OptionalbitmapHeight of an image/bitmap cue as a percentage of the viewport size (typically 0–100).
Only meaningful for image-based cues (e.g. IMSC1 image profile / DVB subtitles). It is
omitted for text cues, and also for bitmap cues that should be displayed at their natural
height. Because it is relative to the viewport rather than a pixel height, it is not
equivalent to measuring the decoded bitmap exposed via the event's image field.
OptionallineCue position on the axis perpendicular to the text flow.
For horizontal captions this controls vertical placement:
{ value: 85, unit: 'percent' } — 85% down the viewport.{ value: 12, unit: 'line' } — 12 rendered text-line slots from the edge.undefined — the underlying subtitle renderer determines line placement automatically.For vertical captions this controls horizontal placement.
OptionallineWhich edge of the cue box is anchored at line.
Does not control text alignment inside the box; see textAlign for that.
OptionalpositionCue box position as a percentage of the viewport on the axis orthogonal to line.
When omitted, the underlying subtitle renderer determines cue box position automatically.
OptionalpositionWhich edge of the cue box is anchored at position.
OptionalsizeWidth of the cue box as a percentage of the viewport dimension in the writing direction.
OptionaltextText alignment inside the cue box.
OptionalwritingVertical writing direction of the cue text.
When omitted, consumers should treat the cue as using the default horizontal writing direction.
This affects how line, position, and size are interpreted.
Cue-box geometry converted to the shared React Native event shape.
Platform-specific SDK values are converted to shared JS units/enums when the native cue exposes them. Fields with automatic or unset values, values not applicable to a cue, or values not exposed by the active native subtitle pipeline are omitted.