Tk and mouse position

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

Fellow monks,

I am in need of a gentle nudge in the right direction here. Can anyone be so kind as to point me in the direction of some sample code or docs on how to find the cursor's position on a canvas, relative to the top left corner (0,0) in Tk?

I am currently playing with event and $widget->x and $widget->y but haven't got very far at all.

I have looked through the Tk docs and event was the closest thing I can find to use as a starting point.

I have also looked on CPAN but all I found was an interface for the Qt toolkit.

Anyone have any leads or done something like this? Is it even posible?

Comment on Tk and mouse position

Replies are listed 'Best First'.
Re: Tk and mouse position by ariels (Curate) on May 01, 2002 at 06:38 UTC
Tk runs by `MainLoop`; it only talks to your app via events. The trick is to bind some event to a subroutine in your app, and then access the coordinates you want (probably via the `x` and `y` methods, or possibly `rootx` and `rooty` methods, of the Tk::event object your receive). A simple example `#!/usr/local/bin/perl -w use strict; use Tk; my $mw = new Tk::MainWindow; my $c = $mw->Canvas->pack; my $tx = $c->createText(20, 10, -text => 'X: UNKNOWN'); my $ty = $c->createText(20, 25, -text => 'Y: UNKNOWN'); $c->Tk::bind('<Motion>' => [sub { my ($e,$x,$y) = (@_); $c->itemconfigure($tx, -text => "X: $x"); $c->itemconfigure($ty, -text => "Y: $y"); }, Ev('x'), Ev('y')]); MainLoop;` [download]	[reply] [d/l] [select]
Re: Re: Tk and mouse position by Popcorn Dave (Abbot) on May 02, 2002 at 19:36 UTC
Thanks for that! But I do have a couple of questions: I understand everything you've done except what $e does. Are there some docs that you can point me at to explain that particular point? What is the advantage or disadvantage in using pointerxy as opposed to what you wrote?	[reply]


Keep It Simple, Stupid
	PerlMonks

Tk and mouse position

A simple example