compute-rect2.kt

    data class SelectedArea(val x: Int, val y: Int, val width: Int, val height: Int) {
        companion object {
            fun computeSelectedArea(selectedCells: ObservableList<TablePosition<*, *>>): SelectedArea? {
                if (selectedCells.size == 0) {
                    return null
                }

                val minCol = selectedCells.minOf { it.column }
                val maxCol = selectedCells.maxOf { it.column }
                val minRow = selectedCells.minOf { it.row }
                val maxRow = selectedCells.maxOf { it.row }

                val numCols = (maxCol - minCol) + 1
                val numRows = (maxRow - minRow) + 1
                val markers = IntArray(numRows * numCols)
                selectedCells.forEach { p ->
                    markers[((p.row - minRow) * numCols) + (p.column - minCol)]++
                }
                if (!markers.all { it == 1 }) {
                    return null
                }

                return SelectedArea(minCol, minRow, numCols, numRows)
            }
        }
    }