Aseprite MCP Tools

Instructions

Implementation Reference

• aseprite_mcp/tools/export.py:76-147 (handler)

  The export_layers function is defined here, which validates inputs, builds a Lua script to export individual layers of an Aseprite file, and executes the script using the LuaBuilder utility.

  async def export_layers(
      filename: str,
      output_dir: str,
      format: str = "png",
      scale: float = 1.0
  ) -> str:
      """Export each layer of the sprite as a separate file.
  
      Args:
          filename: Name of the Aseprite file to export
          output_dir: Directory to save the exported layers
          format: Output format (default: "png")
          scale: Export scale factor (default: 1.0)
      """
      try:
          # Validate inputs
          file_path = validate_file_path(filename, must_exist=True)
          output_path = validate_file_path(output_dir, must_exist=True)
          format = validate_export_format(format)
          
          if not output_path.is_dir():
              raise ValidationError("output_dir", str(output_path), "Must be a directory")
          
          if scale <= 0:
              raise ValidationError("scale", scale, "Scale must be positive")
          
          # Build Lua script to export each layer
          builder = LuaBuilder()
          builder.open_sprite(str(file_path))
          builder.add_line('local spr = app.activeSprite')
          builder.if_condition('not spr')
          builder.add_line('error("No active sprite")')
          builder.end_if()
          builder.add_line()
          
          builder.add_line('local basename = app.fs.fileTitle(spr.filename)')
          builder.for_loop('i', 1, '#spr.layers')
          builder.add_line('local layer = spr.layers[i]')
          builder.add_comment('Hide all layers except current')
          builder.for_loop('j', 1, '#spr.layers')
          builder.add_line('spr.layers[j].isVisible = (i == j)')
          builder.end_loop()
          builder.add_line()
          
          # Export current layer
          output_template = str(output_path / f"{{basename}}_{{layer}}.{format}")
          builder.add_line(f'local outputFile = "{output_template}"')
          builder.add_line('outputFile = outputFile:gsub("{basename}", basename)')
          builder.add_line('outputFile = outputFile:gsub("{layer}", layer.name)')
          
          if scale != 1.0:
              builder.export_sprite('outputFile', scale)
          else:
              builder.add_line('spr:saveCopyAs(outputFile)')
          
          builder.end_loop()
          
          # Restore all layers visibility
          builder.for_loop('i', 1, '#spr.layers')
          builder.add_line('spr.layers[i].isVisible = true')
          builder.end_loop()
          
          # Execute script
          cmd = get_command()
          success, output = cmd.execute_lua_script(builder.build())
          
          return f"Layers exported successfully to {output_path}"
          
      except (ValidationError, AsepriteError) as e:
          return f"Failed to export layers: {e}"
      except Exception as e:
          return f"Unexpected error: {e}"