[gimp] plug-ins: port Python plug-in palette-to-gradient to introspected API.

[Jehan <jehanp src gnome org>]

commit 65fb7536e1e12f5be6356565fa88de145a45755c
Author: Jehan <jehan girinstud io>
Date:   Sun Jul 28 18:29:42 2019 +0200

    plug-ins: port Python plug-in palette-to-gradient to introspected API.
    
    Localization still doesn't work, but this is normal (po-python is not
    installed). I will later make the proper tests for this.
    
    Other than this, it is a pretty simple port. It lost all particularities
    and facilities of pygimp, but the fact that it now works similarly to
    the C API is quite nice too.
    It still uses the legacy API for plug-ins though and will have to be
    ported further when the new API will be stable.
    
    Also I still haven't figured out why we need to return the number of
    returned values. With the proper annotations, an array length parameter
    disappears in introspected Python (because it is useless as Python lists
    know their length). But it would seem that this annotation doesn't work
    the same for returned values, which is a bit sad as it creates ugly
    redundancy.
    
    It can be noted that I an going to move all Python plug-ins from
    plug-ins/pygimp/plug-ins/ to plug-ins/python/. The whole pygimp/
    subdirectory will actually be deleted eventually (I keep it around for
    now as reference) as Python plug-in should not need to be considered
    particularly from now on. They can just be considered as generic
    executables.

 configure.ac                                    |   1 +
 plug-ins/Makefile.am                            |   2 +
 plug-ins/pygimp/plug-ins/Makefile.am            |  64 --------------
 plug-ins/pygimp/plug-ins/palette-to-gradient.py |  88 -------------------
 plug-ins/python/Makefile.am                     |  64 ++++++++++++++
 plug-ins/python/palette-to-gradient.py          | 111 ++++++++++++++++++++++++
 6 files changed, 178 insertions(+), 152 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 2a5881661b..f5a76ce9a4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2869,6 +2869,7 @@ plug-ins/print/Makefile
 dnl plug-ins/pygimp/Makefile
 dnl plug-ins/pygimp/plug-ins/Makefile
 [
+plug-ins/python/Makefile
 plug-ins/screenshot/Makefile
 plug-ins/script-fu/Makefile
 plug-ins/script-fu/ftx/Makefile
diff --git a/plug-ins/Makefile.am b/plug-ins/Makefile.am
index d069024288..23a89c8770 100644
--- a/plug-ins/Makefile.am
+++ b/plug-ins/Makefile.am
@@ -14,6 +14,7 @@ endif
 
 if BUILD_PYTHON
 pygimp = pygimp
+python = python
 endif
 
 if OS_WIN32
@@ -55,6 +56,7 @@ SUBDIRS = \
        metadata                \
        pagecurl                \
        $(print)                \
+       $(python)               \
        screenshot              \
        selection-to-path       \
        $(twain)                \
diff --git a/plug-ins/python/Makefile.am b/plug-ins/python/Makefile.am
new file mode 100644
index 0000000000..dd87529169
--- /dev/null
+++ b/plug-ins/python/Makefile.am
@@ -0,0 +1,64 @@
+## Process this file with automake to produce Makefile.in
+
+pluginexecdir = $(gimpplugindir)/plug-ins
+
+source_scripts = \
+##     colorxhtml.py                   \
+##     file-openraster.py              \
+##     foggify.py                      \
+##     gradients-save-as-css.py        \
+##     histogram-export.py             \
+##     palette-offset.py               \
+##     palette-sort.py                 \
+       palette-to-gradient.py
+##     py-slice.py                     \
+##     python-eval.py                  \
+##     spyro_plus.py                   \
+##                                     \
+##     benchmark-foreground-extract.py \
+##     clothify.py                     \
+##     shadow_bevel.py                 \
+##     sphere.py                       \
+##     whirlpinch.py
+
+scripts = \
+##     colorxhtml/colorxhtml.py                        \
+##     file-openraster/file-openraster.py              \
+##     foggify/foggify.py                              \
+##     gradients-save-as-css/gradients-save-as-css.py  \
+##     histogram-export/histogram-export.py            \
+##     palette-offset/palette-offset.py                \
+##     palette-sort/palette-sort.py                    \
+       palette-to-gradient/palette-to-gradient.py
+##     py-slice/py-slice.py                            \
+##     python-eval/python-eval.py                      \
+##     spyro_plus/spyro_plus.py
+
+#test_scripts = \
+#      benchmark-foreground-extract/benchmark-foreground-extract.py    \
+#      clothify/clothify.py                                            \
+#      shadow_bevel/shadow_bevel.py                                    \
+#      sphere/sphere.py                                                \
+#      whirlpinch/whirlpinch.py
+
+$(scripts) $(test_scripts): $(source_scripts)
+       $(AM_V_GEN) mkdir -p $(@D) && cp -f "$(srcdir)/$(@F)" $@
+
+nobase_pluginexec_SCRIPTS = $(scripts)
+
+if GIMP_UNSTABLE
+nobase_pluginexec_SCRIPTS += $(test_scripts)
+endif
+
+# python-console has a data file.
+# Therefore let's move it to its own sub-directory.
+#consoleexecdir = $(gimpplugindir)/plug-ins/python-console
+#console_scripts = python-console.py
+#consoleexec_SCRIPTS = $(console_scripts)
+#dist_consoleexec_DATA = pyconsole.py
+
+EXTRA_DIST = \
+       $(source_scripts)
+#      $(console_scripts)
+
+CLEANFILES = $(scripts) $(test_scripts)
diff --git a/plug-ins/python/palette-to-gradient.py b/plug-ins/python/palette-to-gradient.py
new file mode 100644
index 0000000000..a96bfae7b4
--- /dev/null
+++ b/plug-ins/python/palette-to-gradient.py
@@ -0,0 +1,111 @@
+#!/usr/bin/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('Gimp', '3.0')
+from gi.repository import Gimp
+import sys
+
+import gettext
+_ = gettext.gettext
+def N_(message): return message
+
+def make_gradient(palette, num_segments, num_colors):
+    gradient = Gimp.gradient_new(palette)
+
+    if (num_segments > 1):
+        Gimp.gradient_segment_range_split_uniform(gradient, 0, -1,
+                                                  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 = Gimp.palette_entry_get_color(palette, color_number)
+        _, color_right = Gimp.palette_entry_get_color(palette, color_number_next)
+        Gimp.gradient_segment_set_left_color(gradient,
+                                             color_number, color_left,
+                                             100.0)
+        Gimp.gradient_segment_set_right_color(gradient,
+                                              color_number, color_right,
+                                              100.0)
+    Gimp.context_set_gradient(gradient)
+    retval = [Gimp.param_from_status (Gimp.PDBStatusType.SUCCESS),
+              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(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("gimp20-python", Gimp.locale_directory())
+    #gettext.install("gimp20-python", localedir=Gimp.locale_directory(), codeset='utf-8')
+
+info = Gimp.PlugInInfo ()
+info.set_callbacks (None, None, query, run)
+Gimp.main_legacy (info, sys.argv)