This commit makes several improvements to video coordination,
and implements a new video control view.
The video support stack in Damus has been re-architected to achieve
this.
The new architecture can be summarized as follows:
1. `DamusVideoCoordinator` is a singleton object in `DamusState`, and it
is responsible for deciding which video should have the "main stage"
focus, based on main stage requests that video player views make when
they become visible.
Having "main stage" focus means that the coordinator will auto-play
that video and pause others, and is used throughout the app to
determine which video to talk to or control, in the case of app-wide
controls (analogous to how Apple Music needs to know which song is
playing for displaying playback controls on the iOS home screen)
Having a singleton take care of this establishes
clear ownership and prevents conflicts such as double-playing video.
This coordinator also holds a pool of video media items (`DamusVideoPlayer`),
with exactly ONE `DamusVideoPlayer` per URL, to reduce
bandwidth and ensure perfect syncing of the same video in different
contexts.
2. `DamusVideoPlayer` objects hold the actual media item (video data, playback state),
much like `AVPlayer`.
In fact, `DamusVideoPlayer` can be described as a wrapper for `AVPlayer`,
except it has an interface that is much more SwiftUI friendly,
enabling playback state syncing with minimal effort.
`DamusVideoPlayer` is NOT a view. And there is only ONE `DamusVideoPlayer`
per URL — held by the coordinator.
However, when the app needs to display that same video in multiple
places, the app can instantiate multiple video player VIEWS of the
same `DamusVideoPlayer`
3. `DamusVideoPlayer.BaseView` is the most basic video player view for a
`DamusVideoPlayer` item. It has basically no features other than
showing the video itself.
4. `DamusVideoPlayerView` is the standard, batteries-included, video
player view for `DamusVideoPlayer` items, that is used throughout the
app.
It also tries to detect its own visibility, and makes requests to
`DamusVideoCoordinator` to take over the main stage when it becomes
visible.
5. `DamusVideoControlsView` is a view that presents video playback
controls (play/pause, mute, scrubbing) for a `DamusVideoPlayer`
object.
How a `DamusVideoPlayerView` gains and loses main stage focus:
1. `DamusVideoPlayerView` uses `VisibilityTracker` to find out when it
becomes visible or not
2. When it becomes visible, it makes a request to the video coordinator
to take main stage focus. The request also specifies which layer the
video view is in (Full screen layer? Normal app layer?), which the
video player view gets from the `\.view_layer_context` environment
variable set by `damus_full_screen_cover`
3. The coordinator (`DamusVideoCoordinator`) keeps all of these
requests, and uses its own internal logic and info to determine which
video should get the main stage.
The logic also depends on whether or not the app finds itself in full
screen mode.
Once the main stage is given to a different video, the previous video
is paused, the main-staged-video is played, and the requestor
receives a callback.
4. Once the video disappears from view, it tells the coordinator that it
is giving up the main stage, and the coordinator then picks another
main stage request again.
On top of this, several of other small changes and improvements were made,
such as video gesture improvements
Note: This commit causes some breakage over the image carousel sizing
logic, which will be addressed separately in the next commit.
Changelog-Fixed: Fixed iOS 18 gesture issues that would take user to the thread view when clicking on a video or unmuting it
Changelog-Fixed: Fixed several issues that would cause video to automatically play or pause incorrectly
Changelog-Fixed: Fixed issue where full screen video would disappear when going to landscape mode
Changelog-Added: Added new easy to use video controls for full screen video
Changelog-Changed: Improved video syncing and bandwidth usage when switching between timeline video and full screen mode
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
58017952bc