[OpenLayers-Users] Visibility of features in vector layer

[Andreas Hocevar]

hi,

the reason why it does not work is that you are using Layer.WFS, which
will load features for the visible extent after a pan/zoom. This means
that your modified features get removed, and replaced by fresh ones
from the server.

I see that you set the visibility based on a feature attribute. In
this case it would be best to set the visibility with a context in the
stylemap. See the stylemap-context.html example to see what I mean.

Regards,
Andreas.

On 7/9/09, Matthew Doyle <M.Doyle at bom.gov.au> wrote:
>
> Hi Eric, Andreas and Paul,
>
> Many thanks for getting back to me, and thanks for the suggestions. I have
> tried both ways, and the features still don't remember which renderIntent or
> "style" they have been changed to, always reverting back to the default.
>
> Andreas - I did have a styleMap called "hidden" but i've now renamed that to
> "delete" as suggested, I had assumed you could create your own renderIntent
> names paired with Style objects, now I realise it's best to stick with
> default, selected and delete.
>
> Here's my code: I hope you can perhaps see where I am going wrong?
> First, the StyleMaps and WFS Layer instantiation:
>
> 	var pacificStyleMap = new OpenLayers.StyleMap({
> 			"default": {
> 				externalGraphic : "/ol/img/capital-city.png",
> 				cursor: "pointer",
> 				graphicWidth : 10,
> 				graphicHeight : 10,
> 				graphicXOffset : -6,
> 				graphicYOffset : -6,
> 				graphicOpacity : 1
> 			},
> 			"select": {
> 				externalGraphic : "/ol/img/capital-city.png",
> 				cursor: "pointer",
> 				graphicWidth : 12,
> 				graphicHeight : 12,
> 				graphicXOffset : -7,
> 				graphicYOffset : -7,
> 				graphicOpacity : 1
> 			},
> 			"delete": {
> 				display: "none"
> 			}
> 	});
>
> 	pacificWFS = new OpenLayers.Layer.WFS('Weather Stations',
> OpenLayers.serviceURL, {typename: 'PI-STATIONS', format:
> OpenLayers.Format.WFS}, {
> 				extractAttributes: true,
> 				displayOutsideMaxExtent: true,
> 				styleMap: pacificStyleMap
> 	});
>
>
> (... and then the function which is trying to hide/show the features)
>
>
> function toggleDataType(dataType) {
> 	var renderIntent;
> 	for(var i = 0; i< pacificWFS.features.length; i++) {
> 		if(dataType == "rain") {
> 			if(pacificWFS.features[i].attributes.rain != "True") {
> 				renderIntent = "delete";
> 			} else {
> 				renderIntent = "default";
> 			}
> 		} else if(dataType == "tmax") {
> 			if(pacificWFS.features[i].attributes.tmax != "True") {
> 				renderIntent = "delete";
> 			} else {
> 				renderIntent = "default";
> 			}
> 		}
> 		pacificWFS.features[i].renderIntent = renderIntent;
> 		pacificWFS.drawFeature(pacificWFS.features[i]);
> 	}
> }
>
>
> The toggleDataType(dataType) is called onclick from a drop-down menu, all is
> working well with this as i have debugged the code thoroughly. I have 30
> features, and they have differing dataType attributes.
>
> I hope you guys can spot something that i'm missing here.
>
> I have also tried Eric's suggestion:
> 	pacificWFS.features[i].style = OpenLayers.Feature.Vector.style["delete"];
> instead of setting the renderIntent at the bottom of the loop.  In either
> method, the features do hide, but as soon as i pan around or zoom (causing a
> redraw) then the features come back.
>
> Best regards,
> Matt
>
>
>
>
>
> Eric Lemoine-2-2 wrote:
>>
>> On Wednesday, July 8, 2009, Paul Spencer <pagameba at gmail.com> wrote:
>>> Eric,
>>>
>>> On 8-Jul-09, at 9:25 AM, Eric Lemoine wrote:
>>>
>>>
>>> On Wednesday, July 8, 2009, Matthew Doyle <M.Doyle at bom.gov.au> wrote:
>>>
>>>
>>> Hello all,
>>>
>>> Sorry for resurrecting this topic, but i am having trouble getting my
>>> features to "remember" which StylemMap they have been changed to, using
>>> the
>>> renderIntent.
>>>
>>> After following Heidtmare's suggestions below, my WFS layer is now
>>> showing
>>> and hiding features on the fly using the renderIntent and then calling
>>> drawFeature, as follows:
>>>
>>> for(var i = 0; i < WFSLayer.features.length; i++) {
>>>   WFSLayer.features[i].renderIntent = "hidden";
>>>   WFSLayer.drawFeature(WFSLayer.features[i]);
>>> }
>>>
>>> This works great, right up until i zoom the map or move to a different
>>> extent. Each feature goes back to their "default" renderIntent and the
>>> features are shown once again.
>>>
>>> How can i force a permanent change for each feature so that when the user
>>> zooms it remembers what changes have just been made?
>>>
>>>
>>> Hi
>>>
>>> You can use the "style" property. E.g.
>>>
>>> feature.style = OpenLayers.Feature.Vector.style["delete"];
>>>
>>>
>>>
>>> why does the renderIntent approach not work?  It does work for controls
>>> like SelectFeature.  From what I see in the code, the renderIntent of the
>>> feature is changed in createSymbolizer called from drawFeature, which
>>> should use the renderIntent of the feature (in this case, 'hidden').
>>>  Unless the style map doesn't contain a 'hidden' style, in which case it
>>> would default back to ... um ... 'default' :)
>>
>>
>> I agree with your reasonning Paul - setting feature.renderIntent to
>> "delete" should work equally.
>>
>>
>>>
>>> Paul
>>>
>>>
>>
>> --
>> Eric Lemoine
>>
>> Camptocamp France SAS
>> Savoie Technolac, BP 352
>> 73377 Le Bourget du Lac, Cedex
>>
>> Tel : 00 33 4 79 44 44 96
>> Mail : eric.lemoine at camptocamp.com
>> http://www.camptocamp.com
>> _______________________________________________
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>> http://openlayers.org/mailman/listinfo/users
>>
>>
>
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-- 
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Andreas Hocevar
OpenGeo - http://opengeo.org/
Expert service straight from the developers.