TEXT 18
API.txt Guest on 13th October 2020 07:56:51 AM
  1. Flot Reference
  2. --------------
  3.  
  4. Consider a call to the plot function:
  5.  
  6.    var plot = $.plot(placeholder, data, options)
  7.  
  8. The placeholder is a jQuery object or DOM element or jQuery expression
  9. that the plot will be put into. This placeholder needs to have its
  10. width and height set as explained in the README (go read that now if
  11. you haven't, it's short). The plot will modify some properties of the
  12. placeholder so it's recommended you simply pass in a div that you
  13. don't use for anything else. Make sure you check any fancy styling
  14. you apply to the div, e.g. background images have been reported to be a
  15. problem on IE 7.
  16.  
  17. The format of the data is documented below, as is the available
  18. options. The plot object returned from the call has some methods you
  19. can call. These are documented separately below.
  20.  
  21. Note that in general Flot gives no guarantees if you change any of the
  22. objects you pass in to the plot function or get out of it since
  23. they're not necessarily deep-copied.
  24.  
  25.  
  26. Data Format
  27. -----------
  28.  
  29. The data is an array of data series:
  30.  
  31.   [ series1, series2, ... ]
  32.  
  33. A series can either be raw data or an object with properties. The raw
  34. data format is an array of points:
  35.  
  36.   [ [x1, y1], [x2, y2], ... ]
  37.  
  38. E.g.
  39.  
  40.   [ [1, 3], [2, 14.01], [3.5, 3.14] ]
  41.  
  42. Note that to simplify the internal logic in Flot both the x and y
  43. values must be numbers (even if specifying time series, see below for
  44. how to do this). This is a common problem because you might retrieve
  45. data from the database and serialize them directly to JSON without
  46. noticing the wrong type. If you're getting mysterious errors, double
  47. check that you're inputting numbers and not strings.
  48.  
  49. If a null is specified as a point or if one of the coordinates is null
  50. or couldn't be converted to a number, the point is ignored when
  51. drawing. As a special case, a null value for lines is interpreted as a
  52. line segment end, i.e. the points before and after the null value are
  53. not connected.
  54.  
  55. Lines and points take two coordinates. For filled lines and bars, you
  56. can specify a third coordinate which is the bottom of the filled
  57. area/bar (defaults to 0).
  58.  
  59. The format of a single series object is as follows:
  60.  
  61.   {
  62.     color: color or number
  63.     data: rawdata
  64.     label: string
  65.     lines: specific lines options
  66.     bars: specific bars options
  67.     points: specific points options
  68.     xaxis: number
  69.     yaxis: number
  70.     clickable: boolean
  71.     hoverable: boolean
  72.     shadowSize: number
  73.   }
  74.  
  75. You don't have to specify any of them except the data, the rest are
  76. options that will get default values. Typically you'd only specify
  77. label and data, like this:
  78.  
  79.   {
  80.     label: "y = 3",
  81.     data: [[0, 3], [10, 3]]
  82.   }
  83.  
  84. The label is used for the legend, if you don't specify one, the series
  85. will not show up in the legend.
  86.  
  87. If you don't specify color, the series will get a color from the
  88. auto-generated colors. The color is either a CSS color specification
  89. (like "rgb(255, 100, 123)") or an integer that specifies which of
  90. auto-generated colors to select, e.g. 0 will get color no. 0, etc.
  91.  
  92. The latter is mostly useful if you let the user add and remove series,
  93. in which case you can hard-code the color index to prevent the colors
  94. from jumping around between the series.
  95.  
  96. The "xaxis" and "yaxis" options specify which axis to use. The axes
  97. are numbered from 1 (default), so { yaxis: 2} means that the series
  98. should be plotted against the second y axis.
  99.  
  100. "clickable" and "hoverable" can be set to false to disable
  101. interactivity for specific series if interactivity is turned on in
  102. the plot, see below.
  103.  
  104. The rest of the options are all documented below as they are the same
  105. as the default options passed in via the options parameter in the plot
  106. commmand. When you specify them for a specific data series, they will
  107. override the default options for the plot for that data series.
  108.  
  109. Here's a complete example of a simple data specification:
  110.  
  111.   [ { label: "Foo", data: [ [10, 1], [17, -14], [30, 5] ] },
  112.     { label: "Bar", data: [ [11, 13], [19, 11], [30, -7] ] } ]
  113.  
  114.  
  115. Plot Options
  116. ------------
  117.  
  118. All options are completely optional. They are documented individually
  119. below, to change them you just specify them in an object, e.g.
  120.  
  121.   var options = {
  122.     series: {
  123.       lines: { show: true },
  124.       points: { show: true }
  125.     }
  126.   };
  127.  
  128.   $.plot(placeholder, data, options);
  129.  
  130.  
  131. Customizing the legend
  132. ======================
  133.  
  134.   legend: {
  135.     show: boolean
  136.     labelFormatter: null or (fn: string, series object -> string)
  137.     labelBoxBorderColor: color
  138.     noColumns: number
  139.     position: "ne" or "nw" or "se" or "sw"
  140.     margin: number of pixels or [x margin, y margin]
  141.     backgroundColor: null or color
  142.     backgroundOpacity: number between 0 and 1
  143.     container: null or jQuery object/DOM element/jQuery expression
  144.   }
  145.  
  146. The legend is generated as a table with the data series labels and
  147. small label boxes with the color of the series. If you want to format
  148. the labels in some way, e.g. make them to links, you can pass in a
  149. function for "labelFormatter". Here's an example that makes them
  150. clickable:
  151.  
  152.   labelFormatter: function(label, series) {
  153.     // series is the series object for the label
  154.     return '<a href="#' + label + '">' + label + '</a>';
  155.   }
  156.  
  157. "noColumns" is the number of columns to divide the legend table into.
  158. "position" specifies the overall placement of the legend within the
  159. plot (top-right, top-left, etc.) and margin the distance to the plot
  160. edge (this can be either a number or an array of two numbers like [x,
  161. y]). "backgroundColor" and "backgroundOpacity" specifies the
  162. background. The default is a partly transparent auto-detected
  163. background.
  164.  
