Prima::VB::Classes - Visual Builder widgets and types


Prima::VB::Classes - Visual Builder widgets and types


Visual Builder is designed without a prior knowledge of the widget classes that would be contained in its widget palette. Instead, it provides a registration interface for new widgets and their specific properties.

This document describes API, provided by the builder, and the widget interface. Through the document, widget or widget class mean not the original widget or class, but their representatives.


The widget must provide specific methods to cooperate with the builder. It is not required, however, to contain these methods in its base module or package; it can delegate its representation to another, usually very light class, which is used by the builder.

Such a class must be derived from Prima::VB::Object, which provides base functionality. One of basic features here is overloading of property change method. Since the user can change any property interactively, the class can catch the properties of interest by declaring prf_XXX method, where XXX is the property name. Prima::VB::Widget declares set of these methods, assuming that a widget would repaint when, for example, its color or font properties change.

The hierarchy of VB classes mimics the one of the core toolkit classes, but this is a mere resemblance, no other dependencies except the names are present. The hierarchy is as follows:

    Prima::VB::Object   Prima::Widget

NB: Prima::VB::CoreClasses extends the hierarchy to the full set of default widget palette in the builder. This module is not provided with documentation though since its function is obvious and its code is trivial.

Since the real widgets are used in the interaction with the builder, their properties are not touched when changed by the object inspector or otherwise. The widgets keep the set of properties in a separated hash. The properties are accessible by prf and prf_set methods.

A type object is a class used to represent a particular type of property in object inspector window in the builder. The type objects, like the widget classes, also are not hard-coded. The builder presents a basic set of the type objects, which can be easily expanded. The hierarchy ( incomplete ) of the type objects classes is as follows:


The document does not describe the types, since their function can be observed at runtime in the object inspector. Only Prima::VB::Types::generic API is documented.



class STRING
Selects the original widget class. Create-only property.

creationOrder INTEGER
Selects the creation order of the widget.

module STRING
Selects the module that contains the original widget class. Create-only property.

profile HASH
Selects the original widget profile. Create-only property. Changes to profile at run-time performed by prf_set method.


Returns hash of callbacks to be stored in the form file and executed by Prima::VB::VBLoader when the form file is loaded. The hash keys are names of VBLoader events and values - strings with code to be eval'ed. See Events in the Prima::VB::VBLoader manpage for description and format of the callbacks.

Called when the builder writes a form file.

add_hooks @PROPERTIES
Registers the object as a watcher to set of PROPERTIES. When any object changes a property listed in the hook record, on_hook callback is triggered.

Special name 'DESTROY' can be used to set a hook on object destruction event.

Returns a class-specific hash, written in a form file. Its use is to serve as a set of extra parameters, passed from the builder to act_profile events.

prf_set %PROIFLE
A main method for setting a property of an object. PROFILE keys are property names, and value are property values.

prf_adjust_default PROFILE, DEFAULT_PROFILE
DEFAULT_PROFILE is a result of profile_default call of the real object class. However, not all properties usually are exported to the object inspector. prf_adjust_default deletes the unneeded property keys from PROFILE hash.

prf_delete @PROPERTIES
Removes PROPERTIES from internal properties hash. This action results in that the PROPERTIES in the object inspector are set back to their default values.

Returns hash of a class-specific events. These appear in the object inspector on Events page. The hash keys are event names; the hash values are default code pieces, that describe format of the event parameters. Example:
   sub prf_events { return (
      $_[0]-> SUPER::prf_events,
      onSelectItem  => 'my ( $self, $index, $selectState) = @_;',

Maps array of PROPERTIES names to their values. If called in scalar context, returns the first value only; if in array context, returns array of property values.

Returns an anonymous hash, where keys are names of the type class without Prima::VB::Types:: prefix, and values are arrays of property names.

This callback returns an inverse mapping of properties by the types.

prf_types_add PROFILE1, PROFILE2
Adds PROFILE2 content to PROFILE1. PROFILE1 and PROFILE2 are hashes in format of result of prf_types method.

remove_hooks @PROPERTIES
Cancels watch for set of PROPERTIES.


Called for all objects, registered as watchers by add_hooks when PROPERTY on object NAME is changed from OLD_VALUE to NEW_VALUE. Special PROPERTY 'DESTROY' hook is called when object NAME is destroyed.



Selects marked state of a widget. If MARKED flag is 1, the widget is selected as marked. If 0, it is selected as unmarked. If EXCLUSIVE flag is set to 1, then all marked widgets are unmarked before the object mark flag is set.

sizeable BOOLEAN
If 1, the widget can be resized by the user. If 0, in can only be moved.

mainEvent STRING
Selects the event name, that will be opened in the object inspector when the user double clicks on the widget.


common_paint CANVAS
Draws selection and resize marks on the widget if it is in the selected state. To be called from all on_paint callbacks.

Returns offset to the owner widget. Since the builder does not insert widgets in widgets to reflect the user-designed object hierarchy, this method is to be used to calculate children widgets relative positions.

xy2part X, Y
Maps X, Y point into part of widget. If result is not equal to 'client' string, the event in X, Y point must be ignored.

iterate_children SUB, @ARGS
Traverses all children widget in the hierarchy, calling SUB routine with widget, self, and @ARGS parameters on each.

Invokes an alternative, class-specific popup menu, if present. The popup object must be named 'AltPopup'.


Called when the widget is loaded from a file or the clipboard.


Root of all type classes.

A type class can be used with and without object instance. The instantiated class contains reference to ID string, which is a property name that the object presents in the object inspector, and WIDGET, which is the property applied to. When the object inspector switches widgets, the type object is commanded to update the references.

A class must also be usable without object instance, in particular, in write method. It is called to export the property value in a storable format as a string, better as a perl-evaluable expression.


Constructor method. CONTAINER is a panel widget in the object inspector, where the type object can insert property value selector widgets.

renew ID, WIDGET
Resets property name and the widget.

quotable STRING
Returns quotable STRING.

printable STRING
Returns a string that can be stored in a file.


Called when the widget property value is changed.

Called when the property name ( ID ) is changed. The type object may consider update its look or eventual internal variables on this event.

Returns property value, based on the selector widgets value.

Called when the type object is to be visualized first time. The object must create property value selector widgets in the {container} panel widget.

Returns array of strings of modules, needed to be pre-loaded before a form file with type class-specific information can be loaded. Usually it is used when write method exports constant values, which are defined in another module.

set DATA
Called when a new value is set to the widget property by means other than the selector widgets, so these can be updated. DATA is the property new value.

Checks internal state of data and returns a boolean flag, if the type object data can be exported and set to widget profile.

Called when DATA is to be written in form. write must return such a string that can be loaded by Prima::VB::VBLoader later.


Dmitry Karasik, <>.


VB, the Prima::VB::VBLoader manpage, the Prima::VB::CfgMaint manpage.

 Prima::VB::Classes - Visual Builder widgets and types