overlay

The subtitles that were on screen, laid out for THIS frame's own size after its crop and turned by rotationDegrees, or null. Turn and mirror the planes as the frame says, then draw these on top, as the screen did (#428).

Null when the capture did not ask for them and when nothing was showing. Laid out for the frame rather than for the screen because a screenshot is the frame's size, not the phone's: reusing the on-screen overlay would put the text wherever it happened to sit on a display of a different shape.