[Qgis-developer] questions on rendering

[Mohammed Rashad]

does QGIS paint points to QPixMap and render the image or QGIS directly
draws the point
like painter->drawCircle/point

On Tue, Sep 27, 2011 at 9:34 PM, Mohammed Rashad <mohammedrashadkm at gmail.com
> wrote:

>
>
> 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
>
>


-- 
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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