[gegl] libs/rgbe: fix handling of exponent=0

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 5561c7121aae019068d1ad86ae34a23cb693d0f6
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Feb 25 18:28:44 2021 +0100

    libs/rgbe: fix handling of exponent=0
    
    The existing code skipped setting alpha=1.0f for files with an exponent
    component of 0.0, resulting in transparent output pixels. Fixing issue #275.

 libs/rgbe/rgbe.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)
---
diff --git a/libs/rgbe/rgbe.c b/libs/rgbe/rgbe.c
index fc0e0a609..94f4fa94f 100644
--- a/libs/rgbe/rgbe.c
+++ b/libs/rgbe/rgbe.c
@@ -14,6 +14,7 @@
  * License along with GEGL; if not, see <https://www.gnu.org/licenses/>.
  *
  * Copyright 2010 Danny Robson <danny blubinc net>
+ *           2021 Øyvind Kolås <pippin gimp org>
  */
 
 #include "config.h"
@@ -529,23 +530,22 @@ rgbe_apply_exponent (const rgbe_file *file,
   if (e == 0)
     {
       rgb[OFFSET_R] = rgb[OFFSET_G] = rgb[OFFSET_B] = 0;
-      goto cleanup;
+    }
+  else
+    {
+      mult = ldexp (1.0, e - (128 + 8));
+      rgb[OFFSET_R] *= mult                  *
+                       file->header.exposure *
+                       file->header.colorcorr[OFFSET_R];
+      rgb[OFFSET_G] *= mult                  *
+                       file->header.exposure *
+                       file->header.colorcorr[OFFSET_G];
+      rgb[OFFSET_B] *= mult                  *
+                       file->header.exposure *
+                       file->header.colorcorr[OFFSET_B];
     }
 
-  mult = ldexp (1.0, e - (128 + 8));
-  rgb[OFFSET_R] *= mult                  *
-                   file->header.exposure *
-                   file->header.colorcorr[OFFSET_R];
-  rgb[OFFSET_G] *= mult                  *
-                   file->header.exposure *
-                   file->header.colorcorr[OFFSET_G];
-  rgb[OFFSET_B] *= mult                  *
-                   file->header.exposure *
-                   file->header.colorcorr[OFFSET_B];
-  rgb[OFFSET_A]  = 1.0f;
-
-cleanup:
-  return;
+  rgb[OFFSET_A] = 1.0f;
 }