Hi Paul,
as discussed in the ticket, a "random" tiled preview would be slower, not
faster, than the single tile one, because
it won't hit a tile cache and will end up drawing a larger image (768x768
vs 768x300).
Issues in the preview that prevent tile caching:
- The bounds are the ones of the layer and the tile grid is aligned to
them (not to a gridset)
- The CRS is the native one of the layer, which might or might not be
cached (e.g., often only 3857 and 4326 are tile cached)
- The zoom levels are typically not a match for the gridset
The GWC preview instead is setup based on the chosen gridset, and its code
is quite different from the one of the normal preview.
I would not go for having a "tiled" option, on master we already have a
choice between OL2 and OL3 (see previous discussion on
this list on why OL3+ is sometimes problematic), if we go for tiled and
untiled we'd end up with 4 options, and as seen above,
for no gain in the common case.
Modest proposition: why, instead of having one more option, don't we expose
the tiled layer page to the public, maybe hiding
the admin related portions (info about disk quota, blobstore, seeding).
Something like this:
[image: Inline image 1]
At least this would have guarantee it is being cached, and thus "fast" (if
the cache is not full, it's actually
going to be slower than then normal preview at the first hit, because the
meta-tiling factor
is even higher than with the standard preview, 4x4 by default, but many
pump it up to a higher value).
Cheers
Andrea
On Mon, Nov 27, 2017 at 3:10 PM, Paul Wittle via Geoserver-devel <
[email protected]> wrote:
> Hi,
>
>
>
> I think I said I would try to move this discussion to the dev list; not
> sure if that is the right method but here we go anyway.
>
>
>
> The basic comments appear to be summarised as follows:
>
>
>
> -> I have noticed that some of our layers are very slow loading in the
> layer preview and I would usually switch it straight to cache mode. On this
> basis and in discussion with Ian T we raised the ticket 8413 to suggest
> that tiled ‘might’ be a preferable starting situation.
>
> -> Andrea noted that in some cases it is preferable to use single tiles
> due to labelling etc. Suggested a configuration option instead of default?
>
> -> Jukka noted that the default map window is 768x330 so the single tile
> request may not actually be that much different
>
> -> Andrea noted that the default tiled map is 3x3 which is actually an
> area of 768x768 in reality.
>
>
>
> So in terms of the comments I do take the point that the area requested
> may be actually smaller in terms of the data behind the scenes but I had
> primarily raised the issue on the basis if the general feeling when using
> the layer preview. In my view the point of tiling is primarily to ensure
> that the user can see the data loading rather than waiting for the single
> render. I do accept the points raised but I do still feel there may be some
> benefit in allow the user to decide.
>
>
>
> I think Andrea was indicating that the tiles may not actually come from
> the tile cache but my understanding is that this would be the case if you
> open the links via the Tile Layers screen.
>
>
>
> Primarily I had added this one as I hoped it might be something very
> simple that I could look at whilst I’m learning to be a contributing
> developer but of course I will be guided by your views.
>
>
>
> Could we just add an extra option to the dropdown list as OpenLayers is
> already duplicated in that list?
>
>
>
> The proposal would simply be to add OpenLayers (Tiled) as an option in the
> UI.
>
>
>
> Cheers,
>
> Paul
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--
Regards,
Andrea Aime
==
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