#!/usr/bin/env python

# This is a GIMP script written in Python for putting an outline around text (or indeed anything
# else).
#
# To use this script, make sure that the selected layer is the one that you want to outline, then
# choose "Text Outliner" from the "Layer" menu.
#
# You will then be able to set various parameters for the outline. They are:
#       Thickness - thickness of the outline (in pixels)
#       Feather - how soft you want the edge of the outline to be
#
# The script will create a new, transparent layer underneath your selected layer filled with
# the background color. Then the text layer will merge down onto the outline layer and will
# add a new animstack tag with the original layer name.

from gimpfu import *

# Adds a new layer beneath the given layer. Return value is the new layer
def add_new_layer_beneath(image, layer):
    # Get the layer position.
    pos = 0;
    for l in image.layers:
        if (l == layer):
            break
        else:
            pos += 1

    if image.base_type is RGB:
        type = RGBA_IMAGE
    else:
        type = GRAYA_IMAGE

    # Add a new layer below the selected one
    title = layer.name + ' [fg>' + layer.name + ']'
    new_layer = gimp.Layer(image, title, image.width, image.height, type, 100, NORMAL_MODE)
    image.add_layer(new_layer, pos+1)
    return new_layer

# Selects the contents of the given layer, then grows it by "thickness"
# and feathers it by "feather" pixels
def create_selection(image, layer, thickness, feather):
    # Select the text
    pdb.gimp_selection_layer_alpha(layer)

    # Grow the selection
    pdb.gimp_selection_grow(image, thickness)

    # Feather it
    if (feather > 0):
        pdb.gimp_selection_feather(image, feather)
    return

# Fills the current selection using the given colour, painting onto the
# given layer.
def fill_selection(layer):
    # Fill the selection using the background color
    pdb.gimp_bucket_fill(layer, 1, 0, 100, 0, 0, 1, 1)
    return

def merge_down(image, layer):
    # Merge the existing layer down. Second argument is GimpMergeType:
    # https://developer.gimp.org/api/2.0/libgimp/libgimp-gimpenums.html#GimpMergeType
    image.merge_down(layer, 1);  # Clip to image
    return

# our script
def add_text_outline(image, layer, thickness, feather) :
    gimp.progress_init("Drawing outline around text")
    new_layer = add_new_layer_beneath(image, layer)
    gimp.progress_update(33)
    create_selection(image, layer, thickness, feather)
    gimp.progress_update(66)
    fill_selection(new_layer)
    merge_down(image, layer)
    gimp.progress_update(100)
    return

# This is the plugin registration function
register(
    "text_outliner",
    "Text Outliner",
    "Will draw an outline around text using the background color.",
    "Pete Nu",
    "Pete Nu",
    "Feb 2015",
    "<Image>/Layer/Text Outline",
    "*",
    [
        (PF_INT, 'outline_thickness', 'Thickness', 6),
        (PF_INT, 'outline_featheriness', 'Feather', 7)
    ],
    [],
    add_text_outline)

main()