Function isEmptyCellByIndex

src/ink/screen.ts:453–458

(screen: Screen, index: number)

}

function isEmptyCellByIndex(screen: Screen, index: number): boolean {
  // An empty/unwritten cell has both words === 0:
  // word0 = EMPTY_CHAR_INDEX (0), word1 = packWord1(emptyStyleId=0, 0, 0) = 0.
  const ci = index << 1
  return screen.cells[ci] === 0 && screen.cells[ci | 1] === 0
}

export function isEmptyCellAt(screen: Screen, x: number, y: number): boolean {
  if (x < 0 || y < 0 || x >= screen.width || y >= screen.height) return true