Function writePlainAsciiLineAt

src/ink/screen.ts:1051–1130

(
  screen: Screen,
  x: number,
  y: number,
  line: string,
  styleId: number,
)

 * Returns the exclusive end column after the written content.
 */
export function writePlainAsciiLineAt(
  screen: Screen,
  x: number,
  y: number,
  line: string,
  styleId: number,
): number {
  if (y < 0 || y >= screen.height || line.length === 0 || x >= screen.width) {
    return x
  }

  let sourceIndex = 0
  let startX = x
  if (startX < 0) {
    sourceIndex = -startX
    startX = 0
  }

  const available = screen.width - startX
  const length = Math.min(line.length - sourceIndex, available)
  if (length <= 0) {
    return x
  }

  const cells = screen.cells
  const packedWord = packWord1(styleId, 0, CellWidth.Narrow)
  let minAffectedX = startX
  let maxAffectedX = startX + length - 1
  const rowBase = y * screen.width

  for (let i = 0; i < length; i += 1) {
    const screenX = startX + i
    const ci = (rowBase + screenX) << 1
    const prevWidth = cells[ci + 1]! & WIDTH_MASK

    if (prevWidth === CellWidth.Wide) {
      const spacerX = screenX + 1
      if (spacerX < screen.width) {
        const spacerCI = ci + 2
        if ((cells[spacerCI + 1]! & WIDTH_MASK) === CellWidth.SpacerTail) {
          cells[spacerCI] = EMPTY_CHAR_INDEX
          cells[spacerCI + 1] = packWord1(
            screen.emptyStyleId,
            0,
            CellWidth.Narrow,
          )
          maxAffectedX = Math.max(maxAffectedX, spacerX)
        }
      }
    } else if (prevWidth === CellWidth.SpacerTail && screenX > 0) {
      const wideCI = ci - 2
      if ((cells[wideCI + 1]! & WIDTH_MASK) === CellWidth.Wide) {
        cells[wideCI] = EMPTY_CHAR_INDEX
        cells[wideCI + 1] = packWord1(screen.emptyStyleId, 0, CellWidth.Narrow)
        minAffectedX = Math.min(minAffectedX, screenX - 1)
      }
    }