[OpenLayers-Users] limiting a Vector layer to the last feature added

[Eric Lemoine]

On Friday, August 14, 2009, John Cartwright
<john.c.cartwright at comcast.net> wrote:
> Hello All,
>
> I'm using OL 2.8 and trying to implement the behavior where the user can
> digitize points, lines, or polygons, but only the last created feature
> will be kept and displayed.  I've attempted this via a handler on the
> Layer's "beforefeatureadded" event like:
>
> function clearPreviousFeatures(evt) {
>     dojo.forEach(vectorLayer.features, function(f) {
>        if (http://f.id != http://evt.feature.id) {
>           vectorLayer.removeFeatures([f], {silent:true});
>        }
>     });
>     vectorLayer.redraw();

removing objects within a dojo.forEach loop may not be safe.

why don't you have you beforefeatureadded listener destroy all
features (with layer.destroyFeature)?

Cheers,


> }
>
>
> However,  I find that the previous drawn features remain until the
> DrawFeature control is changed.  Also as soon as the second feature is
> added, the code above complains that "f is undefined".  Finally, any
> features added subsequent to the first do not display in the style
> defined for the layer.
>
> I feel like this should be a simple task and that I'm missing something
> fundamental here.  Can someone show me what's wrong or suggest a better
> strategy for accomplishing this goal?
>
> Thanks!
>
> --john
>
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-- 
Eric Lemoine

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