[gdk-pixbuf] Add some missing nullability annotations.

[Evan Nemerson <evann src gnome org>]

commit bf4681da30e2892aabed7ad3ffdbe55d1c6c4557
Author: Evan Nemerson <evan nemerson com>
Date:   Sun May 11 20:18:53 2014 -0700

    Add some missing nullability annotations.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=730161

 gdk-pixbuf/gdk-pixbuf-io.c     |   12 +++++++-----
 gdk-pixbuf/gdk-pixbuf-loader.c |    5 +++--
 gdk-pixbuf/gdk-pixbuf-scale.c  |    8 ++++----
 gdk-pixbuf/gdk-pixdata.c       |    5 +++--
 4 files changed, 17 insertions(+), 13 deletions(-)
---
diff --git a/gdk-pixbuf/gdk-pixbuf-io.c b/gdk-pixbuf/gdk-pixbuf-io.c
index 39f85a4..377aaaa 100644
--- a/gdk-pixbuf/gdk-pixbuf-io.c
+++ b/gdk-pixbuf/gdk-pixbuf-io.c
@@ -1867,14 +1867,16 @@ info_cb (GdkPixbufLoader *loader,
 /**
  * gdk_pixbuf_get_file_info:
  * @filename: The name of the file to identify.
- * @width: (out): Return location for the width of the image, or %NULL
- * @height: (out): Return location for the height of the image, or %NULL
+ * @width: (optional) (out): Return location for the width of the
+ *     image, or %NULL
+ * @height: (optional) (out): Return location for the height of the
+ *     image, or %NULL
  * 
  * Parses an image file far enough to determine its format and size.
  * 
- * Returns: (transfer none): A #GdkPixbufFormat describing the image
- *    format of the file or %NULL if the image format wasn't
- *    recognized. The return value is owned by GdkPixbuf and should
+ * Returns: (nullable) (transfer none): A #GdkPixbufFormat describing
+ *    the image format of the file or %NULL if the image format wasn't
+ *    recognized. The return value is owned by #GdkPixbuf and should
  *    not be freed.
  *
  * Since: 2.4
diff --git a/gdk-pixbuf/gdk-pixbuf-loader.c b/gdk-pixbuf/gdk-pixbuf-loader.c
index edcc905..1835a47 100644
--- a/gdk-pixbuf/gdk-pixbuf-loader.c
+++ b/gdk-pixbuf/gdk-pixbuf-loader.c
@@ -857,8 +857,9 @@ gdk_pixbuf_loader_close (GdkPixbufLoader *loader,
  * Obtains the available information about the format of the 
  * currently loading image file.
  *
- * Returns: (transfer none): A #GdkPixbufFormat or %NULL. The return
- * value is owned by GdkPixbuf and should not be freed.
+ * Returns: (nullable) (transfer none): A #GdkPixbufFormat or
+ * %NULL. The return value is owned by GdkPixbuf and should not be
+ * freed.
  * 
  * Since: 2.2
  */
diff --git a/gdk-pixbuf/gdk-pixbuf-scale.c b/gdk-pixbuf/gdk-pixbuf-scale.c
index acae7cd..d6d4392 100644
--- a/gdk-pixbuf/gdk-pixbuf-scale.c
+++ b/gdk-pixbuf/gdk-pixbuf-scale.c
@@ -383,8 +383,8 @@ gdk_pixbuf_composite_color_simple (const GdkPixbuf *src,
  * Rotates a pixbuf by a multiple of 90 degrees, and returns the
  * result in a new pixbuf.
  *
- * Returns: (transfer full): the new #GdkPixbuf, or %NULL if not enough memory could be
- * allocated for it.
+ * Returns: (nullable) (transfer full): the new #GdkPixbuf, or %NULL
+ * if not enough memory could be allocated for it.
  *
  * Since: 2.6
  */
@@ -476,8 +476,8 @@ gdk_pixbuf_rotate_simple (const GdkPixbuf   *src,
  * Flips a pixbuf horizontally or vertically and returns the
  * result in a new pixbuf.
  *
- * Returns: (transfer full): the new #GdkPixbuf, or %NULL if not enough memory could be
- * allocated for it.
+ * Returns: (nullable) (transfer full): the new #GdkPixbuf, or %NULL
+ * if not enough memory could be allocated for it.
  *
  * Since: 2.6
  */
diff --git a/gdk-pixbuf/gdk-pixdata.c b/gdk-pixbuf/gdk-pixdata.c
index 9c992b6..d0fe7d5 100644
--- a/gdk-pixbuf/gdk-pixdata.c
+++ b/gdk-pixbuf/gdk-pixdata.c
@@ -319,8 +319,9 @@ free_buffer (guchar *pixels, gpointer data)
  * pixel data is run-length encoded into newly-allocated memory and a 
  * pointer to that memory is returned. 
  *
- * Returns: If @ure_rle is %TRUE, a pointer to the newly-allocated memory 
- *   for the run-length encoded pixel data, otherwise %NULL.
+ * Returns: (nullable): If @use_rle is %TRUE, a pointer to the
+ *   newly-allocated memory for the run-length encoded pixel data,
+ *   otherwise %NULL.
  **/
 gpointer
 gdk_pixdata_from_pixbuf (GdkPixdata      *pixdata,