Deprecate crop/rotation support for Android plugins, consider Dart alternative

[johnmccutchan]

The tests as written today are testing Android features and code paths that aren't consistently supported on Android and thus can't be used. Also of note, these functions are not used by our popular plugins.

There are three paths currently tested today:

1. MediaRenderer (applies rotation) -> ImageRenderer (applies crop) -> SurfaceView [correctly handles crop and rotation]
2. MediaRenderer (applies rotation) -> ImageRenderer (applies crop) -> SurfaceProducer(ST-backed) [correctly handles crop and rotation]
3. MediaRenderer (applies rotation) -> ImageRenderer (applies crop) -> SurfaceProducer(IR-backed) [does not handle crop or rotation]

Due to an oversight by Android, ImageReader backed surfaces do not respect metadata applied to the surface (rotation & crop). Rotation information is not available at all and crop information is corrupted by the ImageReader (only the width/height is propagated the origin offset is not).

Two action items:

• We need to replace the Android code with Dart based texture rotation and cropping.
• We need to make the SurfaceTexture backend ignore the crop and rotation metadata when we render so that it is consistent with ImageReader. We can/should probably make this behaviour SurfaceProducer specific so we don't break any legacy apps.

[matanlurey]

I am not currently working on this, but @johnmccutchan I know you had something WIP so I'll keep it assigned to you?

[johnmccutchan]

Yes, I'll get back to this soon. The action items I filed above are still the current status.

[matanlurey]

@johnmccutchan @jonahwilliams and I chatted about whether or not this should be a blocker for Impeller on Android (Vulkan edition). We decided that this is rather rare functionality, this would only block a user migrating to Impeller if and only if:

• They have a plugin that uses SurfaceTextures
• That plugin migrates to SurfaceProducer

In other words, plugins could continue to just provide a SurfaceTexture API if they want native crop/rotation, of course that means the plugins would not be compatible with Android + Vulkan. We should have an answer for this eventually (including in docs) but it seems non-critical to have for the initial opt-out period and moving our own internal plugins (that don't use this feature) to SurfaceProducer (unless we find that we indeed are using this functionality, which is unlikely).

Let us know if you disagree strongly, and we can re-evaluate, but for now I'm removing as a blocker/moving to P2.

[johnmccutchan]

The crop/rotation parts of the scenario_app tests are actually testing Android functionality and not Flutter functionality.

The action items in my first comment still stand however I don't think they are priorities as I don't think any plugins are actually using this functionality in practice.

[matanlurey]

Removing e: scenario-app as this is no longer in scope for the e2e test suite.