#!/usr/bin/env python

from gimpfu import *

def layergrid(image, drawable, rows):
    w, h = image.width, image.height
    num_layers = len(image.layers)

    pdb.gimp_image_undo_group_start(image)

    if num_layers > 1: # layers -> grid

        if rows == 0: rows = num_layers
        cols = (num_layers + rows - 1) // rows

        x = 0
        y = 0
        col = 0
        for layer in image.layers:
            pdb.gimp_layer_set_offsets(layer, x, y)
            x += w
            col += 1
            if col == cols:
                x = 0
                y += h
                col = 0
        
        background = pdb.gimp_image_merge_visible_layers(image, EXPAND_AS_NECESSARY)
        pdb.gimp_layer_set_name(background, "background")
        pdb.gimp_image_resize_to_layers(image)
        pdb.gimp_image_grid_set_spacing(image, w, h)
        pdb.gimp_image_grid_set_offset(image, 0, 0)

    else: # grid -> layers
        
        gw, gh = pdb.gimp_image_grid_get_spacing(image)
        gx, gy = pdb.gimp_image_grid_get_offset(image)
        gw, gh = int(gw), int(gh)
        gx, gy = int(gx), int(gy)

        background = pdb.gimp_image_get_active_layer(image)

        for y in range(gy, h, gh):
            for x in range(gx, w, gw):
                pdb.gimp_rect_select(image, x, y, gw, gh, CHANNEL_OP_REPLACE, False, 0)
                fsel = pdb.gimp_selection_float(drawable, -x, -y)
                pdb.gimp_floating_sel_to_layer(fsel)
                layer = pdb.gimp_image_get_active_layer(image)
                pdb.gimp_layer_set_name(layer, "cell " + str(x) + " " + str(y))
                pdb.gimp_image_lower_layer_to_bottom(image, layer)
                pdb.gimp_image_set_active_layer(image, background)
                
        pdb.gimp_image_remove_layer(image, background)
        pdb.gimp_image_resize_to_layers(image)

    pdb.gimp_image_undo_group_end(image)
    return

register(
    "layergrid",
	"Collapse layers into a grid or splits a grid into layers.",
	"""If your image has multiple layers, this will create a grid out of
them and adjust the grid settings accordingly. Otherwise the single
layer of the image is transformed into layers according to the current
grid settings with one layer per grid cell.""".replace("\n", " "),
	"Al Lefant",
	"Al Lefant",
	"2011",
	"<Image>/Layer/Layergrid...",
	"*",
	[
    (PF_INT,        "rows", "Rows, for Layers->Grid only", 1),
	],
	[],
	layergrid)

main()