  165. If you want the legend to appear somewhere else in the DOM, you can
  166. specify "container" as a jQuery object/expression to put the legend
  167. table into. The "position" and "margin" etc. options will then be
  168. ignored. Note that Flot will overwrite the contents of the container.
  169.  
  170.  
  171. Customizing the axes
  172. ====================
  173.  
  174.   xaxis, yaxis: {
  175.     show: null or true/false
  176.     position: "bottom" or "top" or "left" or "right"
  177.     mode: null or "time"
  178.  
  179.     color: null or color spec
  180.     tickColor: null or color spec
  181.    
  182.     min: null or number
  183.     max: null or number
  184.     autoscaleMargin: null or number
  185.    
  186.     transform: null or fn: number -> number
  187.     inverseTransform: null or fn: number -> number
  188.    
  189.     ticks: null or number or ticks array or (fn: range -> ticks array)
  190.     tickSize: number or array
  191.     minTickSize: number or array
  192.     tickFormatter: (fn: number, object -> string) or string
  193.     tickDecimals: null or number
  194.  
  195.     labelWidth: null or number
  196.     labelHeight: null or number
  197.     reserveSpace: null or true
  198.    
  199.     tickLength: null or number
  200.  
  201.     alignTicksWithAxis: null or number
  202.   }
  203.  
  204. All axes have the same kind of options. The following describes how to
  205. configure one axis, see below for what to do if you've got more than
  206. one x axis or y axis.
  207.  
  208. If you don't set the "show" option (i.e. it is null), visibility is
  209. auto-detected, i.e. the axis will show up if there's data associated
  210. with it. You can override this by setting the "show" option to true or
  211. false.
  212.  
  213. The "position" option specifies where the axis is placed, bottom or
  214. top for x axes, left or right for y axes. The "mode" option determines
  215. how the data is interpreted, the default of null means as decimal
  216. numbers. Use "time" for time series data, see the time series data
  217. section.
  218.  
  219. The "color" option determines the color of the labels and ticks for
  220. the axis (default is the grid color). For more fine-grained control
  221. you can also set the color of the ticks separately with "tickColor"
  222. (otherwise it's autogenerated as the base color with some
  223. transparency).
  224.  
  225. The options "min"/"max" are the precise minimum/maximum value on the
  226. scale. If you don't specify either of them, a value will automatically
  227. be chosen based on the minimum/maximum data values. Note that Flot
  228. always examines all the data values you feed to it, even if a
  229. restriction on another axis may make some of them invisible (this
  230. makes interactive use more stable).
  231.  
  232. The "autoscaleMargin" is a bit esoteric: it's the fraction of margin
  233. that the scaling algorithm will add to avoid that the outermost points
  234. ends up on the grid border. Note that this margin is only applied when
  235. a min or max value is not explicitly set. If a margin is specified,
  236. the plot will furthermore extend the axis end-point to the nearest
  237. whole tick. The default value is "null" for the x axes and 0.02 for y
  238. axes which seems appropriate for most cases.
  239.  
  240. "transform" and "inverseTransform" are callbacks you can put in to
  241. change the way the data is drawn. You can design a function to
  242. compress or expand certain parts of the axis non-linearly, e.g.
  243. suppress weekends or compress far away points with a logarithm or some
  244. other means. When Flot draws the plot, each value is first put through
  245. the transform function. Here's an example, the x axis can be turned
  246. into a natural logarithm axis with the following code:
  247.  
  248.   xaxis: {
  249.     transform: function (v) { return Math.log(v); },
  250.     inverseTransform: function (v) { return Math.exp(v); }
  251.   }
  252.  
  253. Similarly, for reversing the y axis so the values appear in inverse
  254. order:
  255.  
  256.   yaxis: {
  257.     transform: function (v) { return -v; },
  258.     inverseTransform: function (v) { return -v; }
  259.   }
  260.  
  261. Note that for finding extrema, Flot assumes that the transform
  262. function does not reorder values (it should be monotone).
  263.  
  264. The inverseTransform is simply the inverse of the transform function
  265. (so v == inverseTransform(transform(v)) for all relevant v). It is
  266. required for converting from canvas coordinates to data coordinates,
  267. e.g. for a mouse interaction where a certain pixel is clicked. If you
  268. don't use any interactive features of Flot, you may not need it.
  269.  
  270.  
  271. The rest of the options deal with the ticks.
  272.  
  273. If you don't specify any ticks, a tick generator algorithm will make
  274. some for you. The algorithm has two passes. It first estimates how
  275. many ticks would be reasonable and uses this number to compute a nice
  276. round tick interval size. Then it generates the ticks.
  277.  
  278. You can specify how many ticks the algorithm aims for by setting
  279. "ticks" to a number. The algorithm always tries to generate reasonably
  280. round tick values so even if you ask for three ticks, you might get
  281. five if that fits better with the rounding. If you don't want any
  282. ticks at all, set "ticks" to 0 or an empty array.
  283.  
  284. Another option is to skip the rounding part and directly set the tick
  285. interval size with "tickSize". If you set it to 2, you'll get ticks at
  286. 2, 4, 6, etc. Alternatively, you can specify that you just don't want
  287. ticks at a size less than a specific tick size with "minTickSize".
  288. Note that for time series, the format is an array like [2, "month"],
  289. see the next section.
  290.  
  291. If you want to completely override the tick algorithm, you can specify
  292. an array for "ticks", either like this:
  293.  
  294.   ticks: [0, 1.2, 2.4]
  295.  
  296. Or like this where the labels are also customized:
  297.  
  298.   ticks: [[0, "zero"], [1.2, "one mark"], [2.4, "two marks"]]
  299.  
  300. You can mix the two if you like.
  301.  
  302. For extra flexibility you can specify a function as the "ticks"
  303. parameter. The function will be called with an object with the axis
  304. min and max and should return a ticks array. Here's a simplistic tick
  305. generator that spits out intervals of pi, suitable for use on the x
  306. axis for trigonometric functions:
  307.  
  308.   function piTickGenerator(axis) {
  309.     var res = [], i = Math.floor(axis.min / Math.PI);
  310.     do {
  311.       var v = i * Math.PI;
  312.       res.push([v, i + "\u03c0"]);
  313.       ++i;
  314.     } while (v < axis.max);
  315.    
  316.     return res;
  317.   }
  318.  
