indexing
	description: "[
		Base class for all items that may be held in EV_ITEM_LISTs.
	]"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	keywords: "item"
	date: "$Date: 2007-04-24 11:17:35 -0700 (Tue, 24 Apr 2007) $"
	revision: "$Revision: 67962 $"

deferred class interface
	EV_ITEM


feature -- Access

	accept_cursor: EV_POINTER_STYLE
			-- `Result' is cursor displayed when the screen pointer is over a
			-- target that accepts pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			result_not_void: Result /= Void
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.accept_cursor

	configurable_target_menu_handler: PROCEDURE [ANY, TUPLE [menu: EV_MENU; target_list: ARRAYED_LIST [EV_PND_TARGET_DATA]; source: EV_PICK_AND_DROPABLE; source_pebble: ANY]]
			-- Agent used for customizing the Pick and Drop Target Menu of `Current'.
			-- (from EV_PICK_AND_DROPABLE)

	data: ANY
			-- Arbitrary user data may be stored here.
			-- (from EV_ANY)

	default_identifier_name: STRING_8
			-- Default name if no other name is set.
			-- (from EV_IDENTIFIABLE)
		ensure -- from EV_IDENTIFIABLE
			result_not_void: Result /= Void
			result_not_empty: not Result.is_empty
			no_period_in_result: not Result.has ('.')

	deny_cursor: EV_POINTER_STYLE
			-- `Result' is cursor displayed when the screen pointer is over a
			-- target that does not accept pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			result_not_void: Result /= Void
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.deny_cursor

	full_identifier_path: STRING_8
			-- Full name of object by prepending path of parent
			-- Uses '.' as a separator.
			-- (from EV_IDENTIFIABLE)
		ensure -- from EV_IDENTIFIABLE
			result_not_void: Result /= Void
			result_correct: parent = Void implies Result.is_equal (identifier_name)
			result_correct: parent /= Void implies Result.is_equal (parent.full_identifier_path + "." + identifier_name)

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generating_type_not_void: Result /= Void
			generating_type_not_empty: not Result.is_empty

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generator_not_void: Result /= Void
			generator_not_empty: not Result.is_empty

	frozen id_object (an_id: INTEGER_32): ?IDENTIFIED
			-- Object associated with `an_id' (void if no such object)
			-- (from IDENTIFIED)
		ensure -- from IDENTIFIED
			consistent: Result = Void or else Result.object_id = an_id

	identifier_name: STRING_8
			-- Name of object
			-- If no specific name is set, default_identifier_name is used.
			-- (from EV_IDENTIFIABLE)
		ensure -- from EV_IDENTIFIABLE
			result_not_void: Result /= Void
			result_not_empty: not Result.is_empty
			no_period_in_result: not Result.has ('.')
			default_name_available: not has_identifier_name_set implies Result.is_equal (default_identifier_name)

	frozen object_id: INTEGER_32
			-- Unique for current object in any given session
			-- (from IDENTIFIED)
		ensure -- from IDENTIFIED
			valid_id: Result > 0 implies id_object (Result) = Current

	parent: EV_ITEM_LIST [EV_ITEM]
			-- Item list containing `Current'.
		require -- from EV_IDENTIFIABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_IDENTIFIABLE
			correct: has_parent implies Result /= Void
			correct: not has_parent implies Result = Void
		ensure then
			bridge_ok: Result = implementation.parent

	pebble: ANY
			-- Data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble

	pebble_function: FUNCTION [ANY, TUPLE, ANY]
			-- Returns data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_function

	pebble_positioning_enabled: BOOLEAN
			-- If `True' then pick and drop start coordinates are
			-- pebble_x_position, pebble_y_position.
			-- If `False' then pick and drop start coordinates are
			-- the pointer coordinates.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_positioning_enabled

	pebble_x_position: INTEGER_32
			-- Initial x position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_x_position

	pebble_y_position: INTEGER_32
			-- Initial y position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_y_position

	pixmap: EV_PIXMAP
			-- Copy of image displayed on `Current'.
			-- Void if none.
			-- (from EV_PIXMAPABLE)
		require -- from EV_PIXMAPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PIXMAPABLE
			bridge_ok: (Result = Void and implementation.pixmap = Void) or Result.is_equal (implementation.pixmap)

	target_data_function: FUNCTION [ANY, TUPLE [ANY], EV_PND_TARGET_DATA]
			-- Function for computing target meta data based on source pebble.
			-- Primarily used for Pick and Drop target menu.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)

	target_name: STRING_GENERAL
			-- Optional textual name describing `Current' pick and drop hole.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)
	
feature -- Measurement

	height: INTEGER_32
			-- Vertical size in pixels.
			-- Same as minimum_height when not displayed.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.height

