[gimp] plug-ins: fix and install the Lua goat-exercise.

[Jehan <jehanp src gnome org>]

commit 0abdbebaad63a0814ceaa66bd561d0383b187748
Author: Jehan <jehan girinstud io>
Date:   Fri Aug 16 19:46:32 2019 +0200

    plug-ins: fix and install the Lua goat-exercise.
    
    So procedure:new_return_values() just seems broken with LGI. It doesn't
    even look like it reaches the C code.
    Anyway we can also just reconstruct the GimpValueArray, which works
    fine. We now have official support for Lua plug-ins!

 configure.ac                                  | 49 ++++++++++++++++++++++++++-
 plug-ins/goat-exercises/Makefile.am           |  8 +++++
 plug-ins/goat-exercises/goat-exercise-lua.lua | 21 ++++++++----
 3 files changed, 71 insertions(+), 7 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index e2c7c3566d..1ac9c4e40c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2359,6 +2359,52 @@ fi
 AM_CONDITIONAL(HAS_JAVASCRIPT_INTERP, test "x$GJS" != "xno")
 AM_CONDITIONAL(BUILD_JAVASCRIPT, test "x$with_javascript" != xno)
 
+####################################
+# Check for Lua runtime dependencies
+####################################
+
+AC_ARG_WITH(lua,
+            [  --with-lua=no|yes|force install Lua plug-ins (default=yes)], ,
+            [with_lua=yes])
+
+if test "x$with_lua" = xno; then
+  warning_lua="
+WARNING: you disabled the installation of core Lua plug-ins. This
+         is discouraged as it won't provide the full GIMP experience.
+         Note that you may install the Lua plug-ins even if Lua LGI
+         is not installed at build-time by passing the configure option
+         --with-lua=force.
+         Just make sure that it is available at run-time."
+elif test "x$with_lua" = xforce; then
+  with_lua="yes"
+  warning_lua=
+  AC_CHECK_PROGS(LUA, luajit, no)
+  if test "x$LUA" = xno; then
+    warning_lua="
+WARNING: luagit not found.
+         Lua plug-ins will be installed anyway but you should make
+         sure that luagit and LGI are available at installation,
+         otherwise installed plug-ins won't be usable."
+    with_lua="yes (see warning below)"
+  fi
+else
+  with_lua="yes"
+  AC_CHECK_PROGS(LUA, luajit, no)
+  if test "x$GJS" = xno; then
+    required_deps="$required_deps
+    - luagit not found.
+        *** Please install the Lua interpreter luagit.
+        *** Note that you may install the Lua plug-ins even if luajit
+        *** is not installed at build-time by passing the configure
+        *** option --with-lua=force.
+        *** Just make sure that luajit and LGI are available at run-time."
+    with_lua="no"
+  fi
+fi
+
+AM_CONDITIONAL(HAS_LUA_INTERP, test "x$LUA" != "xno")
+AM_CONDITIONAL(BUILD_LUA, test "x$with_lua" != xno)
+
 ###########################################################
 # Some plug-ins don't build on Win32, others are Win32-only
 ###########################################################
@@ -3092,6 +3138,7 @@ Optional Plug-Ins:
   Print:                     $enable_print
   Python 3 plug-ins:         $with_python
   JavaScript plug-ins:       $with_javascript
+  Lua plug-ins:              $with_lua
   TWAIN (Win32):             $os_win32
   Webpage:                   $have_webkit
   WMF:                       $have_libwmf
@@ -3110,7 +3157,7 @@ Tests:
   Test desktop file          $have_desktop_file_validate
 
