wxPython before MainLoop

[[david]]

I'd like to refresh the display before I start the main loop.

I have code like this:

app = App()
app.Show()
app.long_slow_i nit()
app.MainLoop()
The main frame partly loads at Show, but because the mainloop has not
started yet, the display does not update until long_slow_init( ) finishes.

Alternatively, I could code

app = App()
app.long_slow_i nit()
app.Show()
app.MainLoop()

Which would give me a crisp Show, but there would be a long slow wait
before the app showed any activity at all. I would need a splash screen.

I'd rather not have a splash screen (and I don't know how anyway). I'd
like to just make app.Show() finish correctly before running
long_slow_init.

Is there a wx internal method that I can use to give Windows the
opportunity to finish painting the frame before I run long_slow_init( )?

Or is there a better idea?

(david)

[7stud]

On Aug 8, 11:25 pm, "[david]" <da...@nospam.s pamwrote:

I'd like to refresh the display before I start the main loop.

I have code like this:

app = App()
app.Show()
app.long_slow_i nit()
app.MainLoop()

The main frame partly loads at Show, but because the mainloop has not
started yet, the display does not update until long_slow_init( ) finishes.

Alternatively, I could code

app = App()
app.long_slow_i nit()
app.Show()
app.MainLoop()

Which would give me a crisp Show, but there would be a long slow wait
before the app showed any activity at all. I would need a splash screen.

I'd rather not have a splash screen (and I don't know how anyway). I'd
like to just make app.Show() finish correctly before running
long_slow_init.

Is there a wx internal method that I can use to give Windows the
opportunity to finish painting the frame before I run long_slow_init( )?

Or is there a better idea?

(david)

You can use a separate thread to execute long_slow_init( ):

--------------------------
import wx
import threading
import time

class MyFrame(wx.Fram e):
def __init__(self):
wx.Frame.__init __(self, None, -1, "My Window")

panel = wx.Panel(self, -1)
button = wx.Button(panel , -1, "click me, quick!", pos=(40,
40))
self.Bind(wx.EV T_BUTTON, self.onclick)

def onclick(self, event):
print "button clicked"

def receive_result( self, result):
print "Hey, I'm done with that long, slow initialization. "
print "The result was:", result
class MyApp(wx.App):
def __init__(self):
wx.App.__init__ (self, redirect=False)
def OnInit(self):
the_frame = MyFrame()
the_frame.Show( )

t = MyThread(the_fr ame)
t.start() #calls run() in t's class

return True
class MyThread(thread ing.Thread):
def __init__(self, a_frame):
threading.Threa d.__init__(self )

self.frame_obj = a_frame

def run(self):
self.result = self.long_slow_ init()

def long_slow_init( self):
print "starting long_slow_init( )..."
time.sleep(6)
result = 20.5

#Send result to frame:
wx.CallAfter(se lf.frame_obj.re ceive_result, result)

app = MyApp()
app.MainLoop()
----------------------------

[7stud]

I reorganized my Thread class a little bit:

------------
class MyThread(thread ing.Thread):
def __init__(self, a_frame):
threading.Threa d.__init__(self )
self.frame_obj = a_frame

def run(self):
result = self.long_slow_ init()

wx.CallAfter(se lf.frame_obj.re ceive_result, result)
#CallAfter() calls the specified function with the specified
argument
#when the next pause in execution occurs in this thread.

def long_slow_init( self):
print "starting long_slow_init( )..."
time.sleep(6)
result = 20.5
return result
--------------

[Bjoern Schliessmann]

[david] wrote:

I'd like to refresh the display before I start the main loop.
[...]
I'd like to just make app.Show() finish correctly before running
long_slow_init.

IMHO, this will bring no gain. If you see an inresponsive user
interface or not is quite meaningless.

Or is there a better idea?

As suggested, a solution using threads is feasible.

Regards,
Björn

--
BOFH excuse #422:

Someone else stole your IP address, call the Internet detectives!

[kyosohma]

On Aug 9, 12:25 am, "[david]" <da...@nospam.s pamwrote:

I'd like to refresh the display before I start the main loop.

