horizontal and vertical lines

    val X_PARTITION_RATIO = 1 / 3f
    val Y_PARTITION_RATIO = 1 / 3f
    ...
    private fun drawVerticalLines(canvas: Canvas) {
        canvas.drawLine(width * X_PARTITION_RATIO, 0f, width * X_PARTITION_RATIO, height.toFloat(), paint)
        canvas.drawLine(width * (2 * X_PARTITION_RATIO), 0f, width * (2 * X_PARTITION_RATIO), height.toFloat(), paint)
    }

    private fun drawHorizontalLines(canvas: Canvas) {
        canvas.drawLine(0f, height * Y_PARTITION_RATIO, width.toFloat(), height * Y_PARTITION_RATIO, paint)
        canvas.drawLine(0f, height * (2 * Y_PARTITION_RATIO), width.toFloat(), height * (2 * Y_PARTITION_RATIO), paint)
    }