Hi,
I have been thinking about how to implement an aspect of OGC Styled Layer Descriptors with OpenLayers vector renderers: using an external graphic as style for a point.
I came up with a quite simple solution, for which I created a patch and an extended vector-features.html example. For now, I only implemented it for the SVG renderer, where PNG, JPEG and SVG files can be used as external graphic.
How it works:
The setStyle method of the renderer checks for a style property "externalGraphic", which contains an URI to a bitmap. If this property is set, the original "circle" node is removed from the root node, and a new "image" node with the same properties and the required attributes is created.
As in the SLD specification, only a size for the bitmap can be specified. So external graphics will always be rendered with same width and height. For width and height, the existing pointRadius property is used.
I would appreciate your comments, and I will gladly implement it for VML, too. But I would like to know if the way I did it is the way to go, or if there are proposals for a different way.
Regards,
Andreas Hocevar.
