Tile grid decoration

[joto]

Feature description

I often work with (raster or vector) tiles in QGIS and want to know where tile boundaries are and what tile coordinates the visible tiles have. I would like to have a map decoration similar to the existing grid, but with tile grid and tile coordinate labels.

Additional context

I have implemented a proof-of-concept of this based on the existing grid map decoration. I will provide a PR with the implementation if you want to test this.

The current implementation provides

• A configuration dialog
• Grid display with lines or markers
• Optional display of tile coordinates in the middle of tiles
• Either display dynamic grid based on visible extent (set zoom level to 0 in config dialog) or fixed to a specified zoom level (set zoom in config dialog)

The current implementation is not finished:

• Works only in EPSG:3857 (with anything else it just does nothing)
• No check against some boundary conditions (too far zoomed in or out)
• Dynamic vs. static zoom level configuration could be better
• It is not clear which zoom level to show with dynamic setting (configurable?)
• Load/save of settings are untested
• Is it good to have this as an extra decoration or should we fold this into the existing grid decoration?
• Do we need the coordinate display configurable?
• Display of coordinates at view port boundaries instead of in the middle of tiles?

Here are some screen shots:

I'd be interested in feedback, especially on

• whether this is generally a good idea
• the implementation as a (separate) decoration is a good idea
• the display looks okay or what other ideas people have

[joto]

I have some new features and the code is much better. Load/save works. More settings.

Here is how the dialog looks now:

Here is how it looks with the coordinates on the canvas border:

I have created a new PR #46200, because the old one was auto-closed.

Still have no idea how to get this into a plugin...