Graphical User Interfaces

Moderator: Jim Fulton, USGS
Date: May 24, 1995
URL: http://www.python.org/misc/workshop5-95/guiProgNotes.html

Introduction (Jim Fulton)

Wanted - Visual Python
Should there be a standard GUI extension for python?
Should it be free? ...or layered over commercial toolkits (e.g. wxWindows - actually wxWindows is not commercial, but under the same kind of copyright as Python, and freely available through ftp)

Microsoft Foundation Classes (Jim Ahlstrom)

Crash course on MFC - System Model
- win32 is the windows os interface
- win32s is a subset for windows 3.1
- MFC is a C++ thin layer over win32
- MFC and win32 are alternative interfaces
- most MFC features are duplicates to win32
- MFC may be able to support the MAC
Crash course on MFC - GUI Model
- is a document/view model
- has a complete C++ class heirachy
- has a SDI and MDI model
- is large and complex
- uses resources and resources editor
- shows installed base syndrome
Crash course on MFC - Message Model
- 'command' messages agressively routed
- 'window' message go to the window
- user char and mouse messages go to the View
Crash course on TK
- not like MFC
- command languyage model
- good powerfull commands
- has widgets based on X widgets
- does not have 'windows' in the win32 sense
- easy to write in
- Sun promises portability to windows (Osterhout)
Mark Hammond is doing work to make MFC visible from Python (actual classes are inherited as Python classes)

wxPython (Harri Pasanen)

a Python interface to wxWin
WxWin reference page
WxPython reference page.
Status
- about 40 classes finished
- under unix, usable as a standard Python extension
- MS-Windows version not finished
- next public release in June 95
- Other developers: Robin Dunn
  robin@usin.com
  & Edward Zimmerman
  edz@bsn.com

Pesto (Denis Bohm - Firefly Design)

Fresco
- Fresco home page
Pesto
- Pesto - Mixing Python and Fresco

Fresco Object Builder - using Pesto (Steve Tang)

URL Coming soon...

A Python GUI Model (Jim Ahlstrom - Interet Inc.)

Wpy - a python GUI language
a language to write python gui code
you import wpy.py and get its methods
using Wpy on unix
- you must have Tk 4.0
using Wpy on Windows
- stock build of python
- replay myreadline.c for console
- C++ and C support for GUI using VC++ 2.0
- software available from: ftp.interet.com in /pub/python
- Contact:
  jim@interet.com
Does it work? Yes, mostly
Features
- High level programming interface
- good menuy support
- Basic support to make menus
- Buttons
- Static controls (e.g. lines)
What's missing
- Missing controls
- wont draw text
- no scroll bar
Design Objectives
- must support native look-and-feel
- must have a class library design
- high level moduel gives portabilty
- should be a thin layer, small & simple
- take advantage of pythoin features
- python is in control
- future: remote GUI
GUI Model
- class heirachy is MFC
- app document frame view template
- message are MFC but much fewer
- message routing is MFC
- methods are MFC but much fewer
- geometry management in python
- no use of resources (*.rc files)

'Hello World' Code Example

	from wpy import *
	class MyView(CScrollView)
	  def OnCreate(self, event):
 	  b = CPushButton(self, "Quit")
	  b.Create()
	  self.button = b
        def OnSize(self, rect):
	  self.button.WpyPlace(rect, 0.5, 0.5, "center")

	class MyApp(CWinApp):
	  def InitInstance(self):
	  templ = CSingleDocTemplate(CDocument, CFrameWnd, MyView)
  	  templ.wpyText = "Hello World"
	  self.AddDocTemplate(templ)
	  self.FileNew()
	def OneButtonQuit(self, control):
	  self.Exit()

	# Start the App, respond to events...
	app = MyApp()

Tk interface toolkit 'The IT' (John Viega - UVA)

jtv2j@virginia.edu
TkInter replacement
Tommy Burdette passed this work onto Matt Conway
Current implementation is too slow to use
Goal is to get the tk look-and-feel out of the toolkit
Goal is to create an object-oriented intuitive structure
Looking for feed-back
One of the big areas that needs improvments is properties
planning on using the windows port of Tk
unix version should be ready by end-of-summer 95
'IT' will be freely available to all
promised a URL pointer with more detail soon...

C and Python interface to Tk (Brian Warkentine)

Problems with tKinter
- lack of documentation
- oddly organized class stucture
- dictionaries as arguments
- embedded Tcl
- requires porting to new releases of Tk
Tkgu
- simple python wrapper to Tcl/tk
- enables intermixed python and Tcl
- easy to port existing Tcl apps to python
- independent of new Tk features
- simplier than Tkinter
- no interface for conversions
- functional interface - one class encapsulates a Tcl Context

A Tkgu example...

	import Tkgu
	def printit():
		print 'howdy'
	top = Tkgu.Tkgu()
	frame1 = top.frame('.', '-relief raised -bd 2')
	button1 = top.button(frame1)
	top.tcl(button1,'configure-command', printit, '-text "Hello World"')
	Tkgu.mainloop()

Problems with Tkgu
- slow startup
- callback interface is not completely transparent
- embedded Tcl
- global namespaces
Alternatives
- IT
- Guile
- TkPerl

Rivet

goals
- c interface to Tk
- C pointers as identifiers
- miniamal changes to Tk sources
- No Tcl evaluation, commands, identifiers
- a python binding
non-goals
- beaty of C interface
- avoiding of type conversions (e.g. coordinates as strings)
- removal of all vestigial Tcl

A rivet example...

	import rivet
        def printit():
                print 'howdy'
        top = rivet.init()
        frame1 = top.frame('-bd', 4, '-relief', 'raised')
        button1 = frame1.button()
	rivet.pack(frame1, button1, '-expand', 'yes', '-fill', 'both')
	rivet.mainloop()

Experience so far
- better startup times compared with Tkgu
- largely indistinguishable from Tcl/Tk
Status
- No Tcl parser in here!
- in process of building
Python Wish list
- py_FindMethod() without it's linear searchg
- add some 'client data' to the PyMethodDef type, accessable when the method is envoked

Discussion

Comments and Summary to be posted by Jim Fulton soon...