[Mapserver-dev] Re: 3.7 and native image rendering support

Chris G. Nicholas cgn at globexplorer.com
Fri Feb 7 17:43:06 EST 2003

It would be nice to keep the "native" .png support, with perhaps some hook for external synchronization. (use O_EXCL flag on open perhaps?)  

For example, we at GlobeXplorer might want to dynamically generate a Mapfile on the fly and create a temporary /tmp/foo1234.png, where a thread would at least open that file with a lock, and fire off the back-end raster rendering in parallel with mapserver's main thread parsing the dynamic mapfile, which would turn around and try to open /tmp/foo1234.png, and hang until it was unlocked, etc.

just a thought...

Chris Nicholas

-----Original Message-----
From:	Sean Gillies [mailto:sgillies at frii.com]
Sent:	Fri 2/7/2003 2:34 PM
To:	Frank Warmerdam
Cc:	Steve Lime; Mapserver-dev at lists.gis.umn.edu
Subject:	Re: [Mapserver-dev] Re: 3.7 and native image rendering support
On Friday, February 7, 2003, at 03:01  PM, Frank Warmerdam wrote:

> Steve Lime wrote:
>> Frank: What would you think about loosing all native raster support 
>> in favor
>> of OGR? The only obstacle I see is the EPPL7 support but perhaps that 
>> could
>> be added to OGR. It's a pretty straight forward format I think. I'm 
>> just
>> thinking that simplifying the configuration options, not to mention 
>> the code
>> maintenance, is a good idea at this point.
> Steve,
> I think this makes sense from a maintenance point of view, but I am 
> concerned
> that it makes it impossible to built a light version of mapserver with
> raster input support.
> I am thinking we should move the EPPL7 format into GDAL and then blow 
> away
> all format support except for PNG and GIF done using GD (pseudocolored 
> only),
> with world files.  Furthermore I think we should only use these 
> drivers if
> GDAL is not enabled, and we would need to better clarify the 
> limitations
> of the non-GDAL drivers.
> In particular, I would like to get rid of the existing TIFF driver 
> which
> has some significant flaws, and often gets used instead of GDAL.
> I have cc:ed this to the developers list to see if anyone else has an
> opinion on the importance of a "light" option for MapServer.
> Best regards,

I think that the "light" option should also support JPEG through GD
so that users have an option for serving a large volume of compressed
RGB imagery.  Am with you on the TIFF driver.


Sean Gillies
sgillies at frii.com

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