[gnome-photos] Add an asynchronous version of gdk_pixbuf_new_from_file_at_size

[Debarshi Ray <debarshir src gnome org>]

commit 8be5958122fa529bbc5e2be43d7153915fe65afd
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon Feb 13 19:02:47 2017 +0100

    Add an asynchronous version of gdk_pixbuf_new_from_file_at_size
    
    The underlying gdk_pixbuf_new_from_file_at_size is not cancellable,
    which is problematic, but will do for the time being. This should be
    added to gdk-pixbuf proper and the lack of cancellation addressed.
    
    We can't put this code in photos-utils.[ch] because we will need to use
    it from the thumbnailer. There are too many build dependencies
    associated with photos-utils.[ch] that we can't have in the
    thumbnailer.

 src/photos-pixbuf.c |  120 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/photos-pixbuf.h |   40 +++++++++++++++++
 2 files changed, 160 insertions(+), 0 deletions(-)
---
diff --git a/src/photos-pixbuf.c b/src/photos-pixbuf.c
new file mode 100644
index 0000000..efa9e79
--- /dev/null
+++ b/src/photos-pixbuf.c
@@ -0,0 +1,120 @@
+/*
+ * Photos - access, organize and share your photos on GNOME
+ * Copyright © 2017 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 the Free Software Foundation; either version 2
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+
+#include "config.h"
+
+#include "photos-pixbuf.h"
+
+
+typedef struct _PhotosPixbufNewFromFileData PhotosPixbufNewFromFileData;
+
+struct _PhotosPixbufNewFromFileData
+{
+  gchar *filename;
+  gint height;
+  gint width;
+};
+
+
+static PhotosPixbufNewFromFileData *
+photos_pixbuf_new_from_file_data_new (const gchar *filename, gint height, gint width)
+{
+  PhotosPixbufNewFromFileData *data;
+
+  data = g_slice_new0 (PhotosPixbufNewFromFileData);
+  data->filename = g_strdup (filename);
+  data->height = height;
+  data->width = width;
+
+  return data;
+}
+
+
+static void
+photos_pixbuf_new_from_file_data_free (PhotosPixbufNewFromFileData *data)
+{
+  g_free (data->filename);
+  g_slice_free (PhotosPixbufNewFromFileData, data);
+}
+
+
+static void
+photos_pixbuf_new_from_file_at_size_in_thread_func (GTask *task,
+                                                    gpointer source_object,
+                                                    gpointer task_data,
+                                                    GCancellable *cancellable)
+{
+  GError *error;
+  GdkPixbuf *result = NULL;
+  PhotosPixbufNewFromFileData *data = (PhotosPixbufNewFromFileData *) task_data;
+
+  error = NULL;
+  result = gdk_pixbuf_new_from_file_at_size (data->filename, data->width, data->height, &error);
+  if (error != NULL)
+    {
+      g_task_return_error (task, error);
+      goto out;
+    }
+
+  g_task_return_pointer (task, g_object_ref (result), g_object_unref);
+
+ out:
+  g_clear_object (&result);
+}
+
+
+void
+photos_pixbuf_new_from_file_at_size_async (const gchar *filename,
+                                           gint width,
+                                           gint height,
+                                           GCancellable *cancellable,
+                                           GAsyncReadyCallback callback,
+                                           gpointer user_data)
+{
+  GTask *task;
+  PhotosPixbufNewFromFileData *data;
+
+  g_return_if_fail (filename != NULL && filename[0] != '\0');
+  g_return_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable));
+
+  data = photos_pixbuf_new_from_file_data_new (filename, width, height);
+
+  task = g_task_new (NULL, cancellable, callback, user_data);
+  g_task_set_return_on_cancel (task, TRUE);
+  g_task_set_source_tag (task, photos_pixbuf_new_from_file_at_size_async);
+  g_task_set_task_data (task, data, (GDestroyNotify) photos_pixbuf_new_from_file_data_free);
+
+  g_task_run_in_thread (task, photos_pixbuf_new_from_file_at_size_in_thread_func);
+  g_object_unref (task);
+}
+
+
+GdkPixbuf *
+photos_pixbuf_new_from_file_at_size_finish (GAsyncResult *res, GError **error)
+{
+  GTask *task = G_TASK (res);
+
+  g_return_val_if_fail (g_task_is_valid (res, NULL), NULL);
+  g_return_val_if_fail (g_task_get_source_tag (task) == photos_pixbuf_new_from_file_at_size_async, NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  return g_task_propagate_pointer (task, error);
+}
diff --git a/src/photos-pixbuf.h b/src/photos-pixbuf.h
new file mode 100644
index 0000000..9270c59
--- /dev/null
+++ b/src/photos-pixbuf.h
@@ -0,0 +1,40 @@
+/*
+ * Photos - access, organize and share your photos on GNOME
+ * Copyright © 2017 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 the Free Software Foundation; either version 2
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef PHOTOS_PIXBUF_H
+#define PHOTOS_PIXBUF_H
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include <gio/gio.h>
+
+G_BEGIN_DECLS
+
+void             photos_pixbuf_new_from_file_at_size_async     (const gchar *filename,
+                                                                gint width,
+                                                                gint height,
+                                                                GCancellable *cancellable,
+                                                                GAsyncReadyCallback callback,
+                                                                gpointer user_data);
+
+GdkPixbuf       *photos_pixbuf_new_from_file_at_size_finish    (GAsyncResult *res, GError **error);
+
+G_END_DECLS
+
+#endif /* PHOTOS_PIXBUF_H */