OGR auto style: use opacity parameter

[assefa]

When the OGR auto styling is used, the tools are parsed for color values and color objects in the style are set using that. But we do not take take advantage of the alpha value that could be present in the color string coming from OGR styles. We could use this alpha value to set the opacity parameter on the style object when It make sense. At least AGG driver would be able to use it.

[assefa]

possible patch

[assefa]

Attached is possible patch to take advantage of this.

[tbonfort]

the patch seems ok to me, and anyhow setting the style->opacity value should not have any effect on renderers that do not support it. all the cairo backends should also honor the style->opacity value, so this would also be effective for pdf and svg output.

[assefa]

beside the opacity issue described here, I also added the ability to use symbols that can be stored externally and accessed through http. This is the case for example of kml files. Right now, this is done for symbol styles. committed in r10904

[dmorissette]

Setting opacity sounds fine to me too. Since the change is committed (r10904), should this ticket be closed?

[assefa]

Change it to docs. Here is what I should be added more or less in http://mapserver.org/input/vector/ogr.html#styleitem-auto-rendering-layers-using-style-information-from-the-ogr-file

• if the color parameter for form the ogr style contains an alpha value, the value will be used to set the opacity parameter in the style object

• if the symbol id refers to a symbol on the web using the ​http://.../mysymbol.png, the symbol will be downloaded and a new symbol entry will be created referring to it.

[havatv]

I have attempted to fix the OGR documentation for trunk and 6.0 in r12575.