[QGIS-Developer] QGIS WMS provider firing too many requests !?

[Jeff McKenna]

On 2021-02-25 3:24 p.m., Richard Duivenvoorde wrote:
> On 2/13/21 8:01 PM, pathmapper wrote:
>> Hi,
>>
>> here's a related thread (i.e. xyz tiles, but I guess it's also valid vor wms):
>> https://github.com/qgis/QGIS/issues/34813
>>
>> Some quotes:
>> "QGIS renders the surrounding areas in a background job to make subsequent pan actions faster. Therefore it sends more tile requests than necessary for the current map extent."
>>
>> "Btw, we now have the code in place to fine-tune prefetching behavior for all raster layers on a per-layer basis, for now I just blacklisted osm tiles."
>>
>> It sounds like the plan is to make the prefetching behavior configurable via QGIS settings.
> 
> See https://github.com/qgis/QGIS/pull/41832 to prevent prefetching for true WMS's...
> 
> Now I like to have some input indeed making prefetching behaviour more configurable:
> 
> - where to put a checkbox/setting about prefetching tiles (global raster, or per wms service or just global, or a hidden setting)?
> - what to make default (with or without prefetching...?)
> 
> My first idea:
> - add a checkbox "Prefetch surrounding WMS(T) images" in the WMS/WMTS Connection dialog in the 'WMS/WMTS Options' section; default FALSE (unless see below)
> - In General Options / Network / Cache Settings add a  tab or just a checkbox with "Default prefetch WMS(T) images" (defaulting to FALSE, but if enabled the above mentioned checkbox will always be enabled too)
> - also make this an option in the provider uri

I really like that Richard, since I am always in the 
Settings/Options/CacheSettings to clear my cache anyway (as I am 
constantly changing already-parsed WMS services), having a checkbox in 
the "Content" tab of "Default prefetch WMS(T) images" (default to false) 
makes sense.

I also like having a checkbox in the WMS/WMTS dialog, in the 'Options' 
section near bottom, defaulting to false.

(so I'm in total agreement to both your proposals, ha)

Big thanks from the east coast of Canada!

-jeff


-- 
Jeff McKenna
GatewayGeo: MapServer Consulting and Training Services
co-founder of FOSS4G
http://gatewaygeo.com/