Hi Rob,
This small example should give you the idea I had in mind:
http://dev5.mapgears.com/openlayers/2.12/examples/modify-feature-vertex-click.html
You'll notice I extended the ModifyFeature control class. It's
recommended to do that than modifying the source code (in fact, you
should never edit the source code of a lib).
What do you think ?
HTH,
Alexandre
On 13-02-28 09:42 AM, Robert Smart wrote:
Great! I’m using version 2.12.
Thanks,
Rob Smart
*From:* Alexandre Dubé <mailto:ad...@mapgears.com>
*Sent:* Thursday, February 28, 2013 1:59 PM
*Cc:* openlayers-users@lists.osgeo.org
<mailto:openlayers-users@lists.osgeo.org>
*Subject:* Re: [OpenLayers-Users] ModifyControl Select/Delete Vertex?
Sure, I'd be glad to help. What version do you use ?
Alexandre
On 13-02-27 12:36 PM, Robert Smart wrote:
Hi,
Thanks for a really in depth answer. It really explains it well.
Unfortunately my javascript skills are pretty basic at the moment, so
a lot of that went over my head!
I like the sound of the vertexselection event on the vector layer
class. Could you give me a few more hints about how this might work?
Or even better give me an example bit of code :)
We would need to be able to access the vertex index of the selected
vertex, and i guess there would have to be a method of removing the
vertex from the feature, which would trigger a redraw of the feature
on the map.
We would have to also be able to define a style for that selected
vertex too, and i suppose add some error trap to ensure that we can't
select a virtual vertex?
Thanks again,
Rob
On 27 Feb 2013, at 13:51, "Alexandre Dubé" <ad...@mapgears.com
<mailto:ad...@mapgears.com>> wrote:
Hi Rob,
This would indeed be a nice feature to have. Looking at the
ModifyFeature control, I think this could be easily accomplished
with minor modifications.
If we look at the ModifyFeature control, it creates a DragFeature
control to allow dragging the vertices around. When you "mouse
hover" a vertex feature, a callback function is triggered because it
was defined here :
https://github.com/openlayers/openlayers/blob/master/lib/OpenLayers/Control/ModifyFeature.js#L267
That's the callbacks for the OpenLayers.Handler.Feature object the
drag control needs to interact with features on the map. The drag
control defines its callbacks method in the featureCallbacks object :
https://github.com/openlayers/openlayers/blob/master/lib/OpenLayers/Control/DragFeature.js#L119
and here's the list of callbacks you can set to a feature handler:
click, clickout, over, out, and dblclick.
https://github.com/openlayers/openlayers/blob/master/lib/OpenLayers/Handler/Feature.js#L30
So, back in the ModifyFeature control, you could add a 'click'
callback function just next to the 'over' one. Instead of coding
what you want it to do directly in the source, just define an
abstract function that needs to be overriden OR you could fire an
new vector layer event : vertexselected (which would need to be
added to OpenLayer.Layer.Vector).
Whoa, sorry for the long reply :) In short, try to create a
delegate method or event we could register to to do whatever we
wanted on vertex selection.
Does that make sense ?
HTH,
Alexandre
On 13-02-26 11:42 AM, Robert Smart wrote:
Hi All,
I'm trying to port some existing functionality into open layers and
have
managed to get most of it working. I'm just stuck on a seemingly
simple
task.
The current code allows a user to highlight a polygon vertex by
clicking on
it (which changes its colour), so that the user can then press a
delete
button to remove the vertex.
Using the modify control I'm able to display the vertices, and even
delete
them if I click on it and then press 'del' on my keyboard, but this
is not a
great solution as there is no visual clue as to what vertex has been
selected.
So is there a way to highlight or change the colour of a single
vertex the
user has clicked on? is there then a way to remove that vertex via
code and
have the polygon redraw on the screen to suit?
I think this would actually be quite useful as a standard feature
as there
are many cases where one might want to select an individual vertex.
Thanks,
Rob
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