with render caching enabled the overview goes wild

[lutra]

Enable render caching in qgis options, then add a vector layer (I always use the "world borders" shape to make such tests) and then add the layer to the overview.

Many times, but not always, the overview immediately goes wild showing a wrong extent. If you then try resize the overview window it seems to fix the problem, but then you can notice empty spaces between the countries.

If the overview doesn't go immediately wild you can do the following: change symbology to the vector (old or new symbology doesn't matter), then remove the vector from the overview and add it again (to see the overview with the new symbology). Now the overview goes wild.

[smizuno]

For me, this problem always occurs with the sequence of events noted.

I have noticed that the overview map is drawn at the same scale as the main map, which led me to believe that the cached image is used. I tested this by using map data that takes a noticeable amount of time to retrieve. The overview map is drawn almost instantly when the overview is enabled for the layer. Also noticed that the upper left area of the main map is what is shown in the overview, including the buffer around the 'full extent'.

[lutra]

it seems that is still true with the actual trunk r14856.

After adding a layer it does not show in the overview window unless OTFR is activated. If you activate OTFR after having added the layer, then the overview show something but the canvas extent goes wild. In this case using "zoom to layer" does not help, it is needed to give a "touch" with the pan tool and the canvas extent return more or less normal.

If OTFR is activated before adding the layer (and adding it to the overview) then the overview shows the layer but very very small... basically useless... and there is no way to recover the situation, even trying with "zoom to layer" or other tools.

With render caching enabled the crashes when resizing the overview window are still confirmed... but this is another problem already described in another ticket.

[wonder]

Can you please try it out with the threading branch? The render caching problems should be gone there.

(But there are still some bugs which prevent me from merging the branch to trunk)

[lutra]

Hi Martin,

do I compile it as I do normally with trunk?

[lutra]

Replying to wonder:

Can you please try it out with the threading branch?

Hi Martin, confirmed, in the threading branch I don't see the problems described here and I don't get the crashes if resizing the overview window.

I really look forward for your commits fir this an many other reasons! thanks a lot.