Dmitry Karasik > Prima-1.38 > Prima::EventHook

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Source   Latest Release: Prima-1.41

NAME ^

Prima::EventHook - event filtering

SYNOPSIS ^

        use Prima::EventHook;

        sub hook
        {
                my ( $my_param, $object, $event, @params) = @_;
                ...
                print "Object $object received event $event\n";
                ...
                return 1;
        }

        Prima::EventHook::install( \&hook, 
                param    => $my_param,
                object   => $my_window, 
                event    => [qw(Size Move Destroy)],
                children => 1
        );

        Prima::EventHook::deinstall(\&hook);

DESCRIPTION ^

Prima dispatches events by calling notifications registered on one or more objects interested in the events. Also, one event hook can be installed that would receive all events occurred on all objects. Prima::EventHook provides multiplex access to the core event hook and introduces set of dispatching rules so the user hook subs receive only a defined subset of events.

The filtering criteria are event names and object hierarchy.

API ^

install SUB, %RULES

Installs SUB into hook list using hash of RULES.

The SUB is called with variable list of parameters, formed so first passed parameters from 'param' key ( see below ), then event source object, then event name, and finally parameters to the event. SUB must return an integer, either 0 or 1, to block or pass the event, respectively. If 1 is returned, other hook subs are called; if 0 is returned, the event is efficiently blocked and no hooks are further called.

Rules can contain the following keys:

event

Event is either a string, an array of strings, or undef value. In the latter case it is equal to '*' string, which selects all events to be passed in the SUB. A string is either name of an event, or one of pre-defined event groups, declared in %groups package hash. The group names are:

        ability
        focus
        geometry
        keyboard
        menu
        mouse  
        objects
        visibility

These contain respective events. See source for detailed description.

In case 'event' key is an array of strings, each of the strings is also name of either an event or a group. In this case, if '*' string or event duplicate names are present in the list, SUB is called several times which is obviously inefficient.

object

A Prima object, or an array of Prima objects, or undef; the latter case matches all objects. If an object is defined, the SUB is called if event source is same as the object.

children

If 1, SUB is called using same rules as described in 'object', but also if the event source is a child of the object. Thus, selecting undef as a filter object and setting 'children' to 0 is almost the same as selecting $::application, which is the root of Prima object hierarchy, as filter object with 'children' set to 1.

Setting together object to undef and children to 1 is inefficient.

param

A scalar or array of scalars passed as first parameters to SUB whenever it is called.

deinstall SUB

Removes the hook sub for the hook list.

NOTES ^

Prima::EventHook by default automatically starts and stops Prima event hook mechanism when appropriate. If it is not desired, for example for your own event hook management, set $auto_hook to 0.

AUTHOR ^

Dmitry Karasik, <dmitry@karasik.eu.org>.

SEE ALSO ^

Prima, Prima::Object

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