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 <[email protected] > wrote: > > > On Tue, Sep 27, 2011 at 8:25 PM, Marco Hugentobler < > [email protected]> 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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