  319. You can control how the ticks look like with "tickDecimals", the
  320. number of decimals to display (default is auto-detected).
  321.  
  322. Alternatively, for ultimate control over how ticks are formatted you can
  323. provide a function to "tickFormatter". The function is passed two
  324. parameters, the tick value and an axis object with information, and
  325. should return a string. The default formatter looks like this:
  326.  
  327.   function formatter(val, axis) {
  328.     return val.toFixed(axis.tickDecimals);
  329.   }
  330.  
  331. The axis object has "min" and "max" with the range of the axis,
  332. "tickDecimals" with the number of decimals to round the value to and
  333. "tickSize" with the size of the interval between ticks as calculated
  334. by the automatic axis scaling algorithm (or specified by you). Here's
  335. an example of a custom formatter:
  336.  
  337.   function suffixFormatter(val, axis) {
  338.     if (val > 1000000)
  339.       return (val / 1000000).toFixed(axis.tickDecimals) + " MB";
  340.     else if (val > 1000)
  341.       return (val / 1000).toFixed(axis.tickDecimals) + " kB";
  342.     else
  343.       return val.toFixed(axis.tickDecimals) + " B";
  344.   }
  345.  
  346. "labelWidth" and "labelHeight" specifies a fixed size of the tick
  347. labels in pixels. They're useful in case you need to align several
  348. plots. "reserveSpace" means that even if an axis isn't shown, Flot
  349. should reserve space for it - it is useful in combination with
  350. labelWidth and labelHeight for aligning multi-axis charts.
  351.  
  352. "tickLength" is the length of the tick lines in pixels. By default, the
  353. innermost axes will have ticks that extend all across the plot, while
  354. any extra axes use small ticks. A value of null means use the default,
  355. while a number means small ticks of that length - set it to 0 to hide
  356. the lines completely.
  357.  
  358. If you set "alignTicksWithAxis" to the number of another axis, e.g.
  359. alignTicksWithAxis: 1, Flot will ensure that the autogenerated ticks
  360. of this axis are aligned with the ticks of the other axis. This may
  361. improve the looks, e.g. if you have one y axis to the left and one to
  362. the right, because the grid lines will then match the ticks in both
  363. ends. The trade-off is that the forced ticks won't necessarily be at
  364. natural places.
  365.  
  366.  
  367. Multiple axes
  368. =============
  369.  
  370. If you need more than one x axis or y axis, you need to specify for
  371. each data series which axis they are to use, as described under the
  372. format of the data series, e.g. { data: [...], yaxis: 2 } specifies
  373. that a series should be plotted against the second y axis.
  374.  
  375. To actually configure that axis, you can't use the xaxis/yaxis options
  376. directly - instead there are two arrays in the options:
  377.  
  378.    xaxes: []
  379.    yaxes: []
  380.  
  381. Here's an example of configuring a single x axis and two y axes (we
  382. can leave options of the first y axis empty as the defaults are fine):
  383.  
  384.   {
  385.     xaxes: [ { position: "top" } ],
  386.     yaxes: [ { }, { position: "right", min: 20 } ]
  387.   }
  388.  
  389. The arrays get their default values from the xaxis/yaxis settings, so
  390. say you want to have all y axes start at zero, you can simply specify
  391. yaxis: { min: 0 } instead of adding a min parameter to all the axes.
  392.  
  393. Generally, the various interfaces in Flot dealing with data points
  394. either accept an xaxis/yaxis parameter to specify which axis number to
  395. use (starting from 1), or lets you specify the coordinate directly as
  396. x2/x3/... or x2axis/x3axis/... instead of "x" or "xaxis".
  397.  
  398.  
  399. Time series data
  400. ================
  401.  
  402. Time series are a bit more difficult than scalar data because
  403. calendars don't follow a simple base 10 system. For many cases, Flot
  404. abstracts most of this away, but it can still be a bit difficult to
  405. get the data into Flot. So we'll first discuss the data format.
  406.  
  407. The time series support in Flot is based on Javascript timestamps,
  408. i.e. everywhere a time value is expected or handed over, a Javascript
  409. timestamp number is used. This is a number, not a Date object. A
  410. Javascript timestamp is the number of milliseconds since January 1,
  411. 1970 00:00:00 UTC. This is almost the same as Unix timestamps, except it's
  412. in milliseconds, so remember to multiply by 1000!
  413.  
  414. You can see a timestamp like this
  415.  
  416.   alert((new Date()).getTime())
  417.  
  418. Normally you want the timestamps to be displayed according to a
  419. certain time zone, usually the time zone in which the data has been
  420. produced. However, Flot always displays timestamps according to UTC.
  421. It has to as the only alternative with core Javascript is to interpret
  422. the timestamps according to the time zone that the visitor is in,
  423. which means that the ticks will shift unpredictably with the time zone
  424. and daylight savings of each visitor.
  425.  
  426. So given that there's no good support for custom time zones in
  427. Javascript, you'll have to take care of this server-side.
  428.  
  429. The easiest way to think about it is to pretend that the data
  430. production time zone is UTC, even if it isn't. So if you have a
  431. datapoint at 2002-02-20 08:00, you can generate a timestamp for eight
  432. o'clock UTC even if it really happened eight o'clock UTC+0200.
  433.  
  434. In PHP you can get an appropriate timestamp with
  435. 'strtotime("2002-02-20 UTC") * 1000', in Python with
  436. 'calendar.timegm(datetime_object.timetuple()) * 1000', in .NET with
  437. something like:
  438.  
  439.   public static int GetJavascriptTimestamp(System.DateTime input)
  440.   {
  441.     System.TimeSpan span = new System.TimeSpan(System.DateTime.Parse("1/1/1970").Ticks);
  442.     System.DateTime time = input.Subtract(span);
  443.     return (long)(time.Ticks / 10000);
  444.   }
  445.  
  446. Javascript also has some support for parsing date strings, so it is
  447. possible to generate the timestamps manually client-side.
  448.  
  449. If you've already got the real UTC timestamp, it's too late to use the
  450. pretend trick described above. But you can fix up the timestamps by
  451. adding the time zone offset, e.g. for UTC+0200 you would add 2 hours
  452. to the UTC timestamp you got. Then it'll look right on the plot. Most
  453. programming environments have some means of getting the timezone
  454. offset for a specific date (note that you need to get the offset for
  455. each individual timestamp to account for daylight savings).
