PySnippet: JavaScript

Wednesday, January 20, 2010

More fun with QWebKit

In the previous post I wrote about calling python methods and accessing properties from JavaScript executed in QWebKit. In this post I'll show you how to do the other way around, calling a JavaScript function from Python.

I would like to thank Rich Moore for commenting on the previous post and pointing out that you should re-add your python object every time the javaScriptWindowObjectCleared() signal is emitted.

Actually, I think this is almost to simple to do a post about so I'll try doing something fun/useful with it.

QWebFrame contains a public slot:

QVariant evaluateJavaScript(const QString & scriptSource)

You simply pass the JavaScript-snippet to the function. The snippet will be evaluated using the frame as context and returns the result of the last executed statement. This makes it possible to 'click' submit buttons, fill form fields and other interesting stuff in the currently loaded frame. I'll give you an example on how you can create an auto-login GMail widget. The widget will automatically login the user by populating the login form with the user's credentials and 'click' the login button.

#!/usr/bin/env python
from PyQt4 import QtCore
from PyQt4 import QtGui
from PyQt4 import QtWebKit

javaScriptLogin = """
document.getElementsByName('Email').item(0).value='{email}';
document.getElementsByName('Passwd').item(0).value='{password}';
document.getElementsByName('signIn').item(0).click(); void(0);
"""

class GmailWebView(QtWebKit.QWebView):
    def __init__(self, parent=None):
        super(GmailWebView, self).__init__(parent)
        self.loggedIn = False

    def login(self, url, email, password):
        """Login to gmail."""
        self.url = QtCore.QUrl(url)
        self.email = email
        self.password = password  
        self.loadFinished.connect(self._loadFinished)
        self.load(self.url)

    def createWindow(self, windowType):
        """Load links in the same web-view."""
        return self

    def _loadFinished(self):
        if self.loggedIn:
            self.loadFinished.disconnect(self._loadFinished)

        self.loggedIn = True
        jscript = javaScriptLogin.format(email=self.email, password=self.password)
        self.page().mainFrame().evaluateJavaScript(jscript)

    def contextMenuEvent(self, event):
        """Add a 'Back to GMail' entry."""
        menu = self.page().createStandardContextMenu()
        menu.addSeparator()
        action = menu.addAction('Back to GMail')
        @action.triggered.connect
        def backToGMail():
            self.load(self.url)
        menu.exec_(QtGui.QCursor.pos())

def main():
    import sys
    qApp = QtGui.QApplication(sys.argv)

    # Prevents me from posting my password on the blog :)
    password, ok = QtGui.QInputDialog.getText(None, "Password request", "Enter password", QtGui.QLineEdit.Password)
    if not ok:
        return

    gmailWebView = GmailWebView()
    gmailWebView.login('https://mail.google.com/mail',
                       'mario.boikov',
                       password)
    gmailWebView.show()

    sys.exit(qApp.exec_())

if __name__ == "__main__":
    main()

This is just a quick hack, it lacks a bunch of checkings...

Maybe it's time to wipe the dust off my GMonitor-plasmoid and add support for opening my account in a new window based on the GMail widget above.

Saturday, January 16, 2010

Calling Python from JavaScript in PyQt's QWebkit

QtWebKit makes it very easy to expose methods and properties implemented in Python to JavaScript. Qt will automatically expose Qt-slots and Qt-properties to a JavaScript when a QObject is made available in the frame's JavaScript context.

I think the code speaks for itself

import sys
from PyQt4 import QtCore, QtGui, QtWebKit

"""Html snippet."""
html = """
<html><body>
  <center>
  <script language="JavaScript">
    document.write('<p>Python ' + pyObj.pyVersion + '</p>')
  </script>
  <button onClick="pyObj.showMessage('Hello from WebKit')">Press me</button>
  </center>
</body></html>
"""

class StupidClass(QtCore.QObject):
    """Simple class with one slot and one read-only property."""

    @QtCore.pyqtSlot(str)
    def showMessage(self, msg):
        """Open a message box and display the specified message."""
        QtGui.QMessageBox.information(None, "Info", msg)

    def _pyVersion(self):
        """Return the Python version."""
        return sys.version

    """Python interpreter version property."""
    pyVersion = QtCore.pyqtProperty(str, fget=_pyVersion)

def main():
    app = QtGui.QApplication(sys.argv)

    myObj = StupidClass()

    webView = QtWebKit.QWebView()
    # Make myObj exposed as JavaScript object named 'pyObj'
    webView.page().mainFrame().addToJavaScriptWindowObject("pyObj", myObj)
    webView.setHtml(html)

    window = QtGui.QMainWindow()
    window.setCentralWidget(webView)
    window.show()

    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

Some references:

PySnippet

Wednesday, January 20, 2010

More fun with QWebKit

Saturday, January 16, 2010

Calling Python from JavaScript in PyQt's QWebkit

Blog Archive

Projects