<div>Hell QGIS Developers,</div><div><br></div><div><br></div><div>I have couple of questions regarding QGIS and its vector rendering part. I had posted one mail titled "question on qgis rendering" now with more set of questions I am starting a new thread</div>
<div>as the title says I need minimal qgis.</div><div><br></div><div><br></div>does qgis rasterise the vector data before rendering?<div><br>does QGIS paint points to QPixMap and render the image or QGIS directly draws the point<div>
like painter->drawCircle/point</div><div>because QGIS rendering is faster than direct rendering</div><div><br></div><div>How to make a minimal qgis version which renders fast enough. I want to customize QGIS for my needs.</div>
<div><br></div><div>first I want rendering engine of QGIS to be seperate.</div><div><br></div><div>Which files are responsible for QGIS rendering a vector data (OGR) ?</div><div><br></div><div>Which file opens OGR data?</div>
<div><br></div><div>which is responsible for grabing chips from vector data?</div><div><br></div><div>which is responsible for rendering to QGraphicsScene or QPainter?</div><div><br></div><div>Does QGIS cache some data when rendering if yes how is done?</div>
<div><br></div><div>I want all technical details of QGIS rendering?</div><div><br></div><div>what I need is a custom QGIS with only vector RENDERING no labels, no attributes, no projection etc. I had made a small vector rendering system using Qt and GDAL</div>
<div><br></div><div>please review this video</div><div><span style="color: rgb(0, 0, 0); font-family: arial, sans-serif; font-size: 13px; font-style: normal; font-variant: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); "><span style="font-family:arial, sans-serif;font-size:13px;font-weight:bold;background-color:rgb(218, 240, 190)"><a href="http://www.youtube.com/watch?v=KTeYBpSe0kw" style="color:rgb(0, 51, 204);margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;padding-top:0px;padding-right:0px;padding-bottom:0px;padding-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;border-style:initial;border-color:initial;font-size:13px;background-color:transparent;text-decoration:underline" target="_blank">http://www.youtube.com/watch?v=KTeYBpSe0kw</a></span></span></div>
<div><br></div><div>I dont need to link my application to qgis_core and build a simple application on top of QGIS</div><div>I need to know everything about QGIS Vector RENDERING and need to build a new rendering system for vectors. I know my requirement sounds like reinventing wheels but I need to do it</div>
<div><br></div><div>please dont advice me to use qgis_core.so and build a GUI seperately. I need to have full control over the code written for rendering.</div><div><br></div><div>The reason I am not using qgis_core is nothing but it is difficult for me to manage bugs if I use qgis_core. on the other hand if I build my own I can easily track bugs and fix the as soon as possible.</div>
<div><br></div><div>managing qgis_core for a person like me without help of others is a pain!!!</div><div><br></div><div><br></div><div><br></div><div>If you cant tell me how to make qgis minimal version, please point me to qgis very first version and also tell me how to build it...</div>
<div><br></div><div><br></div><div>I hope everyone understandss my requirement. My english is not good so if you have any doubts please feel free to contact me and will surely reply back with your answers</div><div>Anyone please help me...</div>
<div><br></div><div><br></div><div class="gmail_quote">On Wed, Sep 28, 2011 at 5:38 PM, Mohammed Rashad <span dir="ltr"><<a href="mailto:mohammedrashadkm@gmail.com">mohammedrashadkm@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
does QGIS paint points to QPixMap and render the image or QGIS directly draws the point<div>like painter->drawCircle/point<div><div></div><div class="h5"><br><br><div class="gmail_quote">On Tue, Sep 27, 2011 at 9:34 PM, Mohammed Rashad <span dir="ltr"><<a href="mailto:mohammedrashadkm@gmail.com" target="_blank">mohammedrashadkm@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br><br><div class="gmail_quote"><div>On Tue, Sep 27, 2011 at 8:25 PM, Marco Hugentobler <span dir="ltr"><<a href="mailto:marco.hugentobler@sourcepole.ch" target="_blank">marco.hugentobler@sourcepole.ch</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi Mohammed<br>
<div><br>
> How came this time gap?<br>
<br>
</div>A possible reason could be the following:<br>
In QGIS, most point renderers do some caching of the point symbols as QImage.<br>
So in case you invoke a QPainter->drawCircle/drawRectangle etc. command for<br>
every point, it helps a lot do do the rasterisation only once.<br></blockquote></div><div>the point is not clear for me maybe because of my misunderstanding</div><div>will you please eloborate?? </div><div><div></div><div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
<br>
Regards,<br>
Marco<br>
<br>
<br>
Am Dienstag, 27. September 2011, 16.18:25 schrieb Mohammed Rashad:<br>
<div><div></div><div>> Hi All,<br>
> I am developing tiled vector rendering in OSSIM. I like the Qgis vector<br>
> rendering system<br>
><br>
> point.shp contains 9,99,999 points which are generated by grass for using<br>
> v.random and ~27MB in size<br>
> roads.shp contains 2,28,068 linestrings and is ~50MB in size<br>
><br>
> these point.shp and roads.shp data gets rendered in ~10 sec<br>
><br>
> When I read vector using ogr and parse feature and draw point/linestring my<br>
> application taking about 40 sec to render point.shp<br>
> and<br>
><br>
> I am using Qt4 with QPainter not QGraphicsView<br>
><br>
> How came this time gap?<br>
><br>
> i see Rtree and pal libs in src/core source code<br>
> Does they have any role in rendering?<br>
><br>
> Does QGIS Rendering uses threading?<br>
><br>
> How to get a minimal of QGIS code to hack it and build a new vector<br>
> rendering because I need it to make it tiled rendering vectors?<br>
><br>
> How to improve performance in rendering without qgis?<br>
> ---<br>
> Regards,<br>
> Mohammed Rashad K M<br>
> M.S. (By Research) student<br>
> Lab for Spatial Informatics<br>
> Department of CSE<br>
> International Institute of Information Technology<br>
> Hyderabad, India<br>
<br>
</div></div></blockquote></div></div></div><br><br clear="all"><div><br></div>-- <br><div><div></div><div><div><font face="arial, helvetica, sans-serif">Regards,</font></div><font face="arial, helvetica, sans-serif"> Mohammed Rashad K M</font><div>
<font face="arial, helvetica, sans-serif"> M.S. (By Research) student<br>
Lab for Spatial Informatics<br> Department of CSE<br> International Institute of Information Technology</font></div><div><font face="arial, helvetica, sans-serif"> Hyderabad, India</font></div><br>
</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div><font face="arial, helvetica, sans-serif">Regards,</font></div><font face="arial, helvetica, sans-serif"> Mohammed Rashad K M</font><div><font face="arial, helvetica, sans-serif"> M.S. (By Research) student<br>
Lab for Spatial Informatics<br> Department of CSE<br> International Institute of Information Technology</font></div><div><font face="arial, helvetica, sans-serif"> Hyderabad, India</font></div><br>
</div></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div><font face="arial, helvetica, sans-serif">Regards,</font></div><font face="arial, helvetica, sans-serif"> Mohammed Rashad K M</font><div><font face="arial, helvetica, sans-serif"> M.S. (By Research) student<br>
Lab for Spatial Informatics<br> Department of CSE<br> International Institute of Information Technology</font></div><div><font face="arial, helvetica, sans-serif"> Hyderabad, India</font></div><br>
</div>