Function findLineEdgePoint

packages/editor/src/plugin/editable.ts:742–766

(
    editor: Editor,
    { at, edge = 'start' }: { at?: Range; edge?: 'start' | 'end' } = {},
  )

  },

  findLineEdgePoint(
    editor: Editor,
    { at, edge = 'start' }: { at?: Range; edge?: 'start' | 'end' } = {},
  ): Point | null {
    const { selection } = editor
    if (!at && selection) at = selection
    if (!at) return null
    const isStart = edge === 'start'
    const point = isStart ? Range.start(at) : Range.end(at)
    const range = Editable.toDOMRange(editor, {
      anchor: point,
      focus: point,
    })
    range.collapse(isStart)
    const rects = range.getClientRects()
    const rect = rects[rects.length - 1]
    const bottom = rect.top + rect.height / 2
    const block = Editor.above(editor, {
      at: point,
      match: n => Editor.isBlock(editor, n),
    })
    if (!block) return null
    const domBlock = Editable.toDOMNode(editor, block[0])
    return Editable.findClosestPoint(editor, domBlock, isStart ? -99999 : 99999, bottom)
  },

  findNextLinePoint(editor: Editor, at?: Range): Point | null {
    const { selection } = editor