Class: Sirens::WidgetView

Inherits:
AbstractView show all
Defined in:
lib/views/widget_view.rb

Overview

A View is the library binding to a GUI interface handle. It is not a Component but is wrapped by a PrimitiveComponent. a View takes care of handling the internals of the GUI objects such as handles, events, default initialization, etc.

By separating the View from the PrimitiveComponent that wraps it makes the PrimitiveComponents responsibilities more consistent with regular Components and it makes it easier to switch between GUI libraries (say, from Gtk to Qt).

Instance Method Summary collapse

Methods inherited from AbstractView

accepted_styles, #accepted_styles, #attribute_at, #background_color=, #foreground_color=, #height, #height=, #populate_popup_menu_block=, #remove_view, #set_attribute, #show, #show_popup_menu, #state_colors_from, view_accepted_styles, #width, #width=

Constructor Details

#initialize ⇒ WidgetView

Initializes this View handles



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# File 'lib/views/widget_view.rb', line 21

def initialize()
    super()

    @event_handles = Hash[]

    @main_handle = nil

    initialize_handles

    subscribe_to_ui_events
end

Instance Method Details

#add_view(child_view) ⇒ Object

Adds a child_view.



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# File 'lib/views/widget_view.rb', line 90

def add_view(child_view)
    super(child_view)

    main_handle.add(child_view.main_handle)
end

#apply_prop(prop, value) ⇒ Object

Apply the prop to the actual GUI object.



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# File 'lib/views/widget_view.rb', line 81

def apply_prop(prop, value)
    setter = prop.to_s + '='

    send(setter, value)
end

#apply_props(props) ⇒ Object

Applies each prop in props to the actual GUI object.



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# File 'lib/views/widget_view.rb', line 70

def apply_props(props)
    accepted_styles = self.accepted_styles

    props.each_pair { |prop, value|
        apply_prop(prop, value) if accepted_styles.include?(prop)
    }
end

#initialize_handles ⇒ Object

Instantiates this view handles. A View usually has a single handle to the GUI library, but in same cases it may have more than one. For instance when adding a Scroll decorator to the actual widget.

Raises:

  • (RuntimeError) 


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# File 'lib/views/widget_view.rb', line 37

def initialize_handles()
    raise RuntimeError.new("Subclass #{self.class.name} must implement the method ::initialize_handles().")
end

#main_handle ⇒ Object

Returns the main handle of this View. The main handle is the one that this View parent add as its child. Also, it is the handle that receives the style props and events by default.



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# File 'lib/views/widget_view.rb', line 61

def main_handle()
    @main_handle
end

#subscribe_to_ui_events ⇒ Object

Subscribes this View to the events/signals emitted by the GUI handle(s) of interest. When an event/signal is received calls the proper event_handler provided by the PrimitiveComponent, if one was given.

This mechanism of event handler callbacks is more simple and lightweight than making this View to announce events using the Observer pattern, and since there is only one PrimitiveComponent wrapping each View using the Observer pattern would be unnecessary complex.

Raises:

  • (RuntimeError) 


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# File 'lib/views/widget_view.rb', line 50

def subscribe_to_ui_events()
    raise RuntimeError.new("Subclass #{self.class.name} must implement the method ::subscribe_to_ui_events().")
end