[Qgis-developer] line renderer and composition mode

[Andreas Neumann]

Hi,

FYI - here is an explanation of the different composition modes:
http://doc.qt.digia.com/qq/qq17-compositionmodes.html

These are different from blend modes and I think it would be very
useful if they could be exposed to the user. But it would have to be
done on a symbol level and not on the layer level. Or at least as an
option to choose from.

On a similar issue it would be nice if the background (rectangle or
stronger stroke) of a text can hide paint in other layers - with the
goal to make better readable text labels - in german language we call
that a "Textfreistellung" - I don't know the correct english term,
sorry. Hugo Mercier from Oslandia already looked into the issue a bit
and prepared a proposal. This may be solved with the composition modes
as well.

So I would definitely like to see the exposure of the different
composition modes exposed to the user on a symbol level level.

Thanks for bringing up the issue,
Andreas

Am 27.08.2014 15:05, schrieb Jürgen E. Fischer:
> Hi Andrea,
> 
> On Wed, 27. Aug 2014 at 16:20:14 +0200, Andrea Peri wrote:
>> Your solution is not always good. You should could use the level 
>> symbols to give what symbol won in overlap.
> 
> I'm already using symbol levels.  Is there a way to have 
> transparency in higher levels remove earlier rendered stuff on 
> lower levels?
> 
> Level 2 - .. - Level 1 -.-.-.
> 
> Should look like
> 
> - .. -
> 
> if there are level 1 & 2 boundaries on top of each other and not 
> like
> 
> -...--
> 
> Still the transparent bits should not cover (vector/raster) layers 
> below. Putting a fully transparent line on the bottom of each
> level and rendering it in source composition mode would achieve
> that (ie. the transparent bits of the higher level would make
> everything rendered in lower levels transparent again instead of
> leaving it as is).
> 
> 
> Jürgen
> 
> 
> 
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