indexing
	description: "Positions relative to other positions.%NTakes another relative point as origin and then defines a%Nhor. & vert. scaling factor, x, y and angle.%NYou can then access absolute scale_x, scale_y, x, y and angle%Nwhich are recomputed only if invalidate_absolute_position has%Nbeen called.%NYou may also choose to specify a positioner. This is an agent%Nthat gets called everytime a recomputation is requested.%NWhen a positioner is installed, the other attributes are ignored.%NThe x and y are transformed by the angle and scaling of the origin.%NThis implies that the scale_x, scale_y and angle features of this%Nobject are only for propagation to referring points."
	legal: "See notice at end of class."
	status: "See notice at end of class."
	keywords: "point, position, location, origin"
	date: "$Date: 2006-01-22 18:25:44 -0800 (Sun, 22 Jan 2006) $"
	revision: "$Revision: 56675 $"

class interface
	EV_RELATIVE_POINT

create 
	default_create
			-- Base origin.

	make_with_origin (an_origin: EV_RELATIVE_POINT)
			-- Create with `an_origin' on position (0, 0).

	make_with_origin_and_position (an_origin: EV_RELATIVE_POINT; new_x, new_y: INTEGER_32)
			-- Create with `an_origin' on position (`new_x', `new_y').

	make_with_position (new_x, new_y: INTEGER_32)
			-- Create on position (`new_x', `new_y').

	make_with_positioner (pos_agent: like positioner)
			-- Create with `pos_agent'.

feature -- Access

	absolute_coordinates: EV_COORDINATE
			-- Coordinates relative to (0, 0). Updates if necessary.

	angle: REAL_64
			-- Angle in radians relative to origin.

	angle_abs: REAL_64
			-- Angle relative to 0. Updates if necessary.
		ensure
			result_assigned: Result = last_angle_abs

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)

	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

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

	origin: EV_RELATIVE_POINT
			-- Origin the position is relative to.
			-- If this is Void, x and y are relative to (0, 0).

	positioner: PROCEDURE [ANY, TUPLE [like Current]]
			-- Take special absolute positioning action.
			-- A positioner is expected to use the routines:
			-- set_x_abs, set_y_abs.
			-- set_angle_abs, set_scale_x_abs, set_scale_y_abs can be used too
			-- to propagate angle and scaling factor to referring points.

	scale_x: REAL_64
			-- Relative horizontal scaling factor.

	scale_x_abs: REAL_64
			-- Final horizontal scaling factor. Updates if necessary.
		ensure
			result_assigned: Result = last_scale_x_abs

	scale_y: REAL_64
			-- Relative vertical scaling factor.

	scale_y_abs: REAL_64
			-- Final vertical scaling factor. Updates if necessary.
		ensure
			result_assigned: Result = last_scale_y_abs

	x: INTEGER_32
			-- X-coordinate relative to origin.

	x_abs: INTEGER_32
			-- X relative to (0, 0). Updates if necessary.
		ensure
			result_assigned: Result = last_x_abs

	y: INTEGER_32
			-- Y-coordinate relative to origin.

	y_abs: INTEGER_32
			-- Y relative to (0, 0). Updates if necessary.
		ensure
			result_assigned: Result = last_y_abs
	
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 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))

	is_equal (other: like Current): 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: like Current): 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

	being_positioned: BOOLEAN
			-- Used for cycle detection of positioning agents.

	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_positioner: BOOLEAN
			-- Is this point controlled by an agent?
		ensure
			result_assigned: Result = (positioner /= Void)

	relative_to (org: EV_RELATIVE_POINT): BOOLEAN
			-- Does this point have `org' as origin somehow?
			-- This is not the case when it is being positioned.

	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 -- Element change

	change_origin (new_origin: EV_RELATIVE_POINT)
			-- Set point this point is relative to.
			-- Do not change absolute coordinates if
			-- scaling factors and angle do not change.
		require
			new_origin_not_void: new_origin /= Void
			no_dependance_circle: not new_origin.relative_to (Current)

	set_angle (new_angle: REAL_64)
			-- Set angle of this point (in radians).

	set_angle_abs (new_angle_abs: REAL_64)
			-- Change absolute angle.
		ensure
			last_angle_abs_assigned: last_angle_abs = new_angle_abs

	set_origin (new_origin: EV_RELATIVE_POINT)
			-- Set point this point is relative to.
		require
			new_origin_not_void: new_origin /= Void
			no_dependance_circle: not new_origin.relative_to (Current) and new_origin /= Current

	set_position (new_x, new_y: INTEGER_32)
			-- Set both x and y.

	set_positioner (pos_agent: like positioner)
			-- Set a customized positioning routine.
		ensure
			positioner_assigned: positioner = pos_agent

	set_scale (new_scale: REAL_64)
			-- Set relative scaling factor.

	set_scale_x (new_scale_x: REAL_64)
			-- Set relative horizontal scaling factor.

	set_scale_x_abs (new_scale_x_abs: REAL_64)
			-- Change absolute horizontal scaling factor.
		ensure
			last_scale_x_abs_assigned: last_scale_x_abs = new_scale_x_abs

	set_scale_y (new_scale_y: REAL_64)
			-- Set relative vertical scaling factor.

	set_scale_y_abs (new_scale_y_abs: REAL_64)
			-- Change absolute vertical scaling factor.
		ensure
			last_scale_y_abs_assigned: last_scale_y_abs = new_scale_y_abs

	set_x (new_x: INTEGER_32)
			-- Change relative horizontal position.

	set_x_abs (new_x_abs: INTEGER_32)
			-- Change absolute position.
		ensure
			last_x_abs_assigned: last_x_abs = new_x_abs

	set_y (new_y: INTEGER_32)
			-- Change relative vertical position.

	set_y_abs (new_y_abs: INTEGER_32)
			-- Change absolute position.
		ensure
			last_y_abs_assigned: last_y_abs = new_y_abs
	
feature -- Duplication

	copy (other: like Current)
			-- Update current object using fields of object attached
			-- to `other', so as to yield equal objects.
			-- (from 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: like Current)
			-- 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: like Current
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_equal: deep_equal (Current, Result)

	frozen standard_copy (other: like Current)
			-- 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: like Current
			-- 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: like Current
			-- New object equal to `Current'
			-- twin calls copy; to change copying/twining semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result.is_equal (Current)
	
feature -- Basic operations

	frozen default: like Current
			-- Default value of object's type
			-- (from ANY)

	frozen default_pointer: POINTER
			-- Default value of type `POINTER'
			-- (Avoid the need to write `p'.default for
			-- some `p' of type `POINTER'.)
			-- (from ANY)

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
	
feature -- Output

	io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of tagged_out.
			-- (from ANY)

	print (some: ANY)
			-- Write terse external representation of `some'
			-- on standard output.
			-- (from ANY)

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of out.
			-- (from ANY)
	
feature -- Platform

	operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
	
feature -- Representation

	out_abs: STRING_8
			-- A string with absolute coordinates.

	out_rel: STRING_8
			-- A string with all relative coordinates of origins.
	
invariant
	notify_list_exists: notify_list_ids /= Void
	has_origin_implies_origin_notifies: origin /= Void implies origin.notify_list_ids.has (object_id)

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

indexing
	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		356 Storke Road, Goleta, CA 93117 USA
		Telephone 805-685-1006, Fax 805-685-6869
		Website http://www.eiffel.com
		Customer support http://support.eiffel.com
	]"

end -- class EV_RELATIVE_POINT