Re: [Geotools-gt2-users] Creating Point Layers

[Martin D. <mar...@te...>]

Combe, Colin a =E9crit :
> i've been having a go at doing this (files attatched) but i'm a bit con=
fused
> about where responsibility for resetting the mark iterator lies.

Into RenderedMarks.getMarkIterator(). More on it below.

> The attatched example sort of works but, in order to stop the display f=
rom
> flickering when you pan, i had to insert=20
>         iterator.setIteratorPosition(-1);
> at line 241 of RenderedMarks (after iterator.paint(*)). This is because=
 the
> paint method uses setIteratorPosition(index) to get all the points in t=
urn
> but then doesn't reset the counter - which makes be wonder if my simple
> MarkIterator subclass works as its meant to.


Just some slight changes are needed. The old attached files created a=20
MarkIterator once for ever, and returned always the same instance in=20
'getMarkIterator()'. Furthermore, the point data were stored right in=20
the iterator (which is why it was created only once I guess). The=20
'getMarkIterator()' is supposed to returns an iterator initialized=20
before the first mark (like a JDBC RowSet), but the old file didn't=20
ensure that.

The was RenderedMark was designed is more like the Collection framework w=
ay:

     - RenderedMarks is like Collection: it contains the data (or know
       to access them).

     - RenderedMarkIterator is like Iterator: it iterates through the
       data, but doesn't contains the data by itself. A new instance is
       created everytime RenderedMarks.getMarkIterator() is invoked,
       exactly in the same way than a new instance of java.util.Iterator
       is created everytime Collection.iterator() is invoked. It make it
       possible to have many iterators working in same time.


So the needed chages were:

     - Cut and paste yours 'points' array from the 'MyMarkIt' inner class
       to the 'MarkTest' outter class.

     - Delete the 'MyMarkIt it' field in 'MarkTest'.

     - In 'getMarkIterator()', replace the 'returns it' statement by

               return new MyMarkIt();


Thats all. Modified file is attached.

	Regards,

		Martin.