[udig-devel] 3/2 How to render onto an Image using a Map

[Vince Darley]

At 18:17 24/10/2007, Jody Garnett wrote:
 >>>
Have a look at the PNG export; or PDF export community modules in 
Jesse's section of svn. Also the map print functionality does this 
sort of work in order to render the Map onto an image for the "Box" 
you can layout on the page.  Map is "just" a data structure so you 
will find some of these examples going about the rendering process 
with different assumptions (say speed vs. quality).
 >>>

Thanks - I've taken a look at that.  It does look like a good basis 
and certainly helps to make everything a lot clearer, so we'll try to 
work from there.

I've noticed 2 small glitches, for the record:

1) In uDig maps in general, road name labels are drawn on top of the 
'Legend' on the map, even when the legend is the topmost 
layer.  (Everything else is drawn underneath the legend).

2) When exporting (I've tried PDF and PNG) with the export module, no 
labels of any kind are in the exported image.  (But the text in the 
legend and scale shows up nicely).

>If we have done our job right this should only result in a different 
>set of Renderers being selected render the layers of the map. As an 
>example - it may be wise to use WMS when drawing to screen (fast!); 
>but to switch to WFS when drawing to the printer (high resolution).

Sounds interesting -- I haven't got far enough into the code yet to 
see that yet.  I notice that the community plugin has 2 extra 
arguments for ApplicationGIS.drawMap -- 'scaleDenom' and '72', which 
I assume are something to do with dpi/resolution (these arguments 
don't feature in RC12)

regards,

Vince.