Aseprite script to convert all open sprite sheets into sliced sprite sheets

BulkImportSpriteSheets.lua

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--Bulk Import Sprite Sheets -- v0.1
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--[[Instructions:
1. Open your sprite sheets in Aseprite.
2. Close any files that you do not wish to slice/import as sprite sheets (this process will be applied to all open files!)
3. Open the script
4. Enter your desired settings, some are optional
5. Click Import
6. Wait until the process finishes
7. You're done!
--]]

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-- Internal functions
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--Receives a string, returns an int from the enum (idk if Lua supports actual enums but whatever)
--ref: https://github.com/aseprite/api/blob/main/api/spritesheettype.md#spritesheettype
local function GetType(str)
	local _type = 0

	if str == "Horizontal Strip" then
		_type = SpriteSheetType.HORIZONTAL
	elseif str == "Vertical Strip" then
		_type = SpriteSheetType.VERTICAL
	elseif str == "By Rows" then
		_type = SpriteSheetType.ROWS
	elseif str == "By Columns" then
		_type = SpriteSheetType.COLUMNS
	end

	return _type
end

--Receives a table with the dialog data (dlgData or dlg.data), returns a rectangle object with the entered dimensions
--ref: https://github.com/aseprite/api/blob/main/api/rectangle.md
local function GetRectangleObj(t)
	return Rectangle(t.x, t.y, t.width, t.height)
end

--Receives a table with the dialog data (dlgData or dlg.data), returns a size object with some padding (equal to zero if the padding checkbox is disabled)
--ref: https://github.com/aseprite/api/blob/main/api/size.md#size
local function GetSize(t)
	if t.padding == false then 
		return Size(0, 0) 
	else 
		return Size(t.hor, t.ver) 
	end
end

--[[Calls the ImportSpriteSheet app.command
@params: 
  - t = dialog's data table
  - rect = Rectangle object, usually from GetRectangle
  - size = Size object, equal to Size(0, 0) if the padding checkbox is disabled
--ref: https://github.com/aseprite/api/blob/main/api/command/ImportSpriteSheet.md#importspritesheet
--]]
local function DoImport(t, rect, size)
	app.command.ImportSpriteSheet {
		ui = false,
		type = GetType(t.type),
		frameBounds = rect,
		padding = size,
		partialTiles = t.partial
	  }
end

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-- Dialog/UI
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local sheetTypes = { "Horizontal Strip", "Vertical Strip", "By Rows", "By Columns" }

local dlg = Dialog("Import multiple sheets")

dlg
	:combobox{ id = "type", label = "Type:", option = "By Rows", options = sheetTypes }
	:separator()
	:number{ id = "x", label = "X:", decimals = integer, }
	:number{ id = "y", label = "Y:", decimals = integer, }
	:newrow()
	:number{ id = "width", label  = "Width:", decimals = integer, }
	:number{ id = "height", label = "Height:", decimals = integer, }
	:check{ id = "padding", text = "Padding", selected = false, 
		onclick = function() 
			dlg:modify{id = "hor", visible = dlg.data.padding } 
			dlg:modify{id = "ver", visible = dlg.data.padding } 
		end }
	:number{ id = "hor", label = "Horizontal:", decimals = integer, visible = dlg.data.padding }
	:number{ id = "ver", label = "Vertical:", decimals = integer, visible = dlg.data.padding }
	:check{ id = "partial", text = "Include partial tiles at bottom/right edges", selected = false }

	:button{ id = "import", text = "&Import", 
		onclick = function() 
			local dlgData = dlg.data
			local n = #app.sprites
			if n == 0 then
				return app.alert ("No open sprites were found! (Open only the files you want to slice/import)")
			end

			local rectObj = GetRectangleObj(dlgData)
			if rectObj.isEmpty then
				return app.alert ("The width and height fields cannot be equal to 0 nor can be empty")
			end

			local sizeObj = GetSize(dlgData)
			--iterate through the open sprites. Since app.command relies on the open sprite, we set activeSprite with each sprite in the array, then run the command and move on
			for i, sprite in ipairs(app.sprites) do
				app.activeSprite = sprite
				DoImport(dlgData, rectObj, sizeObj)
			end

			app.alert("Imported " .. n .. " sprite sheets")
			dlg:close()
		end }
	:button{ id = "cancel", text = "&Cancel", onclick = function() dlg:close() end }

dlg:show{ wait = false }