Magento 2: Pdf - Add New Page

Question

I want to add custom image in a invoice pdf. The image to display is from my custom table based on order id. I am able to add the image in pdf using the below code.

app/code/Vendor/Module/etc/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference type="Magento\Sales\Model\Order\Pdf\Invoice"
                for="Vendor\Module\Model\Order\Pdf\Invoice"/>
</config>

app/code/Vendor/Module/Model/Order/Pdf/Invoice.php

<?php
/**
 * Copyright © 2013-2017 Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Vendor\Module\Model\Order\Pdf;

use Magento\Sales\Model\Order\Pdf\Config;
/**
 * Sales Order Invoice PDF model
 * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
 */
class Invoice extends \Magento\Sales\Model\Order\Pdf\Invoice
{
    private $ordermoduleCollectionFactory;
    private $directoryList;
    private $filesystem;

    public function __construct(
        \Magento\Payment\Helper\Data $paymentData,
        \Magento\Framework\Stdlib\StringUtils $string,
        \Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig,
        \Vendor\Module\Model\ResourceModel\Ordermodule\Grid\CollectionFactory $ordermoduleCollectionFactory,
        \Magento\Framework\Filesystem $filesystem,
        Config $pdfConfig,
        \Magento\Sales\Model\Order\Pdf\Total\Factory $pdfTotalFactory,
        \Magento\Sales\Model\Order\Pdf\ItemsFactory $pdfItemsFactory,
        \Magento\Framework\Stdlib\DateTime\TimezoneInterface $localeDate,
        \Magento\Framework\Translate\Inline\StateInterface $inlineTranslation,
        \Magento\Sales\Model\Order\Address\Renderer $addressRenderer,
        \Magento\Store\Model\StoreManagerInterface $storeManager,
        \Magento\Framework\Locale\ResolverInterface $localeResolver,
        \Magento\Framework\Filesystem\DirectoryList $directoryList,
        array $data = []
    ) {
        parent::__construct(
            $paymentData,
            $string,
            $scopeConfig,
            $filesystem,
            $pdfConfig,
            $pdfTotalFactory,
            $pdfItemsFactory,
            $localeDate,
            $inlineTranslation,
            $addressRenderer,
            $storeManager,
            $localeResolver,
            $data
        );
        $this->filesystem = $filesystem;
        $this->directoryList = $directoryList;
        $this->ordermoduleCollectionFactory = $ordermoduleCollectionFactory;
    }

    public function getPdf($invoices = [])
    {
        $this->_beforeGetPdf();
        $this->_initRenderer('invoice');

        $pdf = new \Zend_Pdf();
        $this->_setPdf($pdf);
        $style = new \Zend_Pdf_Style();
        $this->_setFontBold($style, 10);

        foreach ($invoices as $invoice) {
            if ($invoice->getStoreId()) {
                $this->_localeResolver->emulate($invoice->getStoreId());
                $this->_storeManager->setCurrentStore($invoice->getStoreId());
            }
            $page = $this->newPage();
            $order = $invoice->getOrder();
            /* Add image */
            $this->insertLogo($page, $invoice->getStore());
            /* Add address */
            $this->insertAddress($page, $invoice->getStore());
            /* Add head */
            $this->insertOrder(
                $page,
                $order,
                $this->_scopeConfig->isSetFlag(
                    self::XML_PATH_SALES_PDF_INVOICE_PUT_ORDER_ID,
                    \Magento\Store\Model\ScopeInterface::SCOPE_STORE,
                    $order->getStoreId()
                )
            );
            /* Add document text and number */
            $this->insertDocumentNumber($page, __('Invoice # ') . $invoice->getIncrementId());
            /* Add table */
            $this->_drawHeader($page);
            /* Add body */
            foreach ($invoice->getAllItems() as $item) {
                if ($item->getOrderItem()->getParentItem()) {
                    continue;
                }
                /* Draw item */
                $this->_drawItem($item, $page, $order);
                $page = end($pdf->pages);
            }
            /* Add totals */
            $this->insertTotals($page, $invoice);
            if ($invoice->getStoreId()) {
                $this->_localeResolver->revert();
            }

        }

        $orderId = $order->getId();
        $module = $this->getAvailableModule($orderId);  
        if ($module != '') {                  
            $this->insertConditions($page,$module);
        }
        $this->_afterGetPdf();
        return $pdf;
    }


    public function insertConditions($page,$module)
    {
        $module =$$module //custom image
        $image = Zend_Pdf_Image::imageWithPath($imageFile,$imageWidth,$imageHeight);
        $y=$pdf->y - $imageHeight /3;
        $page->drawImage($image, 35,$y, 35+ $imageWidth / 2, $y + $imageHeight/2);
    } 

    public function getAvailableModule($orderId)
    {
        $collection = $this->ordermoduleCollectionFactory->create()
                ->addFieldToFilter('order_id', $orderId)
                ->addFieldToFilter('main_table.dealer_id', array('neq' => -1));            
        $image = '';
        foreach($collection as $col) {
            $image = $col->getModule();
        }
        if (!is_null($image)) {
            try 
            {
                $imagePath = '/modulefiles/'.$image;
                $media_dir = $this->filesystem->getDirectoryRead(\Magento\Framework\App\Filesystem\DirectoryList::MEDIA);            
                if ($media_dir->isFile($imagePath)) {
                       return $media_dir->getAbsolutePath($imagePath);
                }
                else
                   return null;
            } catch (Exception $e) {
                return false;
            }
        }
    }

    public function newPage(array $settings = [])
    {
        /* Add new table head */
        $page = $this->_getPdf()->newPage(\Zend_Pdf_Page::SIZE_A4);
        $this->_getPdf()->pages[] = $page;
        $this->y = 800;
        if (!empty($settings['table_header'])) {
            $this->_drawHeader($page);
        }
        return $page;
    }
}

The issue is:

Invoice with a single item in pdf -> my image is displaying properly Invoice with multiple items in order -> don't have space in first page. So displaying as http://i.prntscr.com/CRm-KGvjSimZCFDj2TcLEQ.png

So I have added new page function $page = $this->newPage(); in function insertConditions()

But now my custom image is always showing n the second page. Even if we have space remaining in the first page.

How can I solve this:adding new page only when no remaining space in the first page.