[Qgis-developer] line renderer and composition mode

[Andrea Peri]

Your solution is not always good.

You should could use the level symbols to give what symbol won in overlap.

A.



2014-08-27 14:53 GMT+02:00 Jürgen E. <jef at norbit.de>:
> Hi,
>
> any objections to have the line symbol layer render in composition mode
> "source"?
>
> I have a layer with multiple levels of administrative boundaries, where higher
> level boundaries (eg. state) lie over lower level boundaries (county). Lower
> level boundaries should not be visible if there is a higher level boundary on
> top of them.  The styles are dash-dotted - so the lines don't fully cover the
> lines below.
>
> I could solve that by putting a white line on the bottom of the symbol, but
> that would also mean that layers below are covered, that I still would like
> see.
>
> Rendering the line in "source" composition would allow to have a fully
> transparent line symbol layers on the bottom of the symbol that would overwrite
> the already rendered lines on that layer with transparency.
>
> Is that already possible in a different way (without resorting to multiple
> vector layers) to achieve the same?   Or does it introduce some problem that I
> didn't think of?   It could still be optional...
>
>
> Jürgen
>
>
> diff --git a/src/core/symbology-ng/qgslinesymbollayerv2.cpp b/src/core/symbology-ng/qgslinesymbollayerv2.cpp
> index 5a06f23..e21474a 100644
> --- a/src/core/symbology-ng/qgslinesymbollayerv2.cpp
> +++ b/src/core/symbology-ng/qgslinesymbollayerv2.cpp
> @@ -207,10 +207,12 @@ void QgsSimpleLineSymbolLayerV2::renderPolygonOutline( const QPolygonF& points,
>      return;
>    }
>
> +  p->save();
> +  p->setCompositionMode( QPainter::CompositionMode_Source );
> +
>    if ( mDrawInsidePolygon )
>    {
>      //only drawing the line on the interior of the polygon, so set clip path for painter
> -    p->save();
>      QPainterPath clipPath;
>      clipPath.addPolygon( points );
>
> @@ -236,11 +238,8 @@ void QgsSimpleLineSymbolLayerV2::renderPolygonOutline( const QPolygonF& points,
>        renderPolyline( ring, context );
>    }
>
> -  if ( mDrawInsidePolygon )
> -  {
> -    //restore painter to reset clip path
> -    p->restore();
> -  }
> +  //restore painter's composition mode and reset clip path
> +  p->restore();
>
>  }
>
> @@ -252,6 +251,9 @@ void QgsSimpleLineSymbolLayerV2::renderPolyline( const QPolygonF& points, QgsSym
>      return;
>    }
>
> +  p->save();
> +  p->setCompositionMode( QPainter::CompositionMode_Source );
> +
>    double offset = 0.0;
>    applyDataDefinedSymbology( context, mPen, mSelPen, offset );
>
> @@ -280,6 +282,8 @@ void QgsSimpleLineSymbolLayerV2::renderPolyline( const QPolygonF& points, QgsSym
>      for ( int part = 0; part < mline.count(); ++part )
>        p->drawPolyline( mline[ part ] );
>    }
> +
> +  p->restore();
>  }
>
>  QgsStringMap QgsSimpleLineSymbolLayerV2::properties() const
>
>
>
> --
> Jürgen E. Fischer         norBIT GmbH               Tel. +49-4931-918175-31
> Dipl.-Inf. (FH)           Rheinstraße 13            Fax. +49-4931-918175-50
> Software Engineer         D-26506 Norden               http://www.norbit.de
>
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-- 
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Andrea Peri
. . . . . . . . .
qwerty àèìòù
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