splash使用script模拟鼠标下拉显示更多内容的行为并爬取加载的数据

Question

使用splash模拟鼠标下拉加载更多数据的行为，无效果，未报错并能抓到首页显示数据，下拉之后加载的数据抓不到。是否是我在设置：splash.scroll_position= {1000,700}的定位有问题？又如何定位到触发加载更多页面行为的坐标呢？

代码如下：

import scrapy
from scrapy.selector import Selector
from scrapy_splash import SplashRequest
import json
class gougou(scrapy.Spider):
    name = 'gg'
    allow_domains = ['baidu.com']
    start_urls = ('http://www.tudou.com/sec/%E8%90%8C%E7%89%A9?spm=a2h28.8313475.nav.dn_sec4',)
    f = open("tudou.txt",'a')
    def start_requests(self):
        script = """ 
        function main(splash)
            splash.scroll_position = {1000,700}
            splash:go(splash.args.url)
            splash:wait(3)
            return {
                html = splash:html()
            }
            end
        """
        for url in self.start_urls: 
            yield scrapy.Request(url=url,callback=self.parse,meta={
                'splash':{
                    'args':{'lua_source':script},
                    'endpoint':'execute'
                }
            }) 
    def parse(self,response):
        scs = Selector(response)
        message = scs.xpath('//img[contains(@class, "v-thumb__pic")]/@alt').extract()
        for sc in message:
            self.f.write(sc)
            self.f.write("\r\n")

测试多次未报错。但是结果就只有30条。求大神指教！