[QGIS-Developer] Incremental drawing possible?

[Matthias Kuhn]

On 07/12/2017 12:57 AM, Nyall Dawson wrote:
> On 12 July 2017 at 06:21, Andreas Neumann <a.neumann at carto.net> wrote:
>> Hi Nyall,
>>
>> I compiled your branch / pull request. Quite impressive! I like it.
>>
>> Is it planned to land in master, or are there issues with this improvement?
> 
> Well - from my use case I consider it ready. But there's some
> outstanding questions which need solving (see the PR discussion):
> 
> - should this be normal behavior?
> - should it be enabled for all layer types? wmts only (as per
> sourcepole's original implementation)? local layers only (for those of
> us on crap/expensive internet connections)? rasters only? vectors
> only?
> - is the cpu utilisation for rendering these possibly unseen tiles an
> issue? or is cpu use so cheap nowdays that it's not a factor?
> - should the rendering of the adjacent tiles only begin when a pan
> starts? (would lose the zoom out benefits this brings, plus add a
> delay in showing the nearby area when pan starts>
> 
> My 2c: just enable it for everything and let everyone get the benefits
> without any configuration hassle. But... all my workstations are at
> least 4 cores and lots of memory. So I'm probably not in the best
> position to make this call ;)


Yes, I also think enabling this by default for all kinds of datasources
will be fine. If it turns out to be a problem on some systems we can
still react and either add a blacklist of providers and/or add
configuration options (well hidden away somewhere ;) )

We could also try to play with QThread::setPriority to keep resources
free for other processes that are keen to get them (on systems that do
support thread priority).

Thanks Sourcepole and Nyall!

Matthias


> 
> Nyall
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