Allow paintable deletion

paintable.lua

@@ -292,8 +292,12 @@ function def:on_activate()
 	end, true)
 end
 
--- TODO (engine change needed) remove directory using `minetest.rmdir(self:_get_dir_path())` on object removal
+-- TODO (engine change needed) call this on object removal
 -- See https://github.com/minetest/minetest/pull/11931
+function def:_delete()
+	epidermis.mark_for_deletion(self._.id)
+	self.object:remove()
+end
 
 function def:_get_intersection_infos(mt_pos, mt_direction)
 	local intersection_infos = {}
@@ -404,7 +408,7 @@ function def:_show_control_panel(player)
 	end
 	local backface_culling = self._.backface_culling
 	epidermis.show_formspec(player, table.concat{
-		"size[5.5,1,false]",
+		"size[6.25,1,false]",
 		"real_coordinates[true]",
 		image_button(true, 0.25, "backface_culling", (backface_culling and "backface_visible" or "backface_hidden"),
 			(backface_culling and "Show" or "Hide") .. " back faces"),
@@ -415,7 +419,8 @@ function def:_show_control_panel(player)
 		image_button(false, 2.75, "preview_texture", "checker", "Open texture preview"),
 		image_button(false, 3.5, "upload", "upload", "Upload to SkinDB"),
 		image_button(false, 4, "download", "download", "Pick from SkinDB"),
-		image_button(true, 4.75, "close", "cross", "Close"),
+		image_button(false, 4.75, "delete", "bin", "Delete"),
+		image_button(true, 5.5, "close", "cross", "Close"),
 	}, function(fields)
 		if fields.backface_culling then
 			self:_set_backface_culling(not self._.backface_culling)
@@ -434,6 +439,8 @@ function def:_show_control_panel(player)
 			end)
 		elseif fields.preview_texture then
 			self:_show_texture_preview(player)
+		elseif fields.delete then
+			self:_show_delete_formspec(player)
 		elseif fields.upload then
 			self:_show_upload_formspec(player)
 		elseif fields.download then
@@ -461,6 +468,22 @@ function def:_show_texture_preview(player)
 	end)
 end
 
+function def:_show_delete_formspec(player)
+	epidermis.show_formspec(player, table.concat{
+		"size[6,1,false]",
+		"real_coordinates[true]",
+		"label[0.25,0.5;Irreversably delete paintable?]",
+		"image_button_exit[4.75,0.25;0.5,0.5;epidermis_check.png;confirm;]";
+		"tooltip[confirm;Confirm]",
+		"image_button_exit[5.25,0.25;0.5,0.5;epidermis_cross.png;close;]",
+		"tooltip[close;Close]",
+	}, function(fields)
+		if fields.confirm then
+			self:_delete()
+		end
+	end)
+end
+
 function def:_show_upload_formspec(player, message)
 	local context = {}
 	epidermis.show_formspec(player, table.concat{

persistence.lua

@@ -55,31 +55,48 @@ end)
 -- Remove unused textures & store highest texture ID
 local epidermi_texture_path = epidermis.paths.dynamic_textures.epidermi
 for _, dirname in ipairs(minetest.get_dir_list(epidermi_texture_path, true)) do
+	local dir_path = concat_path{epidermi_texture_path, dirname}
 	local highest_number
 	local last_filename
+	local used = false
 	local function remove_if_unused(filename)
-		if not used_textures[filename] then
-			assert(os.remove(concat_path{epidermi_texture_path, dirname, filename}))
+		if used_textures[filename] then
+			used = true
+		else
+			assert(os.remove(concat_path{dir_path, filename}))
 		end
 	end
-	for _, filename in ipairs(minetest.get_dir_list(concat_path{epidermi_texture_path, dirname}, false)) do
-		local number = filename:match("^" .. modlib.text.escape_magic_chars(dirname) .. "_(%d+)%.png$")
-		if number then
-			number = tonumber(number)
-			if last_filename then
-				if number > highest_number then
-					remove_if_unused(last_filename)
+	local filenames = minetest.get_dir_list(dir_path, false)
+	local delete = modlib.table.contains(filenames, "delete")
+	if delete then
+		-- Move deletion marker to end through a swap so that it is deleted last
+		filenames[#filenames], filenames[delete] = filenames[delete], filenames[#filenames]
+	end
+	for _, filename in ipairs(filenames) do
+		if delete then
+			remove_if_unused(filename)
+		else
+			local number = filename:match("^" .. modlib.text.escape_magic_chars(dirname) .. "_(%d+)%.png$")
+			if number then
+				number = tonumber(number)
+				if last_filename then
+					if number > highest_number then
+						remove_if_unused(last_filename)
+						highest_number = number
+						last_filename = filename
+					else
+						remove_if_unused(filename)
+					end
+				else
 					highest_number = number
 					last_filename = filename
-				else
-					remove_if_unused(filename)
 				end
-			else
-				highest_number = number
-				last_filename = filename
 			end
 		end
 	end
+	if not used and (delete or #filenames == 0) then
+		assert(os.remove(dir_path))
+	end
 end
 
 function epidermis.get_epidermis_path(paintable_id, texture_id)
@@ -117,6 +134,14 @@ function epidermis.write_epidermis(paintable_id, texture_id, raw_png_data)
 	return path, texture_name
 end
 
+function epidermis.mark_for_deletion(paintable_id)
+	assert(modlib.file.write_unsafe(concat_path{
+		epidermi_texture_path,
+		("epidermis_paintable_%d"):format(paintable_id),
+		"delete"
+	}, ""))
+end
+
 -- SkinDB
 
 function epidermis.write_skindb_skin(id, raw_png_data, meta_data)