[Chameleon] mapDHTMLwidget occassionally fails

[Paul Spencer]

I like the onerror idea ... I've toyed with it in some custom apps here 
and it will be one of the things I will incorporate into the 
architecture for a future release (perhaps not 1.99 though)

Cheers,

Paul

Jacob Delfos wrote:
> Bart,
>  
> I actually noticed this problem happening with other images as well 
> (e.g. buttons, legend images, etc, after a submit). They just show up as 
> broken images. And that was on a dial-up connection. I don't think it's 
> anything wrong with the chameleon code, but rather something with how 
> apache interacts with PHP. Chameleon probably pushes that to its limits. 
> The fact that it is so hard to reproduce when you want it to happen 
> makes it annoying to debug. What hardware do you run? I have it 
> happening on a P4 2.8GHz, win2k, Apache 2.0.48.
> By the way, the file I sent you 
> (MapDHTMLWidget.widget.php.forCWC1.0.4) has an extra <<<EOT on line 998, 
> which must be removed.
>  
> I think the best fix would be if every image in chameleon (legend, 
> button, mapimage, etc.) had an 'onError' attribute, which would invoke a 
> function that reloads that image after a delay. I have tried to find out 
> whether there is a function to check whether an image loaded 
> successfully (e.g. by checking filesize), but I couldn't find one.
>  
> BTW Bart, I am Dutch. Moved to Australia 4.5 years ago.
>  
> regards,
>  
> Jacob
>  
>  
>  
>  
> -----Original Message-----
> From: chameleon-bounces at lists.maptools.org 
> <mailto:chameleon-bounces at lists.maptools.org> 
> [mailto:chameleon-bounces at lists.maptools.org] On Behalf Of 
> bartvde at xs4all.nl <mailto:bartvde at xs4all.nl>
> Sent: 27 August 2004 16:38
> To: chameleon at lists.maptools.org <mailto:chameleon at lists.maptools.org>
> Subject: RE: [Chameleon] mapDHTMLwidget occassionally fails
>  
> 
> Hi Jacob,
>  
> thanks. I'll give your fix a try.
>  
> Paul, since more people are experiencing these problems, has the cause of
> this problem been identified and will it be fixed in the next Chameleon?
> Will this change the way the Chameleon map load now works?
>  
> BTW Jacob: did you write the Dutch with an automatic translator, or you
> actually speak it?
>  
> Best regards,
> Bart
>  
>  >
>  > Hi Bart,
>  >
>  > It's not really a fix, more like a cover-up. I did it for the 1.0.4
>  > version,
>  > but just now I managed to get a similar solution working for 1.99.
>  >
>  > For 1.99, in mapDHTMLwidget.js, add the following code at the end:
>  >
>  > --------------------------------------
>  > var backupURL = "";
>  > function imageErrorOccurred (mapurl)
>  >    {
>  >    //alert (mapurl);
>  >    document.images["MapLayerDivImg"].src =
>  > document.images["mapimage"].src;
>  >    backupURL = mapurl;
>  >    setTimeout("reloadImage()",500);
>  >    }
>  >
>  > function reloadImage()
>  >    {
>  >    document.images['MapLayerDivImg'].src = backupURL;
>  >    }
>  > ------------------------------------------
>  >
>  > Then place the following attribute in your MapLayerDivImg definition:
>  >
>  > onError=\"imageErrorOccurred(gMapDHTMLURL)\"
>  >
>  >
>  > What it does: when the image breaks, it immediately replaces the image
>  > source with that of the empty white pixel (to prevent the user from 
> seeing
>  > a
>  > broken image), and after a small delay it loads the correct url into the
>  > image. It works for me.
>  >
>  > It's a slightly different implementation in version 1.0.4 (you'd have to
>  > modify mapDHTMLimage.widget.php). I'm not sure which one you're after, so
>  > I'll attach both files. Use the JS for 1.99, the php for 1.0.4.
>  >
>  > regards,
>  >
>  > Jacob
>  >
>  >
>  > P.S. Sorry voor de onmeundig lelijke PHP code. Geen idee wa'k doe in die
>  > taal. (Forgive me my ugly PHP coding. Have been too lazy to look for good
>  > tutorial.)
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  
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-- 
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|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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