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Documentation Index

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SyllableLayout holds all pre-computed rendering data for a single KaraokeSyllable. It is produced by measureSyllablesAndDetermineAnimation() and consumed by the canvas drawing functions in KaraokeLineText. Each instance is @Stable, meaning Compose can skip recomposition when its fields have not changed.

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Data Class Definition

@Stable
data class SyllableLayout(
    val syllable: KaraokeSyllable,
    val textLayoutResult: TextLayoutResult,
    val wordId: Int,
    val useAwesomeAnimation: Boolean,
    val width: Float = textLayoutResult.size.width.toFloat(),
    val position: Offset = Offset.Zero,
    val wordPivot: Offset = Offset.Zero,
    val wordAnimInfo: WordAnimationInfo? = null,
    val charOffsetInWord: Int = 0,
    val charLayouts: List<TextLayoutResult>? = null,
    val charOriginalBounds: List<Rect>? = null,
    val firstBaseline: Float = 0f,
    val phonetic: String? = null,
    val phoneticLayoutResult: TextLayoutResult? = null,
)

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Fields

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syllable
KaraokeSyllable
required
The source syllable carrying the raw text content and timing data (start, end, content, phonetic). This is the original model object from accompanist-lyrics-core — SyllableLayout wraps it rather than replacing it.
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textLayoutResult
TextLayoutResult
required
The measured TextLayoutResult for the syllable’s content string, produced by TextMeasurer.measure() with the line’s TextStyle. Used during canvas drawing to obtain glyph paths and bounding boxes.
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wordId
Int
required
An integer that groups syllables belonging to the same word. Syllables sharing the same wordId are always kept together on a single line by the line-wrapping algorithm and share a common wordPivot and wordAnimInfo.
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useAwesomeAnimation
Boolean
required
When true, character-level bounce and swell animations are enabled for this syllable’s word. Set to true by measureSyllablesAndDetermineAnimation() when all of the following conditions are met:
  • Per-character duration > 200 ms
  • Total word duration ≥ 1 000 ms
  • Script is not CJK, Arabic, or Devanagari
  • The line is not an accompaniment (background) line
When false, a simpler scale animation is applied to the whole word instead.
​
width
Float
Measured display width of this syllable in pixels. Defaults to textLayoutResult.size.width.toFloat(), but may be larger in two situations:
  1. The syllable content ends with a trailing space — the layout pipeline re-measures the trimmed text and adds spaceWidth × spaceCount back in.
  2. The syllable has a phonetic annotation whose rendered width exceeds the main text width.
Use this value (not textLayoutResult.size.width) when computing line widths or hit-testing.
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position
Offset
The computed top-left canvas position for this syllable. Defaults to Offset.Zero immediately after measureSyllablesAndDetermineAnimation() returns. Populated with real coordinates after calculateStaticLineLayout() runs.
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wordPivot
Offset
The center-bottom point of the bounding box that spans all syllables in the same word. Used as the pivot (transform origin) for the word-level scale animation so that characters appear to grow from their baseline. Populated by calculateStaticLineLayout().
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wordAnimInfo
WordAnimationInfo?
Animation timing data for the entire word this syllable belongs to. null when useAwesomeAnimation is false for this word. Populated by calculateStaticLineLayout(). See WordAnimationInfo below.
​
charOffsetInWord
Int
The index of this syllable’s first character within the concatenated word string. For example, if the word is "hello" split across two syllables "hel" and "lo", then charOffsetInWord is 0 and 3 respectively. Used to look up per-character animation progress during drawing.
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charLayouts
List<TextLayoutResult>?
A pre-measured TextLayoutResult for every individual character in the syllable’s content. Only populated when useAwesomeAnimation = true; null otherwise. Caching these measurements in the layout phase avoids repeated TextMeasurer.measure() calls inside the draw loop.
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charOriginalBounds
List<Rect>?
The bounding Rect for each character as reported by textLayoutResult.getBoundingBox(index). These boxes come from the full-syllable layout and are used as reference positions to correctly offset each character’s individual canvas transform. Only populated when useAwesomeAnimation = true.
​
firstBaseline
Float
The baseline distance from the top of the text layout for this syllable, obtained from textLayoutResult.firstBaseline. Used by calculateStaticLineLayout() to vertically align syllables that may have different font metrics within the same row.
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phonetic
String?
The raw phonetic annotation string for this syllable (e.g., a pinyin syllable like "nǐ" or a romaji string). null when the source KaraokeSyllable carries no phonetic data.
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phoneticLayoutResult
TextLayoutResult?
The measured TextLayoutResult for the phonetic string, or null if there is no phonetic annotation. Measured using phoneticStyle in measureSyllablesAndDetermineAnimation().

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WordAnimationInfo

WordAnimationInfo carries the timing window and content string for a complete word, enabling the drawing layer to derive a single normalized playhead value [0, 1] across all characters. 
@Stable
data class WordAnimationInfo(
    val wordStartTime: Long,
    val wordEndTime: Long,
    val wordContent: String,
    val wordDuration: Long = wordEndTime - wordStartTime
)
​
wordStartTime
Long
required
Timestamp in milliseconds at which the first syllable of this word begins. Equals the minimum syllable.start across all syllables in the word.
​
wordEndTime
Long
required
Timestamp in milliseconds at which the last syllable of this word ends. Equals the maximum syllable.end across all syllables in the word.
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wordContent
String
required
The full concatenated text content of the word (all syllable .content strings joined). Used for script-detection and character-count calculations.
​
wordDuration
Long
Convenience property equal to wordEndTime - wordStartTime. Pre-computed to avoid repeated subtraction inside the animation loop.

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