OpenSCAD surface export plugin for Gimp

#!/usr/bin/env python

# openscad_surface_export.py
# by Rob Antonishen
# http://ffaat.pointclark.net
#
# Version 1.0 (20120907)
#
# Description
# File save handler for openscad dat format
# Borrows heavily from colorxhtml.py
#
# Changes
#
# License:
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# The GNU Public License is available at
# http://www.gnu.org/copyleft/gpl.datfile

import struct
import datetime
import gimp
from gimpfu import *

gettext.install("gimp20-python", gimp.locale_directory, unicode=True)

def save_openscad_dat(img, drawable, filename, raw_filename):
    width = drawable.width
    height = drawable.height
    bpp = drawable.bpp

    gimp.tile_cache_ntiles(width / gimp.tile_width() + 1)

    fileOut = file(filename,"w")

    pr = drawable.get_pixel_rgn(0, 0, width, height, False, False)

    gimp.progress_init(_("Saving as OpenSCAD .dat file"))

    fileOut.write("# Created by gimp plugin openscad_surface_export.py, %s\n" % datetime.datetime.strftime(datetime.datetime.now(), "%c"))
    fileOut.write("# Name: %s\n" % img.name)
    fileOut.write("# type: matrix\n")
    fileOut.write("# Rows: %s\n" % height)
    fileOut.write("# Columns: %s\n" % width)

    for y in range(height-1, -1, -1):
        row = pr[0:width, y]
        for pixel in RowIterator(row, bpp):
            if drawable.is_gray:
                pixval = pixel[0]
            else:
                pixval = (pixel[0] + pixel[1] + pixel[2]) / 3
            fileOut.write(" %s" % str((pixval-128.0)/256.0))
        fileOut.write("\n")
        gimp.progress_update((height-y) / float(height))

    fileOut.close()

class RowIterator:
    def __init__(self, row, bpp):
        self.row = row
        self.bpp = bpp

        self.start = 0
        self.stop = bpp

        self.length = len(row)
        self.fmt = 'B' * bpp

    def __iter__(self):
        return iter(self.get_pixel, None)

    def get_pixel(self):
        if self.stop > self.length:
            return None

        pixel = struct.unpack(self.fmt, self.row[self.start:self.stop])

        self.start += self.bpp
        self.stop += self.bpp

        return pixel

def register_save_dat():
    gimp.register_save_handler("file-openscad-save", "dat", "")

register(
        "file-openscad-save",
        N_("Saves an OpenSCAD surface dat file."),
        "Saves an OpenSCAD surface dat file.",
        "Rob Antonishen",
        "Rob Antonishen",
        "2012",
        N_("OpenSCAD Surface"),
        "RGB, GRAY",
        [
            (PF_IMAGE, "image", "Input image", None),
            (PF_DRAWABLE, "drawable", "Input drawable", None),
            (PF_STRING, "filename", "The name of the file", None),
            (PF_STRING, "raw-filename", "The name of the file", None),
        ],
        [],
        save_openscad_dat, on_query=register_save_dat,
        menu="<Save>", domain=("gimp20-python", gimp.locale_directory))
main()