Don't modify source TileMap TileSetAtlasSource when copying between scenes

[rakkarage]

Closes: #83218

This fixes the issue by effectively reversing some changes from #78477 for internal tilesets. and fixing it another way.

I am unsure exactly when it is the right time to delete the source from the old tilemap so maybe these conditions are wrong but seems to work.

EDIT: TODO: need to ensure this issue is not "unfixed". which it seems to be now? #77045 (ya condition must be wrong as that example uses internal tileset too.)

Thanks.

[groud]

Hey, thanks for trying to fix the issue.

I am not sure this is the right way to fix the problem. Whatever happens, a TileSetSource should always be used by a single TileSet. I feel the issue is that copy-pasting a TileMap duplicates the TileSet resource while it should not, or something like that, because there's no reason copy-pasting a TileMap would cause its TileSet's sources to be duplicated.

[rakkarage]

Thanks.
Old fix seems to act as a toggle between this bug and that bug.
This seems to fix both. Removing old fix, and calling TileData.set_tile_set in TileMapLayer.get_cell_tile_data instead.

no reason copy-pasting a TileMap would cause its TileSet's sources to be duplicated.

I can understand why this is true for external (all point to same) TileSet, but not internal (each needs own)?
Idk.

[KoBeWi]

Copy pasting node will duplicate all built-in resources, because they can't be shared between scenes.

If the problem is that the new TileSet uses old sources, maybe the sources should be always duplicated? duplicate() is virtual, so TileSet can implement its own. Or they could use PROPERTY_USAGE_ALWAYS_DUPLICATE flag.

[groud]

If the problem is that the new TileSet uses old sources, maybe the sources should be always duplicated? duplicate() is virtual, so TileSet can implement its own. Or they could use PROPERTY_USAGE_ALWAYS_DUPLICATE flag.

Oh ok, I did not know that there was a situation where duplicating a node would duplicate its resources automatically too. So, yes, that seems to be a good solution. PROPERTY_USAGE_ALWAYS_DUPLICATE may be enough I believe, but if it does not work, implementing a TileSet::duplicate would work too.

[rakkarage]

"calling TileData.set_tile_set in TileMapLayer.get_cell_tile_data instead fixes both issues"? no?

How does old fix work to fix the null tile_set error in cell_tile_data? Delete atlas? Try doing this instead... there is no problem, it works fine.

Excuse my ignorance...
Thanks.

[akien-mga]

Superseded by #88280. Thanks for the contribution!