[Qgis-developer] vector rendering improvement patch

[A Huarte]

Hi Vincent!

My simplification algorithm is a new method that uses the MapToPixel data of current QgsRenderContext to ignore in the drawing of geometry the "equal-pixel device points". It has no effect if the geometry is not far of current point of view of map.

It does not uses the ST_Simplify() method (douglas-peucker algorithm) where the geometry is simplified for other "similar" geometry.

I think the appearance of painted geometry is not affected except that it does not draw the unnecessary "equal-pixel device points".
The simplification will be configurable by user, then we can test this issue.


Alvaro



>________________________________
> De: Vincent Picavet <vincent.ml at oslandia.com>
>Para: qgis-developer at lists.osgeo.org 
>Enviado: Martes 22 de octubre de 2013 14:57
>Asunto: Re: [Qgis-developer] vector rendering improvement patch
> 
>
>Hello,
>
>Le mardi 22 octobre 2013 14:03:53, Andreas Neumann a écrit :
>> Hi,
>> 
>> Thank you for your work!
>> 
>> Yes - I think it should be configurable. 
>
>A use case is for example when a "line of symbol" symbology is used, with a 
>symbol on each vertex. Simplifying the geometry, even when it is not 
>supposed to be visible, could have undesired consequences on display.
>
>> It should also automatically be
>> turned off if a layer is in edit mode.
>+1
>
>Vincent
>
>> 
>> Just my opinion,
>> Andreas
>> 
>> Am 22.10.2013 14:01, schrieb A Huarte:
>> > Hello Vincent!
>> > For now, it is not configurable, automatically applies to all vector
>> > layer to be painted.
>> > 
>> > I think that the userneed not configure this, of course, if dev-community
>> > suggests, will be as you say! :-)
>> > 
>> >> Is it configurable in the interface for each layer independantly ? >It
>> >> should probably be, as according to the style applied to the
>> >> geometries, >the simplification could be something we want for some
>> >> layers and not for >others. >A checkbox in the layer properties dialog
>> >> could be interesting. >Then we would have to decide if we want it
>> >> activated by default or not for >dataproviders supporting it. We could
>> >> have a global option for that default >too. >Vincent
>> >> 
>> >> 
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>
>> 
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