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Thomas D edited this page Nov 11, 2020 · 28 revisions

How to debug errors ?

Look at this first: https://github.com/maaaaz/webscreenshot/wiki/How-to-debug-errors

SSL/TLS errors in old Phantomjs versions

  • Q: webscreenshot does not work with certain or all HTTPS Websites (getting QSslSocket: cannot call unresolved function SSLv23_client_method errors or similar with --debug true)
  • A: You are probably using an old version of PhantomJS, update it to the latest version of the branch 2.X. Up to the version 2.0, PhantomJS does only support SSLv2, SSLv3 and TLSv1.0 protocols (nor TLSv1.1 neither TLSv1.2), the Web server you are trying to screenshot might only offer TLSv1.1 and TLSv1.2.

Headless OS

  • Q: I'm running an headless OS and executing phantomjs in a shell returns "QXcbConnection: Could not connect to display"
  • A: Install the xvfb dependency (apt-get install xvfb etc.) and use the webscreenshot --no-xserver option, which is wrapper around xvfb-run (cf. that issue). From version 2.92, webscreenshot will try to detect if running on an headless OS or not, and apply automatically --no-xserver

Calling from another script

  • Q: I want to call webscreenshot from inside another Python script
  • A: webscreenshot is not yet coded as a Python lib but you can try the following code in Python 2 or 3 (originally from that issue but the base code evolved). You can, of course, adapt each option to your purpose.
    Note that this method currently does not work when using Python 3.8+ on Windows 
import argparse
from webscreenshot.webscreenshot import *

# url list to screenshot
url_list = ['http://google.fr', 'http://google.com']

# defining options manually
options = argparse.Namespace(URL=None, ajax_max_timeouts='1400,1800', cookie=None, crop=None, custom_js=None, format='png', header=None, http_password=None, http_username=None, imagemagick_binary=None, input_file=None, label=False, label_bg_color='NavajoWhite', label_size=60, log_level='DEBUG', multiprotocol=False, no_error_file=False, no_xserver=False, output_directory='/tmp/screenshots', port=None, proxy=None, proxy_auth=None, proxy_type=None, quality=75, renderer='phantomjs', renderer_binary=None, single_output_file=None, ssl=False, timeout=30, verbosity=2, window_size='1200,800', workers=4)
# actually launching the function
take_screenshot(url_list, options)

File and folder paths with whitespaces on Windows

Webscreenshot currently does not support paths containing whitespaces (for instance in the current working directory, or renderer binary path cf. https://github.com/maaaaz/webscreenshot/issues/48)

Screenshot taken before the page is totally loaded

  • Q: Screenshots are taken before the page is totally loaded
  • A: It is possible to address this issue by playing with the --ajax-max-timeout option, currently only supported by the phantomjs renderer

Non functional screenshot window size

  • Q: The --window-size parameter does not seem to work, or does not work for my current renderer
  • A: Yes, it is known bug for phantomjs, take a look at this issue to find an alternative with ImageMagick

Executing custom JavaScript code before the screenshot is taken

This is currently supported, only for the phantomjs renderer, with the --custom-js option (cf. https://github.com/maaaaz/webscreenshot/issues/34)

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