[Chameleon] QuickZoom bug

[Paul Spencer]

Eric, I have filed bug 617 at www.maptools.org/bugzilla to track this 
bug.  I tried to add you as a cc to the bug but you are not registered 
in bugzilla apparently.

It would be most useful if you could create an account in bugzilla and 
enter problems such as this directly in bugzilla, this gives us the best 
opportunity to track and fix stuff like this.

One problem with the approach you mention here is that if you move the 
selection to the previously selected value after you navigate, then you 
can never select it again unless you select something else first.  For 
instance, if you select PEI, then pan west and PEI stays selected, you 
can't select it again.  So this generates the same problem as you have 
noted with the first element in the list.

The way to handle this in the widget is to make the first view tag a 
static entry, as in:

<view name="Select a location"/>

This way, when you first select a quickzoom location, it will navigate 
to it and set the selection to that entry.  On subsequent pages, it will 
reset to the first element in the list, in this case the "Select a 
location" entry, which allows you to pick any of the quick zoom locations.

The best enhancement would be to have the widget detect that the current 
extents match the extents for a particular view and set that view as 
selected ... this would require a lot of processing and would probably 
require a buffer operation to provide a small tolerance to the selection

A compromise would be for the widget to remember the last set of extents 
that it used and keep the selection as long as those extents don't 
change.  This would mean that you would zoom to PEI and then could 
change layer visibility etc and PEI would stay selected in the list.  As 
soon as you navigate away from those exact extents, then it would reset 
the list to the first entry ...

I've put a copy of this in the bug.

Comments and suggestions welcome.

Cheers,

Paul

Eric Bridger wrote:

> I noticed a bug in the QuickZoom widget (Chameleon 1.99 beta 1 and 2).
> 
> The current selection: SEL_QUICKZOOM hidden variable was not getting
> set, after the first submit, i.e. it was not sticky.  So if you quick
> zoom, then pan, you lose the previous selection and wind up with the
> first choice in your select list selected.  A minor problem since you
> can then not select the first choice (it's an onChange event).
> 
> The problem is in the 
> 
> GetHTMLHiddenVariables() function.  The current value of SEL_QUICKZOOM
> is not retrieved and reset.
> 
> This fix to widgets/QuickZoom.widget.php:
> 
>  function GetHTMLHiddenVariables()
>     {
>         parent::GetHTMLHiddenVariables();
> 
>         $szVariable = "NAV_QUICKZOOM";
>         $szValue = " <INPUT TYPE=HIDDEN NAME=$szVariable VALUE=\"\">\n";
>         $aReturn[$szVariable] = $szValue;
> 
>         $szVariable = "SEL_QUICKZOOM";
> +       $szVal = "";
> +       if ($this->isVarSet( $szVariable ))
> +            $szVal = $this->getVar( $szVariable );
> +      $szValue = " <INPUT TYPE=HIDDEN NAME=$szVariable
> VALUE=\"$szVal\">\n";
>         $aReturn[$szVariable] = $szValue;
> 
>         return $aReturn;
>     }
> 
> This seems to fix the problem.  But I'm not sure if this is the correct
> way to fix it, or how to ensure that this fix get's into a future
> release.
> 
> 
> Eric
> 
> 
> 
> 
> 
> _______________________________________________
> Chameleon mailing list
> Chameleon at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/chameleon
> 

-- 
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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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