| 1 | |
| 2 | =head1 NAME |
| 3 | |
| 4 | Tk::Menu::Item - Base class for Menu items |
| 5 | |
| 6 | =for pm Tk/Menu/Item.pm |
| 7 | |
| 8 | =for category Implementation |
| 9 | |
| 10 | =head1 SYNOPSIS |
| 11 | |
| 12 | require Tk::Menu::Item; |
| 13 | |
| 14 | my $but = $menu->Button(...); |
| 15 | $but->configure(...); |
| 16 | my $what = $but->cget(); |
| 17 | |
| 18 | package Whatever; |
| 19 | require Tk::Menu::Item; |
| 20 | @ISA = qw(Tk::Menu::Item); |
| 21 | |
| 22 | sub PreInit |
| 23 | { |
| 24 | my ($class,$menu,$info) = @_; |
| 25 | $info->{'-xxxxx'} = ... |
| 26 | my $y = delete $info->{'-yyyy'}; |
| 27 | } |
| 28 | |
| 29 | =head1 DESCRIPTION |
| 30 | |
| 31 | Tk::Menu::Item is the base class from which Tk::Menu::Button, |
| 32 | Tk::Menu::Cascade, Tk::Menu::Radiobutton and Tk::Menu::Checkbutton are derived. |
| 33 | There is also a Tk::Menu::Separator. |
| 34 | |
| 35 | Constructors are declared so that $menu-E<gt>Button(...) etc. do what you would |
| 36 | expect. |
| 37 | |
| 38 | The C<-label> option is pre-processed allowing ~ to be prefixed to the character |
| 39 | to derive a C<-underline> value. Thus |
| 40 | |
| 41 | $menu->Button(-label => 'Goto ~Home',...) |
| 42 | |
| 43 | is equivalent to |
| 44 | |
| 45 | $menu->Button(-label => 'Goto Home', -underline => 6, ...) |
| 46 | |
| 47 | The C<Cascade> menu item creates a sub-menu and accepts |
| 48 | these options: |
| 49 | |
| 50 | =over 4 |
| 51 | |
| 52 | =item B<-menuitems> |
| 53 | |
| 54 | A list of items for the sub-menu. |
| 55 | Within this list (which is also accepted by Menu and Menubutton) the first |
| 56 | two elements of each item should be the "constructor" name and the label: |
| 57 | |
| 58 | -menuitems => [ |
| 59 | [Button => '~Quit', -command => [destroy => $mw]], |
| 60 | [Checkbutton => '~Oil', -variable => \$oil], |
| 61 | ] |
| 62 | |
| 63 | =item B<-postcommand> |
| 64 | |
| 65 | A callback to be invoked before posting the menu. |
| 66 | |
| 67 | =item B<-tearoff> |
| 68 | |
| 69 | Specifies whether sub-menu can be torn-off or not. |
| 70 | |
| 71 | =item B<-menuvar> |
| 72 | |
| 73 | Scalar reference that will be set to the newly-created sub-menu. |
| 74 | |
| 75 | =back |
| 76 | |
| 77 | The returned object is currently a blessed reference to an array of two items: |
| 78 | the containing Menu and the 'label'. |
| 79 | Methods C<configure> and C<cget> are mapped onto underlying C<entryconfigure> |
| 80 | and C<entrycget>. |
| 81 | |
| 82 | The main purpose of the OO interface is to allow derived item classes to |
| 83 | be defined which pre-set the options used to create a more basic item. |
| 84 | |
| 85 | =head1 BUGS |
| 86 | |
| 87 | This OO interface is very new. Using the label as the "key" is a problem |
| 88 | for separaror items which don't have one. The alternative would be to |
| 89 | use an index into the menu but that is a problem if items are deleted |
| 90 | (or inserted other than at the end). |
| 91 | |
| 92 | There should probably be a PostInit entry point too, or a more widget like |
| 93 | defered 'configure'. |
| 94 | |
| 95 | =cut |
| 96 | |