Perl/Tkx Mousewheel

chiron has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I'm writing a perl app that uses mouse events, however i'm stuck trying to get the delta value for the MouseWheel event, supposedly it should be accessible through Tkx::Ev('%D'); however all that it prints is differing array refs, ie Tcl::Ev=ARRAY(0x335715c). Is there anyway i can extract the delta value for mouseevents, here is a cutdown version of the offending code:

use Tkx;


    $mw = Tkx::widget->new(".");
    $canvas = $mw->new_tk__canvas;
    $canvas->g_grid(-column=>0, -row=>0, -sticky=>"nwes");
    $mw->g_grid_columnconfigure(0, -weight=>1);
    $mw->g_grid_rowconfigure(0, -weight=>1);


    $canvas->g_bind('<Enter>' => sub { Tkx::focus($canvas); });

    $canvas->g_bind("<1>", sub { print "Button 1\n"; });

    $canvas->g_bind("<Double-1>", sub { print "Button 1x2\n"; });

    $canvas->g_bind("<2>", sub { print "Button 2\n"; });

    $canvas->g_bind("<3>", sub { print "Button 3\n"; });

    $canvas->g_bind("<Double-3>", sub { print "Button 3x2\n"; });

    $canvas->g_bind("<MouseWheel>", sub { print Tkx::Ev('%D') . "\n"; 
+});


    Tkx::MainLoop();
[download]

Comment on Perl/Tkx Mousewheel Download Code

Replies are listed 'Best First'.
Re: Perl/Tkx Mousewheel by Crian (Curate) on Mar 10, 2009 at 14:41 UTC
In one of my programs i found this lines: `$mw->bind('<MouseWheel>', [ sub { my $wert = -($_[1]/120); $wert = '+' . $wert unless $wert =~ /^-/; animation_schalten($wert); }, Tk::Ev('D') ] );` [download] Perhaps it helps?	[reply] [d/l]
Re^2: Perl/Tkx Mousewheel by chiron (Novice) on Mar 10, 2009 at 14:50 UTC
Using: `$canvas->g_bind("<MouseWheel>", [ sub { my $wert = -($_[1]/120); $wert = '+' . $wert unless $wert =~ /^-/; print $wert . "\n"; }, Tkx::Ev('D') ]);` [download] just gives me '-0' all the time	[reply] [d/l]
Re^3: Perl/Tkx Mousewheel by Crian (Curate) on Mar 10, 2009 at 15:09 UTC
Note: I use Tk::Ev not Tkx::Ev. I don't know, but it might be a difference.	[reply]
Re: Perl/Tkx Mousewheel by jethro (Monsignor) on Mar 10, 2009 at 16:07 UTC
You might use Data::Dumper to show you the contents of the array you are getting, i.e. `use Data::Dumper; ... $canvas->g_bind("<MouseWheel>", sub { Dumper( Tkx::Ev('%D')) . "\n";` [download] Presumably the information you are looking for is in that array, just an indirection away UPDATE: Tkx::Ev seems to return an object!!! Accessing the array would be a hack, maybe you can find the right accessor in the documentation.	[reply] [d/l]
Re^2: Perl/Tkx Mousewheel by chiron (Novice) on Mar 10, 2009 at 17:08 UTC
I've worked out a solution to this problem, however I'm still slightly unsure of whats going on here. Thanks for your help. `$canvas->g_bind("<MouseWheel>", [ sub { my($D) = @_; print $D . "\n"; +}, Tkx::Ev("%D") ]);` [download]	[reply] [d/l]
Re^3: Perl/Tkx Mousewheel by jethro (Monsignor) on Mar 10, 2009 at 17:47 UTC
This seems to be a special two-parameter form for the binding (it uses an anonymous array), where the first parameter (or array value) is the sub as before, and the second furnishes the parameters for the sub. Tkx::Ev just does that. See http://www.tkdocs.com/tutorial/concepts.html for this explanation: Tkx lets us provide command callbacks as just a Perl function (the first four), or as a two element array (the last case). The first element is the Perl code to be called, while the second array element specifies parameters to pass to that code. The function "Tkx::Ev()" will expand its parameter ("%x %y" in this case) when the callback is invoked, which will perform the percent substitutions. These then are passed as parameters to our function.	[reply]


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