mirror of
https://github.com/dawidolko/Website-Templates.git
synced 2025-10-31 00:13:11 +01:00
144 lines
4.2 KiB
Markdown
144 lines
4.2 KiB
Markdown
## 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.
|