[OpenLayers-Users] externalGraphic anchoring points?

[Stephen Woodbridge]

I believe the origin of an image is the upper-left corner, so you need 
to specify your offsets based on that point.

-Steve

William Martin wrote:
> All,
> 
> Hi, new user.  I'm using a vector layer for placing markers on the map, and I'm using the externalGraphic property to specify a marker of my own.  How is that image anchored with respect to the lat/lon coordinates that it represents?
> 
> That is, if exactly one pixel in the external graphic corresponds to the point on the map, is it:
> 
> a) The top left corner pixel
> b) The top right corner pixel
> c) The bottom left corner pixel
> d) The bottom right corner pixel
> e) The exact center pixel
> f) A pixel halfway along one edge
> Or g) something else entirely?
> 
> I need to know so that I can figure out the correct offsets to use with my graphic.
> 
> I tried to figure this out by using an external graphic for the marker which was a 1x1 pixel animated GIF blinking red/white/red/white and then defining another marker for the same coordinates with a translucent version of the regular image.  But the 1x1 graphic refused to show up, even when I disabled the other marker so that it was on its own.  Weird.
> 
> Thanks!
> 
> Will Martin
> Web Services Librarian
> Chester Fritz Library, University of North Dakota
> 
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