fix: black screen in ExoPlayer on rotate

[k1rill]

Workaround with VideoPlayer flow on configuration changes.

What was done:

1. Shared EncodedVideoUnitViewModel between VideoUnitFragment and VideoFullScreenFragment and storing exoPlayer instance in it.
2. VideoFullScreenFragment became DialogFragment to have access to the shared viewModel
3. VideoFullScreenFragment moved to Compose

Known problem: subtitles not working in fullscreen

[HamzaIsrar12]

I conducted a manual review on the emulator last week, where things still felt quite laggy. However, I tested it again on my own device today, and the experience was much improved. The lag decreased from 5–6 seconds to 1–2 seconds. Great job on that!

I did notice two issues from a learner's perspective:

• Rotating the phone to change orientation in fullscreen causes the video to pause, which shouldn’t happen.
• The on-player captions aren’t working at all. (For clarity, I’ll refer to the on-player captions as subtitles and the captions below the player as transcription.)

Note: @omerhabib26 is performing an in-depth review.

[omerhabib26]

Hey @k1rill, great job on the revamp! The lag has dropped to just 1-2 seconds, which is a big improvement. However, there are still a couple of issues that need attention:

• When the device is in portrait mode and the user taps on the fullscreen button, the player switches to fullscreen, but the video size doesn’t adjust—it stays in portrait orientation. Ideally, the player should expand to full-screen size and switch to landscape mode. A good example of this behavior is the YouTube app.

• When the device is in portrait mode and the user rotates it, a white gap appears at the bottom of the screen, covering the player’s bottom options.

Screen_Recording_20250127-181703_edX.mp4