[udig-devel] Trouble with modifying feature attributes

[Jesse Eichar]

The eSetDeliver is not what I want completely.  I want to eventually  
come up with a nicer way to do eventing and rendering and provide  
some control.  But for now this is the solution.

Jesse

On Oct 5, 2007, at 1:38 AM, tony.roth at GMX.de wrote:

> Hi Jesse,
> thanks (!!) for the eSetDeliver(..) hint. I've never used it  
> before. I think I can speed up my application in general with using  
> it in some more scenarios.
>
> tony roth
>
>
> I think what you need to do is ensure that the rendering is  
> triggered after the updates.  The quick way is:
>
> Layer layer2 = (Layer)layer;
> try{
> layer2.eSetDeliver(false);
> // do your stuff
> layer.refresh(areaToRefresh);
> }finally{
> layer2.eSetDeliver(true);
> }
>
> As you can probably guess the eSetDeliver() turns off events for  
> the layer.
>
> Hope this helps,
>
> Jesse
>
>
>
> On Oct 4, 2007, at 6:01 AM, tony.roth at GMX.de wrote:
>
>> situation:
>> The features of a point layer are symbolized with external  
>> graphics. All elements are presented to the user in a table and if  
>> he selectes one or more in this table the items shall be  
>> highlighted in the map. The SLD specification defines that a  
>> graphic either contains a mark or an external graphic, therefore  
>> it's not possible to surround the external graphic with a red  
>> square or something like that: I need another external grahpic.
>> To realize this my features have the featureattribute 'selected'  
>> and I generate a bunch of sld rulez: For each category of my items  
>> and for {selected;unselected} I generate a rule with a certain  
>> external graphic. (The categories define the symbol like windmill  
>> or tower)
>> If the user selects one or more items of the table this happens:
>>  public void setSelection(List<Integer> selectedItems){
>>   try {
>>    FeatureStore fs = layer.getResource(FeatureStore.class, null);
>>    // deselect all: setting the dedictated attribute type to   
>> UNSELECTED (static variable)
>>    // this happens since we don't know which of the elements are  
>> selected at the moment
>>    fs.modifyFeatures(selectionAttributeType, UNSELECTED,  
>> Filter.NONE);
>>    FilterFactory filterFactory =  
>> FilterFactoryFinder.createFilterFactory();
>>    // set the selected ones
>>    for (Integer id:selectedItems){
>>     AttributeExpression attributeExpression =  
>> filterFactory.createAttributeExpression(IDAttributeName);
>>     LiteralExpression literalExpression =  
>> filterFactory.createLiteralExpression(id);
>>     CompareFilter compareFilter = filterFactory.createCompareFilter 
>> (FilterType.COMPARE_EQUALS);
>>     compareFilter.addLeftValue(attributeExpression);
>>     compareFilter.addRightValue(literalExpression);
>>     // this sets the filtered features to SELECTED
>>     fs.modifyFeatures(selectionAttributeType, SELECTED,  
>> compareFilter);
>>    }
>>   } catch (Exception e) {
>>     // ...
>>   }
>>  }
>> It works... somehow .. but not the way I wanted:
>> The renderer starts and on the first modifyFeatures comand (the  
>> deselection) all items are rendered. This takes about 14 seconds  
>> (on a pentium 4) with just four features in the layer. And only  
>> the graphics / symbols are rendered, the labels below the symbols  
>> are destroyed and I have to update the layer.
>> Another way could be to check which features switch >from selected  
>> to not selected and just modify these in the first step but with  
>> hundreds or more featuers this also takes a while.
>> Is this approach to be doomed and / or crap?
>> What is the best way to realize a kind of highlight features in  
>> the map with external graphics?
>> tony roth
>> _______________________________________________
>> User-friendly Desktop Internet GIS (uDig)
>> http://udig.refractions.net
>> http://lists.refractions.net/mailman/listinfo/udig-devel
>
> _______________________________________________
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> http://udig.refractions.net
> http://lists.refractions.net/mailman/listinfo/udig-devel
>
> _______________________________________________
> User-friendly Desktop Internet GIS (uDig)
> http://udig.refractions.net
> http://lists.refractions.net/mailman/listinfo/udig-devel

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