[josm-dev] Selection Performance

[Karl Guggisberg]

Before, we had node.selected = true or if 'way.selected then' everywhere.
The plan was, 
1. to migrate to node.setSelected(..) and way.isSelected()
2. to change the behaviour behind OsmPrimitive:setSelected()/isSelected(),
possibly using a reference from
   the primitive to it's "parent" dataset  (see recent dicussion about
backreference in this list)
3. to provide a more efficient getSelected() on the DataSet 

We've done step 1, it looks like Jiri is working on the reference step 2,
and then it will be easy to do step 3.

> Do you have a better suggestion on where to stick the "selection cache"
> or whatever we want to call it than in the DataSet?
I think the "selection cache" (a collection of the currently selected
primitives) should be maintained for each data layer (either by the layer or
by some global selection cache which keeps a selection state per layer). If
the dataset wasn't attached to a data layer why would you want to
select/unselect objects? What I never liked is that there is a boolean field
'selected' on OsmPrimitive - this looks weired.

Regards
Karl 


-----Ursprüngliche Nachricht-----
Von: josm-dev-bounces at openstreetmap.org
[mailto:josm-dev-bounces at openstreetmap.org] Im Auftrag von Dave Hansen
Gesendet: Donnerstag, 8. Oktober 2009 17:59
An: Petr Nejedlý
Cc: josm-dev
Betreff: Re: [josm-dev] Selection Performance

On Thu, 2009-10-08 at 10:18 +0200, Petr Nejedlý wrote:
> First and foremost, selection status is not a property of the data.
> Changing the data set just because the user have selected something is 
> plain wrong. Having a per-dataset selection is quite disturbing too - 
> there should be only one, system-wide.

OK, so you're saying that because selecting things is not a property of the
data that it shouldn't be a part of the data set?  Uh, ok.  Aren't ways and
nodes part of the data set?  Check out OsmPrimitive.setSelected().  Sure
seems to *ME* like selections are part of the data set.

In any case, there's code cleanliness and order, and then there's the ugly
fact that it takes a full *SECOND* to process a mouse click.  I'd rather
have fast ugly code than slow clean code. :)

Do you have a better suggestion on where to stick the "selection cache"
or whatever we want to call it than in the DataSet?

-- Dave


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