Tcl/Tk mouse events

[Sandy]

UPDATE

To use the Eval from Tcl, it must be the first parameters passed to the callback function.

Example:

    $cn->toplevel->bind(
        '<ButtonPress>',
        [
           sub {  my ( $x, $y, $cn ) = @_;
               $lx = $x;
               $ly = $y;
               _start_draw($cn);
           },
           Tcl::Ev('%x', '%y'),
           $cn,
        ]
    );

END UPDATE

Ok, I am stumped

Checking what it takes to convert to Tcl/Tk from Perl/Tk.

Was good, until I tried to work with a mouse event

How do I get the position of the mouse?

Tried many things, (latest shown below), but can't seem to get what I need. Anybody know?

    $cn->toplevel->bind(
        '<ButtonPress>',
        [
           sub {print "hello sandy\n";
                   print "anonymous: ",join(", ",@_),"\n";
               
               my ( $cn, $x, $y ) = @_;
               $lx = $x;
               $ly = $y;
               _start_draw($cn);
           },
           $cn,
           $int->Eval('set lx %x'),
           Ev('%y')
        ]
    );

just tried $int->Ev which returns a Tcl::Ev event... not quite sure what to do with yet...

[Anonymous Monk]

How do I get the position of the mouse?

Does this help?

Canvas item selection by mouse click

There are 2 problems when looking for items at a given position:

On mouse click, you get window coordinates, but you need canvas coordinates for "find".

Canvas find returns only the ID of the item, that's a plain number. You will need to retrieve the parameters of the item by further functions.

Example:

canvas .c1
bind .c1 <Double-1> { onDblClick %x %y }
proc onDblClick {x y} {
        set x [.c1 canvasx $x] ; set y [.c1 canvasy $y]
        set i [.c1 find closest $x $y]
        set t [.c1 gettags $i]
        puts "$i $t"
}

[Anonymous Monk]

What module are you using?

[Sandy]

Tcl::Tk

[Anonymous Monk]

I see. So the info that Tcl::Ev() should come first can be found as example in http://search.cpan.org/grep?cpanid=VKON&release=Tcl-Tk-1.04&string=bind&i=1&n=1&C=9, https://metacpan.org/source/VKON/Tcl-Tk-1.04/tk-demos/widget

$T->tagBind(qw/demo <Motion>/ => [sub {
    my($x, $y) = (shift,shift);
    my($text, $sv) = @_;
    #my $e = $text->XEvent;
    #my($x, $y) = ($e->x, $e->y);
    my $new_line = $text->index("\@$x,$y linestart");
    if ($new_line ne $last_line) {
        $text->tagRemove(qw/hot 1.0 end/);
        $last_line = $new_line;
        $text->tagAdd('hot', $last_line, "$last_line lineend");
    }
    show_stat $sv, $text, $text->index('current');
    }, Tcl::Ev('%x','%y'), \$STATUS_VAR]
);

It is also documented in Tcl

4. As a special case, there is a mechanism to deal with Tk's special event variables (they are mentioned as '%x', '%y' and so on throughout Tcl). When creating a subroutine reference that uses such variables, you must declare the desired variables using Tcl::Ev as the first argument to the subroutine.

[vkon]

actually most "mouse events" are better done on pure-tcl level, only calling your perl calback when necessary - this is my approach.

but - yes, your approach is also possible, you only must give to tcl/tk an idea that you're waiting for '%x,%y' or '%X,%Y' event variables.

you will have much quicker responces if you'll ask this question to devoted mailing list - tcltk at perl dot org.

regards,
Vadim

[vkon]

...and I will add here that "Tcl::pTk" promises much better support of perl/Tk compatibility, although I haven't really verified that, and I prefer minimalistic modules that solve the task, rather than having thick full 100% compatibility layer that support different levels of old bugs.