Provided by: perl-tk_804.033-1build1_amd64 
NAME
Tk::Balloon - pop up help balloons.
SYNOPSIS
use Tk::Balloon;
...
$b = $top->Balloon(-statusbar => $status_bar_widget);
# Normal Balloon:
$b->attach($widget,
-balloonmsg => "Balloon help message",
-statusmsg => "Status bar message");
# Balloon attached to entries in a menu widget:
$b->attach($menu, -state => 'status',
-msg => ['first menu entry',
'second menu entry',
...
],
);
# Balloon attached to individual items in a canvas widget:
$b->attach($canvas, -balloonposition => 'mouse',
-msg => {'item1' => 'msg1',
'tag2' => 'msg2',
...
},
);
# Balloon attached to items in a listbox widget:
$b->attach($listbox, -balloonposition => 'mouse',
-msg => ['first listbox element',
'2nd listbox element',
...
],
);
DESCRIPTION
Balloon provides the framework to create and attach help balloons to various widgets so
that when the mouse pauses over the widget for more than a specified amount of time, a
help balloon is popped up.
Balloons and Menus or Listboxes
If the balloon is attached to a Menu or Listbox widget and the message arguments are array
references, then each element in the array will be the message corresponding to a menu
entry or listbox element. The balloon message will then be shown for the entry which the
mouse pauses over. Otherwise it is assumed that the balloon is to be attached to the Menu
or Listbox as a whole. You can have separate status and balloon messages just like normal
balloons.
Balloons and Canvases
If the balloon is attached to a Canvas widget and the message arguments are hash
references, then each hash key should correspond to a canvas item ID or tag and the
associated value will correspond to the message for that canvas item. The balloon message
will then be shown for the current item (the one at the position of the mouse). Otherwise
it is assumed that the balloon is to be attached to the Canvas as a whole. You can have
separate status and balloon messages just like normal balloons.
Balloons and HLists
If the balloon is attached to a HList widget and the message arguments are hash
references, then each hash key should correspond to a HList path and the associated value
will correspond to the message for that HList item. The balloon message will then be shown
for the current item (the one at the position of the mouse). Otherwise it is assumed that
the balloon is to be attached to the HList as a whole. You can have separate status and
balloon messages just like normal balloons.
Balloon Position
By default, the balloon pops up at the lower right side of the client. If it would extend
outside the lower screen border, its positioned at the upper right side. If it would
extend outside the right screen border it's shown on the lower left side of the client. If
it would extend outside both the lower and the right screen border, it's positioned at the
upper left side of the client. Thus, the little arrow always points to the attached
client.
OPTIONS
Balloon accepts all of the options that the Frame widget accepts. In addition, the
following options are also recognized.
-initwait
Specifies the amount of time to wait without activity before popping up a help
balloon. Specified in milliseconds. Defaults to 350 milliseconds. This applies to both
the popped up balloon and the status bar message.
-state
Can be one of 'balloon', 'status', 'both' or 'none' indicating that the help balloon,
status bar help, both or none respectively should be activated when the mouse pauses
over the client widget. Default is 'both'.
-statusbar
Specifies the widget used to display the status message. This widget should accept the
-text option and is typically a Label. If the widget accepts the -textvariable option
and that option is defined then it is used instead of the -text option.
-balloonposition
Can be one of 'widget' or 'mouse'. It controls where the balloon will popup. 'widget'
makes the balloon appear at the lower right corner of the widget it is attached to
(default), and 'mouse' makes the balloon appear below and to the right of the current
mouse position.
-postcommand
This option takes a CODE reference which will be executed before the balloon and
statusbar messages are displayed and should return a true or false value to indicate
whether you want the balloon to be displayed or not. This also lets you control where
the balloon is positioned by returning a true value that looks like X,Y (matches this
regular expression: "/^(\d+),(\d+)$/"). If the postcommand returns a value that
matches that re then those coordinates will be used as the position to post the
balloon. Warning: this subroutine should return quickly or the balloon response will
appear slow.
