Modern gestures - Githubissues

Now that YouTube, Netflix and similar apps made them popular, we should consider adding double tap gestures to skip. Content gravity, currently triggered with a double tap, should be triggered with a pinch gesture instead.

To be done at the technical level:

[x] Double tap to skip.
[x] Pinch to zoom.
[x] Detect pinch direction to zoom in / out when pinching in / out.
[x] Disable when controls are not togglable.
[x] Check that other view capabilities do not conflict and have consistent behavior (e.g. with audio content).
[x] Check that full screen toggles are consistent with button visibility / UI togglability / visibility. In particular full screen should be disabled if the UI is hidden and not togglable.
[x] Ensure that any kind of visual clue used behaves well when the view size is small.

Should continue to work as before:

[x] Single tap Toggle to show / hide controls (must be fast enough for a good UX).
[x] Timeline cell selection must still work correctly.
[x] User activity detection. In particular the controls must remain visible while the user is scrolling or navigating the timeline.
[x] Pan gesture to dismiss in demo player must still work in the demo (it should be disabled in landscape orientation for a better user experience, as we do in Play, but the current behavior is still useful for test purposes).
[x] Must not conflict with accessibility via VoiceOver.

Design / UX discussions are required in addition to the above:

[x] We need a basic visual clue when a double tap triggers a seek. Maybe only useful when controls are hidden since otherwise it is pretty clear what happens (the slider is moving).
[x] Should a visual clue be displayed when seeking was attempted but could not be performed? (most probably: At the end of the content). No
[x] Should we have symmetric values for double taps? (+10 / -10) Yes
[x] Discuss if some dead zone is required at the center (e.g. 10% of width) where double taps do not trigger skips. Yes, to avoid conflicts with skip controls in the center
[x] An overlay is displayed under the activity indicator. Should we get rid of it so that we avoid the screen flickering when fast double-tapping? Yes

SRGSSR / srgletterbox-apple

Modern gestures #261