[gimp] plug-ins: start porting palette-to-gradient to new GimpPlugIn API.

[Jehan <jehanp src gnome org>]

commit 17667b7ddf0b50c6af325d65bc1e889e7703e135
Author: Jehan <jehan girinstud io>
Date:   Thu Aug 1 20:34:14 2019 +0200

    plug-ins: start porting palette-to-gradient to new GimpPlugIn API.
    
    Several aspects of the new API are kind of broken in the Python binding,
    especially the arguments. So this first version has no arguments at all.
    This also means it cannot be installed in "<Palettes>" menu for the time
    being. This is work-in-progress and the missing parts will be
    uncommented later when we figure out how to fix the problems.

 plug-ins/python/palette-to-gradient.py | 139 +++++++++++++++++++--------------
 1 file changed, 81 insertions(+), 58 deletions(-)
---
diff --git a/plug-ins/python/palette-to-gradient.py b/plug-ins/python/palette-to-gradient.py
index 3fdc54aa0a..efea15df52 100644
--- a/plug-ins/python/palette-to-gradient.py
+++ b/plug-ins/python/palette-to-gradient.py
@@ -16,6 +16,9 @@
 import gi
 gi.require_version('Gimp', '3.0')
 from gi.repository import Gimp
+from gi.repository import GObject
+from gi.repository import GLib
+from gi.repository import Gio
 import sys
 
 import gettext
@@ -47,63 +50,83 @@ def make_gradient(palette, num_segments, num_colors):
               Gimp.param_from_string(gradient)]
     return len(retval), retval
 
-def palette_to_gradient_repeating(palette):
-    (_, num_colors) = Gimp.palette_get_info(palette)
-    num_segments = num_colors
-    return make_gradient(palette, num_segments, num_colors)
+def palette_to_gradient(procedure, args, data):
+    # Localization
+    plug_in = procedure.get_plug_in()
+    plug_in.set_translation_domain ("gimp30-python",
+                                    Gio.file_new_for_path(Gimp.locale_directory()))
 
-def palette_to_gradient(palette):
+    palette = Gimp.context_get_palette()
     (_, num_colors) = Gimp.palette_get_info(palette)
-    num_segments = num_colors - 1
-    return make_gradient(palette, num_segments, num_colors)
-
-def run(name, n_params, params):
-    # run_mode = params[0].get_int32()
-    if name == 'python-fu-palette-to-gradient-repeating':
-        return palette_to_gradient_repeating(Gimp.context_get_palette())
-    else:
-        return palette_to_gradient(Gimp.context_get_palette())
-
-def query():
-    param = Gimp.ParamDef()
-    param.type = Gimp.PDBArgType.INT32
-    param.name = "run-mode"
-    param.description = _("Run mode")
-
-    retval = Gimp.ParamDef()
-    retval.type = Gimp.PDBArgType.STRING
-    retval.name = "new-gradient"
-    retval.description = _("Result")
-
-    Gimp.install_procedure(
-        "python-fu-palette-to-gradient-repeating",
-        N_("Create a repeating gradient using colors from the palette"),
-        "Create a new repeating gradient using colors from the palette.",
-        "Carol Spears, reproduced from previous work by Adrian Likins and Jeff Trefftz",
-        "Carol Spears",
-        "2006",
-        N_("Palette to _Repeating Gradient"),
-        "",
-        Gimp.PDBProcType.PLUGIN,
-        [ param ],
-        [ retval ])
-    Gimp.plugin_menu_register("python-fu-palette-to-gradient-repeating", "<Palettes>")
-
-    Gimp.install_procedure(
-        "python-fu-palette-to-gradient",
-        N_("Create a gradient using colors from the palette"),
-        "Create a new gradient using colors from the palette.",
-        "Carol Spears, reproduced from previous work by Adrian Likins and Jeff Trefftz",
-        "Carol Spears",
-        "2006",
-        N_("Palette to _Gradient"),
-        "",
-        Gimp.PDBProcType.PLUGIN,
-        [ param ],
-        [ retval ])
-    Gimp.plugin_menu_register("python-fu-palette-to-gradient", "<Palettes>")
-    Gimp.plugin_domain_register("gimp30-python", Gimp.locale_directory())
-
-info = Gimp.PlugInInfo ()
-info.set_callbacks (None, None, query, run)
-Gimp.main_legacy (info, sys.argv)
+
+    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
+    # GIMP_PDB_SUCCESS status.
+    # See pygobject#351
+    retval = procedure.new_return_values(Gimp.PDBStatusType.SUCCESS, GLib.Error())
+
+    # TODO: uncomment when GParamSpec bug is fixed.
+    #value = retval.index(1)
+    #value.set_string (gradient);
+    return retval
+
+class PaletteToGradient (Gimp.PlugIn):
+    def do_query_procedures(self):
+        # XXX See pygobject#352 for the weird return value.
+        return ['python-fu-palette-to-gradient',
+                'python-fu-palette-to-gradient-repeating'], 2
+
+    def do_create_procedure(self, name):
+        procedure = Gimp.Procedure.new(self, name,
+                                       Gimp.PDBProcType.PLUGIN,
+                                       palette_to_gradient, None)
+        if name == 'python-fu-palette-to-gradient':
+            procedure.set_menu_label(N_("Palette to _Gradient"))
+            procedure.set_documentation(N_("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(N_("Palette to _Repeating Gradient"))
+            procedure.set_documentation(N_("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")
+            returnspec = GObject.param_spec_string("new-gradient",
+                                                    "Name of the newly created gradient",
+                                                    "Name of the newly created gradient",
+                                                    None,
+                                                    GObject.ParamFlags.READWRITE)
+            # Passing a GObjectParamSpec currently fails.
+            # TODO: see pygobject#227
+            #procedure.add_return_value(returnspec)
+
+            paramspec = GObject.param_spec_enum("run-mode",
+                                                "Run mode",
+                                                "The run mode",
+                                                Gimp.RunMode.__gtype__,
+                                                Gimp.RunMode.NONINTERACTIVE,
+                                                GObject.ParamFlags.READWRITE)
+            # TODO: see pygobject#227
+            #procedure.add_argument(paramspec)
+
+            # TODO: To be installed in '<Palettes>', we need a run mode
+            # parameter. Wait for the GParamSpec bug to be fixed before
+            # uncommenting.
+            #procedure.add_menu_path ('<Palettes>')
+
+        return procedure
+
+Gimp.main(PaletteToGradient.__gtype__, sys.argv)