html or issue
147.
415 if (check_dst
&& d
.getTimezoneOffset() != start_offset_min
) {
416 var delta_min
= d
.getTimezoneOffset() - start_offset_min
;
417 t
+= delta_min
* 60 * 1000;
419 start_offset_min
= d
.getTimezoneOffset();
421 // Check whether we've backed into the previous timezone again.
422 // This can happen during a "spring forward" transition. In this case,
423 // it's best to skip this tick altogether (we may be shooting for a
424 // non-existent time like the 2AM that's skipped) and go to the next
426 if (new Date(t
+ spacing
).getTimezoneOffset() != start_offset_min
) {
429 start_offset_min
= d
.getTimezoneOffset();
434 label
: formatter(d
, granularity
, opts
, dg
)
438 // Display a tick mark on the first of a set of months of each year.
439 // Years get a tick mark iff y % year_mod == 0. This is useful for
440 // displaying a tick mark once every 10 years, say, on long time scales.
442 var year_mod
= 1; // e.g. to only print one point every 10 years.
444 if (granularity
< Dygraph
.NUM_GRANULARITIES
) {
445 months
= Dygraph
.LONG_TICK_PLACEMENTS
[granularity
].months
;
446 year_mod
= Dygraph
.LONG_TICK_PLACEMENTS
[granularity
].year_mod
;
448 Dygraph
.warn("Span of dates is too long");
451 var start_year
= new Date(start_time
).getFullYear();
452 var end_year
= new Date(end_time
).getFullYear();
453 var zeropad
= Dygraph
.zeropad
;
454 for (var i
= start_year
; i
<= end_year
; i
++) {
455 if (i
% year_mod
!== 0) continue;
456 for (var j
= 0; j
< months
.length
; j
++) {
457 var date_str
= i
+ "/" + zeropad(1 + months[j]) + "/01";
458 t
= Dygraph
.dateStrToMillis(date_str
);
459 if (t
< start_time
|| t
> end_time
) continue;
461 label
: formatter(new Date(t
), granularity
, opts
, dg
)
470 // These are set here so that this file can be included after dygraph.js
473 Dygraph
.DEFAULT_ATTRS
&&
474 Dygraph
.DEFAULT_ATTRS
['axes'] &&
475 Dygraph
.DEFAULT_ATTRS
['axes']['x'] &&
476 Dygraph
.DEFAULT_ATTRS
['axes']['y'] &&
477 Dygraph
.DEFAULT_ATTRS
['axes']['y2']) {
478 Dygraph
.DEFAULT_ATTRS
['axes']['x']['ticker'] = Dygraph
.dateTicker
;
479 Dygraph
.DEFAULT_ATTRS
['axes']['y']['ticker'] = Dygraph
.numericTicks
;
480 Dygraph
.DEFAULT_ATTRS
['axes']['y2']['ticker'] = Dygraph
.numericTicks
;