Make it easier to set up terrain

[bjorn]

Feedback from @therahedwig:

• Click dragging sides to be marker a color for example... I had hoped that if I were dragging over the top of tiles to mark all the top-parts with the color, it ended also doing the sides.
• There's no way to remove a single marking, only all colors on a single tile. I attempted clicking again, right clicking, middle clicking, ctrl+clicking etc.
• Hopefully we'll be able to "copy paste" wang tile configurations somehow from tileset to tileset, or at the least some kind of common preset to color tiles with.

Hopefully @Bdtrotte will still find some time to continue working on this, and otherwise I shall need to have a look before the 1.1 release.

[bjorn]

The only thing that was done regarding this issue is that you can now only remove single markings. It would still be nice, to improve the behavior when dragging while marking edges, as well as to be able to copy patterns across multiple tiles.

[eishiya]

Being able to copy terrains across tilesets would also be helpful. For example, this tileset and this tileset are very similar, it would be great to be able to copy+paste the terrains from one to the other and just change the terrain set and terrain names.
Currently, this can be done by copying data from one Tileset file to the other, or by creating the second tileset by copying the first, but that's not as intuitive.

Being able to select a group of tiles and have Tiled remap the colours in them would also be great for when you make mistakes. For example, say I have 4 terrain colours and I got two of them backwards on a subset of the tiles. I'd like to be able to select those tiles, replace all of Color 1 with Color 4 (let's say I'm not otherwise using that one on the tiles, so it's just a placeholder), then replace all of Color 2 with Color 1, and replace Color 4 (our placeholder) with Color 2. On mixed terrains especially, it can be easy to make mistakes like this, and it's punishing to fix them.

Being able to copy terrains within a tileset and replace colours in them would be great for labelling tilesets like the examples above, where the tiles follow specific layouts and only the colours differ.

Edit: In 2022 I wrote a script for copy+pasting terrains: https://github.com/eishiya/tiled-scripts/blob/main/CopyPasteTerrains.js
It allows copy+pasting terrains exactly, as well as copying a single terrain's labels and pasting them as another terrain.
While it would be great for Tiled to support this natively, since this script does exist, I think better tools for making an initial set of labels should be the focus.
One usability problem with the script is that you have to leave the Terrain editing mode to be able to change which tiles are selected for copy+pasting, and then of course you can't see the terrains any more xP Some way to select tiles while in Terrain mode would be a great help for this script, and would be a necessity if this feature were added natively.