-cancelcommand
This option takes a CODE reference which will be executed before the balloon and
statusbar messages are canceled and should return a true or false value to indicate
whether you want the balloon to be canceled or not. Warning: this subroutine should
return quickly or the balloon response will appear slow.
-motioncommand
This option takes a CODE reference which will be executed for any motion event and
should return a true or false value to indicate whether the currently displayed
balloon should be canceled (deactivated). If it returns true then the balloon will
definitely be canceled, if it returns false then it may still be canceled depending
the internal rules. Note: a new balloon may be posted after the -initwait time
interval, use the -postcommand option to control that behavior. Warning: the
subroutine should be extremely fast or the balloon response will appear slow and
consume a lot of CPU time (it is executed every time the mouse moves over the widgets
the balloon is attached to).
-numscreens
This option accepts an integer 1 or greater. This option should be used to avoid
disjointed balloons across multiple screens in single logical sceen (SLS) mode. This
only currently works in the horizontal direction. Example: If you are running dual
screens in SLS mode then you would set this value to 2. Default value is 1.
METHODS
The Balloon widget supports only three non-standard methods:
attach(widget, options)
Attaches the widget indicated by widget to the help system. The allowed options are:
-statusmsg
The argument is the message to be shown on the status bar when the mouse pauses over
this client. If this is not specified, but -msg is specified then the message
displayed on the status bar is the same as the argument for -msg. If you give it a
scalar reference then it is dereferenced before being displayed. Useful if the
postcommand is used to change the message.
-balloonmsg
The argument is the message to be displayed in the balloon that will be popped up when
the mouse pauses over this client. As with -statusmsg if this is not specified, then
it takes its value from the -msg specification if any. If neither -balloonmsg nor -msg
are specified, or they are the empty string then no balloon is popped up instead of an
empty balloon. If you give it a scalar reference then it is dereferenced before being
displayed. Useful if the postcommand is used to change the message.
-msg
The catch-all for -statusmsg and -balloonmsg. This is a convenient way of specifying
the same message to be displayed in both the balloon and the status bar for the
client.
-initwait
-state
-statusbar
-balloonposition
-postcommand
-cancelcommand
-motioncommand
These options allow you to override the balloon's default value for those option for
some of the widgets it is attached to. It accepts the same values as above and will
default to the Balloon's value.
detach(widget)
Detaches the specified widget from the help system.
destroy
Destroys the specified balloon.
ADVERTISED SUBWIDGETS
The balloon label is advertised as "message".
EXAMPLES
See the balloon demo included with the widget demo script that came with the distribution
for examples on various ways to use balloons.
NOTES
Because of the overhead associated with each balloon you create (from tracking the mouse
movement to know when to activate and deactivate them) you will see the best performance
(low CPU consumption) if you create as few balloons as possible and attach them to as many
widgets as you can. In other words, don't create a balloon for each widget you want to
attach one to.
CAVEATS
Pressing any button will deactivate (cancel) the current balloon, if one exists. You can
usually make the balloon reappear by moving the mouse a little. Creative use of the 3
command options can help you out also. If the mouse is over the balloon when a menu is
unposted then the balloon will remain until you move off of it.
BUGS
If using balloons attached to listbox entries or canvas items in a scrolled widget, then
the subwidget have to be used:
$balloon->attach($w->Subwidget("scrolled"), -msg => ...);
AUTHORS
Rajappa Iyer <rsi@earthling.net> did the original coding.
Jason A. Smith <smithj4@rpi.edu> added support for menus and made some other enhancements.
Slaven Rezic <srezic@cpan.org> added support for canvas items.
Gerhard Petrowitsch <gerhard@petrowitsch.de> added intelligent positioning
Jack Dunnigan <dunniganj@cpan.org> Made positioning more intelligent and added support for
multiple monitors under single logical screen.
HISTORY
The code and documentation was derived from Balloon.tcl from the Tix4.0 distribution by
Ioi Lam and modified by the above mentioned authors. This code may be redistributed under
the same terms as Perl.