  456.  
  457. Once you've gotten the timestamps into the data and specified "time"
  458. as the axis mode, Flot will automatically generate relevant ticks and
  459. format them. As always, you can tweak the ticks via the "ticks" option
  460. - just remember that the values should be timestamps (numbers), not
  461. Date objects.
  462.  
  463. Tick generation and formatting can also be controlled separately
  464. through the following axis options:
  465.  
  466.   minTickSize: array
  467.   timeformat: null or format string
  468.   monthNames: null or array of size 12 of strings
  469.   twelveHourClock: boolean
  470.  
  471. Here "timeformat" is a format string to use. You might use it like
  472. this:
  473.  
  474.   xaxis: {
  475.     mode: "time"
  476.     timeformat: "%y/%m/%d"
  477.   }
  478.  
  479. This will result in tick labels like "2000/12/24". The following
  480. specifiers are supported
  481.  
  482.   %h: hours
  483.   %H: hours (left-padded with a zero)
  484.   %M: minutes (left-padded with a zero)
  485.   %S: seconds (left-padded with a zero)
  486.   %d: day of month (1-31), use %0d for zero-padding
  487.   %m: month (1-12), use %0m for zero-padding
  488.   %y: year (four digits)
  489.   %b: month name (customizable)
  490.   %p: am/pm, additionally switches %h/%H to 12 hour instead of 24
  491.   %P: AM/PM (uppercase version of %p)
  492.  
  493. Inserting a zero like %0m or %0d means that the specifier will be
  494. left-padded with a zero if it's only single-digit. So %y-%0m-%0d
  495. results in unambigious ISO timestamps like 2007-05-10 (for May 10th).
  496.  
  497. You can customize the month names with the "monthNames" option. For
  498. instance, for Danish you might specify:
  499.  
  500.   monthNames: ["jan", "feb", "mar", "apr", "maj", "jun", "jul", "aug", "sep", "okt", "nov", "dec"]
  501.  
  502. If you set "twelveHourClock" to true, the autogenerated timestamps
  503. will use 12 hour AM/PM timestamps instead of 24 hour.
  504.  
  505. The format string and month names are used by a very simple built-in
  506. format function that takes a date object, a format string (and
  507. optionally an array of month names) and returns the formatted string.
  508. If needed, you can access it as $.plot.formatDate(date, formatstring,
  509. monthNames) or even replace it with another more advanced function
  510. from a date library if you're feeling adventurous.
  511.  
  512. If everything else fails, you can control the formatting by specifying
  513. a custom tick formatter function as usual. Here's a simple example
  514. which will format December 24 as 24/12:
  515.  
  516.   tickFormatter: function (val, axis) {
  517.     var d = new Date(val);
  518.     return d.getUTCDate() + "/" + (d.getUTCMonth() + 1);
  519.   }
  520.  
  521. Note that for the time mode "tickSize" and "minTickSize" are a bit
  522. special in that they are arrays on the form "[value, unit]" where unit
  523. is one of "second", "minute", "hour", "day", "month" and "year". So
  524. you can specify
  525.  
  526.   minTickSize: [1, "month"]
  527.  
  528. to get a tick interval size of at least 1 month and correspondingly,
  529. if axis.tickSize is [2, "day"] in the tick formatter, the ticks have
  530. been produced with two days in-between.
  531.  
  532.  
  533.  
  534. Customizing the data series
  535. ===========================
  536.  
  537.   series: {
  538.     lines, points, bars: {
  539.       show: boolean
  540.       lineWidth: number
  541.       fill: boolean or number
  542.       fillColor: null or color/gradient
  543.     }
  544.  
  545.     points: {
  546.       radius: number
  547.       symbol: "circle" or function
  548.     }
  549.  
  550.     bars: {
  551.       barWidth: number
  552.       align: "left" or "center"
  553.       horizontal: boolean
  554.     }
  555.  
  556.     lines: {
  557.       steps: boolean
  558.     }
  559.  
  560.     shadowSize: number
  561.   }
  562.  
  563.   colors: [ color1, color2, ... ]
  564.  
  565. The options inside "series: {}" are copied to each of the series. So
  566. you can specify that all series should have bars by putting it in the
  567. global options, or override it for individual series by specifying
  568. bars in a particular the series object in the array of data.
  569.  
  570. The most important options are "lines", "points" and "bars" that
  571. specify whether and how lines, points and bars should be shown for
  572. each data series. In case you don't specify anything at all, Flot will
  573. default to showing lines (you can turn this off with
  574. lines: { show: false }). You can specify the various types
  575. independently of each other, and Flot will happily draw each of them
  576. in turn (this is probably only useful for lines and points), e.g.
  577.  
  578.   var options = {
  579.     series: {
  580.       lines: { show: true, fill: true, fillColor: "rgba(255, 255, 255, 0.8)" },
  581.       points: { show: true, fill: false }
  582.     }
  583.   };
  584.  
  585. "lineWidth" is the thickness of the line or outline in pixels. You can
  586. set it to 0 to prevent a line or outline from being drawn; this will
  587. also hide the shadow.
  588.  
  589. "fill" is whether the shape should be filled. For lines, this produces
  590. area graphs. You can use "fillColor" to specify the color of the fill.
  591. If "fillColor" evaluates to false (default for everything except
  592. points which are filled with white), the fill color is auto-set to the
  593. color of the data series. You can adjust the opacity of the fill by
  594. setting fill to a number between 0 (fully transparent) and 1 (fully
  595. opaque).
  596.  
  597. For bars, fillColor can be a gradient, see the gradient documentation
  598. below. "barWidth" is the width of the bars in units of the x axis (or
  599. the y axis if "horizontal" is true), contrary to most other measures
  600. that are specified in pixels. For instance, for time series the unit
  601. is milliseconds so 24 * 60 * 60 * 1000 produces bars with the width of
  602. a day. "align" specifies whether a bar should be left-aligned
  603. (default) or centered on top of the value it represents. When
  604. "horizontal" is on, the bars are drawn horizontally, i.e. from the y
  605. axis instead of the x axis; note that the bar end points are still
  606. defined in the same way so you'll probably want to swap the
  607. coordinates if you've been plotting vertical bars first.
