Fix multiple issues with 'add alternative tile' tileset editor button

[olanti-p]

Fix multiple issues with 'add alternative tile' tileset editor button in "Alternative tiles" section:

1. Fix button being oversized and not rendered properly on small (texture region size < 12px) tilesets (fixes In tileset editor, attempting to paint terrain over alternative tile instead creates a new alternative tile #99764)
2. Stop button from interfering with MMB panning
3. Fix undo not working on tiles created with this button
4. Stop the button from appearing while painting tile properties

The undo doesn't undo increments in next_alternative_id counter within TileSetAtlasSource, but that's an existing issue that also happens when creating alternative tiles via RMB.

Before/after:

[groud]

The commits should likely be squashed, but aside from that, looks good to me.

[KoBeWi]

Suggested change

	// FIXME: doesn't undo changes to `next_alternative_id` counter
	// FIXME: Doesn't undo changes to `next_alternative_id` counter.

It just means that some alternative IDs will be skipped when you undo and make them again, no?

[olanti-p]

Correct. I mention it because the counter is saved, so a sequence of user actions "create tile"->"undo"->"save" produces an unexpected change in the resource file. Intuitive behavior would be to leave no evidence of undone change.

[KoBeWi]

Actually there is some error spam when creating new alternate tiles

ERROR: No cached rect for tile coords:(1, 2) alternative_id:5
   at: (C:\godot_source\editor/plugins/tiles/tile_atlas_view.cpp:585)
ERROR: No cached rect for tile coords:(1, 2) alternative_id:5
   at: (C:\godot_source\editor/plugins/tiles/tile_atlas_view.cpp:585)
ERROR: No cached rect for tile coords:(1, 2) alternative_id:5
   at: (C:\godot_source\editor/plugins/tiles/tile_atlas_view.cpp:585)
ERROR: No cached rect for tile coords:(1, 2) alternative_id:6

Probably related to the ID problem you mentioned.

[olanti-p]

Actually there is some error spam when creating new alternate tiles

That seems to happen whenever an alternative tile is created while painting any kind of property.

I'm not sure how to fix these errors, but I could make it so the button is disabled while "Paint" tab is active, and user can't create alternative tiles while painting properties. Would such solution be fine?

Edit: this would be consistent with how alternative tiles can be created via RMB only in "Setup" and "Select" tabs, but not "Paint" tab.

[KoBeWi]

@groud ^

[groud]

I'm not sure how to fix these errors, but I could make it so the button is disabled while "Paint" tab is active, and user can't create alternative tiles while painting properties. Would such solution be fine?

Well, in theory, the create alternative button should only be visible in the "setup" tab. That's where you define tiles and their alternatives.

[olanti-p]

Applied suggested changes, and also stopped the button from appearing in "paint" tab.

Well, in theory, the create alternative button should only be visible in the "setup" tab. That's where you define tiles and their alternatives.

At this moment the UI already allows creating and deleting tiles (both base and alternative) in both "setup" and "select" tabs with RMB, and entire alternative tile config has to be done in "select" tab anyway, so stopping the button from appearing in "select" tab feels unnecessarily restrictive. Although if that's something still wanted, I'll change it.

[groud]

At this moment the UI already allows creating and deleting tiles (both base and alternative) in both "setup" and "select" tabs with RMB, and entire alternative tile config has to be done in "select" tab anyway, so stopping the button from appearing in "select" tab feels unnecessarily restrictive. Although if that's something still wanted, I'll change it.

Well, in the "select" mode I think it kind of make sense to make it a bit more difficult to create tiles, as a missclick could easily happen and would maybe be a bit annoying. You can create alternatives there with right click too (though I think the option to create a new alternative should be available in the dropdown menu of alternative tiles too).

In any case, I don't really have a strong opinion on that, so if others want the button, I guess it makes sense to add it there.

[KoBeWi]

I tested the updated version and it works in both Setup and Select modes without errors, so it's fine.

[Repiteo]

Thanks! Congratulations on your first merged contribution! 🎉