Add error domain, TumblerThumbnailFlavor and thumbnail helper functions.

This commit adds the TUMBLER_ERROR_DOMAIN and TUMBLER_ERROR defines and
a TumblerErrorEnum with currently only containing TUMBLER_ERROR_FAILED.

Also new is the TumblerThumbnailFlavor enum type, together with a few
utility functions related to creating thumbnails:

  - tumbler_thumbnail_get_flavors() returns all flavors supported by
    the current build of tumbler,

  - tumbler_thumbnail_flavor_get_size() returns the size corresponding
    to a flavor (e.g. 128 for TUMBLER_THUMBNAIL_FLAVOR_NORMAL),

  - tumbler_thumbnail_flavor_get_directory() returns a GFile pointing
    to the flavor directory (e.g. $HOME/.thumbnails/normal/ for
    TUMBLER_THUMBNAIL_FLAVOR_NORMAL),

  - tumbler_thumbnail_get_file() returns a GFile pointing to the
    thumbnail destination file of an URI and a flavor,

  - tumbler_thumbnail_create_and_open_file() tries to create such a
    GFile and also tries to open it for writing, returning the
    GFileOutputStream if possible.

1 files changed, 202 insertions, 0 deletions

diff --git a/tumbler/tumbler-thumbnail.c b/tumbler/tumbler-thumbnail.c
new file mode 100644
index 0000000..635512e
--- /dev/null
+++ b/tumbler/tumbler-thumbnail.c
@@ -0,0 +1,202 @@
+/* vi:set et ai sw=2 sts=2 ts=2: */
+/*-
+ * Copyright (c) 2009 Jannis Pohlmann <jannis@xfce.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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 Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General 
+ * Public License along with this library; if not, write to the 
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <glib/gi18n.h>
+#include <gio/gio.h>
+
+#include <tumbler/tumbler-enum-types.h>
+#include <tumbler/tumbler-error.h>
+#include <tumbler/tumbler-thumbnail.h>
+
+
+
+TumblerThumbnailFlavor *
+tumbler_thumbnail_get_flavors (void)
+{
+  static TumblerThumbnailFlavor flavors[] = 
+  {
+#ifdef ENABLE_LARGE_THUMBNAILS
+    TUMBLER_THUMBNAIL_FLAVOR_NORMAL,
+#endif
+#ifdef ENABLE_LARGE_THUMBNAILS
+    TUMBLER_THUMBNAIL_FLAVOR_LARGE,
+#endif
+#ifdef ENABLE_CROPPED_THUMBNAILS
+    TUMBLER_THUMBNAIL_FLAVOR_CROPPED,
+#endif
+    TUMBLER_THUMBNAIL_FLAVOR_INVALID, /* this always has to come last */
+  };
+
+  return flavors;
+}
+
+
+
+gint 
+tumbler_thumbnail_flavor_get_size (TumblerThumbnailFlavor flavor)
+{
+  g_return_val_if_fail (flavor != TUMBLER_THUMBNAIL_FLAVOR_INVALID, 0);
+
+  switch (flavor)
+    {
+    case TUMBLER_THUMBNAIL_FLAVOR_NORMAL:
+      return 128;
+      break;
+    case TUMBLER_THUMBNAIL_FLAVOR_LARGE:
+      return 256;
+      break;
+    case TUMBLER_THUMBNAIL_FLAVOR_CROPPED:
+      return 124;
+      break;
+    default:
+      g_assert_not_reached ();
+      break;
+    }
+
+  return 0;
+}
+
+
+
+GFile *
+tumbler_thumbnail_flavor_get_directory (TumblerThumbnailFlavor flavor)
+{
+  const gchar *home;
+  const gchar *basename = NULL;
+  GFile       *file;
+  gchar       *path;
+
+  g_return_val_if_fail (flavor != TUMBLER_THUMBNAIL_FLAVOR_INVALID, NULL);
+
+  /* determine the correct .thumbnails/ subdir for the flavor */
+  switch (flavor)
+    {
+    case TUMBLER_THUMBNAIL_FLAVOR_NORMAL:
+      basename = "normal";
+      break;
+    case TUMBLER_THUMBNAIL_FLAVOR_LARGE:
+      basename = "large";
+      break;
+    case TUMBLER_THUMBNAIL_FLAVOR_CROPPED:
+      basename = "cropped";
+      break;
+    default:
+      g_assert_not_reached ();
+      break;
+    }
+
+  /* determine the user's home directory */
+  home = g_getenv ("HOME") ? g_getenv ("HOME") : g_get_home_dir ();
+
+  /* build the flavor directory path and create a file for it */
+  path = g_build_filename (home, ".thumbnails", basename, NULL);
+  file = g_file_new_for_path (path);
+  g_free (path);
+
+  return file;
+}
+
+
+
+GFile *
+tumbler_thumbnail_get_file (const gchar           *uri,
+                            TumblerThumbnailFlavor flavor)
+{
+  GFile       *file;
+  GFile       *parent;
+  gchar       *basename;
+  gchar       *md5_hash;
+
+  g_return_val_if_fail (uri != NULL, NULL);
+
+  /* compute the MD5 hash of the URI and use it for the basename */
+  md5_hash = g_compute_checksum_for_string (G_CHECKSUM_MD5, uri, -1);
+  basename = g_strdup_printf ("%s.png", md5_hash);
+  g_free (md5_hash);
+
+  /* determine the thumbnail directory for this flavor */
+  parent = tumbler_thumbnail_flavor_get_directory (flavor);
+
+  /* create a file for the thumbnail destination */
+  file = g_file_resolve_relative_path (parent, basename);
+
+  /* destroy the directory file and basename */
+  g_object_unref (parent);
+  g_free (basename);
+
+  return file;
+}
+
+
+
+GFileOutputStream *
+tumbler_thumbnail_create_and_open_file (GFile   *file,
+                                        GError **error)
+{
+  GFileOutputStream *output_stream = NULL;
+  GError            *err = NULL;
+  GFile             *parent;
+  gchar             *path;
+
+  g_return_val_if_fail (G_IS_FILE (file), NULL);
+
+  /* determine the directory of the file */
+  parent = g_file_get_parent (file);
+
+  if (parent == NULL)
+    {
+      path = g_file_get_path (file);
+
+      /* cache files reside in $HOME/.thumbnails/ and thus always have a parent
+       * directory. if the input file doesn't it's invalid */
+      g_set_error (error, TUMBLER_ERROR, TUMBLER_ERROR_FAILED, 
+                   _("Invalid cache filename: \"%s\""), path);
+
+      g_free (path);
+
+      return NULL;
+    }
+
+  /* create the directory if it doesn't exist yet */
+  if (!g_file_query_exists (parent, NULL))
+    {
+      if (!g_file_make_directory_with_parents (parent, NULL, &err))
+        {
+          g_propagate_error (error, err);
+          return NULL;
+        }
+    }
+
+  /* open the file for writing */
+  output_stream = g_file_create (file, G_FILE_CREATE_NONE, NULL, &err);
+
+  /* propagate error if opening the file failed */
+  if (err != NULL)
+    {
+      g_propagate_error (error, err);
+      return NULL;
+    }
+  
+  return output_stream;
+}