使用 Google Chrome Headless 模式强制执行屏幕截图分辨率

Question

I'm having an issue with Nightwatch and Chrome when it launches in headless mode. I've setup a script to take screenshots of my page which I later compare against in order to figure out what the difference is between them. The problem I'm running into is that depending on the machine that runs my script the screenshots are always different as they are not the same resolution.

Here is a screenshot that Nightwatch captured on my Mac with a retina display.

And here is the one which was captured in CircleCI when it ran the same script:

Is there a way to enforce a screen resolution when launching Chrome in headless mode? I've worked with other libraries such as Puppeteer and it seems to be consistent across the board. The window width/height is always respected, but the size of the actual images is what's causing issues here.

Here is what my launch settings look like from my Nightwatch config file:

"chrome_launch" : {
  "launch_url" : "https://localhost:8000",
  "globals" : {
    "abortOnAssertionFailure": false,
    "env" : "local"
  },
  "desiredCapabilities": {
    "chromeOptions" : {
      "args" : ["window-size=1280,2480", "headless", "disable-gpu", "hide-scrollbars"]
    },
    "resolution": "1440x900"
  }
}

Any help would be greatly appreciated.

Answer 1

我遇到了同样的问题，在 chrome 中传递这个参数--force-device-scale-factor=1对我有用：

google-chrome --headless --force-device-scale-factor=1 --window-size=1200,800