Function stepPreparedChunkLineGeometry

src/line-break.ts:787–1034

(
  prepared: PreparedLineBreakData,
  cursor: LineBreakCursor,
  chunkIndex: number,
  maxWidth: number,
)

}

function stepPreparedChunkLineGeometry(
  prepared: PreparedLineBreakData,
  cursor: LineBreakCursor,
  chunkIndex: number,
  maxWidth: number,
): number | null {
  const chunk = prepared.chunks[chunkIndex]!
  if (chunk.startSegmentIndex === chunk.endSegmentIndex) {
    cursor.segmentIndex = chunk.consumedEndSegmentIndex
    cursor.graphemeIndex = 0
    return 0
  }

  const {
    widths,
    kinds,
    breakableFitAdvances,
    breakablePreferredBreaks,
    discretionaryHyphenWidth,
  } = prepared
  const engineProfile = getEngineProfile()
  const lineFitEpsilon = engineProfile.lineFitEpsilon
  const fitLimit = maxWidth + lineFitEpsilon

  const lineStartSegmentIndex = cursor.segmentIndex
  const lineStartGraphemeIndex = cursor.graphemeIndex
  let lineW = 0
  let hasContent = false
  let lineEndSegmentIndex = cursor.segmentIndex
  let lineEndGraphemeIndex = cursor.graphemeIndex
  let pendingBreakSegmentIndex = -1
  let pendingBreakFitWidth = 0
  let pendingBreakPaintWidth = 0
  let pendingBreakKind: SegmentBreakKind | null = null

  function getCurrentLinePaintWidth(): number {
    return (
      pendingBreakKind === 'soft-hyphen' &&
      pendingBreakSegmentIndex === lineEndSegmentIndex &&
      lineEndGraphemeIndex === 0
    )
      ? pendingBreakPaintWidth
      : lineW
  }

  function finishLine(
    endSegmentIndex = lineEndSegmentIndex,
    endGraphemeIndex = lineEndGraphemeIndex,
    width = getCurrentLinePaintWidth(),
  ): number | null {
    if (!hasContent) return null
    cursor.segmentIndex = endSegmentIndex
    cursor.graphemeIndex = endGraphemeIndex
    return finalizeLinePaintWidth(
      prepared,
      width,
      lineStartSegmentIndex,
      lineStartGraphemeIndex,