[wxPython] Problems with focus events

Magnus_Lycka · October 11, 2001, 4:44am

I tried to send this a few days ago, but it seems I managed to
foul up. Apologies if you get it twice...

I want to be able to move between some grids in a wxFlexGridSizer
using Ctrl-Arrow, and that works ok, but I also want things to
happen in the grids that I leave and arrive to... It doesn't...
I assumed the correct thing would be to use OnSetFocus and OnKillFocus.

The code below illustrates the problem.

I obviously set focus to diffeent grids using .SetFocus(), but
no EVT_SET_FOCUS or EVT_KILL_FOCUS seem to occur until I close
the application. Only then I get the print outs from OnSetFocus
and OnKillFocus. They seem to print the id for the grid where I
have my focus when the app is closed, but on the other hand, they
never point to the same object as wxWindow_FindFocus()!

Why doesn't this work? Doesn't the grid get the focus? Is it
a cell in the grid that gets the focus? What do I do?

class MyGrid(wxGrid):
     def __init__(self, parent, id, x, y):
         [snip]
        EVT_SET_FOCUS(self, self.OnSetFocus)
         EVT_KILL_FOCUS(self, self.OnKillFocus)

     def OnSetFocus(self, evt):
         print "Set focus", self
         print "Focus", wxWindow_FindFocus()

     def OnKillFocus(self, evt):
         print "Kill focus", self
         print "Focus", wxWindow_FindFocus()

Can anyone enlighten me please?

Platform is Win2k, ActivePython 2.1.1 (running from cmd line) and
wxPython 2.3.1.

TIA

Magnus

Entire program:

#evt_demo.py
#Magnus Lyckå, Thinkware AB, 2001

from wxPython.wx import *
from wxPython.grid import *

def invertDict(d):
     result = {}
     for key, value in d.items():
         result[value] = key
     return result

class MyFrame(wxFrame):
     def __init__(self, parent, id, title):
         wxFrame.__init__(self, parent, id, title,
                          wxPoint(100, 100), wxSize(600, 400))
         self.locationOfGrids = {} # Used for movement between grids.

     def AddGrids(self, gridArray):
         #grid array contains a list of lists.
         #Each inner list is a row of grids to
         #be positioned from top to bottom.
         assert type(gridArray)==type([])
         self.rows = len(gridArray)
         self.cols = len(gridArray[0])
         self.sizer = wxFlexGridSizer(self.rows, self.cols, 1, 1)
         for i in range(self.cols):
             self.sizer.AddGrowableCol(i)
         for i in range(self.rows):
             self.sizer.AddGrowableRow(i)
         self.SetSizer(self.sizer)
         for row, y in zip(gridArray,range(self.rows)):
             assert type(row) == type([])
             assert len(row) == self.cols
             for grid, x in zip(row, range(self.cols)):
                 self.locationOfGrids[grid] = (x,y)
                 self.sizer.AddWindow(grid, 0, wxGROW>wxALIGN_CENTER_VERTICAL|wxALL, 5)
         self.sizer.Fit(self)
         self.SetAutoLayout(true)

     def GoTo(self, callingGrid, direction):
         assert direction in ['up', 'down', 'right', 'left'], \
                "GoTo doesn't understand direction %s" % str(direction)
         print "Moving", direction
         print "Focus", wxWindow_FindFocus()
         x,y = self.locationOfGrids[callingGrid]
         if direction == 'up':
             if y == 0:
                 return
             else:
                 y -= 1
         elif direction == 'down':
             if y == self.rows - 1:
                 return
             else:
                 y += 1
         elif direction == 'left':
             if x == 0:
                 return
             else:
                 x -= 1
         else: #right
             if x == self.cols - 1:
                 return
             else:
                 x += 1
         gridInLocation = invertDict(self.locationOfGrids)
         newGrid = gridInLocation[(x,y)]
         newGrid.SetFocus()

class MyGrid(wxGrid):
     def __init__(self, parent, id, x, y):
         self.parent = parent
         wxGrid.__init__(self, parent, id, wxDefaultPosition,
                         wxSize(x, y),
                         wxWANTS_CHARS)
         self.CreateGrid(10, 4)
         self.SetColLabelSize(0)
         self.SetRowLabelSize(0)
         EVT_KEY_DOWN(self, self.OnKeyDown)
         EVT_SET_FOCUS(self, self.OnSetFocus)
         EVT_KILL_FOCUS(self, self.OnKillFocus)

     def OnSetFocus(self, evt):
         print "Set focus", self
         print "Focus", wxWindow_FindFocus()

     def OnKillFocus(self, evt):
         print "Kill focus", self
         print "Focus", wxWindow_FindFocus()

