From: Lars Ingebrigtsen <larsi@gnus.org>
Date: Tue, 12 Apr 2022 14:22:27 +0000 (+0200)
Subject: Improve DISPOSE_PREVIOUS in gif_load slightly
X-Git-Tag: emacs-29.0.90~1931^2~626
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=a987e66e6ba014795ba4540c5fedeb9894bdd94e;p=emacs.git

Improve DISPOSE_PREVIOUS in gif_load slightly

* src/image.c (gif_load): Tweak how DISPOSE_PREVIOUS is handled.
It's still not right, but it's less glaringly wrong.
---

diff --git a/src/image.c b/src/image.c
index 530819eab9d..45de7ae83d3 100644
--- a/src/image.c
+++ b/src/image.c
@@ -9115,6 +9115,14 @@ gif_load (struct frame *f, struct image *img)
       if (disposal == DISPOSAL_UNSPECIFIED)
 	disposal = DISPOSE_DO_NOT;
 
+      /* This is not quite correct -- the specification is unclear,
+	 but I think we're supposed to restore to the frame before the
+	 previous frame?  And we don't have that data at this point.
+	 But DISPOSE_DO_NOT is less wrong than substituting the
+	 background, so do that for now.  */
+      if (disposal == DISPOSE_PREVIOUS)
+	disposal = DISPOSE_DO_NOT;
+
       gif_color_map = subimage->ImageDesc.ColorMap;
       if (!gif_color_map)
 	gif_color_map = gif->SColorMap;