Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP

Fetching latest commit…

Cannot retrieve the latest commit at this time

..
Failed to load latest commit information.
README
annotations.js
axes.js
base.js
chart-labels.js
grid.js
install.js
legend.js

README

dygraphs plugins
----------------

A single dygraph is actually a collection of dygraphs plugins, each responsible
for some portion of the chart: the plot area, the axes, the legend, the labels,
etc.

This forces the dygraphs code to be more modular and encourages better APIs.

The "legend" plugin (plugins/legend.js) can be used as a template for new
plugins.

Here is a simplified version of it, with comments to explain the plugin
lifecycle and APIs:

----------------

// (standard JavaScript library wrapper; prevents polluting global namespace)
Dygraph.Plugins.Legend = (function() {

// Plugin constructor. This is invoked once for every chart which uses the
// plugin. You can't actually access the Dygraph object at this point, so the
// initialization you do here shouldn't be chart-specific. (For that, use
// the activate() method).
var legend = function() {
  this.div_ = null;
};

// Plugins are expected to implement this method for debugging purposes.
legend.toString = function() {
  return "Legend";
};

// This is called once the dygraph is ready. The chart data may not be
// available yet, but the options specified in the constructor are.
// 
// Proper tasks to do here include:
// - Reading your own options
// - DOM manipulation
// - Registering event listeners
//
// "dygraph" is the Dygraph object for which this instance is being activated.
// "registerer" allows you to register event listeners.
legend.prototype.activate = function(dygraph, registerer) {
  // Create the legend div and attach it to the chart DOM.
  this.div_ = document.createElement("div");
  dygraph.graphDiv.appendChild(this.div_);

  // Add event listeners. These will be called whenever points are selected
  // (i.e. you hover over them) or deselected (i.e. you mouse away from the
  // chart). This is your only chance to register event listeners! Once this
  // method returns, the gig is up.
  registerer.addEventListener('select', legend.select);
  registerer.addEventListener('deselect', legend.deselect);
};

// The functions called by event listeners all take a single parameter, an
// event object. This contains properties relevant to the particular event, but
// you can always assume that it has:
//
// 1. A "dygraph" parameter which is a reference to the chart on which the
//    event took place.
// 2. A "stopPropagation" method, which you can call to prevent the event from
//    being seen by any other plugins after you. This effectively cancels the
//    event.
// 3. A "preventDefault" method, which prevents dygraphs from performing the
//    default action associated with this event.
//
legend.select = function(e) {
  // These are two of the properties specific to the "select" event object:
  var xValue = e.selectedX;
  var points = e.selectedPoints;

  var html = xValue + ':';
  for (var i = 0; i < points.length; i++) {
    var point = points[i];
    html += ' ' + point.name + ':' + point.yval;
  }

  // In an event listener, "this" refers to your plugin object.
  this.div_.innerHTML = html;
};

// This clears out the legend when the user mouses away from the chart.
legend.deselect = function(e) {
  this.div_.innerHTML = '';
};

return legend;
})();

----------------

Plugin Events Reference:

- predraw
- clearChart
- drawChart
- select
- deselect

TODO(danvk): document all event properties for each event.


Special methods:
- (constructor)
- activate
- destroy


----------------

Notes on plugin registration and event cascade ordering/behavior.
Something went wrong with that request. Please try again.