<div dir="ltr">I too am curious, my software uses QWebElement extensively, and was a little surprised how page visibility there is available.<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jan 5, 2015 at 8:27 PM, Florian Bruhin <span dir="ltr"><<a href="mailto:me@the-compiler.org" target="_blank">me@the-compiler.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">* David Cortesi <<a href="mailto:davecortesi@gmail.com">davecortesi@gmail.com</a>> [2015-01-05 19:59:13 -0800]:<br>
<div><div class="h5">> On Mon, Jan 5, 2015 at 3:26 PM, Andreas Pakulat <<a href="mailto:apaku@gmx.de">apaku@gmx.de</a>> wrote:<br>
><br>
> ><br>
> > I'm a bit at a loss what to do following a call to such a method. What is<br>
> >> the best way to "idle" until the callback comes? n.b. I don't see any<br>
> >> WebEngine specific guidance at the PyQt5 doc [2].<br>
> >><br>
> ><br>
> > I'd say just as all other callbacks in Qt (i.e. signal/slots), return<br>
> > control to the qt event loop.<br>
> ><br>
><br>
> Could you clarify a bit? The doc [1] for QWebEnginePage.toPlainText() will<br>
> at some unknown future time call my callback passing the text of the page.<br>
> But I would make that call in some code that needs that text -- to write it<br>
> to a file, say. So in a custom class based on QWebEngineView, I capture the<br>
> ^S key, perhaps, for Save. I put a findSaveDialog and get a path string and<br>
> open a text stream for output. Then...<br>
><br>
> self.page().toPlainText( lambda s : self.save_plain_text = s )<br>
> # Here -- twiddle my thumbs until I can...<br>
> output_stream << self.save_plain_text<br>
><br>
> Is this the kind of thing you have in mind?<br>
><br>
> self.save_plain_text = None<br>
> self.page().toPlainText( lambda s : self.save_plain_text = s )<br>
> while self.save_plain_text is None : QCoreApplication.processEvents()<br>
> output_stream << self.save_plain_text<br>
<br>
</div></div>Probably something like this:<br>
<br>
def handle_ctrl_s(self):<br>
self.save_filename = get_filename_from_user()<br>
self.page().toPlainText(self.do_save)<br>
<br>
def do_save(self, data):<br>
with open(self.save_filename, 'w') as f:<br>
f.write(data)<br>
<br>
Or this using functools.partial, i.e. it won't break if the user<br>
presses Ctrl-S again before the text is ready:<br>
<br>
def handle_ctrl_s(self):<br>
filename = get_filename_from_user()<br>
self.page().toPlainText(partial(self.do_save, filename))<br>
<br>
def do_save(self, filename, data):<br>
with open(filename, 'w') as f:<br>
f.write(data)<br>
<br>
I think this is a general concept which is very important to grasp<br>
(and also took me a while) when programming with something like PyQt:<br>
<br>
Try to make everything happen async - the majority of the time should<br>
be spent in the Qt event loop (i.e. the app.exec_() call). Any code<br>
you write gets called from that event loop usually, and should finish<br>
"immediately". So here, you don't "wait" until the data is ready, you<br>
tell Qt "call me back when the data is ready", return to the event<br>
loop, and *then* save it when it *is* ready.<br>
<span class="HOEnZb"><font color="#888888"><br>
Florian<br>
<br>
--<br>
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