It seems that the API demo stopped working due to a documented behavior
change for the GraphicsMagick 1.3.40 release:
API Updates:
* AppendImageToList() now updates the image list pointer to be the
image which was just added. Use GetFirstImageInList() when the
pointer to the first image in the list is needed.
GraphicsMagick rarely changes its API behavior. This change was made
due to observing performance issues with many (e.g. 10k) images in a
list. It is much more efficient to remember the end of the list while
appending additional frames to the list rather than re-starting from the
beginning.
Bob
On 7/28/26 08:34, Christophe Beauregard wrote:
The following change to the demo code fixes the problem (which is what
ConvertImageCommand() does):
$ diff demo.c.bak demo.c
68a69
> thumbnails=GetFirstImageInList(thumbnails);
Presumably some change internally stopped the GIF coder from finding
the head of the list, or the Append call changed the ordering, or
something?
$ sh test.sh
libgraphicsmagick1-dev 1.4+really1.3.45+hg17696-1
Reading 1.png ... 1 frames
Reading 2.png ... 1 frames
Reading 3.png ... 1 frames
Reading 4.png ... 1 frames
Reading 5.png ... 1 frames
Reading 6.png ... 1 frames
Writing out.gif ... 6 frames
out.gif[0] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u
0m:0.000000s
out.gif[1] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u
0m:0.000034s
out.gif[2] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u
0m:0.000036s
out.gif[3] GIF 106x80+0+0 PseudoClass 128c 8-bit 9.1Ki 0.000u
0m:0.000034s
out.gif[4] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u
0m:0.000034s
out.gif[5] GIF 106x80+0+0 PseudoClass 256c 8-bit 9.1Ki 0.000u
0m:0.000035s