	minimum_height: INTEGER_32
			-- Lower bound on height in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.minimum_height
			positive_or_zero: Result >= 0

	minimum_width: INTEGER_32
			-- Lower bound on width in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.minimum_width
			positive_or_zero: Result >= 0

	screen_x: INTEGER_32
			-- Horizontal offset relative to screen.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.screen_x

	screen_y: INTEGER_32
			-- Vertical offset relative to screen.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.screen_y

	width: INTEGER_32
			-- Horizontal size in pixels.
			-- Same as minimum_width when not displayed.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.width

	x_position: INTEGER_32
			-- Horizontal offset relative to parent x_position in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.x_position

	y_position: INTEGER_32
			-- Vertical offset relative to parent y_position in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.y_position
	
feature -- Comparison

	frozen deep_equal (some: ?ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			shallow_implies_deep: standard_equal (some, other) implies Result
			both_or_none_void: (some = Void) implies (Result = (other = Void))
			same_type: (Result and (some /= Void)) implies (other /= Void and then some.same_type (other))
			symmetric: Result implies deep_equal (other, some)

	frozen equal (some: ?ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

	frozen is_deep_equal (other: EV_ITEM): BOOLEAN
			-- Are `Current' and `other' attached to isomorphic object structures?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			shallow_implies_deep: standard_is_equal (other) implies Result
			same_type: Result implies same_type (other)
			symmetric: Result implies other.is_deep_equal (Current)

	is_equal (other: EV_ITEM): BOOLEAN
			-- Is `other' attached to an object considered
			-- equal to current object?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			symmetric: Result implies other.is_equal (Current)
			consistent: standard_is_equal (other) implies Result

	frozen standard_equal (some: ?ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

	frozen standard_is_equal (other: EV_ITEM): BOOLEAN
			-- Is `other' attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
	
feature -- Status report

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of `other' (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void

	has_identifier_name_set: BOOLEAN
			-- Is a specific identifier name set?
			-- (from EV_IDENTIFIABLE)

	has_parent: BOOLEAN
			-- Does identifiable has a parent?
			-- (from EV_IDENTIFIABLE)

	mode_is_configurable_target_menu: BOOLEAN
			-- Is the user interface mode a configurable pop-up menu of targets?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_configurable_target_menu

	mode_is_drag_and_drop: BOOLEAN
			-- Is the user interface mode drag and drop?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_drag_and_drop

	mode_is_pick_and_drop: BOOLEAN
			-- Is the user interface mode pick and drop?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_pick_and_drop

	mode_is_target_menu: BOOLEAN
			-- Is the user interface mode a pop-up menu of targets?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_target_menu

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of `other'?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
	
feature -- Status setting

	disable_pebble_positioning
			-- Assign `False' to pebble_positioning_enabled.
			-- The pick and drop will start at the pointer position.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_positioning_updated: not pebble_positioning_enabled

	enable_pebble_positioning
			-- Assign `True' to pebble_positioning_enabled.
			-- Use pebble_x_position and pebble_y_position as the initial coordinates
			-- for the pick and drop in pixels relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_positioning_updated: pebble_positioning_enabled

	remove_pebble
			-- Make pebble `Void' and pebble_function `Void,
			-- Removing transport.
			-- (from EV_PICK_AND_DROPABLE)
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_removed: pebble = Void and pebble_function = Void

	set_accept_cursor (a_cursor: like accept_cursor)
			-- Set `a_cursor' to be displayed when the screen pointer is over a
			-- target that accepts pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_cursor_not_void: a_cursor /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			accept_cursor_assigned: accept_cursor.is_equal (a_cursor)

	set_configurable_target_menu_handler (a_handler: PROCEDURE [ANY, TUPLE [menu: EV_MENU; target_list: ARRAYED_LIST [EV_PND_TARGET_DATA]; source: EV_PICK_AND_DROPABLE; source_pebble: ANY]])
			-- Set Configurable Target Menu Handler to `a_handler'.
			-- (from EV_PICK_AND_DROPABLE)
		ensure -- from EV_PICK_AND_DROPABLE
			configurable_target_menu_hander_assigned: configurable_target_menu_handler = a_handler

	set_configurable_target_menu_mode
			-- Set user interface mode to pop-up menu of targets.
			-- Target menu is configurable as the first option can be used to
			-- initiate a regular 'pick and drop' of the source pebble.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			target_menu_mode_set: mode_is_configurable_target_menu

	set_deny_cursor (a_cursor: like deny_cursor)
			-- Set `a_cursor' to be displayed when the screen pointer is not
			-- over a valid target.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_cursor_not_void: a_cursor /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			deny_cursor_assigned: deny_cursor.is_equal (a_cursor)

	set_drag_and_drop_mode
			-- Set user interface mode to drag and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			drag_and_drop_set: mode_is_drag_and_drop

