[gimp/gimp-2-10] app: accept a const GimpTempBuf in more temp-buf functions

[Ell <ell src gnome org>]

commit 25ed35af628a7b6cc1b60ced67f0381d87f3e4f2
Author: Ell <ell_se yahoo com>
Date:   Sun Feb 24 12:46:34 2019 -0500

    app: accept a const GimpTempBuf in more temp-buf functions
    
    In gimp_temp_buf_{ref,unref}(), and
    gimp_temp_buf_create_{buffer,pixmap}(), accept a const GimpTempBuf
    argument.
    
    (cherry picked from commit 0a1e62768a891380ab04d8b53412b76257b39322)

 app/core/gimptempbuf.c | 23 +++++++++++------------
 app/core/gimptempbuf.h |  8 ++++----
 2 files changed, 15 insertions(+), 16 deletions(-)
---
diff --git a/app/core/gimptempbuf.c b/app/core/gimptempbuf.c
index 0d84d779e2..2879be9241 100644
--- a/app/core/gimptempbuf.c
+++ b/app/core/gimptempbuf.c
@@ -153,24 +153,22 @@ gimp_temp_buf_copy (const GimpTempBuf *src)
 }
 
 GimpTempBuf *
-gimp_temp_buf_ref (GimpTempBuf *buf)
+gimp_temp_buf_ref (const GimpTempBuf *buf)
 {
   g_return_val_if_fail (buf != NULL, NULL);
 
-  buf->ref_count++;
+  g_atomic_int_inc ((gint *) &buf->ref_count);
 
-  return buf;
+  return (GimpTempBuf *) buf;
 }
 
 void
-gimp_temp_buf_unref (GimpTempBuf *buf)
+gimp_temp_buf_unref (const GimpTempBuf *buf)
 {
   g_return_if_fail (buf != NULL);
   g_return_if_fail (buf->ref_count > 0);
 
-  buf->ref_count--;
-
-  if (buf->ref_count < 1)
+  if (g_atomic_int_dec_and_test ((gint *) &buf->ref_count))
     {
       g_atomic_pointer_add (&gimp_temp_buf_total_memsize,
                             -gimp_temp_buf_get_memsize (buf));
@@ -179,7 +177,7 @@ gimp_temp_buf_unref (GimpTempBuf *buf)
       if (buf->data)
         gegl_free (buf->data);
 
-      g_slice_free (GimpTempBuf, buf);
+      g_slice_free (GimpTempBuf, (GimpTempBuf *) buf);
     }
 }
 
@@ -365,8 +363,8 @@ gimp_temp_buf_get_memsize (const GimpTempBuf *buf)
   return 0;
 }
 
-GeglBuffer  *
-gimp_temp_buf_create_buffer (GimpTempBuf *temp_buf)
+GeglBuffer *
+gimp_temp_buf_create_buffer (const GimpTempBuf *temp_buf)
 {
   GeglBuffer *buffer;
 
@@ -382,13 +380,14 @@ gimp_temp_buf_create_buffer (GimpTempBuf *temp_buf)
                                       (GDestroyNotify) gimp_temp_buf_unref,
                                       gimp_temp_buf_ref (temp_buf));
 
-  g_object_set_data (G_OBJECT (buffer), "gimp-temp-buf", temp_buf);
+  g_object_set_data (G_OBJECT (buffer),
+                     "gimp-temp-buf", (GimpTempBuf *) temp_buf);
 
   return buffer;
 }
 
 GdkPixbuf *
-gimp_temp_buf_create_pixbuf (GimpTempBuf *temp_buf)
+gimp_temp_buf_create_pixbuf (const GimpTempBuf *temp_buf)
 {
   GdkPixbuf    *pixbuf;
   const Babl   *format;
diff --git a/app/core/gimptempbuf.h b/app/core/gimptempbuf.h
index 1569138345..d5228f5e8b 100644
--- a/app/core/gimptempbuf.h
+++ b/app/core/gimptempbuf.h
@@ -26,8 +26,8 @@ GimpTempBuf * gimp_temp_buf_new_from_pixbuf   (GdkPixbuf         *pixbuf,
                                                const Babl        *f_or_null) G_GNUC_WARN_UNUSED_RESULT;
 GimpTempBuf * gimp_temp_buf_copy              (const GimpTempBuf *src) G_GNUC_WARN_UNUSED_RESULT;
 
-GimpTempBuf * gimp_temp_buf_ref               (GimpTempBuf       *buf);
-void          gimp_temp_buf_unref             (GimpTempBuf       *buf);
+GimpTempBuf * gimp_temp_buf_ref               (const GimpTempBuf *buf);
+void          gimp_temp_buf_unref             (const GimpTempBuf *buf);
 
 GimpTempBuf * gimp_temp_buf_scale             (const GimpTempBuf *buf,
                                                gint               width,
@@ -53,8 +53,8 @@ void          gimp_temp_buf_unlock            (const GimpTempBuf *buf,
 
 gsize         gimp_temp_buf_get_memsize       (const GimpTempBuf *buf);
 
-GeglBuffer  * gimp_temp_buf_create_buffer     (GimpTempBuf       *temp_buf) G_GNUC_WARN_UNUSED_RESULT;
-GdkPixbuf   * gimp_temp_buf_create_pixbuf     (GimpTempBuf       *temp_buf) G_GNUC_WARN_UNUSED_RESULT;
+GeglBuffer  * gimp_temp_buf_create_buffer     (const GimpTempBuf *temp_buf) G_GNUC_WARN_UNUSED_RESULT;
+GdkPixbuf   * gimp_temp_buf_create_pixbuf     (const GimpTempBuf *temp_buf) G_GNUC_WARN_UNUSED_RESULT;
 
 GimpTempBuf * gimp_gegl_buffer_get_temp_buf   (GeglBuffer        *buffer);