[josm-dev] Automatic tiles downloading in WMSPlugin

[Bodo Meissner]

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Petr Dlouhý wrote on 28.08.2008 15:51:

> Ok, I implemented save and load (bud I doubt, if it is usefull).

I think loading the images from a file must prevent the plugin from
downloading the images again. It might even be useful to optionally
switch off the automatic downloading when I know I already have the area
i'm interested in.

> I also  
> implemented grabber choosing through getGrabber(), but to get OSGBGrabber  
> working, it needs to be rewriten to thread support.

Does the plugin download several tiles at the same time? I hope this
does not place too much load on the servers.
Even with the old WMS plugin the Landsat WMS server was sometimes very
slow or down because of overload. If the load gets higher this might
annoy the people who run a WMS server.

> The new version could be downloaded from:
[...]

I will be in holidays for the next two weeks. That's why I don't have
time to test it now.

> 
> I don't like waiting before the tiles get loaded, it would be very tiring.

If there was a configurable delay you could set the delay to 0 to get
the tiles downloaded immediately. I, personally, would set the delay to
something like 2 seconds

> The tiles are downloaded only if it's zoomed enough, so if you want to  
> look around without downloading new tiles, then just zoom out a little. I  
> found that very intuitive.

I do not want to look around but move the display to the next place to
work on. When I stop at some place only to release the mouse button,
move the mouse to the other end of the screen and then press the button
again, there is no need to start downloading this tile.

I think I had to zoom out very much to stop the automatic downloading.

Regarding zoom and automatic downloading I see a different problem.
I know one WMS server that returns white images if I zoomed in too much.
Normally I zoom out enough before manually downloading images, then I
zoom in to draw or check objects. In this zoom level I do not want any
downloads because it would fill the area with white images. To prevent
this problem with your plugin I would need a server specific limit for
the zoom level or image resolution. When I have zoomed in too much the
plugin should either not download any tiles or download tiles with the
maximum resolution available for this server.


Bodo

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