[Qgis-developer] Questions about labels and animation in QGIS

[Hugo Mercier]

Hi,

On 09/11/2015 07:20, 151612463 wrote:
> Hi,
> I'm new to QGIS, and I want to use QGIS to develop a software to show
> and editing flight tracks. My development environment is as follow:
> 1 Windows 7
> 2 Qt4.8.6
> 3 QGIS2.4(Build from sourcecode).

Why not a more recent version ?

> I have displayed vector and raster in a canvas(QgsMapCanvas)
> successfully, but I don't know how to show labels in QGIS and how to
> animate them.
> I used to do the same job in MapX. In MapX, a user drawing layer is
> provided to decrease CPU usage when some elements must be refreshed
> frequently. However, it seems like that QGIS doesn't provide such layer,
> so how to animate a moving track without refreshing the whole map? 
> A colleage use a QWidget window to draw the labels and the QWidget
> window overlays on the canvas(QgsMapCanvas). By this method, he can draw
> anything he want in the QWidget window and refresh the elements. But I
> feel that this is not the recommended way in QGIS. Is there any better
> way to achieve the requirements?
> 
> Can anyone tell me how or provide development documents to refer to? Thanks.

If I understand correctly your needs: you need to animate a layer with
labels and you don't want all the layers to be refreshed at each frame ?
For performance reasons ?
How many layers have labels ?