openjp2/j2k: Report error if all wanted components are not decoded.

[sebras]

Previously the caller had to check whether each component data had
been decoded. This means duplicating the checking in every user of
openjpeg which is unnecessary. If the caller wantes to decode all
or a set of, or a specific component then openjpeg ought to error
out if it was unable to do so.

Fixes #1158.

[sebras]

After several iterations I figured out that the latter commit was the only one needed to resolve this issue, and that the prior commit actually requires more input. I'll submit that separately later

[rouault]

This is reasonable but a change in behaviour. Perhaps there are people who deal with corrupt images, and are used to try to recover the non-corrupted components. Although they will have the workaround of decoding each component individually. @detonin thoughts about this ?

[sebras]

@rouault: The current check in opj_decompress only checks the first component to determine if all components have been sucessfully decoded. That doesn't look right, and the comment above that check indicated that this ought to be done inside the library for the benefit of all users.

Also note that while this is a behavioural change it only affects clients decoding broken images where the decoding of one or more components fails and the client wants to keep the other components. Is this a common situation?

[rouault]

We can go with your approach and see if people complain. However, I think a similar check should be added to opj_j2k_decode_one_tile(), no ? (in which case, please create a common function called by the 2 call sites)

[sebras]

@rouault Thanks for the reply. Yes, that does seem like an omission. I'll update the commit in a bit.

[sebras]

I did address the review comments long while back. What needs to be done for this to be merged?

The error from continuous-integration/appveyor/pr failed, but it seems to have failed due to a network outage:

Build started
git clone -q --depth=50 https://github.com/uclouvain/openjpeg.git C:\projects\openjpeg
fatal: unable to access 'https://github.com/uclouvain/openjpeg.git/': Could not resolve host: github.com
Command exited with code 128

[rouault]

Thanks. Merged

[sebras]

Excellent, thank you! :)