Aseprite MCP Tools

Instructions

Implementation Reference

• aseprite_mcp/tools/palette.py:305-378 (handler)

  The remap_colors tool implementation which performs color mapping using Aseprite scripting.

  async def remap_colors(
      filename: str,
      color_map: Dict[str, str]
  ) -> str:
      """Remap colors in an Aseprite file.
  
      Args:
          filename: Name of the Aseprite file to modify
          color_map: Dictionary mapping old colors to new colors (e.g., {"FF0000": "00FF00"})
      """
      try:
          # Validate inputs
          file_path = validate_file_path(filename, must_exist=True)
          
          if not color_map:
              raise ValidationError("color_map", color_map, "Color map cannot be empty")
          
          # Validate all colors
          validated_map = {}
          for old_color, new_color in color_map.items():
              old_validated = validate_color(old_color)
              new_validated = validate_color(new_color)
              validated_map[old_validated] = new_validated
          
          # Build Lua script
          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()
          
          # Create color mapping table
          builder.add_line('local colorMap = {}')
          for old_color, new_color in validated_map.items():
              old_r, old_g, old_b = int(old_color[0:2], 16), int(old_color[2:4], 16), int(old_color[4:6], 16)
              new_r, new_g, new_b = int(new_color[0:2], 16), int(new_color[2:4], 16), int(new_color[4:6], 16)
              builder.add_line(f'colorMap[Color{{r={old_r}, g={old_g}, b={old_b}, a=255}}.rgbaPixel] = Color{{r={new_r}, g={new_g}, b={new_b}, a=255}}')
          builder.add_line()
          
          # Remap colors in all cels
          builder.begin_transaction()
          builder.for_loop('_, cel', 'ipairs(spr.cels)')
          builder.add_line('local img = cel.image:clone()')
          builder.add_line('local changed = false')
          builder.for_loop('y', 0, 'img.height - 1')
          builder.for_loop('x', 0, 'img.width - 1')
          builder.add_line('local pixel = img:getPixel(x, y)')
          builder.add_line('local newColor = colorMap[pixel]')
          builder.if_condition('newColor')
          builder.add_line('img:putPixel(x, y, newColor.rgbaPixel)')
          builder.add_line('changed = true')
          builder.end_if()
          builder.end_loop()
          builder.end_loop()
          builder.if_condition('changed')
          builder.add_line('cel.image = img')
          builder.end_if()
          builder.end_loop()
          builder.end_transaction()
          
          builder.save_sprite()
          
          # Execute script
          cmd = get_command()
          success, output = cmd.execute_lua_script(builder.build())
          
          return f"Successfully remapped {len(validated_map)} colors in {file_path}"
          
      except (ValidationError, AsepriteError) as e:
          return f"Failed to remap colors: {e}"
      except Exception as e:
          return f"Unexpected error: {e}"