[OpenLayers-Dev] editing controls, preserve selection

[Pierre GIRAUD]

Comments below.

On 8/23/07, Tim Schaub <tschaub at openplans.org> wrote:
> Steven M. Ottens wrote:
> > Hi Pierre,
> >
> > I'm currently more involved in user interaction design and not so
> > much in coding so it could be that I'm cutting corners which are hard
> > to cut but:
> >
> > why do you need to switch between modifyFeature control and
> > deleteVertex control?
> > IMO you can stay in modfiyFeature mode and allow the user to delete a
> > vertex by selecting it and press the delete key or hit the right
> > mouse button and select 'delete' .
> > I am aware that this approach forces the user to understand that a
> > webpage has more controls than mere links: keyboard, scrollwheel and
> > the right mouse button behave differently than in the classic Web.
> > I've been a great advisory (?) of backwards compatibility but
> > sometimes you need to take the extra step and force people to spend
> > 10s more time to get the new paradigm to save 9s every time they do
> > the action.
> >
> > This rambling has mainly focussed on your approach of feature editing
> > and doesn't solve you core question of preservation of selection,
> > sorry about that. I hope you solve your issue but even more I hope
> > you reconsider your current design (TBH there are valid reasons to
> > keep your current design, but ease of coding isn't one IMHO :)
> >
>
> I like the idea of creating small, single function controls.  Then
> additional controls can be created that aggregate these.  I think this
> gives us the most flexibility.
>
> We've done a lot of work to get things this way currently.
>
> So you've got a drag handler.  A box handler has a drag handler.  Then,
> a zoom box control has a box handler.  This way, other things can also
> make use of the drag handler (like the drag pan control) and other
> things can make use of the box handler (like a box selection control).
>
> The same goes for feature editing.  We've now got a drag feature control
> in the trunk.  This uses a drag handler and a feature handler.  Alone,
> it doesn't do that much, it lets you drag feature around.  We're also
> putting together a modify feature control.  This uses a select feature
> control and a drag feature control.  Together, it lets you select a
> feature and drag around its verticies.
>
> Next, we need delete vertex and add vertex controls.  Alone, these would
> do just what they say.  These could be aggregated with a modify feature
> control (and even a draw feature control if you like) into a single
> feature editing control that lets you drag around verticies, add new
> ones, and delete existing ones. Combined with a draw feature control,
> this would give you one control to draw and edit.
>
> Of course, there will be a lot of room for help from interaction
> designers.  Ideally, we'll be able to use a combination of keyboard and
> mouse input to activate and deactivate specific functionality in these
> controls.
>
> So, perhaps you were suggesting the same - but I wanted to make sure
> that it was clear that it *doesn't* make sense to develop the
> full-featured editing control before having the individual pieces in
> place.

I'm okay with that.
In the camptocamp/feature sandbox modify-feature's example, we can add
a vertex by moving a virtual point. This way I think we don't need an
individual addVertex control. I might be wrong.
On the other hand, I agree that the deleteVertex needs to be
redesigned to become an individual piece.

About the problem of selection preservation, I pushed my reflexions further.
First of all, the unselect was called in the full featured controls. I
just have to comment some code to keep the features selected when I
switch between tools. My problem now is that I probably don't want to
preserve the selection when I use a drawFeature control.
I had a look at some vector editing desktop software. Inkscape is a
good reference IMO and switching between different tools, the
selection is kept until user starts drawing a new geometry.
So, I now think that the drawFeature control could have an optional
selectControl that selects the drawn feature and unselects in the same
way the previous selected one.

What is your opinion about that ?

Pierre

>
> Tim
>
> > good luck
> > steven
> >
> > On Aug 22, 2007, at 2:44 PM, Pierre GIRAUD wrote:
> >
> >> Hello all,
> >>
> >> Recently I worked on Tim's code to enhance the editing
> >> functionnalities.
> >>
> >> The result can be seen in the camptocamp/feature sandbox.
> >>
> >> I'm now facing an little issue. What is frustrating for the user is
> >> that each time he switches between the two different editing controls
> >> (modifyFeature and deleteVertex), the current selection is lost. The
> >> user need to reselect a feature so that he can modify it.
> >>
> >> The problem is that when a control is deactivated, the select control
> >> it relies on is also deactivate and the selectFeature.unselect()
> >> method is called.
> >>
> >> Does someone has an idea of a workaround to let a control preserve
> >> selection so that another control can use it ?
> >>
> >> Regards
> >>
> >> Pierre
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