Function diffEach

src/ink/screen.ts:1489–1547

(
  prev: Screen,
  next: Screen,
  cb: DiffCallback,
)

 * Returns true if the callback ever returned true (early exit signal).
 */
export function diffEach(
  prev: Screen,
  next: Screen,
  cb: DiffCallback,
): boolean {
  const prevWidth = prev.width
  const nextWidth = next.width
  const prevHeight = prev.height
  const nextHeight = next.height

  let region: Rectangle
  if (prevWidth === 0 && prevHeight === 0) {
    region = { x: 0, y: 0, width: nextWidth, height: nextHeight }
  } else if (next.damage) {
    region = next.damage
    if (prev.damage) {
      region = unionRect(region, prev.damage)
    }
  } else if (prev.damage) {
    region = prev.damage
  } else {
    region = { x: 0, y: 0, width: 0, height: 0 }
  }

  const contentEndRegion = contentEndDamageRegion(prev, next)
  if (contentEndRegion) {
    region =
      region.width === 0 || region.height === 0
        ? contentEndRegion
        : unionRect(region, contentEndRegion)
  }

  if (prevHeight > nextHeight) {
    region = unionRect(region, {
      x: 0,
      y: nextHeight,
      width: prevWidth,
      height: prevHeight - nextHeight,
    })
  }
  if (prevWidth > nextWidth) {
    region = unionRect(region, {
      x: nextWidth,
      y: 0,
      width: prevWidth - nextWidth,
      height: prevHeight,
    })
  }

  const maxHeight = Math.max(prevHeight, nextHeight)
  const maxWidth = Math.max(prevWidth, nextWidth)
  const endY = Math.min(region.y + region.height, maxHeight)
  const endX = Math.min(region.x + region.width, maxWidth)

  if (prevWidth === nextWidth) {
    return diffSameWidth(prev, next, region.x, endX, region.y, endY, cb)
  }
  return diffDifferentWidth(prev, next, region.x, endX, region.y, endY, cb)