[gimp] plug-ins: assume RGB/RGBA for JPEG2000 without declared color space.

[Jehan Pagès <jehanp src gnome org>]

commit 6f5c20eef1f944063445e1f265ffd3ad6395676c
Author: Jehan <jehan girinstud io>
Date:   Fri Mar 9 21:59:04 2018 +0100

    plug-ins: assume RGB/RGBA for JPEG2000 without declared color space.
    
    It seems that the color space is not necessarily declared for a JPEG2000
    image. From tests, it looks like it especially happens with JPEG2000
    codestream (.j2c or .j2k). This variant is apparently mostly designed to
    be embedded (from what I read), which may explain why the color space is
    not always set (I assume the embedding format would have the color space
    information). Mostly a guess.

 plug-ins/common/file-jp2-load.c |   31 +++++++++++++++++++++++++++----
 1 files changed, 27 insertions(+), 4 deletions(-)
---
diff --git a/plug-ins/common/file-jp2-load.c b/plug-ins/common/file-jp2-load.c
index 4a4f654..dad1941 100644
--- a/plug-ins/common/file-jp2-load.c
+++ b/plug-ins/common/file-jp2-load.c
@@ -933,10 +933,33 @@ load_image (const gchar  *filename,
     }
   else
     {
-      g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
-                   _("Unsupported color space in JP2 image '%s'."),
-                   gimp_filename_to_utf8 (filename));
-      goto out;
+      /* Sometimes the color space is not set at this point, which
+       * sucks. It seems to happen in particular with codestream images
+       * (.j2c or .j2k) which, if I understand well, are meant to be
+       * embedded by other files. So maybe that means that the color
+       * space information is in this container file?
+       * For now, let's just assume RGB/RGBA space when this happens,
+       * but this is not ideal. We should instead pop-up a dialog asking
+       * one to specify the color space in interactive mode (and add a
+       * parameter for the API.
+       * TODO!
+       */
+      base_type  = GIMP_RGB;
+      if (num_components == 3)
+        {
+          image_type = GIMP_RGB_IMAGE;
+        }
+      else if (num_components == 4)
+        {
+          image_type = GIMP_RGBA_IMAGE;
+        }
+      else
+        {
+          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
+                       _("Unsupported color space in JP2 image '%s'."),
+                       gimp_filename_to_utf8 (filename));
+          goto out;
+        }
     }
 
   /* FIXME */