  608.  
  609. For lines, "steps" specifies whether two adjacent data points are
  610. connected with a straight (possibly diagonal) line or with first a
  611. horizontal and then a vertical line. Note that this transforms the
  612. data by adding extra points.
  613.  
  614. For points, you can specify the radius and the symbol. The only
  615. built-in symbol type is circles, for other types you can use a plugin
  616. or define them yourself by specifying a callback:
  617.  
  618.   function cross(ctx, x, y, radius, shadow) {
  619.       var size = radius * Math.sqrt(Math.PI) / 2;
  620.       ctx.moveTo(x - size, y - size);
  621.       ctx.lineTo(x + size, y + size);
  622.       ctx.moveTo(x - size, y + size);
  623.       ctx.lineTo(x + size, y - size);
  624.   }
  625.  
  626. The parameters are the drawing context, x and y coordinates of the
  627. center of the point, a radius which corresponds to what the circle
  628. would have used and whether the call is to draw a shadow (due to
  629. limited canvas support, shadows are currently faked through extra
  630. draws). It's good practice to ensure that the area covered by the
  631. symbol is the same as for the circle with the given radius, this
  632. ensures that all symbols have approximately the same visual weight.
  633.  
  634. "shadowSize" is the default size of shadows in pixels. Set it to 0 to
  635. remove shadows.
  636.  
  637. The "colors" array specifies a default color theme to get colors for
  638. the data series from. You can specify as many colors as you like, like
  639. this:
  640.  
  641.   colors: ["#d18b2c", "#dba255", "#919733"]
  642.  
  643. If there are more data series than colors, Flot will try to generate
  644. extra colors by lightening and darkening colors in the theme.
  645.  
  646.  
  647. Customizing the grid
  648. ====================
  649.  
  650.   grid: {
  651.     show: boolean
  652.     aboveData: boolean
  653.     color: color
  654.     backgroundColor: color/gradient or null
  655.     labelMargin: number
  656.     axisMargin: number
  657.     markings: array of markings or (fn: axes -> array of markings)
  658.     borderWidth: number
  659.     borderColor: color or null
  660.     minBorderMargin: number or null
  661.     clickable: boolean
  662.     hoverable: boolean
  663.     autoHighlight: boolean
  664.     mouseActiveRadius: number
  665.   }
  666.  
  667. The grid is the thing with the axes and a number of ticks. Many of the
  668. things in the grid are configured under the individual axes, but not
  669. all. "color" is the color of the grid itself whereas "backgroundColor"
  670. specifies the background color inside the grid area, here null means
  671. that the background is transparent. You can also set a gradient, see
  672. the gradient documentation below.
  673.  
  674. You can turn off the whole grid including tick labels by setting
  675. "show" to false. "aboveData" determines whether the grid is drawn
  676. above the data or below (below is default).
  677.  
  678. "labelMargin" is the space in pixels between tick labels and axis
  679. line, and "axisMargin" is the space in pixels between axes when there
  680. are two next to each other. Note that you can style the tick labels
  681. with CSS, e.g. to change the color. They have class "tickLabel".
  682.  
  683. "borderWidth" is the width of the border around the plot. Set it to 0
  684. to disable the border. You can also set "borderColor" if you want the
  685. border to have a different color than the grid lines.
  686. "minBorderMargin" controls the default minimum margin around the
  687. border - it's used to make sure that points aren't accidentally
  688. clipped by the canvas edge so by default the value is computed from
  689. the point radius.
  690.  
  691. "markings" is used to draw simple lines and rectangular areas in the
  692. background of the plot. You can either specify an array of ranges on
  693. the form { xaxis: { from, to }, yaxis: { from, to } } (with multiple
  694. axes, you can specify coordinates for other axes instead, e.g. as
  695. x2axis/x3axis/...) or with a function that returns such an array given
  696. the axes for the plot in an object as the first parameter.
  697.  
  698. You can set the color of markings by specifying "color" in the ranges
  699. object. Here's an example array:
  700.  
  701.   markings: [ { xaxis: { from: 0, to: 2 }, yaxis: { from: 10, to: 10 }, color: "#bb0000" }, ... ]
  702.  
  703. If you leave out one of the values, that value is assumed to go to the
  704. border of the plot. So for example if you only specify { xaxis: {
  705. from: 0, to: 2 } } it means an area that extends from the top to the
  706. bottom of the plot in the x range 0-2.
  707.  
  708. A line is drawn if from and to are the same, e.g.
  709.  
  710.   markings: [ { yaxis: { from: 1, to: 1 } }, ... ]
  711.  
  712. would draw a line parallel to the x axis at y = 1. You can control the
  713. line width with "lineWidth" in the range object.
  714.  
  715. An example function that makes vertical stripes might look like this:
  716.  
  717.   markings: function (axes) {
  718.     var markings = [];
  719.     for (var x = Math.floor(axes.xaxis.min); x < axes.xaxis.max; x += 2)
  720.       markings.push({ xaxis: { from: x, to: x + 1 } });
  721.     return markings;
  722.   }
  723.  
  724.  
  725. If you set "clickable" to true, the plot will listen for click events
  726. on the plot area and fire a "plotclick" event on the placeholder with
  727. a position and a nearby data item object as parameters. The coordinates
  728. are available both in the unit of the axes (not in pixels) and in
  729. global screen coordinates.
  730.  
  731. Likewise, if you set "hoverable" to true, the plot will listen for
  732. mouse move events on the plot area and fire a "plothover" event with
  733. the same parameters as the "plotclick" event. If "autoHighlight" is
  734. true (the default), nearby data items are highlighted automatically.
  735. If needed, you can disable highlighting and control it yourself with
  736. the highlight/unhighlight plot methods described elsewhere.
  737.  
  738. You can use "plotclick" and "plothover" events like this:
  739.  
  740.     $.plot($("#placeholder"), [ d ], { grid: { clickable: true } });
  741.  
  742.     $("#placeholder").bind("plotclick", function (event, pos, item) {
  743.         alert("You clicked at " + pos.x + ", " + pos.y);
  744.         // axis coordinates for other axes, if present, are in pos.x2, pos.x3, ...
