Keeping transparent pixels when using the API

[spillerrec]

I wan't to try using FLIF instead of WebP for one of my projects, but it stores special information in transparent pixels used when overlaying two images. However I cannot find out how to get it stop using the default behavior of only being visual lossless. (Which I personally find terrifying, as I expect lossless formats not to modify my data.)

I have tried to call flif_encoder_set_alpha_zero_lossless but that does not appear to do anything. #349 might be related.

Test image:

Test image end. Ends up being 20 bytes when using the API, instead of 617 KiB with -K.

[jonsneyers]

You have to set the option before calling flif_encoder_add_image, maybe that is the problem?

[spillerrec]

I'm calling it right after flif_create_encoder. Call order of all FLIF functions:

1. flif_create_encoder()
2. flif_encoder_set_alpha_zero_lossless( encoder );
3. flif_create_image( width, height )
4. flif_image_write_row_RGBA8 * height
5. flif_encoder_add_image
6. flif_destroy_image
7. flif_encoder_encode_memory
8. flif_destroy_encoder