[PyQt] binary file viewer with textEdit (PyQt)

Mark Summerfield list at qtrac.plus.com
Thu Jun 24 13:13:36 BST 2010

On 2010-06-24, sandokan wrote:
> Mark Summerfield-4 wrote:
> > One thing that slows QTextEdit down is its sophisticated layout engine.
> > If you can live without that and use a QPlainTextEdit you should get
> > some speedup straightaway.
> Wow, this works perfectly fine. However, I still have a problem with 
> file representation in a text field. Zeros (00h) are not visible at all
> (zeros are not represented by white space as expected). So for example:
> this:
> "2E 64 6C 6C 00 4F 4C 45" (in hex)
> should be represented as:
> ".dll OLE"
> but is represented as:
> ".dllOLE"
> Maybe its because of chosen encoding but "mbcs" was only one which could
> displayed binary file in QTextEdit at all:
> s = codecs.open(self.filename,'rb','mbcs').read()
> self.ui.textEditAscii1.setPlainText(s)
> Do you know any other encoding for binary files which could be used and
> handled correctly by QTextEdit or should I change my approach completely
> and try to display binary files other way?

Personally, I wouldn't take that approach at all. If the file is binary
then it isn't a text file so no encoding is correct.

So I'd do something like this (untested):

    file = QFile(self.filename)
    if file.open(QIODevice::ReadOnly):
	ba = file.readAll() # ba is a QByteArray filled with raw bytes
	for i in range(ba.count()):
	    if QChar(" ") < QChar(ba[i]) < QChar(128):
		ba[i] = ba[i].toAscii()

Mark Summerfield, Qtrac Ltd, www.qtrac.eu
    C++, Python, Qt, PyQt - training and consultancy
        "Rapid GUI Programming with Python and Qt" - ISBN 0132354187

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