  745.         // if you need global screen coordinates, they are pos.pageX, pos.pageY
  746.  
  747.         if (item) {
  748.           highlight(item.series, item.datapoint);
  749.           alert("You clicked a point!");
  750.         }
  751.     });
  752.  
  753. The item object in this example is either null or a nearby object on the form:
  754.  
  755.   item: {
  756.       datapoint: the point, e.g. [0, 2]
  757.       dataIndex: the index of the point in the data array
  758.       series: the series object
  759.       seriesIndex: the index of the series
  760.       pageX, pageY: the global screen coordinates of the point
  761.   }
  762.  
  763. For instance, if you have specified the data like this
  764.  
  765.     $.plot($("#placeholder"), [ { label: "Foo", data: [[0, 10], [7, 3]] } ], ...);
  766.  
  767. and the mouse is near the point (7, 3), "datapoint" is [7, 3],
  768. "dataIndex" will be 1, "series" is a normalized series object with
  769. among other things the "Foo" label in series.label and the color in
  770. series.color, and "seriesIndex" is 0. Note that plugins and options
  771. that transform the data can shift the indexes from what you specified
  772. in the original data array.
  773.  
  774. If you use the above events to update some other information and want
  775. to clear out that info in case the mouse goes away, you'll probably
  776. also need to listen to "mouseout" events on the placeholder div.
  777.  
  778. "mouseActiveRadius" specifies how far the mouse can be from an item
  779. and still activate it. If there are two or more points within this
  780. radius, Flot chooses the closest item. For bars, the top-most bar
  781. (from the latest specified data series) is chosen.
  782.  
  783. If you want to disable interactivity for a specific data series, you
  784. can set "hoverable" and "clickable" to false in the options for that
  785. series, like this { data: [...], label: "Foo", clickable: false }.
  786.  
  787.  
  788. Specifying gradients
  789. ====================
  790.  
  791. A gradient is specified like this:
  792.  
  793.   { colors: [ color1, color2, ... ] }
  794.  
  795. For instance, you might specify a background on the grid going from
  796. black to gray like this:
  797.  
  798.   grid: {
  799.     backgroundColor: { colors: ["#000", "#999"] }
  800.   }
  801.  
  802. For the series you can specify the gradient as an object that
  803. specifies the scaling of the brightness and the opacity of the series
  804. color, e.g.
  805.  
  806.   { colors: [{ opacity: 0.8 }, { brightness: 0.6, opacity: 0.8 } ] }
  807.  
  808. where the first color simply has its alpha scaled, whereas the second
  809. is also darkened. For instance, for bars the following makes the bars
  810. gradually disappear, without outline:
  811.  
  812.   bars: {
  813.       show: true,
  814.       lineWidth: 0,
  815.       fill: true,
  816.       fillColor: { colors: [ { opacity: 0.8 }, { opacity: 0.1 } ] }
  817.   }
  818.  
  819. Flot currently only supports vertical gradients drawn from top to
  820. bottom because that's what works with IE.
  821.  
  822.  
  823. Plot Methods
  824. ------------
  825.  
  826. The Plot object returned from the plot function has some methods you
  827. can call:
  828.  
  829.   - highlight(series, datapoint)
  830.  
  831.     Highlight a specific datapoint in the data series. You can either
  832.     specify the actual objects, e.g. if you got them from a
  833.     "plotclick" event, or you can specify the indices, e.g.
  834.     highlight(1, 3) to highlight the fourth point in the second series
  835.     (remember, zero-based indexing).
  836.  
  837.  
  838.   - unhighlight(series, datapoint) or unhighlight()
  839.  
  840.     Remove the highlighting of the point, same parameters as
  841.     highlight.
  842.  
  843.     If you call unhighlight with no parameters, e.g. as
  844.     plot.unhighlight(), all current highlights are removed.
  845.  
  846.  
  847.   - setData(data)
  848.  
  849.     You can use this to reset the data used. Note that axis scaling,
  850.     ticks, legend etc. will not be recomputed (use setupGrid() to do
  851.     that). You'll probably want to call draw() afterwards.
  852.  
  853.     You can use this function to speed up redrawing a small plot if
  854.     you know that the axes won't change. Put in the new data with
  855.     setData(newdata), call draw(), and you're good to go. Note that
  856.     for large datasets, almost all the time is consumed in draw()
  857.     plotting the data so in this case don't bother.
  858.  
  859.    
  860.   - setupGrid()
  861.  
  862.     Recalculate and set axis scaling, ticks, legend etc.
  863.  
  864.     Note that because of the drawing model of the canvas, this
  865.     function will immediately redraw (actually reinsert in the DOM)
  866.     the labels and the legend, but not the actual tick lines because
  867.     they're drawn on the canvas. You need to call draw() to get the
  868.     canvas redrawn.
  869.    
  870.   - draw()
  871.  
  872.     Redraws the plot canvas.
  873.  
  874.   - triggerRedrawOverlay()
  875.  
  876.     Schedules an update of an overlay canvas used for drawing
  877.     interactive things like a selection and point highlights. This
  878.     is mostly useful for writing plugins. The redraw doesn't happen
  879.     immediately, instead a timer is set to catch multiple successive
  880.     redraws (e.g. from a mousemove). You can get to the overlay by
  881.     setting up a drawOverlay hook.
  882.  
  883.   - width()/height()
  884.  
  885.     Gets the width and height of the plotting area inside the grid.
  886.     This is smaller than the canvas or placeholder dimensions as some
  887.     extra space is needed (e.g. for labels).
  888.  
  889.   - offset()
  890.  
  891.     Returns the offset of the plotting area inside the grid relative
  892.     to the document, useful for instance for calculating mouse
  893.     positions (event.pageX/Y minus this offset is the pixel position
  894.     inside the plot).
  895.  
  896.   - pointOffset({ x: xpos, y: ypos })
  897.  
  898.     Returns the calculated offset of the data point at (x, y) in data
  899.     space within the placeholder div. If you are working with multiple axes, you
  900.     can specify the x and y axis references, e.g.
  901.  
  902.       o = pointOffset({ x: xpos, y: ypos, xaxis: 2, yaxis: 3 })
  903.       // o.left and o.top now contains the offset within the div
  904.  
