+ +
+
+

phantom.py: A lean replacement for bulky headless browser frameworks

+ + + +
+ +

This is a simple but fully scriptable headless QtWebKit browser using PyQt5 in Python3, specialized in executing external JavaScript and generating PDF files. A lean replacement for other bulky headless browser frameworks. (Source code at end of this post as well as in this github gist)

+ + + +

Usage

+ + + +

If you have a display attached:

+ + + +
./phantom.py <url> <pdf-file> [<javascript-file>]
+ + + +

If you don’t have a display attached (i.e. on a remote server):

+ + + +
xvfb-run ./phantom.py <url> <pdf-file> [<javascript-file>]
+ + + +

Arguments:

+ + + +
  • <url> Can be a http(s) URL or a path to a local file
  • <pdf-file> Path and name of PDF file to generate
  • [<javascript-file>] (optional) Path and name of a JavaScript file to execute
+ + + +

Features

+ + + +
  • Generate a PDF screenshot of the web page after it is completely loaded.
  • Optionally execute a local JavaScript file specified by the argument <javascript-file> after the web page is completely loaded, and before the PDF is generated.
  • console.log’s will be printed to stdout.
  • Easily add new features by changing the source code of this script, without compiling C++ code. For more advanced applications, consider attaching PyQt objects/methods to WebKit’s JavaScript space by using QWebFrame::addToJavaScriptWindowObject().
+ + + +

If you execute an external <javascript-file>, phantom.py has no way of knowing when that script has finished doing its work. For this reason, the external script should execute console.log("__PHANTOM_PY_DONE__"); when done. This will trigger the PDF generation, after which phantom.py will exit. If no __PHANTOM_PY_DONE__ string is seen on the console for 10 seconds, phantom.py will exit without doing anything. This behavior could be implemented more elegantly without console.log’s but it is the simplest solution.

+ + + +

It is important to remember that since you’re just running WebKit, you can use everything that WebKit supports, including the usual JS client libraries, CSS, CSS @media types, etc.

+ + + +

Dependencies

+ + + +
  • Python3
  • PyQt5
  • xvfb (optional for display-less machines)
+ + + +

Installation of dependencies in Debian Stretch is easy:

+ + + +
apt-get install xvfb python3-pyqt5 python3-pyqt5.qtwebkit
+ + + +

Finding the equivalent for other OSes is an exercise that I leave to you.

+ + + +

Examples

+ + + +

Given the following file /tmp/test.html:

+ + + +
<html>
+  <body>
+    <p>foo <span id="id1">foo</span> <span id="id2">foo</span></p>
+  </body>
+  <script>
+    document.getElementById('id1').innerHTML = "bar";
+  </script>
+</html>
+ + + +

… and the following file /tmp/test.js:

+ + + +
document.getElementById('id2').innerHTML = "baz";
+console.log("__PHANTOM_PY_DONE__");
+ + + +

… and running this script (without attached display) …

+ + + +
xvfb-run python3 phantom.py /tmp/test.html /tmp/out.pdf /tmp/test.js
+ + + +

… you will get a PDF file /tmp/out.pdf with the contents “foo bar baz”.

+ + + +

Note that the second occurrence of “foo” has been replaced by the web page’s own script, and the third occurrence of “foo” by the external JS file.

+ + + +

Source Code

+ + + +
"""
+# phantom.py
+
+Simple but fully scriptable headless QtWebKit browser using PyQt5 in Python3,
+specialized in executing external JavaScript and generating PDF files. A lean
+replacement for other bulky headless browser frameworks.
+
+Copyright 2017 Michael Karl Franzl
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+"""
+
+import sys
+from PyQt5.QtCore import QUrl
+from PyQt5.QtWebKitWidgets import QWebPage
+from PyQt5.QtWidgets import QApplication
+from PyQt5.QtPrintSupport import QPrinter
+from PyQt5.QtCore import QTimer
+import traceback
+
+  
+class Render(QWebPage):
+  def __init__(self, url, outfile, jsfile):
+    self.app = QApplication(sys.argv)
+    
+    QWebPage.__init__(self)
+
+    self.jsfile = jsfile
+    self.outfile = outfile
+    
+    qurl = QUrl.fromUserInput(url)
+    
+    print("phantom.py: URL=", qurl, "OUTFILE=", outfile, "JSFILE=", jsfile)
+    
+    # The PDF generation only happens when the special string __PHANTOM_PY_DONE__
+    # is sent to console.log(). The following JS string will be executed by
+    # default, when no external JavaScript file is specified.
+    self.js_contents = "setTimeout(function() { console.log('__PHANTOM_PY_DONE__') }, 500);";
+    
+    if jsfile:
+      try:
+        f = open(self.jsfile)
+        self.js_contents = f.read()
+        f.close()
+      except:
+        print(traceback.format_exc())
+        self._exit(10)
+        
+    self.loadFinished.connect(self._loadFinished)
+    self.mainFrame().load(qurl)
+    self.javaScriptConsoleMessage = self._onConsoleMessage
+    
+    # Run for a maximum of 10 seconds
+    watchdog = QTimer()
+    watchdog.setSingleShot(True)
+    watchdog.timeout.connect(lambda: self._exit(1))
+    watchdog.start(10000)
+    
+    self.app.exec_()
+    
+    
+  def _onConsoleMessage(self, txt, lineno, filename):
+    print("CONSOLE", lineno, txt, filename)
+    if "__PHANTOM_PY_DONE__" in txt:
+      # If we get this magic string, it means that the external JS is done
+      self._print()
+      self._exit(0)
+  
+  
+  def _loadFinished(self, result):
+    print("phantom.py: Loading finished!")
+    print("phantom.py: Evaluating JS from", self.jsfile)
+    self.frame = self.mainFrame()
+    self.frame.evaluateJavaScript(self.js_contents)
+    
+
+  def _print(self):
+    print("phantom.py: Printing...")
+    printer = QPrinter()
+    printer.setPageMargins(10, 10, 10, 10, QPrinter.Millimeter)
+    printer.setPaperSize(QPrinter.A4)
+    printer.setCreator("phantom.py by Michael Karl Franzl")
+    printer.setOutputFormat(QPrinter.PdfFormat);
+    printer.setOutputFileName(self.outfile);
+    self.frame.print(printer)
+    
+  def _exit(self, val):
+    print("phantom.py: Exiting with val", val)
+    self.app.exit(val) # Qt exit
+    exit(val) # Python exit
+    
+    
+def main():
+  if (len(sys.argv) < 3):
+    print("USAGE: ./phantom.py <url> <pdf-file> [<javascript-file>]")
+  else:
+    url = sys.argv[1]
+    outfile = sys.argv[2]
+    jsfile = sys.argv[3] if len(sys.argv) > 3 else None
+    r = Render(url, outfile, jsfile)
+
+
+if __name__ == "__main__":
+  main()
+
+ + +
+ +
+ +

+ 2 thoughts on “phantom.py: A lean replacement for bulky headless browser frameworks”

+ + +
    +
  1. +
    + Pingback: PhantomJS alternative: Write short PyQt scripts: phantom.py - Michael Franzl
    +
    2. +
  2. +
    + Pingback: PhantomJS alternative: Write short PyQt scripts instead (phantom.py) - Michael Franzl
    +
    3. +
+ + + + +
+

Leave a Reply

Your email address will not be published.

+ +

+

+ +

+

This site uses Akismet to reduce spam. Learn how your comment data is processed.

+
+ + +