@cocoa-xu thanks for your help, I applied your patch, but it seems that the issue still persists. You can try it with my horse GIF.

@cocoa-xu Thank you so much. The problem is solved. I hope the author @nothings can merge your pull request soon.

@cocoa-xu Thank you again for your help. In my program, I merge each frame's texture into a large texture, and then use UV coordinates based on the delay time read from the GIF to display the animation. I found that the following code seems to be necessary for correct display:

if (dispose == 3) {
// background is what out is after the undoing of the previous frame;
memcpy(g->background, g->out, 4 * g->w * g->h);
}
Please try this

@cocoa-xu Thank you again for your help.

Not a problem!

In my program, I merge each frame's texture into a large texture, and then use UV coordinates based on the delay time read from the GIF to display the animation. I found that the following code seems to be necessary for correct display:

if (dispose == 3) {
// background is what out is after the undoing of the previous frame;
memcpy(g->background, g->out, 4 * g->w * g->h);
}
Please try this

Ah I wasn't really sure about this, but I did get the same results when using if (dispose == 3) {.

I wonder if you happen to have any example file(s) that you can share for this case, which gives wrong data if we use if (dispose == 2 || dispose == 3) { while returning the correct data when we do if (dispose == 3) {.

@cocoa-xu Thank you again for your help.

Not a problem!

In my program, I merge each frame's texture into a large texture, and then use UV coordinates based on the delay time read from the GIF to display the animation. I found that the following code seems to be necessary for correct display:
if (dispose == 3) {
// background is what out is after the undoing of the previous frame;
memcpy(g->background, g->out, 4 * g->w * g->h);
}
Please try this

Ah I wasn't really sure about this, but I did get the same results when using if (dispose == 3) {.

I wonder if you happen to have any example file(s) that you can share for this case, which gives wrong data if we use if (dispose == 2 || dispose == 3) { while returning the correct data when we do if (dispose == 3) {.

Yes, you can try this GIF file. In my program, I found that there are still incorrect frames when it is equal to 2 or equal to 3.
This is a screenshot of each frame from my program.

Okay gotcha, I've updated the PR! Thanks for sending the test file! ;)