indexing
	description: "This class processes the scroll messages associated to a window."
	legal: "See notice at end of class."
	status: "See notice at end of class."
	date: "$Date: 2006-09-21 17:04:32 -0700 (Thu, 21 Sep 2006) $"
	revision: "$Revision: 63798 $"

class interface
	WEL_SCROLLER

create 
	make (a_window: WEL_COMPOSITE_WINDOW; horizontal_size, vertical_size, line, page: INTEGER_32)
			-- Make a scroller associated to `a_window' using
			-- `horizontal_size' and `vertical_size' as the
			-- size of the scrollable area. `line' and `page'
			-- specify the scroll incrementation for a line and
			-- a page.
		require
			a_window_not_void: a_window /= Void
			a_window_exists: a_window.exists
			positive_horizontal_size: horizontal_size > 0
			positive_vertical_size: vertical_size > 0
			positive_line: line >= 0
			valid_line: line < horizontal_size and then line < vertical_size
			positive_page: page >= 0
			valid_page: page < horizontal_size and then page < vertical_size
		ensure
			window_set: window = a_window

	make_with_options (a_window: WEL_COMPOSITE_WINDOW; a_minimal_horizontal_position, a_maximal_horizontal_position, a_minimal_vertical_position, a_maximal_vertical_position, a_horizontal_line, a_horizontal_page, a_vertical_line, a_vertical_page: INTEGER_32)
			-- Make a scroller associated to `a_window'.
			-- `a_minimal_horizontal_position' and
			-- `a_maximal_horizontal_position' specify the
			-- horizontal scroll range.
			-- `a_minimal_vertical_position' and
			-- `a_maximal_vertical_position' specify the
			-- vertical scroll range.
			-- `a_horizontal_line' and `a_horizontal_page' specify
			-- the scroll incrementation for a horizontal line and
			-- page.
			-- `a_vertical_line' and `a_vertical_page' specify
			-- the scroll incrementation for a vertical line and
			-- page.
		require
			a_window_not_void: a_window /= Void
			a_window_exists: a_window.exists
			consistent_horizontal_range: a_minimal_horizontal_position < a_maximal_horizontal_position
			consistent_vertical_range: a_minimal_vertical_position < a_maximal_vertical_position
			positive_horizontal_line: a_horizontal_line >= 0
			positive_vertical_line: a_vertical_line >= 0
			positive_horizontal_page: a_horizontal_page >= 0
			positive_vertical_page: a_vertical_page >= 0
		ensure
			window_set: window = a_window
			minimal_horizontal_position_set: minimal_horizontal_position = a_minimal_horizontal_position
			maximal_horizontal_position_set: maximal_horizontal_position = a_maximal_horizontal_position
			minimal_vertical_position_set: minimal_vertical_position = a_minimal_vertical_position
			maximal_vertical_position_set: maximal_vertical_position = a_maximal_vertical_position

feature -- Initialization

	make (a_window: WEL_COMPOSITE_WINDOW; horizontal_size, vertical_size, line, page: INTEGER_32)
			-- Make a scroller associated to `a_window' using
			-- `horizontal_size' and `vertical_size' as the
			-- size of the scrollable area. `line' and `page'
			-- specify the scroll incrementation for a line and
			-- a page.
		require
			a_window_not_void: a_window /= Void
			a_window_exists: a_window.exists
			positive_horizontal_size: horizontal_size > 0
			positive_vertical_size: vertical_size > 0
			positive_line: line >= 0
			valid_line: line < horizontal_size and then line < vertical_size
			positive_page: page >= 0
			valid_page: page < horizontal_size and then page < vertical_size
		ensure
			window_set: window = a_window

	make_with_options (a_window: WEL_COMPOSITE_WINDOW; a_minimal_horizontal_position, a_maximal_horizontal_position, a_minimal_vertical_position, a_maximal_vertical_position, a_horizontal_line, a_horizontal_page, a_vertical_line, a_vertical_page: INTEGER_32)
			-- Make a scroller associated to `a_window'.
			-- `a_minimal_horizontal_position' and
			-- `a_maximal_horizontal_position' specify the
			-- horizontal scroll range.
			-- `a_minimal_vertical_position' and
			-- `a_maximal_vertical_position' specify the
			-- vertical scroll range.
			-- `a_horizontal_line' and `a_horizontal_page' specify
			-- the scroll incrementation for a horizontal line and
			-- page.
			-- `a_vertical_line' and `a_vertical_page' specify
			-- the scroll incrementation for a vertical line and
			-- page.
		require
			a_window_not_void: a_window /= Void
			a_window_exists: a_window.exists
			consistent_horizontal_range: a_minimal_horizontal_position < a_maximal_horizontal_position
			consistent_vertical_range: a_minimal_vertical_position < a_maximal_vertical_position
			positive_horizontal_line: a_horizontal_line >= 0
			positive_vertical_line: a_vertical_line >= 0
			positive_horizontal_page: a_horizontal_page >= 0
			positive_vertical_page: a_vertical_page >= 0
		ensure
			window_set: window = a_window
			minimal_horizontal_position_set: minimal_horizontal_position = a_minimal_horizontal_position
			maximal_horizontal_position_set: maximal_horizontal_position = a_maximal_horizontal_position
			minimal_vertical_position_set: minimal_vertical_position = a_minimal_vertical_position
			maximal_vertical_position_set: maximal_vertical_position = a_maximal_vertical_position
	
feature -- Access

	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)

	horizontal_line: INTEGER_32
			-- Number of horizontal scroll units per line

	horizontal_page: INTEGER_32
			-- Number of scroll units per page
		require
			window_exists: window.exists