  905.   - resize()
  906.  
  907.     Tells Flot to resize the drawing canvas to the size of the
  908.     placeholder. You need to run setupGrid() and draw() afterwards as
  909.     canvas resizing is a destructive operation. This is used
  910.     internally by the resize plugin.
  911.  
  912.   - shutdown()
  913.  
  914.     Cleans up any event handlers Flot has currently registered. This
  915.     is used internally.
  916.  
  917.  
  918. There are also some members that let you peek inside the internal
  919. workings of Flot which is useful in some cases. Note that if you change
  920. something in the objects returned, you're changing the objects used by
  921. Flot to keep track of its state, so be careful.
  922.  
  923.   - getData()
  924.  
  925.     Returns an array of the data series currently used in normalized
  926.     form with missing settings filled in according to the global
  927.     options. So for instance to find out what color Flot has assigned
  928.     to the data series, you could do this:
  929.  
  930.       var series = plot.getData();
  931.       for (var i = 0; i < series.length; ++i)
  932.         alert(series[i].color);
  933.  
  934.     A notable other interesting field besides color is datapoints
  935.     which has a field "points" with the normalized data points in a
  936.     flat array (the field "pointsize" is the increment in the flat
  937.     array to get to the next point so for a dataset consisting only of
  938.     (x,y) pairs it would be 2).
  939.  
  940.   - getAxes()
  941.  
  942.     Gets an object with the axes. The axes are returned as the
  943.     attributes of the object, so for instance getAxes().xaxis is the
  944.     x axis.
  945.  
  946.     Various things are stuffed inside an axis object, e.g. you could
  947.     use getAxes().xaxis.ticks to find out what the ticks are for the
  948.     xaxis. Two other useful attributes are p2c and c2p, functions for
  949.     transforming from data point space to the canvas plot space and
  950.     back. Both returns values that are offset with the plot offset.
  951.     Check the Flot source code for the complete set of attributes (or
  952.     output an axis with console.log() and inspect it).
  953.  
  954.     With multiple axes, the extra axes are returned as x2axis, x3axis,
  955.     etc., e.g. getAxes().y2axis is the second y axis. You can check
  956.     y2axis.used to see whether the axis is associated with any data
  957.     points and y2axis.show to see if it is currently shown.
  958.  
  959.   - getPlaceholder()
  960.  
  961.     Returns placeholder that the plot was put into. This can be useful
  962.     for plugins for adding DOM elements or firing events.
  963.  
  964.   - getCanvas()
  965.  
  966.     Returns the canvas used for drawing in case you need to hack on it
  967.     yourself. You'll probably need to get the plot offset too.
  968.  
  969.   - getPlotOffset()
  970.  
  971.     Gets the offset that the grid has within the canvas as an object
  972.     with distances from the canvas edges as "left", "right", "top",
  973.     "bottom". I.e., if you draw a circle on the canvas with the center
  974.     placed at (left, top), its center will be at the top-most, left
  975.     corner of the grid.
  976.  
  977.   - getOptions()
  978.  
  979.     Gets the options for the plot, normalized, with default values
  980.     filled in. You get a reference to actual values used by Flot, so
  981.     if you modify the values in here, Flot will use the new values.
  982.     If you change something, you probably have to call draw() or
  983.     setupGrid() or triggerRedrawOverlay() to see the change.
  984.    
  985.  
  986. Hooks
  987. =====
  988.  
  989. In addition to the public methods, the Plot object also has some hooks
  990. that can be used to modify the plotting process. You can install a
  991. callback function at various points in the process, the function then
  992. gets access to the internal data structures in Flot.
  993.  
  994. Here's an overview of the phases Flot goes through:
  995.  
  996.   1. Plugin initialization, parsing options
  997.  
  998.   2. Constructing the canvases used for drawing
  999.  
  1000.   3. Set data: parsing data specification, calculating colors,
  1001.      copying raw data points into internal format,
  1002.      normalizing them, finding max/min for axis auto-scaling
  1003.  
  1004.   4. Grid setup: calculating axis spacing, ticks, inserting tick
  1005.      labels, the legend
  1006.  
  1007.   5. Draw: drawing the grid, drawing each of the series in turn
  1008.  
  1009.   6. Setting up event handling for interactive features
  1010.  
  1011.   7. Responding to events, if any
  1012.  
  1013.   8. Shutdown: this mostly happens in case a plot is overwritten
  1014.  
  1015. Each hook is simply a function which is put in the appropriate array.
  1016. You can add them through the "hooks" option, and they are also available
  1017. after the plot is constructed as the "hooks" attribute on the returned
  1018. plot object, e.g.
  1019.  
  1020.   // define a simple draw hook
  1021.   function hellohook(plot, canvascontext) { alert("hello!"); };
  1022.  
  1023.   // pass it in, in an array since we might want to specify several
  1024.   var plot = $.plot(placeholder, data, { hooks: { draw: [hellohook] } });
  1025.  
  1026.   // we can now find it again in plot.hooks.draw[0] unless a plugin
  1027.   // has added other hooks
  1028.  
  1029. The available hooks are described below. All hook callbacks get the
  1030. plot object as first parameter. You can find some examples of defined
  1031. hooks in the plugins bundled with Flot.
  1032.  
  1033.  - processOptions  [phase 1]
  1034.  
  1035.    function(plot, options)
  1036.    
  1037.    Called after Flot has parsed and merged options. Useful in the
  1038.    instance where customizations beyond simple merging of default
  1039.    values is needed. A plugin might use it to detect that it has been
  1040.    enabled and then turn on or off other options.
  1041.  
  1042.  
  1043.  - processRawData  [phase 3]
  1044.  
  1045.    function(plot, series, data, datapoints)
  1046.  
  1047.    Called before Flot copies and normalizes the raw data for the given
  1048.    series. If the function fills in datapoints.points with normalized
  1049.    points and sets datapoints.pointsize to the size of the points,
  1050.    Flot will skip the copying/normalization step for this series.
  1051.    
  1052.    In any case, you might be interested in setting datapoints.format,
  1053.    an array of objects for specifying how a point is normalized and
  1054.    how it interferes with axis scaling.
  1055.  
