[OpenLayers-Users] question about the measure control

[Andreas Hocevar]

Hi,

there is already a ticket for this issue:

http://trac.openlayers.org/ticket/2094

Regards,
Andreas.

On Thu, Jul 2, 2009 at 9:47 AM, Andreas Hocevar<ahocevar at opengeo.org> wrote:
> Hi,
>
> On Thu, Jul 2, 2009 at 12:33 AM, <Aaron_Gundel at sjwater.com> wrote:
>> I have a question about the measure control in openlayers....  I noticed
>> today that after we upgraded to Openlayers 2.8, the behavior for the control
>> is somewhat different than it was in 2.7, with the primary difference being
>> that if you're "in a hurry" so to speak and don't make your clicks slow and
>> deliberate, an invalid distance appears on the initial click.  I checked and
>> it doesn't look like its just me -- it happens on the example page also.
>>
>> http://openlayers.org/dev/examples/measure.html
>>
>> Click while you're in motion and it's fairly easy to replicate.  Your
>> initial distance will vary based on...well I'm not sure, but the distance is
>> not zero as you might expect.  Any thoughts on what might be causing this
>> behavior?
>
> The distance you see is the distance at the time the calculation is
> done, which happens later than the click.
>
> It is because the measure calculation is now called using setTimeout
> (due to issues in IE, IIRC), and takes the geometry which already has
> a length when the calculation is done. If you want to create a bug
> report: the fix is easy. In the first line of the measurePartial
> method in Control.Measure, you have to add
>
> geometry = geometry.clone();
>
> BTW, the final result of the measure calculation is still correct.
>
> Also, you can configure the measure control to update the distance
> while moving the mouse:
>
> var control = new OpenLayers.Control.Measure(/* your config here */);
> control.handler.callbacks.modify = function(point, feature) {
>    control.measurePartial(point, feature.geometry);
> };
>
> Regards,
> Andreas.
>
>
> --
> Andreas Hocevar
> OpenGeo - http://opengeo.org/
> Expert service straight from the developers.
>



-- 
Andreas Hocevar
OpenGeo - http://opengeo.org/
Expert service straight from the developers.