     def OnKeyDown(self, evt):
         directions = {WXK_LEFT: 'left',
                       WXK_UP: 'up',
                       WXK_RIGHT: 'right',
                       WXK_DOWN: 'down'}
         keyCode, ctrl = evt.KeyCode(), evt.ControlDown()
         if keyCode in directions.keys() and ctrl:
             self.DisableCellEditControl()
             self.parent.GoTo(self, directions[keyCode])
         else:
             evt.Skip()

class MyApp(wxApp):
     def OnInit(self):
         self.frame = MyFrame(NULL, -1, "This is an event demo")
         self.idCnt = 6000
         g = [[self.newGrid(),self.newGrid(),self.newGrid()],
              [self.newGrid(),self.newGrid(),self.newGrid()],
              [self.newGrid(),self.newGrid(),self.newGrid()]]
         self.frame.AddGrids(g)
         self.frame.Show(true)
         self.SetTopWindow(self.frame)
         return true
     def newGrid(self):
         self.idCnt += 1
         return MyGrid(self.frame, self.idCnt, 200, 100)

def main():
app = MyApp(0)
app.MainLoop()

if __name__ == '__main__':
main()

···

--
Magnus Lyckå, Thinkware AB
Älvans väg 99, SE-907 50 UMEÅ
tel 070-582 80 65, fax: 070-612 80 65
http://www.thinkware.se/ mailto:magnus@thinkware.se

Robin · October 11, 2001, 5:11pm

I obviously set focus to diffeent grids using .SetFocus(), but
no EVT_SET_FOCUS or EVT_KILL_FOCUS seem to occur until I close
the application.

The wxGrid is actually composed of several windows, one for the row and
column label areas, one for the grid itself, one of the bit in the corner,
and one to handle the scrolling. If you attach your events to the grid
window (which is accessible with theGrid.GetGridWindow()) then you'll
probably get closer to the functionality you are after.

···

--
Robin Dunn
Software Craftsman
robin@AllDunn.com Java give you jitters?
http://wxPython.org Relax with wxPython!

Magnus_Lycka · October 12, 2001, 6:02am

Splendid! Just what I needed.

Thanks,

Magnus

P.S. Am I blind, or is there an ommission in the docs here?

···

At 17:10 2001-10-11 -0700, Robin Dunn wrote:

> I obviously set focus to diffeent grids using .SetFocus(), but
> no EVT_SET_FOCUS or EVT_KILL_FOCUS seem to occur until I close
> the application.

The wxGrid is actually composed of several windows, one for the row and
column label areas, one for the grid itself, one of the bit in the corner,
and one to handle the scrolling. If you attach your events to the grid
window (which is accessible with theGrid.GetGridWindow()) then you'll
probably get closer to the functionality you are after.

--
Magnus Lyckå, Thinkware AB
Älvans väg 99, SE-907 50 UMEÅ
tel 070-582 80 65, fax: 070-612 80 65
http://www.thinkware.se/ mailto:magnus@thinkware.se

Magnus_Lycka · October 12, 2001, 6:33am

I was happy for a minute, but now it crashes on program
exit in Win 98 SE.

def OnKillFocus(self, evt):
self.SetGridLineColour(wxBLACK)

The grid has already been removed from the screen when
self.SetGridLineColour(wxBLACK) is executed so I get an
illegal page error.

How do I check for this? It wasn't as easy as "if self:"

Is there a good general solution to this, or is there a chance
that I might have to litter event methods with guards?

/Magnus

···

--
Magnus Lyckå, Thinkware AB
Älvans väg 99, SE-907 50 UMEÅ
tel 070-582 80 65, fax: 070-612 80 65
http://www.thinkware.se/ mailto:magnus@thinkware.se

Robin · October 12, 2001, 9:18am

I was happy for a minute, but now it crashes on program
exit in Win 98 SE.

def OnKillFocus(self, evt):
self.SetGridLineColour(wxBLACK)

The grid has already been removed from the screen when
self.SetGridLineColour(wxBLACK) is executed so I get an
illegal page error.

How do I check for this? It wasn't as easy as "if self:"

Is there a good general solution to this, or is there a chance
that I might have to litter event methods with guards?

There's a cookbook entry in the wiki about this, but it is dead at the
moment... The problem is that on wxMSW if a window has the focus when it is
destroyed then Windows sends a kill focus message. Since the Python object
still exists at that time you get a crash when you try to do anything with
the C++ object.

Possible workarounds:

1. Set a flag when closing and check it in your OnKillFocus.

2. Explicitly set focus to some other control before closing the app.

3. Disconnect the kill focus event before closing the app.
"grid.GetGridWindow().Disconnect(-1,-1,wxEVT_KILL_FOCUS)"

···

--
Robin Dunn
Software Craftsman
robin@AllDunn.com Java give you jitters?
http://wxPython.org Relax with wxPython!