  1056.    The default format array for points is something along the lines of:
  1057.  
  1058.      [
  1059.        { x: true, number: true, required: true },
  1060.        { y: true, number: true, required: true }
  1061.      ]
  1062.  
  1063.    The first object means that for the first coordinate it should be
  1064.    taken into account when scaling the x axis, that it must be a
  1065.    number, and that it is required - so if it is null or cannot be
  1066.    converted to a number, the whole point will be zeroed out with
  1067.    nulls. Beyond these you can also specify "defaultValue", a value to
  1068.    use if the coordinate is null. This is for instance handy for bars
  1069.    where one can omit the third coordinate (the bottom of the bar)
  1070.    which then defaults to 0.
  1071.  
  1072.  
  1073.  - processDatapoints  [phase 3]
  1074.  
  1075.    function(plot, series, datapoints)
  1076.  
  1077.    Called after normalization of the given series but before finding
  1078.    min/max of the data points. This hook is useful for implementing data
  1079.    transformations. "datapoints" contains the normalized data points in
  1080.    a flat array as datapoints.points with the size of a single point
  1081.    given in datapoints.pointsize. Here's a simple transform that
  1082.    multiplies all y coordinates by 2:
  1083.  
  1084.      function multiply(plot, series, datapoints) {
  1085.          var points = datapoints.points, ps = datapoints.pointsize;
  1086.          for (var i = 0; i < points.length; i += ps)
  1087.              points[i + 1] *= 2;
  1088.      }
  1089.  
  1090.    Note that you must leave datapoints in a good condition as Flot
  1091.    doesn't check it or do any normalization on it afterwards.
  1092.  
  1093.  
  1094.  - drawSeries  [phase 5]
  1095.  
  1096.    function(plot, canvascontext, series)
  1097.  
  1098.    Hook for custom drawing of a single series. Called just before the
  1099.    standard drawing routine has been called in the loop that draws
  1100.    each series.
  1101.    
  1102.  
  1103.  - draw  [phase 5]
  1104.  
  1105.    function(plot, canvascontext)
  1106.  
  1107.    Hook for drawing on the canvas. Called after the grid is drawn
  1108.    (unless it's disabled or grid.aboveData is set) and the series have
  1109.    been plotted (in case any points, lines or bars have been turned
  1110.    on). For examples of how to draw things, look at the source code.
  1111.    
  1112.  
  1113.  - bindEvents  [phase 6]
  1114.  
  1115.    function(plot, eventHolder)
  1116.  
  1117.    Called after Flot has setup its event handlers. Should set any
  1118.    necessary event handlers on eventHolder, a jQuery object with the
  1119.    canvas, e.g.
  1120.  
  1121.      function (plot, eventHolder) {
  1122.          eventHolder.mousedown(function (e) {
  1123.              alert("You pressed the mouse at " + e.pageX + " " + e.pageY);
  1124.          });
  1125.      }
  1126.  
  1127.    Interesting events include click, mousemove, mouseup/down. You can
  1128.    use all jQuery events. Usually, the event handlers will update the
  1129.    state by drawing something (add a drawOverlay hook and call
  1130.    triggerRedrawOverlay) or firing an externally visible event for
  1131.    user code. See the crosshair plugin for an example.
  1132.      
  1133.    Currently, eventHolder actually contains both the static canvas
  1134.    used for the plot itself and the overlay canvas used for
  1135.    interactive features because some versions of IE get the stacking
  1136.    order wrong. The hook only gets one event, though (either for the
  1137.    overlay or for the static canvas).
  1138.  
  1139.    Note that custom plot events generated by Flot are not generated on
  1140.    eventHolder, but on the div placeholder supplied as the first
  1141.    argument to the plot call. You can get that with
  1142.    plot.getPlaceholder() - that's probably also the one you should use
  1143.    if you need to fire a custom event.
  1144.  
  1145.  
  1146.  - drawOverlay  [phase 7]
  1147.  
  1148.    function (plot, canvascontext)
  1149.  
  1150.    The drawOverlay hook is used for interactive things that need a
  1151.    canvas to draw on. The model currently used by Flot works the way
  1152.    that an extra overlay canvas is positioned on top of the static
  1153.    canvas. This overlay is cleared and then completely redrawn
  1154.    whenever something interesting happens. This hook is called when
  1155.    the overlay canvas is to be redrawn.
  1156.  
  1157.    "canvascontext" is the 2D context of the overlay canvas. You can
  1158.    use this to draw things. You'll most likely need some of the
  1159.    metrics computed by Flot, e.g. plot.width()/plot.height(). See the
  1160.    crosshair plugin for an example.
  1161.  
  1162.  
  1163.  - shutdown  [phase 8]
  1164.  
  1165.    function (plot, eventHolder)
  1166.  
  1167.    Run when plot.shutdown() is called, which usually only happens in
  1168.    case a plot is overwritten by a new plot. If you're writing a
  1169.    plugin that adds extra DOM elements or event handlers, you should
  1170.    add a callback to clean up after you. Take a look at the section in
  1171.    PLUGINS.txt for more info.
  1172.  
  1173.    
  1174. Plugins
  1175. -------
  1176.  
  1177. Plugins extend the functionality of Flot. To use a plugin, simply
  1178. include its Javascript file after Flot in the HTML page.
  1179.  
  1180. If you're worried about download size/latency, you can concatenate all
  1181. the plugins you use, and Flot itself for that matter, into one big file
  1182. (make sure you get the order right), then optionally run it through a
  1183. Javascript minifier such as YUI Compressor.
  1184.  
  1185. Here's a brief explanation of how the plugin plumbings work:
  1186.  
  1187. Each plugin registers itself in the global array $.plot.plugins. When
  1188. you make a new plot object with $.plot, Flot goes through this array
  1189. calling the "init" function of each plugin and merging default options
  1190. from the "option" attribute of the plugin. The init function gets a
  1191. reference to the plot object created and uses this to register hooks
  1192. and add new public methods if needed.
  1193.  
  1194. See the PLUGINS.txt file for details on how to write a plugin. As the
  1195. above description hints, it's actually pretty easy.
  1196.  
  1197.  
  1198. Version number
  1199. --------------
  1200.  
  1201. The version number of Flot is available in $.plot.version.

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