[Qgis-developer] line renderer and composition mode

[Martin Dobias]

On Wed, Aug 27, 2014 at 8:19 PM, Anita Graser <anitagraser at gmx.at> wrote:
> Hi,
>
> On Wed, Aug 27, 2014 at 2:53 PM, Jürgen E. <jef at norbit.de> wrote:
>> any objections to have the line symbol layer render in composition mode
>> "source"?
>
> Having this mode would be useful but imho it should not be the default
> mode and it should definitely not be the only mode. I can think of
> many cases where I wanted to have multiple lines drawn over each other
> without the "source" effect you describe. Couldn't it just be another
> feature blending mode?

Agreed with Anita. We could just add 'source' feature blending mode to
the list. Just tried the styling as described by Jürgen and then run
this in python console:
>>> iface.activeLayer().setFeatureBlendMode(QPainter.CompositionMode_Source)

And it worked as expected - transparent line from "upper" symbol
removed the previously painted dashed line.

Cheers
Martin