[Chameleon] tiff hang

Bart van den Eijnden bartvde at xs4all.nl
Wed Dec 8 16:08:27 EST 2004

Hi Assefa,

my Chameleon app MAP file has the following:

     NAME png
     MIMETYPE image/png
     EXTENSION png

my Chameleon config has the following:


So I don't see how this could explain the difference ... okay, maybe the  
file goes through my png alpha hack now, since it is a static image now  
with extension png. That must be the cause for this.

So using this approach you can use pnghacks to display the image properly.  
I could not get the png hack to work using the drawmap approach.


Best regards,

On Wed, 08 Dec 2004 16:03:05 -0500, Yewondwossen Assefa  
<assefa at dmsolutions.ca> wrote:

> Bart,
>   Here is what could be happening : drawmap.php used the image_type  
> parameter set in chamleon.xml to select the output format that will be  
> used (just before the rendering). Maybe there is a diffrence between  
> what you setup in the map file outputformat and the one which is  
> selected by drawmap.php. Could this explain your problem ? (Note that  
> $oMapSession->oMap->selectOutputFormat($szImgType) done in drawmap.php  
> compares first for the mimetype and then the name for all the  
> outputformat defined to do it's selection).
>   The approch of writing the map to a temporary file does not use the  
> selectOutputFormat.
>   Both approchs use the same php mapscript draw function so the output  
> selection seems to be the only diffrence from what I can tell.
> Later,
> Bart van den Eijnden wrote:
>> Assefa and list,
>>  if I use this approach the 24 bit transparency problems in Internet   
>> Explorer (grey background) are also gone.
>>  I reported those problems in the Mapserver bugzilla:
>> http://mapserver.gis.umn.edu/bugs/show_bug.cgi?id=1089
>>  Is this explainable for you guys?
>>  Best regards,
>> Bart
>>  On Wed, 08 Dec 2004 15:06:59 -0500, Yewondwossen Assefa   
>> <assefa at dmsolutions.ca> wrote:
>>> Ken,
>>> Thanks for testing.
>>> AFAIK, the changes would only affect the Query widget if it is used  
>>> with  the parameters  HIGHLIGHTRESULTS and PERSISTENTRESULTS.  Maybe  
>>> Paul can  comment on other widgets that I may have overlooked.
>>>   As for the drawmap.php, It does several functionnalities (every  
>>> thing  drawn in chamelon like map, scalebar, keymap) pass trough that  
>>> function.  The idea behind it is that if you assigning a URL to the  
>>> image source  (http::../drawmap.php?...), the main application page  
>>> does not need to  wait for the map to be drawn to load completly and  
>>> thus It is supposed  to give a better "smooth" looking apps.
>>>   Your are the 2nd person who tried this solution and reported that  
>>> the  application was faster considerably. When using the drawmap.php  
>>> method,  there is a time cost associated with calling the server,  
>>> loading the  session and then drawing the map. I would have imagined  
>>> that this  solution would improve the rendering time slightly (since  
>>> session  loading and call to the server are cut) but I am surprised a  
>>> bit to know  that It has considerable effect since I always thought  
>>> that the main  bulk of the time is taken by the map drawing.  I guess  
>>> a good profiling  might give us a better understanding.
>>>   Anyhow I entered a bug 893 on this :
>>>     http://www.maptools.org/bugzilla/show_bug.cgi?id=893
>>> Later,
>>> Ken-ichi wrote:
>>>> Wow, not only did that solve my problem, but it increased map  
>>>> rendering  speed considerably, even with no TIFFs!  Thanks, Assefa  
>>>> and Paul.   Adding a flag in the widget tag to do this would be  
>>>> really helpful.   Are there any widgets that don't work with this  
>>>> adjustment, i.e. can I  alter our "production" copy of Chameleon and  
>>>> expect other Chameleon  projects on the server to work ok?  What  
>>>> exactly is the purpose of  drawmap.php anyway?
>>>> Thanks again.
>>>>  -Ken-ichi
>>>>  Yewondwossen Assefa wrote:
>>>>> The changes are minmal : here is what I did :
>>>>>   1) MapDHTML.widget.php : in function GetJavascriptVariables  
>>>>> (around  line 468) :
>>>>>    comment the 3 lines and add the 3 additional lines :
>>>>>      //$url =   
>>>>> WEBCOMMON."/wrapper/drawmap.php?map_session_mode=$nMapSessionMode&run_query=0&".SID.$szFatalImage;   
>>>>>         //if (!$bCWCJSAPI)
>>>>>         //$url .= "&dummy=".urlencode(microtime());
>>>>>         $oMap = $this->moMapObject->oMap;
>>>>>         $img = $oMap->draw();
>>>>>         $url = $img->saveWebImage();
>>>>>   2) in MapDHTML.js : function MapLayerDivImgOnLoad
>>>>>     comment the line : //url = url + "&UniqId="+unique;
>>>>> Please give it a try and let me know.
