[Phpmyadmin-devel] OpenGIS and Flot

[Madhura Jayaratne]

On Fri, May 20, 2011 at 2:43 PM, Michal Čihař <michal at cihar.com> wrote:

> Hi
>
> Dne Wed, 18 May 2011 18:01:15 +0530
> Madhura Jayaratne <madhura.cj at gmail.com> napsal(a):
>
> > I did it as a test run and it is not finalized. Unfortunately I can't get
> > flot to draw polygons with inner rings and that was a dead end for me. So
> > right now I'm looking into generating all the GIS visualizations with
> SVG.
> > In particular I am trying to generate them with jQuery-SVG.
> >
> > Well, I agree that flot makes the life very easy for developers and the
> > graphs are rich in quality. However you get less control over the plot.
> For
> > example with SVG, I can manipulate each elements in the plot, but in flot
> > that ability is limited to few events they have exposed. I'm not sure how
> > this applies in your case, you might not want to manipulate it at all.
>
> Okay, I think we should use as few graphing libraries as possible,
> ideally only one, but I'm not sure if it is possible. So let's summarize
> what every project needs and try to find viable solution.
>

What it needs to visualize GIS data is a library that lets you draw freely.
On the other hand a charting library would let you enter data for a set of
series and would draw various types of charts accordingly. When trying to
use a charting library to visualize GIS data (for the rich functionality
they offer), most of the time we would have to hack the library.

For example POINT, MULTIPOINT and LINESTRING can be drawn with scatter
charts and line charts. However to draw a MULTILINESTRING with two
LINESTRINGs you'll have to draw 2 series giving them the same series name
and same color, effectively hacking the library. The problem is with
legends, legend would show two entries. The case gets worse when it comes to
POLYGONS and MULTIPOLYGONS, worst when these have inner rings :(

Thats why I had to give up flot and settle for SVG, in particular jQuery
SVG, which gives control over what is being drawn. However now I have to
manage a number of features such as zooming, panning, tooltips with my own
code.

>
> I think for charts, it would be nice to save them, but that does not
> seem to work with neither flot nor jQuery-SVG.
>
>
It certainly is nice to let the user save the charts/visualizations. I found
[1] when looking for a solution. But I am yet to try that out.

-- 
Thanks and Regards,

Madhura Jayaratne

[1]
http://stackoverflow.com/questions/2483919/how-to-save-svg-canvas-to-local-filesystem
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