[gnome-photos/wip/rishi/issue-115-load-error] Propagate any GError while loading a BaseItem

[Debarshi Ray <debarshir src gnome org>]

commit a8c5fad8447e5327a454b9ce4927235901c44ddf
Author: Debarshi Ray <debarshir gnome org>
Date:   Tue Oct 9 15:26:32 2018 +0200

    Propagate any GError while loading a BaseItem
    
    A subsequent commit will use this to provide some visual feedback to
    the user, instead of a blank window, which is the case now.
    
    https://gitlab.gnome.org/GNOME/gnome-photos/issues/115

 po/POTFILES.in             |  1 +
 src/photos-application.c   |  4 ++++
 src/photos-embed.c         | 23 ++++++++++++++++++++---
 src/photos-item-manager.c  | 42 +++++++++++++++++++++++++++++++++++-------
 src/photos-marshalers.list |  1 +
 5 files changed, 61 insertions(+), 10 deletions(-)
---
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 03a82026..919b9c18 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -20,6 +20,7 @@ src/photos-help-overlay.ui
 src/photos-import-dialog.c
 src/photos-import-dialog.ui
 src/photos-indexing-notification.c
+src/photos-item-manager.c
 src/photos-local-item.c
 src/photos-main-toolbar.c
 src/photos-main-window.c
diff --git a/src/photos-application.c b/src/photos-application.c
index fbf81341..03b67b5f 100644
--- a/src/photos-application.c
+++ b/src/photos-application.c
@@ -2905,6 +2905,10 @@ photos_application_startup (GApplication *application)
     gtk_application_set_accels_for_action (GTK_APPLICATION (self), detailed_action_name, zoom_out_accels);
   }
 
+  g_signal_connect_swapped (self->state->item_mngr,
+                            "load-error",
+                            G_CALLBACK (photos_application_load_changed),
+                            self);
   g_signal_connect_swapped (self->state->item_mngr,
                             "load-finished",
                             G_CALLBACK (photos_application_load_changed),
diff --git a/src/photos-embed.c b/src/photos-embed.c
index 45a1b4e6..9106a0cb 100644
--- a/src/photos-embed.c
+++ b/src/photos-embed.c
@@ -346,13 +346,25 @@ photos_embed_prepare_for_preview (PhotosEmbed *self, PhotosWindowMode old_mode)
 
 
 static void
-photos_embed_load_finished (PhotosEmbed *self, PhotosBaseItem *item, GeglNode *node)
+photos_embed_load_error (PhotosEmbed *self, const gchar *primary, GError *error)
 {
+  if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+    goto out;
+
   photos_embed_clear_load_timer (self);
   photos_spinner_box_stop (PHOTOS_SPINNER_BOX (self->spinner_box));
 
-  if (node == NULL)
-    return;
+ out:
+  return;
+}
+
+
+static void
+photos_embed_load_finished (PhotosEmbed *self, PhotosBaseItem *item, GeglNode *node)
+{
+  photos_embed_clear_load_timer (self);
+  photos_spinner_box_stop (PHOTOS_SPINNER_BOX (self->spinner_box));
+  g_return_if_fail (GEGL_IS_NODE (node));
 
   photos_preview_view_set_node (PHOTOS_PREVIEW_VIEW (self->preview), node);
 
@@ -869,6 +881,11 @@ photos_embed_init (PhotosEmbed *self)
                            G_CONNECT_SWAPPED);
 
   self->item_mngr = g_object_ref (state->item_mngr);
+  g_signal_connect_object (self->item_mngr,
+                           "load-error",
+                           G_CALLBACK (photos_embed_load_error),
+                           self,
+                           G_CONNECT_SWAPPED);
   g_signal_connect_object (self->item_mngr,
                            "load-finished",
                            G_CALLBACK (photos_embed_load_finished),
diff --git a/src/photos-item-manager.c b/src/photos-item-manager.c
index cd33ef60..b1fbf3c4 100644
--- a/src/photos-item-manager.c
+++ b/src/photos-item-manager.c
@@ -1,6 +1,6 @@
 /*
  * Photos - access, organize and share your photos on GNOME
- * Copyright © 2012 – 2017 Red Hat, Inc.
+ * Copyright © 2012 – 2018 Red Hat, Inc.
  *
  * 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
@@ -28,6 +28,7 @@
 #include <dazzle.h>
 #include <gio/gio.h>
 #include <glib.h>
+#include <glib/gi18n.h>
 #include <tracker-sparql.h>
 
 #include "photos-debug.h"
@@ -72,6 +73,7 @@ enum
   ACTIVE_COLLECTION_CHANGED,
   CAN_FULLSCREEN_CHANGED,
   FULLSCREEN_CHANGED,
+  LOAD_ERROR,
   LOAD_FINISHED,
   LOAD_STARTED,
   WINDOW_MODE_CHANGED,
@@ -806,18 +808,32 @@ photos_item_manager_item_load (GObject *source_object, GAsyncResult *res, gpoint
     node = photos_base_item_load_finish (item, res, &error);
     if (error != NULL)
       {
-        if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
-          g_warning ("Unable to load the item: %s", error->message);
+        g_autofree gchar *primary = NULL;
 
         self->load_state = PHOTOS_LOAD_STATE_ERROR;
-      }
-    else
-      {
-        self->load_state = PHOTOS_LOAD_STATE_FINISHED;
+
+        if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+          {
+            const gchar *domain_str;
+            const gchar *name;
+
+            domain_str = g_quark_to_string (error->domain);
+            g_warning ("Unable to load the item: (%s, %d) %s", domain_str, error->code, error->message);
+
+            name = photos_base_item_get_name_with_fallback (item);
+            primary = g_strdup_printf (_("Oops! Unable to load “%s”"), name);
+          }
+
+        g_signal_emit (self, signals[LOAD_ERROR], 0, primary, error);
+        goto out;
       }
   }
 
+  self->load_state = PHOTOS_LOAD_STATE_FINISHED;
   g_signal_emit (self, signals[LOAD_FINISHED], 0, item, node);
+
+ out:
+  return;
 }
 
 
@@ -1147,6 +1163,18 @@ photos_item_manager_class_init (PhotosItemManagerClass *class)
                                               1,
                                               G_TYPE_BOOLEAN);
 
+  signals[LOAD_ERROR] = g_signal_new ("load-error",
+                                      G_TYPE_FROM_CLASS (class),
+                                      G_SIGNAL_RUN_LAST,
+                                      0,
+                                      NULL, /*accumulator */
+                                      NULL, /*accu_data */
+                                      _photos_marshal_VOID__STRING_ENUM,
+                                      G_TYPE_NONE,
+                                      2,
+                                      G_TYPE_STRING,
+                                      G_TYPE_ERROR);
+
   signals[LOAD_FINISHED] = g_signal_new ("load-finished",
                                          G_TYPE_FROM_CLASS (class),
                                          G_SIGNAL_RUN_LAST,
diff --git a/src/photos-marshalers.list b/src/photos-marshalers.list
index ea1cd27e..47396eec 100644
--- a/src/photos-marshalers.list
+++ b/src/photos-marshalers.list
@@ -2,4 +2,5 @@ VOID:BOXED,BOXED
 VOID:DOUBLE,ENUM
 VOID:ENUM,ENUM
 VOID:INT,INT
+VOID:STRING,ENUM
 VOID:STRING,STRING