>>>>> Paul, I think we can easily make this a configurable thing as far  
>>>>> as  mapdhtml is concerned. I think there might be a problem though  
>>>>> with  the new query widget that diplays the selected element (and  
>>>>> keep the  selection persitently) but It can also be solved with few  
>>>>> changes.
>>>>> What I propose is that Ken do the tests and if it solves his  
>>>>> problem,  I will enter an enhancement bug on this with the changes  
>>>>> required and  we can implement it after that.
>>>>> Later,
>>>>> Paul Spencer wrote:
>>>>>> Ken,
>>>>>> this is very strange.  Chameleon is not aware of the image formats  
>>>>>> of  the underlying data, it just uses mapscript to do the drawing.
>>>>>> Another solution to this problem may be to have the MapDHTML  
>>>>>> widget  render the map to a file and then load the image source in  
>>>>>> the page  rather than use drawmap.php.
>>>>>> We did this for another client who was having a strange problem  
>>>>>> with  images half loading due to some sort of firewall problem  
>>>>>> (only in IE  strangely).
>>>>>> I've cc'd Assefa since he was the one who sorted that out.   
>>>>>> Assefa,  can you post the solution to getting MapDHTML to render to  
>>>>>> a file?   Do you think we could make this a configurable parameter  
>>>>>> in the  MapDHTML widget (like DELAYDRAW="[true|false]" or  
>>>>>> something)?
>>>>>> Cheers,
>>>>>> Paul
>>>>>> Ken-ichi wrote:
>>>>>>> Thanks Paul.  I tried loading drawmap.php directly, and that  
>>>>>>> usually  renders the map even when the Chameleon app hangs (though  
>>>>>>> sometimes  it hangs too), so I guess drawmap.php may not actually  
>>>>>>> be the  culprit.  I made another, minimal app with just the  
>>>>>>> ZoomIn, ZoomOut,  Recenter, and MapDHTML widgets, and it still  
>>>>>>> hangs on the tiffs, so  I don't think it's any of my custom  
>>>>>>> widgets that are mucking things  up either.
>>>>>>> I am really at a loss here.  The strangest thing about this is  
>>>>>>> that  if I convert the TIFF to an Erdas Imagine file (either in  
>>>>>>> Erdas or  with gdal_translate) everything works fine.  What is it  
>>>>>>> about tiffs  that could possibly hang up Chameleon?  Why would  
>>>>>>> Chameleon even be  aware of input file format?  Don't MapServer  
>>>>>>> and GDAL handle that?   I know they're fine because a  
>>>>>>> non-Chameleon phpMapScript app renders  the map fine, as does the  
>>>>>>> CGI.
>>>>>>> Argh.
>>>>>>> -Ken-ichi
>>>>>>> Paul Spencer wrote:
>>>>>>>> Ken,
>>>>>>>> to debug drawmap.php, you need to grab the URL from the image in   
>>>>>>>> the chameleon app and load it directly in your browser.  You  
>>>>>>>> should  then see any error messages or debug output directly.   
>>>>>>>> Often,  problems with a broken map image are related to error  
>>>>>>>> messages (or  notices) being output before the image contents,  
>>>>>>>> thus creating a  corrupt image.
>>>>>>>> If nothing shows up immediately on viewing the drawmap.php url,  
>>>>>>>> you  can then start to add some debugging code (echo) to  
>>>>>>>> drawmap.php to  try to discover what is going on.
>>>>>>>> Cheers,
>>>>>>>> Paul
>>>>>>>> Ken-ichi wrote:
>>>>>>>>> Hi list.  A while ago I posted an issue I'd been having with   
>>>>>>>>> rendering TIFFs in Chameleon   
>>>>>>>>> (http://lists.maptools.org/pipermail/chameleon/2004-August/thread.html#1245),   
>>>>>>>>> but I never really resolved it.  Essentially, whenever I zoom  
>>>>>>>>> in  on a GeoTIFF so that the TIFF fills the whole map, Chameleon  
>>>>>>>>> hangs  and never displays the map image (I just get the spinner  
>>>>>>>>> icon  indefinitely and then a broken image icon behind it.  Try  
>>>>>>>>> zooming  in on the DRG (Test Raster) at
>>>>>>>>> http://fisher.cnr.berkeley.edu/vtm/data/mapbrowse/
>>>>>>>>> to see what I'm talking about.  I'm fairly sure this is a   
>>>>>>>>> Chameleon issue, most likely with drawmap.php, because this   
>>>>>>>>> mapfile renders just fine via the CGI, and with a rudimentary   
>>>>>>>>> phpMapScript app like this one:
>>>>>>>>> http://fisher.cnr.berkeley.edu/~kueda/mapscript_browse.phtml
>>>>>>>>> The DRG is a 16M GeoTIFF from the California Spatial  
>>>>>>>>> Information  Library, so I don't think it's to blame.  You can  
>>>>>>>>> check out my php  and MapScript config at
>>>>>>>>> http://fisher.cnr.berkeley.edu/~kueda/phpinfo_mapscript.phtml
>>>>>>>>> I'm running MapServer 4.4.0, GDAL 1.2.5, and PHP 4.3.9.  Can   
>>>>>>>>> anyone think of a reason this could be happening, or recommend  
>>>>>>>>> a  way to troubleshoot drawmap.php?
>>>>>>>>> -Ken-ichi
>>>>>>>>> _______________________________________________
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