[Qgis-developer] Rendering Real-Time Data in QGIS

[Chee Kiang Lim]

Hi,

I'm new to the QGIS API and have explored it very briefly. I am trying to
write a c++ plugin that will take in the locations of approximately
*100 vessels
and render their current position* (which varies with time)on top of an
underlying map. I used polygons to represent those vessels on a vector layer
using the memory provider. Each update involves deleting old features and
adding new ones followed by refreshing of mapcanvas triggered when changes
are committed. As there is a need to render updates at a high frequency for
real time display, with *positional data coming in at about 1-2Hz*, the
application was *too occupied refreshing the canvas*. This makes the
application unresponsive to subsequent user commands. I tried
using update(Rect of changedExtent) for localized painting/canvas refreshing
but the rendering is still too taxing. Can you provide some advice on how i
can go about rendering this huge amount of data in real time?

I also tried using rubberbands and they work much better but i need to
display text attributes beside each vessel which i do not know how to
achieve without labels. Any alternative to rendering text at specific map
location that i can update in real time?

Your help is very much appreciated. Thank you.
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