[OpenLayers-Dev] Cluster strategy should not process data when
layer is currently disabled (visibility=false)
Tim Schaub
tschaub at opengeo.org
Thu Nov 13 16:31:16 EST 2008
Hey-
Eric Lemoine wrote:
> Alexandre,
>
> Layers do not have the zoomend event type, so I don't think your patch
> is valid. Try with moveend and a check in the listener to handle zoom
> change only. Eric
>
And note that "moveend" is not triggered for base layers. This is the
issue I was referring to earlier when I said I suspected an issue with
layer events being triggered.
http://trac.openlayers.org/ticket/1831
Tim
> 2008/11/13, Alexandre Dube <adube at mapgears.com>:
>> Hi Eric, Ivan,
>>
>> The following is enough to resolve the bug ( I think ).
>>
>> ##### patch ? start #####
>>
>> --- Cluster.js.original 2008-11-13 14:05:25.000000000 -0500
>> +++ Cluster.js 2008-11-13 14:06:59.000000000 -0500
>> @@ -72,7 +72,7 @@
>> "beforefeaturesadded": this.cacheFeatures,
>> scope: this
>> });
>> - this.layer.map.events.on({"zoomend": this.cluster, scope:
>> this});
>> + this.layer.events.on({"zoomend": this.cluster, scope: this});
>> }
>> return activated;
>> },
>> @@ -93,7 +93,7 @@
>> "beforefeaturesadded": this.cacheFeatures,
>> scope: this
>> });
>> - this.layer.map.events.un({"zoomend": this.cluster, scope:
>> this});
>> + this.layer.events.un({"zoomend": this.cluster, scope: this});
>> }
>> return deactivated;
>> },
>> ##### patch ? end #####
>>
>>
>>
>> Trying that, I found an other bug which occurs with or without this fix.
>>
>> If I pan to some place while the layer is not visible, then set it
>> back to visible, features won't appear. I'm not sure if that's because
>> my vector layer is not in the layerSwitcher. I toggle the vector
>> layer's visibility with a dummy layer, like this :
>>
>>
>>
>> ### code start ###
>> olDummy.events.register("visibilitychanged", olDummy, toggleVisibility);
>>
>> function toggleVisibility()
>> {
>> var bVisible = this.getVisibility();
>> olWMS.setVisibility(bVisible);
>> olWFS.setVisibility(bVisible);
>> }
>> ### code end ###
>>
>> Ivan, could you test the behavior in your application ?
>>
>> Best regards,
>>
>> Alexandre
>>
>> P.S. Being good at finding bugs is easy and not really rewarding...
>> Finding solutions, that's something ! You guys are doing great. Cheers !
>>
>> Eric Lemoine wrote:
>>> You guys are good to find bugs :-)
>>>
>>> I think that, instead of listening to the map's zoomend events, the
>>> cluster strategy should listen to its layer's moveend events and check
>>> in the listener that this is actually a zoom change before doing
>>> anything. The moveend listener receives an object with a zoomChanged
>>> boolean property. Can one of you try modifying the cluster strategy
>>> with that and report back? (don't forget to change the unregistration
>>> as well).
>>>
>>> Thanks.
>>>
>>> Eric
>>>
>>> 2008/11/13, Ivan Grcic <ivan.grcic at geofoto.hr>:
>>>
>>>> Hi Alex,
>>>>
>>>> i made a little hack to it...inside Strategy.Cluster.js inside cluster
>>>> function I added one more check:
>>>> (OpenLayers.Util.indexOf(this.layer.resolutions, resolution) != -1)
>>>>
>>>> it doesnt do the clustering if current resolution is not contained
>>>> inside layers array of resolutions.
>>>>
>>>> Index: Cluster.js
>>>> ===================================================================
>>>> --- Cluster.js (revision 8317)
>>>> +++ Cluster.js (working copy)
>>>> @@ -141,7 +141,8 @@
>>>> cluster: function() {
>>>> if(this.features) {
>>>> var resolution = this.layer.map.getResolution();
>>>> - if(resolution != this.resolution || !this.clustersExist()) {
>>>> + if((OpenLayers.Util.indexOf(this.layer.resolutions,
>>>> resolution) != -1) && (resolution != this.resolution ||
>>>> !this.clustersExist())) {
>>>> this.resolution = resolution;
>>>> var clusters = [];
>>>> var feature, clustered, cluster;
>>>>
>>>> Greetings,
>>>> Ivan
>>>> On Thu, Nov 13, 2008 at 3:02 PM, Alexandre Dube <adube at mapgears.com>
>>>> wrote:
>>>>
>>>>> I get the same behavior as Ivan's on my application which has very
>>>>> similar
>>>>> resolution settings on map an vector layer.
>>>>>
>>>>> Because a layer's features are not destroyed when it goes out of range
>>>>> (inRange) or becomes invisible (visibility), the cluster strategy still
>>>>> clusters those existing features. I don't have that many features to
>>>>> display
>>>>> when the layer becomes inRange, so I never noticed any slowing down.
>>>>>
>>>>> Alexandre
>>>>>
>>>>> Ivan Grcic wrote:
>>>>>
>>>>>> This post evolved from previous discussion named "bbox strategy and
>>>>>> zooming"
>>>>>>
>>>>>> Clustering features with cluster strategy takes some time. If there
>>>>>> are many features to cluster, it will take even more time :)
>>>>>>
>>>>>> So there are some scenarios where clustering shouldnt be recalculated.
>>>>>>
>>>>>> Example:
>>>>>> I want to see my cluster layer only after 5th zoom level. No
>>>>>> clustering should be made when i play on zoom level 0-4 with other
>>>>>> layers,
>>>>>> because it slows things down, and the cluster layer is still not
>>>>>> visible at all (its only clustering features in background)
>>>>>>
>>>>>> It should only cluster when layer is visible (and the current map
>>>>>> resolution is inside array resolution of clustered layer, if we define
>>>>>> seperate set of resolution)
>>>>>>
>>>>>> So if map has:
>>>>>> resolutions: [0,1,2,3,4,5,6,7,8,9]
>>>>>>
>>>>>> and vector layer:
>>>>>> resolutions: [5, 6, 7, 8, 9]
>>>>>>
>>>>>> clustering should occur only on vector layers resolution :5, 6, 7, 8
>>>>>> and
>>>>>> 9.
>>>>>>
>>>>>> I hope you see where im pointing now,
>>>>>>
>>>>>> Best regards,
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>> --
>>>>> Alexandre Dubé
>>>>> Mapgears
>>>>> www.mapgears.com
>>>>>
>>>>>
>>>>>
>>>> --
>>>> Ivan Grcic
>>>> _______________________________________________
>>>> Dev mailing list
>>>> Dev at openlayers.org
>>>> http://openlayers.org/mailman/listinfo/dev
>>>>
>>>>
>>
>> --
>> Alexandre Dubé
>> Mapgears
>> www.mapgears.com
>>
>>
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--
Tim Schaub
OpenGeo - http://opengeo.org
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