[fusion-dev] RE: [mapguide-users] Fusion and Themed Layers - usability

Jason Birch Jason.Birch at nanaimo.ca
Fri Apr 3 18:03:51 EDT 2009


Yeah, I can see how that would be unmanageable.  I wouldn't be surprised if your use case strains fusion to the level that it's not workable for the current version or for 2.1.  I'm surprised it works with the AJAX viewer, but maybe the viewer has a different strategy for managing legend images.

Ideally, MapGuide would support a GetLegendImageStrip operation that Fusion could then use with CSS sprites to reduce (in your case, dramatically) the number of requests to the server.  I believe that there may be functionality for this in MapServer layer types in Fusion 2.0, but I don't think there is in MapGuide.  Bob Bray put in a ticket for this functionality a _long_ time ago, but unfortunately I don't think any work has been done on it:  http://trac.osgeo.org/mapguide/ticket/22

I think that there is a partial measure that could be done in Fusion to improve the situation somewhat.  Currently, Fusion does a reasonable job of caching images; it only requests a new legend image once per scale range context switch.  However, the initial request is done using the exact current scale.  If the request instead used a fixed value within the scale range (bottom + x?) then the images could be better cached by the browser.  If MapGuide sent cache headers (last modified, based on the layer definition?) this would also help.

Any Fusion or MapGuide devs have thoughts on this?


-----Original Message-----
From: djonio
Sent: April-03-09 12:47 PM
To: mapguide-users at lists.osgeo.org
Subject: RE: [mapguide-users] Fusion and Themed Layers - usability


I wanted to respond before the weekend so this is just a very brief note. Fiddler shows about 8000 of these(I assume a series for each LayerDefiniton):
GET /mapguide/mapagent/mapagent.fcgi?OPERATION=GETLEGENDIMAGE&SESSION=2f6bfde6-0000-1000-805a-001aa01bd46c_en_7F0000010AFC0AFB0AFA&VERSION=1.0.0&SCALE=2770.0556443473797&LAYERDEFINITION=Library%3A%2F%2FMIA%2FFacilities%2FFCLTY3000_7.LayerDefinition&THEMECATEGORY=10&TYPE=2&CLIENTAGENT=Fusion%20Viewer HTTP/1.1

And they appear to be 111 byte 16wX16h png images. 
This was "Showing the Legend" and then doing a Zoom. If the Legend is not shown I can Pan and Zoom pretty good. 

I can invest a little more time in this next week. I certainly do like this fusion layout and appearance and am sure the users will to ... but it has to work. Obviously there are alternatives to having a pre-built legend but I really wanted to avoid those alts from the get-go. I will delve into it all more on Monday. Have a good weekend.


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