Support TILED WMS parameter

[BathoryPeter]

QGIS supports the non standard TILED=TRUE which instructs the rendering engine to add a buffer around the requested box.
Documentation: ​https://docs.qgis.org/3.34/en/docs/server_manual/services/wms.html#wms-tiled

Since JOSM queries WMS in tile grid, anomalies may appear at tile boundaries in some cases (eg. for long texts).
For example check the "Magyar Közút / Buszmegállók" layer of WMS ​https://map.cartographia.hu/wms/osm-kozut somewhere in Hungary.

I recommend always sending &TILED=TRUE parameter for GetMap requests.

[BathoryPeter]

"Buszmegállók" WMS layer in JOSM

[BathoryPeter]

With &TILED=true

[stoecker]

As all imagery URLs are specified in the wiki and thus the URL is decided by the entry there is no need for special handling. TILED=TRUE can be added there. For the WMS adding feature in JOSM I don't see much sense in adding a non-standard parameter to work around a consistency issue in the software. As far as I see this "TILED=true" will only reduce the most obvious problem of that way of imagery generating, not fix it entirely.

[BathoryPeter]

JOSM is what makes WMS request in an unconventional way. Most of the WMS clients requests full screen images, where out of screen texts and decorations are not a problem. JOSM's tiled approach is good, but WMS servers are not prepared for this by default.

I checked that adding ?TILED=true to WMS endpoint works in GetMap requests, just the generated url contains & duplicated: …?TILED=true&&FORMAT=image/png&…