Adding a NOOP decoder to Image Loader causes animated GIFs and WEBPs to be static

[valeriyo]

Describe the bug Adding a "no-op" decoder, which according to the documentation

should have no side-effects, causes animated GIFs and WEBPs to no longer be animated

To Reproduce

1. To an ImageLoader builder, add .components { add(Decoder.Factory { _, _, _ -> Decoder { null } }) }
2. Try to load an animated GIF or WEBP
3. The image loads as a static image

Logs/Screenshots No errors are logged

Version 2.2.2

[valeriyo]

This is related to https://github.com/coil-kt/coil/issues/1695 -- because the workaround for that problem (providing a custom decoder) causes animated images to be static.

[colinrtwhite]

This is expected behaviour. Returning null from a Decoder delegates to the next decoder, which is likely BitmapFactoryDecoder which decodes animated images as static.

[valeriyo]

This is expected behaviour. Returning null from a Decoder delegates to the next decoder, which is likely BitmapFactoryDecoder which decodes animated images as static.

And why is "next" decoder not the one that understands how to decode animated GIF/WEBP ? This is not expected at all.