#!/usr/bin/env python
#
# Line Width, v. 1.5 Python-fu GIMP plugin.
# June, 2013.  Under Gnu Public License current at that date.
# This version July, 2013.
# Python-fu Gimp script by Michael B. Stevens

# CHANGES in v. 1.4:
# New user-setting for Temporary-Enlargement size.
# That is the size the image gets enlarged-to while being blurred.
# A "elg" sized thresholding is uded to make the line heavier
# or lighter.
# Size of upper threshold for speed-of-line-change is tweaked.

# CHANGES in v. 1.5:
# Now operates on a new layer that is a copy of the visible image.
# So now you can compare old and new line widths by clicking
# on-and-off visibility of the new layer, and you can simply
# dump the new layer if you don't like what you got.
# Also, the undo is now grouped and there is better error checking.
#
#
# TIPS:
# 
# Try starting with low settings of speed of change and repeats.
# The image in use will have its own requirements.
# Running plug-in multiple times is OK.  Experiment.
#
# A LOW temporary-enlargement multiplier
# ("Temp. enlargement multiplier") allows a run with
# large images in available memory
# and  in a reasonable amount of time.
# HIGHER enlargement settings give somewhat better line quality
# at the expense of program speed.
# High enlargement settings with large image use a _lot_ of memory.
# I suggest you crank down the enlargement multiplier setting.
# But you can also go to GIMP's settings menus at
# <Image>/Edit/Preferences/Environment, and increase the
# cache and undo level memory.
#
# INSTALL:
# Python must be on your system.
# Put this plugin file into ".gimp-2.8" folder's "plug-ins" folder.
# Make sure the file has executable permissions.
# Restart GIMP.  The plugin will appear under the
# "<Image>/Filters" menu as "Line Width".
#
# Tested in GIMP 2.8.  May not run on earlier versions.
#
# Use RGB  or RGBA images.

# WARNING BOILERPLATE:
# This software is provided free under GNU public license without
# any guarantee:  Use at your own risk.




from gimpfu import *

def linewidth(  img, drw, elg, speed, repeats, start ):
    """ Adjust line thickness in b&w RGB or RGBA line art."""
    pdb.gimp_image_undo_group_start(img)
    try:
        w = pdb.gimp_image_width(img)
        h = pdb.gimp_image_height(img)
        lr = pdb.gimp_layer_new_from_visible(img, img, "TweakedLines")
        pdb.gimp_image_insert_layer(img, lr, None, -1)
        pdb.gimp_layer_scale(lr, w*elg, h*elg, FALSE)
        for i in range(int(repeats)):
            pdb.plug_in_blur( img, lr)
            if start == 0:
                pdb.gimp_threshold( lr, 195 + int(speed) , 255 )
            elif start == 1:
                pdb.gimp_threshold( lr, 61 - int(speed) , 255 )
            else:
                pdb.gimp_message("Direction value not specified!")
            pdb.plug_in_antialias(img, lr)
        pdb.gimp_layer_scale(lr, w, h, FALSE)
        pdb.plug_in_antialias( img, lr)
    except StandardError:
        pdb.gimp_message("Python StandardError.  Try other settings.")
    pdb.gimp_image_undo_group_end(img)


register(
    "line-width", # no spaces in procedure database string!
    "Adjust width of lines in black & white line art",
    "RGB or RGBA images",
    "Michael B. Stevens",
    "copyright (C) Michael B. Stevens under Gnu Public License",
    "May 2013, v. 1.5 August 2013",
    "<Image>/Filters/Line Width",
    "RGB, RGBA",
    [
      (PF_SLIDER, "elg", "Temp. enlargement multiplier", 3, (1, 8, 1)),
      (PF_SLIDER, "speed",   "Speed of Change",   10,  (1, 60, 1)),
      (PF_SLIDER, "repeats", "Repeats",           1,  (1, 10, 1)),
      (PF_RADIO, "start","Direction:",0, (("Narrow", 1),("Widen",0)))
    ],
    [],
    linewidth
    )

main()