[Chameleon] IE red cross problem

[Jacob Delfos]

Well, I have to say it's a less frequent problem, but maybe I just haven't noticed as much because I use firefox most of the time. I noticed it only occurs with the combination of internet explorer (not all versions of it though) and Apache. My current version of IE doesn't suffer from it at all. I *think* it also improved since we switched from win2k to windows 2003 server. The essense of the problem is probably requests being fired too quickly, which would explain why win2k3 would deal with it better.

In version 1, the workaround I used made use of the 'onError' attribute of the map image (MapLayerDivImg), which in version 2 sits in MapDHTML.js. This function invoked a function when the image broke, which loaded an empty pixel into the map-image immediately (so users doesn't see red cross), and then (after 0.2 seconds) reloaded the correct URL back into the map image. The users does not notice if anything goes wrong. Legend images and scalebar can still break, though.

I haven't yet had a reason to implement this in version 2. Should be easy to do, so let me know if you want me to post the code, but you could probably figure it out yourself quite easily. You are right, in that it can cause an infinite loop. But only if the configuration of the site is wrong (e.g. error in mapfile). It would not loop if the site normally functions. And I think version 2 has better error-catching (e.g. error message in map image), which would prevent that from happening. It's not a clean solution, but a whole lot more comfortable than the user seeing broken images.

regards,

Jacob


-----Original Message-----
From: chameleon-bounces at lists.maptools.org [mailto:chameleon-bounces at lists.maptools.org] On Behalf Of Paul Spencer
Sent: 12 July 2005 20:17
To: Bart van den Eijnden
Cc: chameleon at lists.maptools.org
Subject: Re: [Chameleon] IE red cross problem

Bart,

sorry but I have never seen this problem :( which makes it difficult to 
troubleshoot.  But I think Jacob did have the same problem.  I wonder if 
he found a solution.

Cheers

Paul

Bart van den Eijnden wrote:
> Hi list,
> 
> in my previous job when working with Chameleon I encountered the same problem, and now I am building a new product based on Chameleon a similar problem has arisen.
> 
> When loading the map in IE, sometimes a red cross appears. I have not been able to reproduce this in Firefox at all. It must have something to do with the image loading. Although I have never seen it happen to scalebar or reference map which are also generated by drawmap.php.
> 
> There were some threads about this in the past, one of them had as a work-around to add an OnError event to the map image, but this has a disadvantage that it can get into an endless loop.
> 
> Are there any new ideas or solutions on this? Are other people still experiencing this behaviour?
> 
> Best regards,
> Bart
> 
> Bart van den Eijnden
> Syncera IT Solutions
> Postbus 270
> 2600 AG  DELFT
> 
> tel.nr.: 015-7512436
> email: BEN at Syncera-ITSolutions.nl
> 
> 
> _______________________________________________
> Chameleon mailing list
> Chameleon at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/chameleon
> 

-- 
+-----------------------------------------------------------------+
|Paul Spencer                           pspencer at dmsolutions.ca   |
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|Applications & Software Development                              |
|DM Solutions Group Inc                 http://www.dmsolutions.ca/|
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