[PyQt] Howto use the Qt documentation successfully - Was: Re: Access to lines of text on textEdit.

[Hans-Peter Jansen]

On Tuesday 14 September 2010, 17:51:28 Steve Borho wrote:
> On Tue, Sep 14, 2010 at 4:08 AM, Hans-Peter Jansen <hpj at urpla.net> wrote:
> > On Tuesday 14 September 2010, 09:48:47 Algis Kabaila wrote:
> >> > On Tuesday 14 September 2010, 01:54:01 Algis Kabaila wrote:
> >> > > Is it possible to access lines of text in a textEdit?  If so how
> >> > > can I find information about it?
> >>
> >> On Tuesday 14 September 2010 10:09:10 Hans-Peter Jansen wrote:
> >> > Depending on document type, try this:
> >> >
> >> >     document().findBlockByLineNumber(lineNumber).text()
> >> >
> >> > Pete
> >>
> >> On Tuesday 14 September 2010 12:24:52 Henning Schröder wrote:
> >> > If you enter findBlockByLineNumber in Qt Assistant you will see that
> >> > this method  belongs to a QTextDocument object and returns a
> >> > QTextBlock object QTextEdit has a method called "document()" which
> >> > returns a QTextDocument.
> >> >
> >> > Henning
> >>
> >> In summary, the i-th line is returned by the following
> >>
> >> line = self.textEdit.document().findBlockByLineNumber(i).text(),
> >>
> >> which at least in part is identical to what Hans-Peter told me to do.
> >> Hennings advice to look up Qt Assistant was an invaluable help.  Thank
> >> you both.
> >
> > Al, I cannot imagine how to work with PyQt successfully _without_ using
> > assistant. Of course, Qt's class hierarchy is quite senseful most of
> > the time in the first place, but due to the sheer volume of it, nobody
> > is able to memorize this all.
> >
> > Just a few words on methology:
> >
> > Searching for some functionality of QTextEdit, e.g. how to get at a
> > specific line via line number:
> >  * Look up QTextEdit in assistant
> >   We read: The QTextEdit class provides a widget that is used to edit
> > and display both plain and rich text.
> >  * Click on more...
> >   We read: QTextEdit works on paragraphs and characters. A paragraph is
> > a formatted string which is word-wrapped to fit into the width of the
> > widget. By default when reading plain text, one newline signifies a
> > paragraph.
> >   Sounds like we're looking for paragraphs in plain text mode
> >  * Check class methods, that do what we want:
> >   Nothing obvious stands out
> >  * Check base classes:
> >   QTextEdit inherits from QAbstractScrollArea only, that won't help us
> >   much here
> >  * Check methods again:
> >   Nothing obvious with paragraphs, but QTextDocument * document() might
> > be interesting
> >  * Click on document() method:
> >   We read: Returns a pointer to the underlying document.
> >  * Check it out: click on QTextDocument
> >   We read: The QTextDocument class holds formatted text that can be
> > viewed and edited using a QTextEdit
> >   We're getting nearer, but still no ball: check out class methods
> >  * It has a method: QTextBlock findBlockByLineNumber ( int lineNumber )
> >   Sounds like the best fit: click on method
> >  * We read: Returns the text block that contains the specified
> > lineNumber. What the hell is a QTextBlock? Click:
> >   It encapsulates text fragments, and provides access to them
> >  * Check methods: QString text() sounds, like what we are looking for
> >   We read: Returns the block's contents as plain text.
> >
> > Target reached.
> >
> > Note, how this transforms to a single line of code. Isn't it
> > impressive, how much power is at our finger tips and how much joy it
> > can be to ignore all this superfluous C++ decoration, that would
> > involve much more work to get right ;-)
>
> How does one get the documentation files to make assistant useful on
> Windows?

Download a matching zip archive, e.g.:
ftp://ftp.qt.nokia.com/qt/source/qt-everywhere-opensource-src-4.6.3.zip, 
extract the doc/qch/*.qch files and register them within assistant.

Pete