[Tutor] Need Help Modifying a wxPython GUI (scrolling display and logging)

[Prasad, Ramit]

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Matt D wrote:
> On 06/04/2013 12:28 PM, Prasad, Ramit wrote:
> > Matt D wrote:
> >> Hello,
> >>
> >> I am using an open source wxPython GUI that I like very very much. I
> >> have ideas about some modifications I need but I cannot be bothering the
> >> author too much so I must learn some very specific things about Python
> >> in order to make the modification myself.  First, I need some help
> >> understanding the code behind this GUI.  From reading the comments I
> >> understand that the part of the program written in C++ sends a Python
> >> pickled dictionary to a msg_queue and when Python decodes the pickle the
> >> TextCtrl fields (in the wxPython GUI I am using) receive/display the
> >> appropriate values. And as new messages are received by Python the GUI
> >> fields are cleared to display the new values.
> >>
> >> For starters I would like the values to be displayed on the GUI in some
> >> sort of a scrolling panel as they are cleared from the TextCtrl fields
> >> so the user can watch recent activity.  I dont know what the best way to
> >> do this would be; the wxpython.scrolledPanel widget?  I am unclear if
> >> this can be put on the same GUI pane as the TextCtrl fields are and I am
> >> unclear about if I can take the values from the TextCtrl fields or have
> >> to use the pickle or what? I dont see any variables declared (like in
> >> Visual Basic) so its not like I can just make a list and a textbox and
> >> print it.
> >
> > Scrolled panel is just a graphical container that allows for scrolling inside,
> > but it is the window that scrolls not widgets inside it. This of it like
> > a webpage that scrolls. If you use web email the text widget in the
> > email needs to scroll so you can see your full email context and not
> > just scroll the page.
> >
> > You will probably need to create a TextCtrl with the appropriate style
> > and append your new data. I have given an example below that should
> > automatically scroll with your new data.
> >
> > #in __init__
> > self.scrolling_widget = wx.TextCtrl( self, wx.ID_ANY, '', size=(-1, 275),
> style=wx.TE_AUTO_SCROLL|wx.TE_READONLY|wx.TE_PROCESS_ENTER|wx.TE_WORDWRAP|wx.TE_MULTILINE )
> >
> > You will probably have to edit TrafficPane.update so that it performs
> > the action you want. BTW, the widgets are all stored in self.fields.
> > You will need to look at the init to see how they stored to get the
> > correct field if you want to change existing field behavior.
> >
> > self.fields["dest"] # Destination TextCtrl
> >
> > That being said, for your desired effect I think all you need to do
> > is change:
> >
> > v.SetValue(f)
> >
> > to:
> >
> > old_text = v.GetValue()
> > # You may need to modify or add some context as otherwise it will
> > # just dump the data and may not make sense when looking at it
> > # scroll.
> > self.scrolling_widget.AppendText(old_text)
> > v.SetValue(f)
> >
> >>
> >> More importantly I need to save the values from the TextCtrl fields,
> >> preferable in a CSV file, for later inspection.  From looking at the
> >> Logging HOWTO and the Logging Cookbook I see there are alot of loggers
> >> available, or ways to log, but they all look like they are orientated
> >> towards exception handling and debugging so I am unsure what is the best
> >> way to go about this; maybe wxLogTextCtrl ?  Utimately I need to log the
> >> values from the TextCtrl fields in a row of comma separated values
> >> adding a time/date stamp as one of the values.  I need this log so the
> >> data can easily be worked on in excel or SAS.  I need the time/date
> >> stamp for time series analysis.
> >
> > Create a list of lists with your data (think table). Then use the
> > csv module to write that data to file. If you need to append,
> > You should read all the existing data. Close the file, append
> > your new data and then write to a new complete file. Once
> > the write has succeeded, rename/overwrite the existing file.
> > That will help prevent you from losing existing data if a problem
> > occurs on write.
> >
> > # Sort the dictionary keys so you get the same order for each row
> > row = [ field_values[k] for sorted(field_values) ]
> > # Now read csv, append row, write new csv, and then overwrite old file
> >
> >>
> >> I attached the code behind the wxPythoin GUI I am using.
> >> Any help will be much appreciated.
> >>
> >> Thanks in advance
> >> --
> >> Matt D
> >> ------------
> >
> > Well that should get you started. Post back if you need specific
> > help with something else.
> >
> >
> >
> > ~Ramit
> >
> >
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> >
> 
> Hello,
> 
> Thank you Ramit for your reply.  I haven't had time to yet use the code
> you have given me but will soon.  But first, I am confused as to how the
> code knows what values to display?  I understand that the data comes out
> of a 'pickle" but I don't understand how or how it is possible for
> you/me (or us) to take only what we need out of the pickle without using
> variable names (i have only used Visual Basic and C++).
> 
> Also, should I just put the code into the file that is running in my
> program? It doesn't need to be compiled right? I have not figured a way
> to use an IDE because the code needs that pickle.
> 
> Cheers,
> Matt

It looks to me like there is a separate thread that pulls data off some queue 
and then hands it to WX in the form of a DataEvent. WX calls display_data 
which unpickles the data. Pickle is just a format of storage and can store 
all Python built-in types. It seems that what is stored is a Python 
dictionary. In fact, you can probably add (and should add) a print statement 
to print attrs in display_data to see the data. It's always important to know 
what your data looks like. If you are only familiar with Visual Basic and C++, 
you may want to familiarize yourself with Dictionaries (aka Hashmaps). They 
are basically containers with key-value pairs for unique keys. By knowing the 
name of the data you want (for example "duid") you can retrieve the value and 
post it back to the appropriate TextCtrl.