Automate page scroll to down in Splash and Scrapy

I am crawling a site which uses lazy loading for product images.

For this reason i included scrapy-splash so that the javascript can be rendered also with splash i can provide a wait argument. Previously i had a though that it is because of the timing that the raw scrapy.Request is returning a placeholder image instead of the originals.

I've tried wait argument to 29.0 secs also, but still my crawler hardly getting 10 items (it should bring 280 items based on calculations). I have a item pipleline which checks if the image is empty in the item so i raise DropItem.

I am not sure, but i also noticed that its not only the wait problem. It looks like that images gets loaded when i scroll down.

What i am looking for is a way to automate a scroll to bottom behaviour within my requests.

Here is my code Spider

  def parse(self, response):
        categories = response.css('div.navigation-top-links a.uppercase::attr(href)').extract()
        for category in categories:
            link = urlparse.urljoin(self.start_urls[0], category)
            yield SplashRequest(link, callback=self.parse_products_listing, endpoint='render.html',
                                       args={'wait': 0.5})

Pipeline

class ScraperPipeline(object):
    def process_item(self, item, spider):
        if not item['images']:
            raise DropItem

        return item

Settings

IMAGES_STORE = '/scraper/images'
        
SPLASH_URL = 'http://172.22.0.2:8050'

DUPEFILTER_CLASS = 'scrapy_splash.SplashAwareDupeFilter'


ITEM_PIPELINES = {
   'scraper.pipelines.ScraperPipeline': 300,
    'scrapy.pipelines.images.ImagesPipeline': 1
}


DOWNLOADER_MIDDLEWARES = {
    'scrapy.downloadermiddleware.useragent.UserAgentMiddleware': None,
    'scrapy_splash.SplashMiddleware': 725,
    'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware': 810,
    # 'custom_middlewares.middleware.ProxyMiddleware': 210,
}