 Bug report URL: $with_bug_report_url
-$override_bug_report_url$warning_vector_icons_windows$warning_glib_networking$warning_gcc$warning_python$warning_javascript"
+$override_bug_report_url$warning_vector_icons_windows$warning_glib_networking$warning_gcc$warning_python$warning_javascript$warning_lua"
 
 if test "x$required_deps" = "x"; then
   AC_OUTPUT
diff --git a/plug-ins/goat-exercises/Makefile.am b/plug-ins/goat-exercises/Makefile.am
index 83e7ad04dd..b16e90743d 100644
--- a/plug-ins/goat-exercises/Makefile.am
+++ b/plug-ins/goat-exercises/Makefile.am
@@ -67,6 +67,13 @@ goat_exercise_gjsdir = $(gimpplugindir)/plug-ins/goat-exercise-gjs
 goat_exercise_gjs_SCRIPTS = goat-exercise-gjs.js
 endif
 
+# Lua (lua-jit + LGI) version.
+
+if BUILD_LUA
+goat_exercise_luadir = $(gimpplugindir)/plug-ins/goat-exercise-lua
+goat_exercise_lua_SCRIPTS = goat-exercise-lua.lua
+endif
+
 # Python 3 (pygobject) version.
 
 # Commented out for now until we figure out the GParamSpec issues.
@@ -78,4 +85,5 @@ endif
 
 EXTRA_DIST = \
        goat-exercise-gjs.js    \
+       goat-exercise-lua.lua   \
        goat-exercise-py3.py
diff --git a/plug-ins/goat-exercises/goat-exercise-lua.lua b/plug-ins/goat-exercises/goat-exercise-lua.lua
index 6b0914e367..72bc025d89 100755
--- a/plug-ins/goat-exercises/goat-exercise-lua.lua
+++ b/plug-ins/goat-exercises/goat-exercise-lua.lua
@@ -33,6 +33,9 @@ local Goat = lgi.package 'Goat'
 local Goat = lgi.Goat
 
 function run(procedure, args, data)
+  -- procedure:new_return_values() crashes LGI so we construct the
+  -- GimpValueArray manually.
+  local retval = Gimp.ValueArray(1)
   local run_mode = GObject.Value.get_enum(args:index(0))
   if run_mode == Gimp.RunMode.INTERACTIVE then
     Gimp.ui_init("goat-exercise-lua", false);
@@ -93,14 +96,16 @@ function run(procedure, args, data)
         Gio.app_info_launch_default_for_uri(url, nil);
       else -- CANCEL, CLOSE, DELETE_EVENT
         dialog:destroy()
-        return procedure:new_return_values(Gimp.PDBStatusType.CANCEL, nil)
+        local cancel = GObject.Value(Gimp.PDBStatusType, Gimp.PDBStatusType.CANCEL)
+        retval:append(cancel)
+        return retval
       end
     end
   end
 
   local drawable_id = args:index(2):get_int()
   local x, y, width, height = Gimp.drawable_mask_intersect (drawable_id)
-  if width > 0 and height > 0 then
+  if width ~= nill and height ~= nil and width > 0 and height > 0 then
     Gegl.init(nil)
 
     local buffer = Gimp.drawable_get_buffer (drawable_id)
@@ -122,12 +127,16 @@ function run(procedure, args, data)
     Gimp.drawable_update(drawable_id, x, y, width, height)
     Gimp.displays_flush()
   else
-    local err = GLib.Error.new_literal(GLib.quark_from_string("goat-error-quark"), 0,
-                                       "No pixels to process in the selected area.")
-    return procedure:new_return_values(Gimp.PDBStatusType.CALLING_ERROR, err)
+    local fail = GObject.Value(Gimp.PDBStatusType, Gimp.PDBStatusType.CALLING_ERROR)
+    retval:append(fail)
+    local err = GObject.Value(GObject.Type.STRING, "No pixels to process in the selected area.")
+    retval:append(err)
+    return retval
   end
 
-  return procedure:new_return_values(Gimp.PDBStatusType.SUCCESS, 0)
+  local success = GObject.Value(Gimp.PDBStatusType, Gimp.PDBStatusType.SUCCESS)
+  retval:append(success)
+  return retval
 end
 
 Goat:class('Exercise', Gimp.PlugIn)