From 880ec7fc587660f18bf7579137ec4b9f6b27e796 Mon Sep 17 00:00:00 2001
From: Bill Ferguson <wpferguson@gmail.com>
Date: Sun, 9 Aug 2020 01:26:45 -0400
Subject: [PATCH] Added check to ensure we are in lighttable view prior to
 callling darktable.register_lib.  If darktable was invoked in single image
 (darkroom) mode, then an event handler is registered to detect the change
 from darkroom mode to lighttable mode so that we can then call
 darktable.register_lib.

---
 contrib/gpx_export.lua | 74 +++++++++++++++++++++++++++++-------------
 1 file changed, 51 insertions(+), 23 deletions(-)

diff --git a/contrib/gpx_export.lua b/contrib/gpx_export.lua
index b6fed82..e36b623 100644
--- a/contrib/gpx_export.lua
+++ b/contrib/gpx_export.lua
@@ -36,6 +36,10 @@ local function _(msgid)
   return gettext.dgettext("gpx_export", msgid)
 end
 
+local gpx = {}
+gpx.module_installed = false
+gpx.event_registered = false
+
 local path_entry = dt.new_widget("entry")
 {
   text = dt.preferences.read("gpx_exporter", "gpxExportPath", "string"),
@@ -127,31 +131,55 @@ local function create_gpx_file()
   end
 end
 
-dt.register_lib(
-  "gpx_exporter",
-  "gpx export",
-  true, -- expandable
-  true, -- resetable
-  {[dt.gui.views.lighttable] = {"DT_UI_CONTAINER_PANEL_RIGHT_CENTER", 100}},   -- containers
+local function install_module()
+  if not gpx.module_installed then
+    dt.register_lib(
+      "gpx_exporter",
+      "gpx export",
+      true, -- expandable
+      true, -- resetable
+      {[dt.gui.views.lighttable] = {"DT_UI_CONTAINER_PANEL_RIGHT_CENTER", 100}},   -- containers
+      gpx.widget,
+      nil,-- view_enter
+      nil -- view_leave
+    )
+    gpx.module_installed = true
+  end
+end
+
+gpx.widget = dt.new_widget("box")
+{
+  orientation = "vertical",
+  dt.new_widget("button")
+  {
+    label = _("export"),
+    tooltip = _("export gpx file"),
+    clicked_callback = create_gpx_file
+  },
   dt.new_widget("box")
   {
-    orientation = "vertical",
-    dt.new_widget("button")
+    orientation = "horizontal",
+    dt.new_widget("label")
     {
-      label = _("export"),
-      tooltip = _("export gpx file"),
-      clicked_callback = create_gpx_file
-    },
-    dt.new_widget("box")
-    {
-      orientation = "horizontal",
-      dt.new_widget("label")
-      {
-        label = _("file:"),
-      },
-      path_entry
+      label = _("file:"),
     },
+    path_entry
   },
-  nil,-- view_enter
-  nil -- view_leave
-)
+}
+
+
+if dt.gui.current_view().name == "lighttable" then
+  install_module()
+else
+  if not gpx.event_registered then
+    dt.register_event(
+      "view-changed",
+      function(event, old_view, new_view)
+        if new_view.name == "lighttable" and old_view.name == "darkroom" then
+          install_module()
+         end
+      end
+    )
+    gpx.event_registered = true
+  end
+end