[OpenLayers-Dev] feature label enhancement

["Dominik Gärner"]

Hi everyone,


I made a patch file for feature labels based on the SVG-textpath element. Right now, only half of the work is done. Only the SVG Renderer is supported, so make sure you use Firefox. As I said earlier, I have some problems using textpaths in VML.
This patch also includes an example, based on the modify-feature example. Here you can try and see the modify- and rotate-controls in action.

I hope you like it.


greets
Dominik




-------- Original-Nachricht --------
> Datum: Mon, 15 Feb 2010 11:07:49 +0100
> Von: "Dominik Gärner" <domi-g at gmx.at>
> An: dev at openlayers.org
> Betreff: Re: [OpenLayers-Dev] feature label enhancement

> 
> 
> > I tried to do this at one point. Because OL ties a single SVG/VML object
> > to a
> > single geometry, it was hard to do right, so I gave up after spending a
> > couple
> > weekends on it.  Good luck. :)
> 
> 
> Where were the problems? I think the label SVG/VML object is also tied to
> this geometry!?
> 
> Right now, I'm creating a textpath instead of the textbox element. I had
> no problems doing this with SVG, so far.
> My problem is (as always -.-) doing the same thing for IE. For some reason
> the textpath in VML is not working... And for some other reason there is
> in OL a flipping of VML-objects around the y-axis...
> 
> 
> Regards
> 
> 
> > Datum: Mon, 15 Feb 2010 09:27:15 +0100
> > Von: "Dominik Gärner" <domi-g at gmx.at>
> > An: domi-g at gmx.at
> > Betreff: Fwd: Re: [OpenLayers-Dev] feature label enhancement
> 
> > 
> > 
> > ------- Weitergeleitete Nachricht -------
> > Von: "Christopher Schmidt" <crschmidt at metacarta.com>
> > An: "Dominik Gärner" <domi-g at gmx.at>
> > Kopie: dev at openlayers.org
> > Betreff: Re: [OpenLayers-Dev] feature label enhancement
> > Datum: Wed, 10 Feb 2010 14:11:22 +0100
> > 
> > On Wed, Feb 10, 2010 at 11:29:48AM +0100, "Dominik Gärner" wrote:
> > > Hi everyone,
> > >
> > > I'd like to do some label enhancement for vector features. I want the 
> > > label to follow the feature shape (e.g. see  
> > > http://www.svgbasics.com/text2.html )
> > > It shouldn't be that hard by using SVG & VML. However, since this
> means 
> > > some changes in the Renderers - and I'm not so familiar with the whole
>  
> > > existing implementations - I need some ideas & help for creating a  
> > > concept:
> > >
> > > - using SVG, a textpath needs a <path> element. In SVG i could link
> the 
> > > text to the path element (using the xlink:href attribute), but
> currently
> >  
> > > only Polygon and Curve geometries are using <path> node types. And I'm
>  
> > > not sure if VML allows links.
> > > The better way will be to create a separate path element for the  
> > > text/label, using the feature's geometry (--> this means changes to
> the 
> > > drawText methods in the Renderers)
> > >
> > > - maybe some additional style attributes for the label have to be
> added.
> > >
> > > - Who knows something about Canvas? Is it possible to implement curved
>  
> > > text like in SVG & VML?
> > >   Where or which component decides what to use (besides of IE->VML,  
> > > Firefox->SVG)
> > 
> > I doubt it.
> > 
> > > - Rotating labels comes for free by rotating the vector feature. Does
> it
> >  
> > > make sense to create an extra Label/Text class for placing just labels
>  
> > > (e.g. if I want to place just a text, not a feature with a label  
> > > attribute)
> > 
> > No, because you can use a feature with no strokeWidth/strokeColor (an
> > invisible
> > feature) if you really want to do that.
> > 
> > > - Did I forget something essential? Sees anyone bigger blockades for
> the
> >  
> > > programming of this?
> > 
> > I tried to do this at one point. Because OL ties a single SVG/VML object
> > to a
> > single geometry, it was hard to do right, so I gave up after spending a
> > couple
> > weekends on it.  Good luck. :)
> > 
> > Regards,
> > 
> > 

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