	set_pebble (a_pebble: like pebble)
			-- Assign `a_pebble' to pebble.
			-- Overrides set_pebble_function.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_pebble_not_void: a_pebble /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_assigned: pebble = a_pebble

	set_pebble_function (a_function: FUNCTION [ANY, TUPLE, ANY])
			-- Set `a_function' to compute pebble.
			-- It will be called once each time a pick occurs, the result
			-- will be assigned to pebble for the duration of transport.
			-- When a pick occurs, the pick position in widget coordinates,
			-- <<x, y>> in pixels, is passed.
			-- To handle this data use `a_function' of type
			-- FUNCTION [ANY, TUPLE [INTEGER, INTEGER], ANY] and return the
			-- pebble as a function of x and y.
			-- Overrides set_pebble.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_function_not_void: a_function /= Void
			a_function_takes_two_integer_open_operands: a_function.valid_operands ([1, 1])
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_function_assigned: pebble_function = a_function

	set_pebble_position (a_x, a_y: INTEGER_32)
			-- Set the initial position for pick and drop
			-- Coordinates are in pixels and are relative to position of `Current'.
			-- Pebble_positioning_enabled must be `True' for the position to be used,
			-- use enable_pebble_positioning.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_position_assigned: pebble_x_position = a_x and pebble_y_position = a_y

	set_pick_and_drop_mode
			-- Set user interface mode to pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pick_and_drop_set: mode_is_pick_and_drop

	set_target_data_function (a_function: FUNCTION [ANY, TUPLE [like pebble], EV_PND_TARGET_DATA])
			-- Set `a_function' to compute target meta data based on transport source.
			-- Overrides any target_name set with set_target_name.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_function_not_void: a_function /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			target_data_function_assigned: target_data_function /= Void and then target_data_function.is_equal (a_function)

	set_target_menu_mode
			-- Set user interface mode to pop-up menu of targets.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			target_menu_mode_set: mode_is_target_menu

	set_target_name (a_name: STRING_GENERAL)
			-- Assign `a_name' to target_name.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_name_not_void: a_name /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			target_name_assigned: a_name /= target_name and a_name.is_equal (target_name)

	show_configurable_target_menu (a_x, a_y: INTEGER_32)
			-- Show the configurable target menu at position `a_x', `a_y' relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
			mode_is_configurable_target_menu: mode_is_configurable_target_menu
			configurable_menu_handler_set: configurable_target_menu_handler /= Void
	
feature -- Element change

	remove_pixmap
			-- Remove image displayed on `Current'.
			-- (from EV_PIXMAPABLE)
		require -- from EV_PIXMAPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PIXMAPABLE
			pixmap_removed: pixmap = Void

	set_data (some_data: like data)
			-- Assign `some_data' to data.
			-- (from EV_ANY)
		require -- from EV_ANY
			not_destroyed: not is_destroyed
		ensure -- from EV_ANY
			data_assigned: data = some_data

	set_identifier_name (a_name: like identifier_name)
			-- Set identifier_name to `a_name'.
			-- (from EV_IDENTIFIABLE)
		require -- from EV_IDENTIFIABLE
			a_name_not_void: a_name /= Void
			a_name_not_empty: not a_name.is_empty
			no_period_in_name: not a_name.has ('.')
		ensure -- from EV_IDENTIFIABLE
			identifier_name_set: identifier_name.is_equal (a_name)

	set_pixmap (a_pixmap: EV_PIXMAP)
			-- Display image of `a_pixmap' on `Current'.
			-- Image of pixmap will be a copy of `a_pixmap'.
			-- Image may be scaled in some descendents, i.e EV_TREE_ITEM
			-- See EV_TREE.set_pixmaps_size.
			-- (from EV_PIXMAPABLE)
		require -- from EV_PIXMAPABLE
			not_destroyed: not is_destroyed
			pixmap_not_void: a_pixmap /= Void
	
feature -- Duplication

	copy (other: EV_ITEM)
			-- Update current object using fields of object attached
			-- to `other', so as to yield equal objects.
			-- (from EV_ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: is_equal (other)

	frozen deep_copy (other: EV_ITEM)
			-- Effect equivalent to that of:
			--		copy (`other' . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)

	frozen deep_twin: EV_ITEM
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_twin_not_void: Result /= Void
			deep_equal: deep_equal (Current, Result)

	frozen standard_copy (other: EV_ITEM)
			-- Copy every field of `other' onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)

	frozen standard_twin: EV_ITEM
			-- New object field-by-field identical to `other'.
			-- Always uses default copying semantics.
			-- (from ANY)
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)

	frozen twin: EV_ITEM
			-- New object equal to `Current'
			-- twin calls copy; to change copying/twining semantics, redefine copy.
			-- (from ANY)
		ensure --<