Jody,
You misunderstand, too :P
I know you don't need to load all the features into memory for "accepts"
to work.
But in the template implementation, "accepts" is *used* to go through
all the features and load them all at once in a list.
In principle, I have nothing against implementing accepts in
MappingFeatureCollection using the iterator, but for this particular
problem it is useless to me, because I don't want to keep loading all
the features in memory, and that is the only thing accepts is used for
in this particular case.
To answer your question, other methods not implemented in
MappingFeatureCollection is "add", "addAll", "remove", etc.. but that is
normal because you cannot possibly modify a MappingFeatureCollection.
To clarify what I was saying about the Collection.
The reason that the template implementation copies all the features in
to a list, is because the template software (freemarker something) wants
a collection. So what I did now is instead of copying all the features
in to a list, making a wrapper around the featureCollection that
implements the Collection interface, so that the feature iterator is
used directly without copying everything in to memory first. This seems
to work well. Though it is using the iterator() method which is deprecated.
Niels
On 24/01/11 14:44, Jody Garnett wrote:
You miss understand; you do not need to load all the features into
memory for "Accepts" to work. It is really intended to be an easier
for loop for people to code against (indeed they are thinking of
making this style of programming part of Java 7 - and calling it an
"inner" iterator).
Here is an implementation you can cut and paste in:
/**
* Accepts a visitor, which then visits each feature in the
collection.
* @throws IOException
*/
public void accepts(FeatureVisitor visitor, ProgressListener
progress ) throws IOException {
Iterator<SimpleFeature> iterator = null;
if( progress == null ) progress = new NullProgressListener();
try{
float size = size();
float position = 0;
progress.started();
for( iterator = iterator(); !progress.isCanceled() &&
iterator.hasNext();){
if (size > 0) progress.progress( position++/size );
try {
SimpleFeature feature = iterator.next();
visitor.visit(feature);
}
catch( Exception erp ){
progress.exceptionOccurred( erp );
}
}
}
finally {
progress.complete();
close( iterator );
}
}
(I moved this discussion to just geotools-devel)
Is there any other part of FeatureCollection you are unable to
implement? We do not expect FeatureCollection to extend
java.util.Collection; and I am interested in learning what you are
having difficulty with.
Letting half implemented feature collections run around the library is
a good way to cause frustration for people trying to use stuff.
--
Jody Garnett
Sent with Sparrow <http://www.sparrowmailapp.com>
On Monday, 24 January 2011 at 3:10 PM, Niels wrote:
Yeah I guess that would be easy to do, but as i said, I don't think
we /want/ all features to be loaded in memory at once.
I was looking at a different option, but need to threat a
FeatureCollection as a Collection for that. I was wondering why it
was chosen not to derive the interface of FeatureCollection from the
general Collection interface in java, as it implements all the same
methods. Because a Feature Collection is not a Collection, I am
making a Collection wrapper for a FeatureCollection, and also
wondering if that maybe already exists somewhere? Seems like an
obvious thing.
On 24/01/11 12:50, Jody Garnett wrote:
That is fine; have a look at one of the other implementations of
accepts - you can make an implementation that is based around your
iterator(). It ends up being a for loop that calls the visitor each
time through the loop; on each feature in turn.
Jody
--
Jody Garnett
Sent with Sparrow <http://www.sparrowmailapp.com>
On Monday, 24 January 2011 at 12:58 PM, Niels wrote:
On 22/01/11 07:39, Jody Garnett wrote:
On 21/01/2011, at 5:01 PM, Niels wrote:
I succeeded in getting wms:getFeatureInfo produce GML3 output from complex
features (Yay!).
However, I am now working on using HTML templates with getFeatureInfo.
I noticed in the code that processes templates, that it loads all features in
memory first.
However, it uses operations in the FeatureCollection that are not supported by
MappingFeatureCollection in app-schema.
What operations in FeatureCollection are not supported by
MappingFeatureCollection? Perhaps you want to take this to the geotools list if
it is a problem to be worked out?
But yeah; there should be no call to load everything at once; but even if the
code does do that - it should not effect your implementation of
FetaureCollection.
Jody
There is a whole series of methods not supported in
MappingFeatureCollection: anything that modifies the list (add,
clear, etc.) but the one used in the template code is "accepts" to
support visitors that visit all features. I think the reason is
that a MappingFeatureCollection doesn't actually hold any features,
the features are only created when you use the iterator.
I don't know if this should or can be worked out, because loading a
whole collection of complex features in memory just doesn't sound
like a good idea...
--
*Niels Charlier*
Software Engineer
CSIRO Earth Science and Resource Engineering
Phone: +61 8 6436 8914
Australian Resources Research Centre
26 Dick Perry Avenue, Kensington WA 6151
--
*Niels Charlier*
Software Engineer
CSIRO Earth Science and Resource Engineering
Phone: +61 8 6436 8914
Australian Resources Research Centre
26 Dick Perry Avenue, Kensington WA 6151
--
*Niels Charlier*
Software Engineer
CSIRO Earth Science and Resource Engineering
Phone: +61 8 6436 8914
Australian Resources Research Centre
26 Dick Perry Avenue, Kensington WA 6151
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