PIKApp/plug-ins/python/palette-to-gradient.py

#!/usr/bin/env python3
#
# 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 3 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.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

import gi
gi.require_version('Pika', '3.0')
from gi.repository import Pika
gi.require_version('PikaUi', '3.0')
from gi.repository import PikaUi
from gi.repository import GObject
from gi.repository import GLib
from gi.repository import Gio
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk
import sys

def N_(message): return message
def _(message): return GLib.dgettext(None, message)


def make_gradient(palette, num_segments, num_colors):

    # name the gradient same as the source palette
    # For now, the name of a resource is the same as the ID
    palette_name = palette.get_name()
    gradient = Pika.Gradient.new(palette_name)
    # assert gradient is valid but is has only one segment
    assert gradient.get_number_of_segments() == 1

    # split one segment into desired count
    # index is zero-based
    gradient.segment_range_split_uniform( 0, 0, num_segments)

    for color_number in range(0,num_segments):
        if color_number == num_colors - 1:
            color_number_next = 0
        else:
            color_number_next = color_number + 1
        _, color_left = palette.entry_get_color(color_number)
        _, color_right = palette.entry_get_color(color_number_next)
        gradient.segment_set_left_color( color_number, color_left, 100.0)
        gradient.segment_set_right_color(color_number, color_right, 100.0)

    # Side effects on the context. Probably not what most would expect.
    Pika.context_set_gradient(gradient)
    return gradient

def run(procedure, config, data):
    # Get the parameters
    run_mode = config.get_property("run-mode")

    if run_mode == Pika.RunMode.INTERACTIVE:
        PikaUi.init(procedure.get_name())
        dialog = PikaUi.ProcedureDialog(procedure=procedure, config=config)

        # Add palette button
        dialog.fill (["palette"])

        if not dialog.run():
            dialog.destroy()
            return procedure.new_return_values(Pika.PDBStatusType.CANCEL, GLib.Error())

        dialog.destroy()

    palette = config.get_property("palette")
    if palette is None or not palette.is_valid():
        if palette is not None:
          sys.stderr.write(f'Invalid palette id: {palette.get_id()}\n')
          sys.stderr.write('This should not happen. Please report to PIKA project.\n')
          sys.stderr.write('Falling back to context palette instead.\n')
        palette = Pika.context_get_palette()
        config.set_property("palette", palette)

    num_colors = palette.get_color_count()

    if procedure.get_name() == 'python-fu-palette-to-gradient':
        num_segments = num_colors - 1
    else: # 'python-fu-palette-to-gradient-repeating'
        num_segments = num_colors
    gradient = make_gradient(palette, num_segments, num_colors)

    # XXX: for the error parameter, we want to return None.
    # Unfortunately even though the argument is (nullable), pygobject
    # looks like it may have a bug. So workaround is to just set a
    # generic GLib.Error() since anyway the error won't be process with
    # PIKA_PDB_SUCCESS status.
    # See pygobject#351
    retval = procedure.new_return_values(Pika.PDBStatusType.SUCCESS, GLib.Error())

    # XXX: I don't try to get the GValue with retval.index(1) because it
    # actually return a string (cf. pygobject#353). Just create a new
    # GValue and replace the default one with this one.
    # This comment dates from when resources are strings:
    # value = GObject.Value(GObject.TYPE_STRING, gradient)

    value = GObject.Value(Pika.Gradient, gradient)
    retval.remove(1)
    retval.insert(1, value)

    return retval

class PaletteToGradient (Pika.PlugIn):
    ## Parameter: run mode ##
    @GObject.Property(type=Pika.RunMode,
                      default=Pika.RunMode.NONINTERACTIVE,
                      nick="Run mode", blurb="The run mode")
    def run_mode(self):
        '''The run mode (unused)'''
        return self.runmode

    @run_mode.setter
    def run_mode(self, runmode):
        self.runmode = runmode

    ## Parameter: palette ##
    @GObject.Property(type=Pika.Palette,
                      default=None,
                      nick= _("_Palette"))
    def palette(self):
        '''Palette or None for the currently selected palette'''
        return self.palette

    @palette.setter
    def palette(self, palette):
        self.palette = palette

    ## Properties: return values ##
    @GObject.Property(type=Pika.Gradient,
                      default="",
                      nick=_("The newly created gradient"),
                      blurb=_("The newly created gradient"))
    def new_gradient(self):
        """Read-write integer property."""
        return self.new_gradient

    @new_gradient.setter
    def new_gradient(self, new_gradient):
        self.new_gradient = new_gradient

    ## PikaPlugIn virtual methods ##
    def do_set_i18n(self, procname):
        return True, 'pika30-python', None

    def do_query_procedures(self):
        return ['python-fu-palette-to-gradient',
                'python-fu-palette-to-gradient-repeating']

    def do_create_procedure(self, name):
        procedure = Pika.Procedure.new(self, name,
                                       Pika.PDBProcType.PLUGIN,
                                       run, None)
        if name == 'python-fu-palette-to-gradient':
            procedure.set_menu_label(_("Palette to _Gradient"))
            procedure.set_documentation(_("Create a gradient using colors from the palette"),
                                        _("Create a new gradient using colors from the palette."),
                                        "")
        elif name == 'python-fu-palette-to-gradient-repeating':
            procedure.set_menu_label(_("Palette to _Repeating Gradient"))
            procedure.set_documentation(_("Create a repeating gradient using colors from the palette"),
                                        _("Create a new repeating gradient using colors from the palette."),
                                        "")
        else:
            procedure = None

        if procedure is not None:
            procedure.set_attribution("Carol Spears, reproduced from previous work by Adrian Likins and Jeff Trefftz",
                                      "Carol Spears", "2006")
            # We don't build a GParamSpec ourselves because passing it
            # around is apparently broken in Python. Hence this trick.
            # See pygobject#227
            procedure.add_argument_from_property(self, "run-mode")
            procedure.add_argument_from_property(self, "palette")
            procedure.add_return_value_from_property(self, "new-gradient")

            procedure.add_menu_path ('<Palettes>')

        return procedure

Pika.main(PaletteToGradient.__gtype__, sys.argv)