[image_picker_platform_interface] Migrate image_picker to package:cross_file

[BeMacized]

Removed the PickedFile implementations and migrated the platform interface to make use of the cross_file library.
Changes have been based on #3388.

Web implementation can be found in: #4083.

Android/iOS implementation can be found in #4073.

Relevant issue:

• [image_picker] Migrate image_picker to package:cross_file flutter#70886

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I listed at least one issue that this PR fixes in the description above.
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• I updated CHANGELOG.md to add a description of the change.
• I updated/added relevant documentation (doc comments with ///).
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[ditman]

@BeMacized I've been going back and forth with this one for a couple of days, but we have some internal customers that would benefit greatly from this being a non-breaking change.

Instead of changing the signature of the methods to return an XFile, could we add a new set of methods that return the new type, while keeping the old methods available (and mark them as deprecated?)

That way our customers are going to be able to see the incoming change before forcing them to update their apps.

At a later date, after a few months, or when the next inescapable major version comes, we can delete the deprecated methods and the PickedFile class :/

What do you think?

[BeMacized]

@ditman If you believe this is something important enough that we should take that route, I'd say we do it.

The only thing I'm a bit vague on atm is what the naming should be for the new alternatives to pickImage, pickVideo and LostData. Just putting a "XFile" suffix on them feels a bit odd, especially considering they will be the only ones left after their deprecated counterparts have been removed in a later version.

Do you happen to have any suggestions?

[ditman]

@BeMacized I think we're at a point where we can reuse the names from v0.6, that have already been removed from everywhere :)

I'd say we replace pick by get, maybe? getImage, getVideo, getMultipleImages... It's not great because we can trigger the camera with this, but at least it doesn't need to use XFile anywhere in the name.

As for the LostData, we might reuse the names from the earlier version? LostData class -> LostDataResponse, and retrieveLostData -> getLostData?

There's some notes about the old method names here: https://pub.dev/documentation/image_picker/latest/#deprecation-warnings-in-pickimage-pickvideo-and-lostdataresponse

[BeMacized]

@ditman Ah, that indeed sounds like a good idea! I'll see if I can update the PRs for this tomorrow.

[ditman]

Thanks for the patience and extra work @BeMacized!

[BeMacized]

@ditman Would it be possible for you to take another look? :)

[ayushin]

Really looking forward to this merged

[ditman]

Apologies, I was working in fixing a framework P2, I'll get on this today.

[ditman]

I just realized that making things @Deprecated here will break other packages when this gets published, see for example the image_picker with this patch:

dit@dit:~/github/plugins/packages/image_picker/image_picker$ flutter analyze
Warning: You are using these overridden dependencies:
! image_picker_platform_interface 2.2.0 from path ../image_picker_platform_interface
Running "flutter pub get" in image_picker...                       807ms
Analyzing image_picker...                                               

   info • 'LostData' is deprecated and shouldn't be used. Switch to using LostDataResponse instead • test/image_picker_test.dart:313:17 •
          deprecated_member_use
   info • 'LostData' is deprecated and shouldn't be used. Switch to using LostDataResponse instead • test/image_picker_test.dart:326:17 •
          deprecated_member_use

For other users the breakage might be different. I'll update this PR removing the @Deprecated annotations. We'll add the deprecation warnings to the image_picker package directly, so when people attempt to use the old methods that return PickedFile, instead of the new ones that return XFile they'll get the message (plugin users, not us!).

That way people will get the deprecation warnings only once everything is in place for them to switch to the new code.

Once the methods that are actually used by users are marked as deprecated, we can revisit this package and mark these as deprecated (even though it shouldn't be needed; they can be directly removed after the deprecated methods are removed from the core plugin).

My bad, I'll fix this PR ASAP!

[ditman]

This looks good to me, I'll take an eye to the tests and see what's going on there (the branch needed a refresh from master to pick some changes from earlier today).

@BeMacized, can you verify that you can still work on the other packages with my changes applied? Once you verify that you can still keep working, we can merge this change.

[BeMacized]

@ditman I can confirm the changes have no effect on the implementation PRs, they have been updated accordingly.

[ditman]

Finally published: https://pub.dev/packages/image_picker_platform_interface/changelog#220