[mapguide-internals] OpenLayers + SVG = MapGuide Vector Viewer

[Martin Morrison]

XP and older versions of IE are going to be around a long time.  Some enterprises don't allow other browsers loaded.

Martin Morrison
Application Engineer
Engineering Design Systems, Inc.
3780 Peters Creek Rd Ext SW
Roanoke, VA  24018
540.345.1410
gis.edsi.com


-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Trevor Wekel
Sent: Wednesday, September 15, 2010 4:23 PM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] OpenLayers + SVG = MapGuide Vector Viewer

Hi Jason,

Yes. That is true.  IE9 requires a newer version of DirectX which will not be made available in XP.  For the XP user base, Firefox and Chrome may be alternatives.  Also, OpenLayers does support vector rendering in IE8 and earlier using VML.  However, the rendering performance is quite slow (10x or slower) compared to native SVG rendering.  From what I have seen, VML will not be able to display complex GIS scenes but may be usable for selection, highlighting, and redlining.  This means that portions of the interaction model could still be offloaded - just not the full scene draw.

We could configure "how much vector" we want to use based on the browser type.  That will be more complicated but should make a "vectorish" viewer possible for all platforms.


Excellent points!

Trevor


-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch
Sent: September 15, 2010 2:12 PM
To: MapGuide Internals Mail List
Subject: Re: [mapguide-internals] OpenLayers + SVG = MapGuide Vector Viewer

Though I also like SVG's future, the fact that Microsoft is limiting its support to IE9 (which will not be available for Windows XP) means that a large proportion of users will be unable to access the maps.  My analytics show XP users at about 45% for a certain local government site, just slightly less for my personal blog, and 30% for an unrelated hobby site with a lower percentage of government users.  Given that MS is committed to long term support for XP (to 2020 if I recall correctly) in the enterprise, I think its attrition rate will be relatively slow.

If we went ahead with something like this, then I'd want to see it done in a way that viewer infrastructure is shared, allowing integrators to easily publish a single map where browser support for SVG could be auto-detected and either automatically used, or present the user with a choice.

If I recall correctly, Traian had a pretty decent working prototype of an SVG-based map viewer that hit a JSON-based data interface on the back end.

Jason

On 15 September 2010 09:02, Trevor Wekel <trevor_wekel at otxsystems.com>wrote:

> Hi everyone,
>
> I have been thinking about our existing client technology.  Currently, 
> the AJAX and Fusion viewers hit the MapGuide Server for many user 
> interactions (pan, zoom, select, turning layers on/off, etc).  The 
> venerable MapGuide 6.5 ActiveX control was different.  It performed 
> client side rendering and would only request the data from the server 
> as required.  Processing was offloaded from the server and "old" 
> MapGuide was more responsive due to the reduced network traffic.
>
> When MapGuide Open Source was designed back in 2004, browser support 
> for SVG was not on the immediate horizon.  In fact, the first browser 
> to support SVG was Firefox 1.5, released on November 29, 2005.  
> According to various internet statistics, Firefox had 10% market share at the end of 2005.
>  Suffice it to say, SVG was not widely available.
>
> Fast forward to today.  Internet Explorer still dominates the market 
> with a 60% share.  Firefox, Chrome, and Safari make up another 35% and 
> they currently support SVG.  So SVG is sitting on the desktop of a 
> third of the internet community.  Internet Explorer 9 will also 
> support SVG.  The IE9 beta is being released as I write this email 
> http://www.microsoft.com/presspass/presskits/internetexplorer/.  As 
> Internet Explorer 9 is adopted, SVG will be deployed to the rest of 
> the internet (and corporate) communities.
>
> Based on this information, I believe the timing is appropriate to 
> implement an OpenLayers/SVG-based MapGuide vector viewer.  Some may 
> ask, "What about Canvas?"  OpenLayers/SVG is still considered better than OpenLayers/Canvas.
>  A decent write up and analysis is posted on 
> http://trac.openlayers.org/wiki/Future/OpenLayersWithCanvas
>
> If I get a resounding "OK" from the community, I will start work on an RFC.
>  Since OpenLayers is the foundation for Fusion and is sometimes used 
> on its own, I think it makes sense to put the rendering support in 
> OpenLayers and any additional control support (properties pane, etc) in Fusion.
>
>
> Regards,
> Trevor
>
>
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