I have code like this:

app = App()
app.Show()
app.long_slow_i nit()
app.MainLoop()

The main frame partly loads at Show, but because the mainloop has not
started yet, the display does not update until long_slow_init( ) finishes.

Alternatively, I could code

app = App()
app.long_slow_i nit()
app.Show()
app.MainLoop()

Which would give me a crisp Show, but there would be a long slow wait
before the app showed any activity at all. I would need a splash screen.

I'd rather not have a splash screen (and I don't know how anyway). I'd
like to just make app.Show() finish correctly before running
long_slow_init.

Is there a wx internal method that I can use to give Windows the
opportunity to finish painting the frame before I run long_slow_init( )?

Or is there a better idea?

(david)

Yeah, I think 7stud's thread is the way to go. It's what I do with
long running tasks, see also:
http://wiki.wxpython.org/LongRunningTasks

If your screen doesn't load correctly, be sure to call the Layout()
method.

Mike

[7stud]

On Aug 8, 11:25 pm, "[david]" <da...@nospam.s pamwrote:

I'd like to refresh the display before I start the main loop.

I have code like this:

app = App()
app.Show()
app.long_slow_i nit()
app.MainLoop()

The main frame partly loads at Show, but because the mainloop has not
started yet, the display does not update until long_slow_init( ) finishes.

Alternatively, I could code

app = App()
app.long_slow_i nit()
app.Show()
app.MainLoop()

Which would give me a crisp Show, but there would be a long slow wait
before the app showed any activity at all. I would need a splash screen.

I'd rather not have a splash screen (and I don't know how anyway). I'd
like to just make app.Show() finish correctly before running
long_slow_init.

Is there a wx internal method that I can use to give Windows the
opportunity to finish painting the frame before I run long_slow_init( )?

Or is there a better idea?

(david)

I don't see my original post, so here it is again....
You can use another thread to execute long_slow_init( ):

--------------
import wx
import threading
import time

class MyFrame(wx.Fram e):
def __init__(self):
wx.Frame.__init __(self, None, -1, "My Window")

panel = wx.Panel(self, -1)
button = wx.Button(panel , -1, "click me, quick!", pos=(40,
40))
self.Bind(wx.EV T_BUTTON, self.onclick)

def onclick(self, event):
print "button clicked"

def receive_result( self, result):
print "Hey, I'm done with that long, slow initialization. "
print "The result was:", result
class MyApp(wx.App):
def __init__(self):
wx.App.__init__ (self, redirect=False)
def OnInit(self): #called by wx.Python
the_frame = MyFrame()
the_frame.Show( )

t = MyThread(the_fr ame)
t.start() #calls t.run()

return True

class MyThread(thread ing.Thread):
def __init__(self, a_frame):
threading.Threa d.__init__(self )
self.frame_obj = a_frame

def run(self):
result = self.long_slow_ init()

wx.CallAfter(se lf.frame_obj.re ceive_result, result)
#CallAfter() calls the specified function with the
#specified argument when the next pause in execution
#occurs in this thread:

def long_slow_init( self):
print "starting long_slow_init( )..."
time.sleep(6)
result = 20.5
return result
app = MyApp()
app.MainLoop()

[[david]]

I'm disappointed that I didn't get a wxPython solution.

If the only way to get wxPython to correctly handle
this simple task is to code around it, I don't think
wxPython is really ready for Windows.

Is there a better place to ask?

Regarding the suggestions:

Bjoern, you're wrong. The GUI needs to be displayed
for the user to analyse. A delay between display and
readiness is much better than a delay before display
or a delay with the GUI half-drawn.

Mike, the screen does display correctly, it's just
that in Windows, screen updates are not processed
while the application is busy.

7Stud, that's a solution. Unless anyone comes up
with a direct solution, I guess I'll have to do that.

[david]
[david] wrote:

I'd like to refresh the display before I start the main loop.

I have code like this:

app = App()
app.Show()
app.long_slow_i nit()
app.MainLoop()
The main frame partly loads at Show, but because the mainloop has not
started yet, the display does not update until long_slow_init( ) finishes.

Alternatively, I could code

app = App()
app.long_slow_i nit()
app.Show()
app.MainLoop()

Which would give me a crisp Show, but there would be a long slow wait
before the app showed any activity at all. I would need a splash screen.

