From 680241cbb652ee29088baa6cde2da02002e5ec47 Mon Sep 17 00:00:00 2001
From: Igor Sfiligoi <isfiligoi@ucsd.edu>
Date: Thu, 7 Nov 2013 12:50:35 -0500
Subject: flot-0.8.1-tooltip-0.6.2

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 PLUGINS.md | 143 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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+## Writing plugins ##
+
+All you need to do to make a new plugin is creating an init function
+and a set of options (if needed), stuffing it into an object and
+putting it in the $.plot.plugins array. For example:
+
+```js
+function myCoolPluginInit(plot) {
+    plot.coolstring = "Hello!";
+};
+
+$.plot.plugins.push({ init: myCoolPluginInit, options: { ... } });
+
+// if $.plot is called, it will return a plot object with the
+// attribute "coolstring"
+```
+
+Now, given that the plugin might run in many different places, it's
+a good idea to avoid leaking names. The usual trick here is wrap the
+above lines in an anonymous function which is called immediately, like
+this: (function () { inner code ... })(). To make it even more robust
+in case $ is not bound to jQuery but some other Javascript library, we
+can write it as
+
+```js
+(function ($) {
+    // plugin definition
+    // ...
+})(jQuery);
+```
+
+There's a complete example below, but you should also check out the
+plugins bundled with Flot.
+
+
+## Complete example ##
+  
+Here is a simple debug plugin which alerts each of the series in the
+plot. It has a single option that control whether it is enabled and
+how much info to output:
+
+```js
+(function ($) {
+    function init(plot) {
+        var debugLevel = 1;
+
+        function checkDebugEnabled(plot, options) {
+            if (options.debug) {
+                debugLevel = options.debug;
+                plot.hooks.processDatapoints.push(alertSeries);
+            }
+        }
+
+        function alertSeries(plot, series, datapoints) {
+            var msg = "series " + series.label;
+            if (debugLevel > 1) {
+                msg += " with " + series.data.length + " points";
+                alert(msg);
+            }
+        }
+
+        plot.hooks.processOptions.push(checkDebugEnabled);
+    }
+
+    var options = { debug: 0 };
+      
+    $.plot.plugins.push({
+        init: init,
+        options: options,
+        name: "simpledebug",
+        version: "0.1"
+    });
+})(jQuery);
+```
+
+We also define "name" and "version". It's not used by Flot, but might
+be helpful for other plugins in resolving dependencies.
+  
+Put the above in a file named "jquery.flot.debug.js", include it in an
+HTML page and then it can be used with:
+
+```js
+    $.plot($("#placeholder"), [...], { debug: 2 });
+```
+
+This simple plugin illustrates a couple of points:
+
+ - It uses the anonymous function trick to avoid name pollution.
+ - It can be enabled/disabled through an option.
+ - Variables in the init function can be used to store plot-specific
+   state between the hooks.
+
+The two last points are important because there may be multiple plots
+on the same page, and you'd want to make sure they are not mixed up.
+
+
+## Shutting down a plugin ##
+
+Each plot object has a shutdown hook which is run when plot.shutdown()
+is called. This usually mostly happens in case another plot is made on
+top of an existing one.
+
+The purpose of the hook is to give you a chance to unbind any event
+handlers you've registered and remove any extra DOM things you've
+inserted.
+
+The problem with event handlers is that you can have registered a
+handler which is run in some point in the future, e.g. with
+setTimeout(). Meanwhile, the plot may have been shutdown and removed,
+but because your event handler is still referencing it, it can't be
+garbage collected yet, and worse, if your handler eventually runs, it
+may overwrite stuff on a completely different plot.
+
+ 
+## Some hints on the options ##
+   
+Plugins should always support appropriate options to enable/disable
+them because the plugin user may have several plots on the same page
+where only one should use the plugin. In most cases it's probably a
+good idea if the plugin is turned off rather than on per default, just
+like most of the powerful features in Flot.
+
+If the plugin needs options that are specific to each series, like the
+points or lines options in core Flot, you can put them in "series" in
+the options object, e.g.
+
+```js
+var options = {
+    series: {
+        downsample: {
+            algorithm: null,
+            maxpoints: 1000
+        }
+    }
+}
+```
+
+Then they will be copied by Flot into each series, providing default
+values in case none are specified.
+
+Think hard and long about naming the options. These names are going to
+be public API, and code is going to depend on them if the plugin is
+successful.
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