DESCRIPTION

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.

USAGE

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
                Prima::VB::Component
                        Prima::VB::Drawable
                                Prima::VB::Widget
                                        Prima::VB::Control
                                                Prima::VB::Window

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:

        Prima::VB::Types::generic
                Prima::VB::Types::bool
                Prima::VB::Types::color
                Prima::VB::Types::point
                Prima::VB::Types::icon
                Prima::VB::Types::Handle
                Prima::VB::Types::textee
                        Prima::VB::Types::text
                        Prima::VB::Types::string
                                Prima::VB::Types::char
                                Prima::VB::Types::name
                                Prima::VB::Types::iv
                                        Prima::VB::Types::uiv

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.

Prima::VB::Object

Properties

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.

Methods

act_profile

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 Prima::VB::VBLoader 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.

ext_profile

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.

prf_events

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) = @_;',
        )}

prf @PROPERTIES

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.

prf_types

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.

prf_types_delete PROFILE, @NAMES

Removes @NAMES from PROFILE. Need to be called if property type if redefined through the inheritance.

remove_hooks @PROPERTIES

Cancels watch for set of PROPERTIES.

Events

on_hook NAME, PROPERTY, OLD_VALUE, NEW_VALUE

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.

Prima::VB::Component

Properties

marked MARKED , EXCLUSIVE

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.

Methods

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.

get_o_delta

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.

altpopup

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

Events

Load

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

Prima::VB::Types::generic

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.

Methods

new CONTAINER, ID, WIDGET

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.

Callbacks

change

Called when the widget property value is changed.

change_id

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

get

Returns property value, based on the selector widgets value.

open

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

preload_modules

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.

valid

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

write CLASS, ID, DATA

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

AUTHOR

Dmitry Karasik, <[email protected]>.