EPSIAE » eneraptor

Frequently asked questions

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Q: How much data can Flot cope with?

A: Flot will happily draw everything you send to it so the answer

depends on the browser. The excanvas emulation used for IE (built with

VML) makes IE by far the slowest browser so be sure to test with that

if IE users are in your target group.

1000 points is not a problem, but as soon as you start having more

points than the pixel width, you should probably start thinking about

downsampling/aggregation as this is near the resolution limit of the

chart anyway. If you downsample server-side, you also save bandwidth.

Q: Flot isn't working when I'm using JSON data as source!

A: Actually, Flot loves JSON data, you just got the format wrong.

Double check that you're not inputting strings instead of numbers,

like [["0", "-2.13"], ["5", "4.3"]]. This is most common mistake, and

the error might not show up immediately because Javascript can do some

conversion automatically.

Q: Can I export the graph?

A: This is a limitation of the canvas technology. There's a hook in

the canvas object for getting an image out, but you won't get the tick

labels. And it's not likely to be supported by IE. At this point, your

best bet is probably taking a screenshot, e.g. with PrtScn.

Q: The bars are all tiny in time mode?

A: It's not really possible to determine the bar width automatically.

So you have to set the width with the barWidth option which is NOT in

pixels, but in the units of the x axis (or the y axis for horizontal

bars). For time mode that's milliseconds so the default value of 1

makes the bars 1 millisecond wide.

Q: Can I use Flot with libraries like Mootools or Prototype?

A: Yes, Flot supports it out of the box and it's easy! Just use jQuery

instead of $, e.g. call jQuery.plot instead of $.plot and use

jQuery(something) instead of $(something). As a convenience, you can

put in a DOM element for the graph placeholder where the examples and

the API documentation are using jQuery objects.

Depending on how you include jQuery, you may have to add one line of

code to prevent jQuery from overwriting functions from the other

libraries, see the documentation in jQuery ("Using jQuery with other

libraries") for details.

Q: Flot doesn't work with [widget framework xyz]!

A: The problem is most likely within the framework, or your use of the

framework.

The only non-standard thing used by Flot is the canvas tag; otherwise

it is simply a series of absolute positioned divs within the

placeholder tag you put in. If this is not working, it's probably

because the framework you're using is doing something weird with the

DOM. As a last resort, you might try replotting and see if it helps.

If you find there's a specific thing we can do to Flot to help, feel

free to submit a bug report. Otherwise, you're welcome to ask for help

on the mailing list, but please don't submit a bug report to Flot -

try the framework instead.