I'd rather not have a splash screen (and I don't know how anyway). I'd
like to just make app.Show() finish correctly before running
long_slow_init.

Is there a wx internal method that I can use to give Windows the
opportunity to finish painting the frame before I run long_slow_init( )?

Or is there a better idea?

(david)

[Heikki Toivonen]

[david] wrote:

I'd like to refresh the display before I start the main loop.

We have this kind of situation in Chandler, where we display and update
the splash screen before we enter MainLoop.

1. Create app object
http://lxr.osafoundation.org/source/...handler.py#080

2. During app object creation, in OnInit, put up splash screen and update it

http://lxr.osafoundation.org/source/...ication.py#433

3. The splash screen refresh is basically: draw new stuff,
self.Layout(), self.Update(), wx.Yield()
http://lxr.osafoundation.org/source/...cation.py#1421

3. Start MainLoop
http://lxr.osafoundation.org/source/...handler.py#086

--
Heikki Toivonen

[kyosohma]

On Aug 9, 8:51 pm, "[david]" <da...@nospam.s pamwrote:

I'm disappointed that I didn't get a wxPython solution.

If the only way to get wxPython to correctly handle
this simple task is to code around it, I don't think
wxPython is really ready for Windows.

Is there a better place to ask?

Regarding the suggestions:

Bjoern, you're wrong. The GUI needs to be displayed
for the user to analyse. A delay between display and
readiness is much better than a delay before display
or a delay with the GUI half-drawn.

Mike, the screen does display correctly, it's just
that in Windows, screen updates are not processed
while the application is busy.

7Stud, that's a solution. Unless anyone comes up
with a direct solution, I guess I'll have to do that.

[david]

[david] wrote:

I'd like to refresh the display before I start the main loop.

I have code like this:

app = App()
app.Show()
app.long_slow_i nit()
app.MainLoop()

The main frame partly loads at Show, but because the mainloop has not
started yet, the display does not update until long_slow_init( ) finishes.

Alternatively, I could code

app = App()
app.long_slow_i nit()
app.Show()
app.MainLoop()

Which would give me a crisp Show, but there would be a long slow wait
before the app showed any activity at all. I would need a splash screen.

I'd rather not have a splash screen (and I don't know how anyway). I'd
like to just make app.Show() finish correctly before running
long_slow_init.

Is there a wx internal method that I can use to give Windows the
opportunity to finish painting the frame before I run long_slow_init( )?

Or is there a better idea?

(david)

Chris is right. The only way to interact with a gui is with a separate
thread, otherwise you're blocking the gui's mainloop thread. That's
why I gave that link. That's how to do it in every GUI I'm aware of.

Mike

[Bjoern Schliessmann]

[david] wrote:

I'm disappointed that I didn't get a wxPython solution.

If the only way to get wxPython to correctly handle
this simple task is to code around it,

LOL -- did you try coding this app with native windows means, like
MFC? You will have *exactly* the same problem, and *exactly* for
the same reason. The organisation of wxWidgets (and thus, wxPython)
is very near to Windows GUI coding philosophy.

I don't think wxPython is really ready for Windows.

I suggest you first went getting experience with other GUI libraries
before you make such statements.

Also, wxPython is a thin wrapper around wxWidgets C++ library which
is widely used for Windows apps. And with wxWidgets, you'd *also*
have the same problem.

Bjoern, you're wrong. The GUI needs to be displayed
for the user to analyse. A delay between display and
readiness is much better than a delay before display
or a delay with the GUI half-drawn.

This may be, but it strongly depends on the application itself.

Mike, the screen does display correctly, it's just
that in Windows, screen updates are not processed
while the application is busy.

That's the matter in just about *every* GUI framework using an event
loop. And I don't know any that doesn't. Thus, there are two widely
used standard solutions:

* use a worker thread, or

* call a "process all pending events now" function repeatedly during
the work (here: wx.Yield, wx.SafeYield, wx.YieldIfNeede d).

Regards,
Björn

--
BOFH excuse #92:

Stale file handle (next time use Tupperware(tm)! )