unable to install wkhtmltopdf with patched qt in ubuntu 16.04

报错如下：

Traceback (most recent call last):
  File "runoob2pdf.py", line 156, in <module>
    main()
  File "/home/itcast/git-project/py34env/lib/python3.4/site-packages/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/home/itcast/git-project/py34env/lib/python3.4/site-packages/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/home/itcast/git-project/py34env/lib/python3.4/site-packages/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/itcast/git-project/py34env/lib/python3.4/site-packages/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "runoob2pdf.py", line 146, in main
    save_pdf(htmls, file_name)
  File "runoob2pdf.py", line 120, in save_pdf
    pdfkit.from_file(htmls, file_name, options=options)
  File "/home/itcast/git-project/py34env/lib/python3.4/site-packages/pdfkit/api.py", line 49, in from_file
    return r.to_pdf(output_path)
  File "/home/itcast/git-project/py34env/lib/python3.4/site-packages/pdfkit/pdfkit.py", line 159, in to_pdf
    raise IOError("wkhtmltopdf exited with non-zero code {0}. error:\n{1}".format(exit_code, stderr))
OSError: wkhtmltopdf exited with non-zero code -6. error:
The switch --outline-depth, is not support using unpatched qt, and will be ignored.QXcbConnection: Could not connect to display 

解决方法：

sudo apt-get update
sudo apt-get install libxrender1 fontconfig xvfb
wget https://github.com/wkhtmltopdf/wkhtmltopdf/releases/download/0.12.4/wkhtmltox-0.12.4_linux-generic-amd64.tar.xz -P /tmp/
cd /opt/
sudo tar xf /tmp/wkhtmltox-0.12.4_linux-generic-amd64.tar.xz

sudo ln -s /opt/wkhtmltox/bin/wkhtmltopdf /usr/bin/wkhtmltopdf