	horizontal_position: INTEGER_32
			-- Current position of the horizontal scroll box
		require
			window_exists: window.exists

	maximal_horizontal_position: INTEGER_32
			-- Maxium position of the horizontal scroll box
		require
			window_exists: window.exists

	maximal_vertical_position: INTEGER_32
			-- Maxium position of the vertical scroll box
		require
			window_exists: window.exists

	minimal_horizontal_position: INTEGER_32
			-- Minimum position of the horizontal scroll box
		require
			window_exists: window.exists

	minimal_vertical_position: INTEGER_32
			-- Minimum position of the vertical scroll box
		require
			window_exists: window.exists

	vertical_line: INTEGER_32
			-- Number of vertical scroll units per line

	vertical_page: INTEGER_32
			-- Number of scroll units per page
		require
			window_exists: window.exists

	vertical_position: INTEGER_32
			-- Current position of the vertical scroll box
		require
			window_exists: window.exists

	window: WEL_COMPOSITE_WINDOW
			-- Window which has the scroller
	
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

	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

	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))

	valid_maximal_horizontal_position (a_position: INTEGER_32): BOOLEAN
			-- Is `a_position' valid for setting the horizontal_position.

	valid_maximal_vertical_position (a_position: INTEGER_32): BOOLEAN
			-- Is `a_position' valid for setting the vertical_position.
	
feature -- Element change

	set_horizontal_line (unit: INTEGER_32)
			-- Set horizontal_line with `unit'.
		require
			positive_unit: unit >= 0
		ensure
			horizontal_line_set: horizontal_line = unit

	set_horizontal_page (page_magnitude: INTEGER_32)
			-- Set horizontal_page with `unit'.
		require
			window_exists: window.exists
			positive_unit: page_magnitude >= 0
		ensure
			horizontal_page_set: horizontal_page = page_magnitude

	set_horizontal_position (position: INTEGER_32)
			-- Set horizontal_position with `position'.
		require
			window_exists: window.exists
			position_small_enough: valid_maximal_horizontal_position (position)
			position_large_enough: position >= minimal_horizontal_position
		ensure
			horizontal_position_set: horizontal_position = position

	set_horizontal_range (minimum, maximum: INTEGER_32)
			-- Set `horizontal_minimum_range' and
			-- `horizontal_maximal_range' with `minimum' and
			-- `maximum'.
		require
			window_exists: window.exists
			consistent_range: minimum <= maximum
		ensure
			horizontal_minimum_range_set: minimal_horizontal_position = minimum
			horizontal_maximal_range_set: maximal_horizontal_position = maximum

	set_vertical_line (unit: INTEGER_32)
			-- Set vertical_line with `unit'.
		require
			positive_unit: unit >= 0
		ensure
			vertical_line_set: vertical_line = unit

	set_vertical_page (page_magnitude: INTEGER_32)
			-- Set vertical_page with `unit'.
		require
			window_exists: window.exists
			positive_unit: page_magnitude >= 0
		ensure
			vertical_page_set: vertical_page = page_magnitude

	set_vertical_position (position: INTEGER_32)
			-- Set vertical_position with `position'.
		require
			window_exists: window.exists
			position_small_enough: valid_maximal_vertical_position (position)
			position_large_enough: position >= minimal_vertical_position
		ensure
			vertical_position_set: vertical_position = position

	set_vertical_range (minimum, maximum: INTEGER_32)
			-- Set minimal_vertical_position and
			-- maximal_vertical_position with `minimum' and
			-- `maximum'.
		require
			window_exists: window.exists
			consistent_range: minimum <= maximum
		ensure
			minimal_vertical_position_set: minimal_vertical_position = minimum
			maximal_vertical_position_set: maximal_vertical_position = maximum
	
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)

	horizontal_update (inc, position: INTEGER_32)
			-- Update the window and the horizontal scroll box with
			-- `inc' and `position'.
		require
			window_exists: window.exists
			position_small_enough: position <= maximal_horizontal_position
			position_large_enough: position >= minimal_horizontal_position
		ensure
			horizontal_position_set: horizontal_position = position

	on_horizontal_scroll (scroll_code, pos: INTEGER_32)
			-- Scroll the window horizontaly.
		require
			window_exists: window.exists

	on_vertical_scroll (scroll_code, pos: INTEGER_32)
			-- Scroll the window verticaly.
		require
			window_exists: window.exists

	vertical_update (inc, position: INTEGER_32)
			-- Update the window and the vertical scroll box with
			-- `inc' and `position'.
		require
			window_exists: window.exists
			position_small_enough: position <= maximal_vertical_position
			position_large_enough: position >= minimal_vertical_position
		ensure
			vertical_position_set: vertical_position = position
	
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)
	
invariant
	window_not_void: window /= Void
	horizontal_position_small_enough: window.exists implies horizontal_position <= maximal_horizontal_position
	horizontal_position_large_enough: window.exists implies horizontal_position >= minimal_horizontal_position
	vertical_position_small_enough: window.exists implies vertical_position <= maximal_vertical_position
	vertical_position_large_enough: window.exists implies vertical_position >= minimal_vertical_position
	consistent_horizontal_range: window.exists implies minimal_horizontal_position <= maximal_horizontal_position
	consistent_vertical_range: window.exists implies minimal_vertical_position <= maximal_vertical_position
	positive_horizontal_line: horizontal_line >= 0
	positive_vertical_line: vertical_line >= 0
	positive_horizontal_page: horizontal_page >= 0
	positive_vertical_page: vertical_page >= 0

		-- 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 WEL_SCROLLER