[Chameleon] change imagetype on the fly

[Jacob Delfos]

Thanks Paul,

I sort of got it working now. My problem was that I didn't realize I was passing parameters into the main php page, which of course wouldn't propagate to drawmap.php (dumb...).

I'm automatically generating a hidden input field in the form when my aerial photo becomes visible (using the legend template). Unfortunately it doesn't get picked up until the next time I submit the form. I may try to resort to iterating through the layers after all. I think it could be a real advantage to switch to indexed colour (GIF) automatically when there is only vector data visible.

Thanks,

Jacob


-----Original Message-----
From: Paul Spencer [mailto:pagameba at magma.ca] 
Sent: 23 August 2004 20:31
To: Jacob Delfos
Cc: chameleon at lists.maptools.org
Subject: Re: [Chameleon] change imagetype on the fly


$http_form_vars is either POST or GET, not both.  You could try:

$http_form_vars = array_merge( $_POST, $_GET );

You can also:

print_r($http_form_vars);

and then view the source of your image to see the contents of the array?

Cheers,

Paul

Jacob Delfos wrote:

> Paul,
>  
> You are right, if I hardcode the szImgType variable, it changes the 
> imagetype. But it doesn't seem to want to change any other way. There is 
> this piece of code in there which doesn't seem to have any effect:
>  
> if (isset($http_form_vars["gszImgType"]) && 
> $http_form_vars["gszImgType"] != "")
>     $szImgType = $http_form_vars["gszImgType"];
>  
> The way I see this, it should allow a parameter in the form called 
> gszImgType to override the imagetype. Why doesn't it work? Even if I 
> just try
>  
> isset($http_form_vars["gszImgType"])
>  
> and place the gszImgType in the url as a parameter, or in the form as an 
> input type, it acts as if this variable isn't set. I'm not much of a php 
> expert, but I thought the isset function checks whether a parameter has 
> a value.....
>  
> Is it because I use a mapfile?
>  
> regards,
>  
> Jacob
>  
>  
>  
>  
> -----Original Message-----
> From: Paul Spencer [mailto:pagameba at magma.ca]
> Sent: 19 August 2004 10:09
> To: Jacob Delfos; chameleon at lists.maptools.org 
> <mailto:chameleon at lists.maptools.org>
> Subject: Re: [Chameleon] change imagetype on the fly
>  
> 
> Jacob, you should be able to modify the image type in drawmap.php since 
> this is the only
> place that it actually draws the map.  Note that drawmap does not save 
> the map state, so
> you would have to change it on every map draw.  The code would look 
> something like:
>  
> $oMap->selectOutputFormat( 'GIF' );
>  
> I think.  And you could insert this just before the $oMap->draw(); 
> call.  You could also
> (at the risk of adding a little overhead) loop through all the layers in 
> the map and test
> for the layer types and only switch to jpeg when a raster layer is 
> visible ...
>  
> Cheers,
>  
> Paul
>  
>  
>  
> On Aug 18, "Jacob Delfos" <jacob.delfos at maunsell.com 
> <mailto:jacob.delfos at maunsell.com>> wrote:
>  > Hi List,
>  >
>  >
>  >
>  > I am attempting to modify chameleon to allow the imagetype to change 
> on the fly.
> Ideally, I want to reach a situation where chameleon is smart enough to 
> know it should use
> gif, except when an aerial photograph is in the background. This will 
> greatly increase the
> speed of the page, because my jpeg maps are typically around 88kb, 
> whereas a gif would be
> ten times smaller for linework and areas.
>  >
>  >
>  >
>  > I tried to override the nImageType in drawmap.php by making it pick 
> it up from the http
> parameters. But even if I hardcode the nImageType variable, I keep 
> getting a jpeg. Also
> (which may be the cause), the temporary map files that are created 
> specify jpeg as imagetype.
>  >
>  >
>  >
>  > If I want to override the imagetype, where do I change that?
>  >
>  >
>  >
>  > regards,
>  >
>  >
>  >
>  > Jacob
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  > JACOB DELFOS
>  >
>  > SPATIAL INFORMATION ANALYST
>  >
>  > Maunsell Australia Pty Ltd
>  >
>  > 629 Newcastle Street
>  >
>  > PO Box 81
>  >
>  > Leederville 6902
>  >
>  > Western Australia
>  >
>  > ABN 20 093 846 925
>  >
>  >
>  >
>  > Tel     + 61 8 9281 6185
>  >
>  > Fax    + 61 8 9281 6297
>  >
>  > jacob.delfos at maunsell.com <mailto:jacob.delfos at maunsell.com>
>  >
>  > _______________________________________________
>  > Chameleon mailing list
>  > Chameleon at lists.maptools.org <mailto:Chameleon at lists.maptools.org>
>  > <a
> href='http://lists.maptools.org/mailman/listinfo/chameleon'>http://lists.maptools.org/mailman/listinfo/chameleon</a>
>  >
>  >
>  
> if (isset($http_form_vars["gszImgType"]) && 
> $http_form_vars["gszImgType"] != "")
>     $szImgType = $http_form_vars["gszImgType"];
> 
> 
> ------------------------------------------------------------------------
> 
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> Chameleon at lists.maptools.org
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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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