Re: EVT_NOTEBOOK_PAGE_CHANGING on Windows

[Mark Dootson]

Hi,

The following 'workaround' seems to work on Windows. Just record every 
Left down mouse position and use it in EVT_NOTEBOOK_PAGE_CHANGING 
handler. You might want to take a look at the flags returned by
$notebook->HitTest.
EVT_LEFT_DOWN($notebook, sub { $_[0]->{last_pos} = $_[1]->GetPosition(); 
$_[1]->Skip(1); });

......
......

sub OnNotebookPageChanging {
    my( $self, $event ) = @_;
    my( $oldSelection ) = $event->GetOldSelection;
    my $notebook = $event->GetEventObject;
    my ($nbitem, $flags ) = $notebook->HitTest($notebook->{last_pos});
        if($nbitem != -1) {
                Wx::LogMessage(qq(New Selection Index is $nbitem));
        }

....
....




On 01/12/2011 18:21, Brad Embree wrote:
I believe this is known behaviour. From
http://docs.wxwidgets.org/stable/wx_wxnotebookevent.html#wxnotebookeventgetselection
:

*"NB:* under Windows, GetSelection() will return the same value as
GetOldSelection()<http://docs.wxwidgets.org/stable/wx_wxnotebookevent.html#wxnotebookeventgetoldselection>when
called from
EVT_NOTEBOOK_PAGE_CHANGING handler and not the page which is going to be
selected. Also note that the values of selection and old selection returned
for an event generated in response to a call to
wxNotebook::SetSelection<http://docs.wxwidgets.org/stable/wx_wxnotebook.html#wxnotebooksetselection>shouldn't
be trusted as they are currently inconsistent under different
platforms (but in this case you presumably don't need them anyhow as you
already have the corresponding information)."


The only way I know to achieve this cross platform is to use
EVT_NOTEBOOK_PAGE_CHANGED. You can use $event->GetOldSelection to see what
the "previous" tab was and GetSelection to see the current tab. Instead of
a Veto, you would need to call SetSelection to move back to the previous
tab.

Hope that helps,

Brad


On 1 December 2011 10:05, Bruce Ravel<bra...@bnl.gov>  wrote:


Hi,

I am surprised by a bit of behavior by a Notebook on my windows
machines.  The short script below distills the problem down to its
essence.

I want to use the EVT_NOTEBOOK_PAGE_CHANGING event to veto the
selection of a tab under a certain situation.  In this simple example,
I intend to veto the selection of tab #0.

My intent is to recognize the newly selected tab using
$event->GetSelection.  On my linux machine, this retuns the index of
the tab clicked on.  Tab #2 is displayed on startup.  Clicking on tab
#1, then on tab #0 does the following:

  bruce@dh10 [demeter]>  perl nb.pl
  old selection = 2, new selection = 1
  old selection = 1, new selection = 0

The second click is vetoed, since GetSelection returns 0.

On my Windows machine (Wx 0.99, wxWidgets 2.8.12, WinXp, perl 5.12.3),
the following happens:

  C:\Documents and Settings\bravel\Desktop>perl nb.pl
  old selection = 2, new selection = 2
  old selection = 1, new selection = 1
  old selection = 0, new selection = 0

Clicking on tab #1, $event->GetSelection returns 2 then displays tab
#1 and so on.

In short, $event->GetSelection is returning the same value as
GetOldSelection on Windows.

Ultimately, my goal is to veto a tab selection under a specified
condition.  Is there another way of doing this that will work on both
platforms?

Thanks in advance,
Bruce




#!/usr/bin/perl
package MyApp;
use base 'Wx::App';
use Wx qw(:everything);
use Wx::Event qw(EVT_NOTEBOOK_PAGE_CHANGING);

sub OnInit {
  my $frame  = Wx::Frame ->   new(undef, -1, 'demo', [-1,-1], [700,150]);
  my $sizer  = Wx::BoxSizer->new(wxVERTICAL);
  my $nb = Wx::Notebook->new( $frame, -1, wxDefaultPosition, wxDefaultSize,
wxNB_TOP );
  $sizer->Add($nb);
  foreach my $i (0..2) {
    my $panel = Wx::Panel->new($nb, -1, wxDefaultPosition, [500,100]);
    $nb  ->  AddPage($panel, $i, $i);
  };
  EVT_NOTEBOOK_PAGE_CHANGING($frame, $nb,
        sub{ my($self, $event) = @_;
             my ($selection) = $event->GetSelection;
             my ($oldselection) = $event->GetOldSelection;
             printf("old selection = %d, new selection = %d\n",
$oldselection,
$selection);
             $event->Veto() if ($selection == 0);
             return;
           });


  $frame->SetSizer($sizer);
  $frame ->   Show(1);
  1;
};
package main;
use Wx qw(:everything);
my $app = MyApp->new->MainLoop;

--

  Bruce Ravel  ------------------------------------ bra...@bnl.gov

  National Institute of Standards and Technology
  Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
  Building 535A
  Upton NY, 11973

  My homepage:    http://xafs.org/BruceRavel
  EXAFS software:  http://cars9.uchicago.edu/ifeffit/Demeter