Perl/TkFAQ-11.10.如何给画布的不同区域设置不同的绑定？

原文：

11.10. How do I bind different actions to different areas of the same Canvas?

KOBAYASI Hiroaki <kobayasi@sowa.is.uec.ac.jp> recently posted an extraordinary little script that addresses this question quite succinctly:

How about this?

## I don't know whether this is a good solution or not.

## but it works under Tk-b9 + perl5.002b1f.

#!/usr/local/bin/perl -w use Tk; ($c = MainWindow->new->Canvas)-> pack(-fill => 'both', -expand => 1); # to survive under Tk-b8. # You don't need paren before pack in b9. ($pop1 = $c->Menu)->command(-label => "FOO"); ($pop2 = $c->Menu)->command(-label => "BAR"); $c->create(oval => 0, 0, 100, 100, -fill => 'black', -tags => ['popup']); $c->Tk::bind($c, '<3>', [\&PopupOnlyThis, $pop1]); $c->bind('popup', '<3>', [\&PopupOnlyThis, $pop2]); sub PopupOnlyThis { print "@_\n"; my($c, $pop) = @_; # to prevent multiple popup. Tk->break if defined $Tk::popup; my $e = $c->XEvent; $pop->Popup($e->X, $e->Y); # Tk::Menu::Popup sets $Tk::popup. } MainLoop; $Tk::popup = undef; # to kill warning. __END__

译文：

11.10. 如何给画布的不同区域设置不同的绑定？

KOBAYASI Hiroaki最近贴出了一个非常短小的脚本可以很简洁的说明这个问题：

怎么样？

＃＃我不知道这是否算是一个很好的解决方法。

＃＃但是它可以在Tk-b9 + perl5.002b1f的环境下运行。（译者注：下面的脚本已经被修改以便可以在Tk8+perl5下较好的运行。）

#!/usr/local/bin/perl -w

use Tk;

($c = MainWindow->new->Canvas)->

pack(-fill => 'both', -expand => 1);

($pop1 = $c->Menu(-tearoff=>0))->command(-label => "FOO");

($pop2 = $c->Menu(-tearoff=>0))->command(-label => "BAR");

$c->create(oval => 0, 0, 100, 100,

-fill => 'black',

-tags => ['popup']);

$c->Tk::bind($c, '<3>', [\&PopupOnlyThis, $pop1]);

$c->bind('popup', '<3>', [\&PopupOnlyThis, $pop2]);

sub PopupOnlyThis {

print "@_\n";

my($c, $pop) = @_;

# to prevent multiple popup.

return if defined $Tk::popup;

my $e = $c->XEvent;

$pop->post($e->X, $e->Y);

# Tk::Menu::post sets $Tk::popup.

}

MainLoop;

$Tk::popup = undef; # to kill warning.

__END__

(译者注：个人感觉这个脚本有点“喧宾夺主”了。因为这里的主题是如何对不同的区域分别进行绑定，所以其实答案就是给需要绑定的特殊区域加上标签——例如上面的圆’popup’——这样就可以在设置绑定的时候直接使用这个标签了！而这个例子中设置的这个弹出菜单有点惹眼——至少我是研究了半天……所以，等我把它调通以后都忘记了这个例子是要说明什么了……:P 记得前面曾经有人问过怎么做这样的弹出菜单的，这个脚本应该可以算是一个不错的例子了吧。)