[Qgis-developer] questions on rendering

[Mohammed Rashad]

On Tue, Sep 27, 2011 at 8:25 PM, Marco Hugentobler <
marco.hugentobler at sourcepole.ch> wrote:

> Hi Mohammed
>
> > How came this time gap?
>
> A possible reason could be the following:
> In QGIS, most point renderers do some caching of the point symbols as
> QImage.
> So in case you invoke a QPainter->drawCircle/drawRectangle etc. command for
> every point, it helps a lot do do the rasterisation only once.
>
the point is not clear for me maybe because of my misunderstanding
will you please eloborate??

>
>
> Regards,
> Marco
>
>
> Am Dienstag, 27. September 2011, 16.18:25 schrieb Mohammed Rashad:
> > Hi All,
> > I am developing tiled vector rendering in OSSIM. I like the Qgis vector
> > rendering system
> >
> > point.shp contains 9,99,999 points which are generated by grass for using
> > v.random and ~27MB in size
> > roads.shp contains 2,28,068 linestrings and is ~50MB in size
> >
> > these point.shp and roads.shp data gets rendered in ~10 sec
> >
> > When I read vector using ogr and parse feature and draw point/linestring
> my
> > application taking about 40 sec to render point.shp
> > and
> >
> > I am using Qt4 with QPainter not QGraphicsView
> >
> > How came this time gap?
> >
> > i see Rtree and pal libs in src/core source code
> > Does they have any role in rendering?
> >
> > Does QGIS Rendering uses threading?
> >
> > How to get a minimal of QGIS code to hack it and build a new vector
> > rendering because I need it to make it tiled rendering vectors?
> >
> > How to improve performance in rendering without qgis?
> > ---
> > Regards,
> >    Mohammed Rashad K M
> >    M.S. (By Research) student
> >    Lab for Spatial Informatics
> >    Department of CSE
> >    International Institute of Information Technology
> >    Hyderabad, India
>
>


-- 
Regards,
   Mohammed Rashad K M
   M.S. (By Research) student
   Lab for Spatial Informatics
   Department of CSE
   International Institute of Information Technology
   Hyderabad, India
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