    indexing
    	description: "Column of an EV_GRID, containing EV_GRID_ITEMs."
    	date: "$Date: 2006-03-22 23:29:03 -0800 (Wed, 22 Mar 2006) $"
    	legal: "See notice at end of class."
    	status: "See notice at end of class."
    	revision: "$Revision: 57641 $"

    class interface
    	EV_GRID_COLUMN

    create {EV_GRID}
    	default_create
    			-- Standard creation procedure.
    			-- (from EV_ANY)
    		require -- from  ANY
    			True
    		ensure then -- from EV_ANY
    			is_coupled: implementation /= Void
    			is_initialized: is_initialized
    			default_create_called_set: default_create_called
    			is_in_default_state: is_in_default_state

    feature -- Access

    	background_color: EV_COLOR
    			-- Color displayed as background of `Current' except where there are items contained that
    			-- have a non-`Void' background_color. If `Void', background_color of parent is displayed.
    			-- See header of `EV_GRID' for a description of this behavior.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

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

    	deselect_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when `Current' is deselected.
    			-- (from EV_GRID_COLUMN_ACTION_SEQUENCES)
    		ensure -- from EV_GRID_COLUMN_ACTION_SEQUENCES
    			result_not_void: Result /= Void

    	foreground_color: EV_COLOR
    			-- Color displayed for foreground features of `Current' except where there are items contained that
    			-- have a non-`Void' foreground_color. If `Void', foreground_color of parent is displayed.
    			-- See header of `EV_GRID' for a description of this behavior.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	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)

    	header_item: EV_GRID_HEADER_ITEM
    			-- Header item used for resizing `Current' in grid.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			result_not_void: Result /= Void

    	is_displayed: BOOLEAN
    			-- May `Current' be displayed when its parent is?
    			-- Will return False if hide has been called on `Current'.
    			-- A column that is_displayed does not necessarily have to be visible on screen at that particular time.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	is_locked: BOOLEAN
    			-- Is `Current' locked so that it no longer scrolls?
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	item (i: INTEGER_32): EV_GRID_ITEM
    			-- Item at `i'-th row, Void if none.
    		require
    			not_destroyed: not is_destroyed
    			i_positive: i > 0
    			i_less_than_count: i <= count
    			is_parented: parent /= Void

    	locked_position: INTEGER_32
    			-- Locked position of `Current' from left edge of viewable area of parent.
    			-- `Result' is 0 if not is_locked.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			not_locked_implies_result_zero: not is_locked implies Result = 0

    	parent: EV_GRID
    			-- Grid to which current column belongs.
    		require
    			not_destroyed: not is_destroyed

    	pixmap: EV_PIXMAP
    			-- Pixmap display on header of parent to left of title.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void

    	select_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when `Current' is selected.
    			-- (from EV_GRID_COLUMN_ACTION_SEQUENCES)
    		ensure -- from EV_GRID_COLUMN_ACTION_SEQUENCES
    			result_not_void: Result /= Void

    	selected_items: ARRAYED_LIST [EV_GRID_ITEM]
    			-- All items selected in `Current'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			result_not_void: Result /= Void

    	title: STRING_32
    			-- Title of Current column. Empty if none.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			title_not_void: Result /= Void

    	virtual_x_position: INTEGER_32
    			-- Horizontal offset of `Current' in relation to the
    			-- the virtual area of parent grid in pixels.
    			-- `Result' is 0 if parent is `Void'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			parent_void_implies_result_zero: parent = Void implies Result = 0

    	virtual_x_position_unlocked: INTEGER_32
    			-- Horizontal offset of unlocked position of `Current', in relation to the
    			-- virtual area of parent grid in pixels.
    			-- If not is_locked, then virtual_x_position = `virtual_y_position_unlocked'.
    			-- If is_locked then `Result' is the "shadow" position where the column would
    			-- be if not locked.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			parent_void_implies_result_zero: parent = Void implies Result = 0

    	width: INTEGER_32
    			-- `Result' is width of `Current'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			result_non_negative: Result >= 0

    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

    	count: INTEGER_32
    			-- Number of items in current.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			count_not_negative: count >= 0

    	index: INTEGER_32
    			-- Position of Current in parent.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			index_positive: Result > 0
    			index_less_than_column_count: Result <= parent.column_count

    	is_selectable: BOOLEAN
    			-- May enable_select be called?
    			-- (from EV_SELECTABLE)
    		require -- from EV_SELECTABLE
    			not_destroyed: not is_destroyed

    	is_selected: BOOLEAN
    			-- Is selected?
    			-- (from EV_SELECTABLE)
    		require -- from EV_SELECTABLE
    			not_destroyed: not is_destroyed
    		ensure -- from EV_SELECTABLE
    			bridge_ok: is_selectable implies Result = implementation.is_selected

    	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_select
    			-- Deselect the object.
    			-- (from EV_DESELECTABLE)
    		require -- from EV_DESELECTABLE
    			not_destroyed: not is_destroyed
    		ensure -- from EV_DESELECTABLE
    			unselected: not is_selected

    	enable_select
    			-- Make is_selected True.
    			-- (from EV_SELECTABLE)
    		require -- from EV_SELECTABLE
    			not_destroyed: not is_destroyed
    			is_selectable: is_selectable
    		ensure -- from EV_SELECTABLE
    			is_selected: is_selected

    	ensure_visible
    			-- Ensure `Current' is visible in viewable area of parent.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void
    			shown: is_displayed
    		ensure
    			parent_virtual_y_position_unchanged: old parent.virtual_y_position = parent.virtual_y_position
    			to_implement_assertion ("old_is_visible_implies_horizontal_position_not_changed")
    			column_visible: virtual_x_position >= parent.virtual_x_position and virtual_x_position + width <= parent.virtual_x_position + (parent.viewable_width).max (width)

    	hide
    			-- Prevent column from being shown in parent.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			not_is_displayed: not is_displayed

    	lock
    			-- Ensure is_locked is `True'.
    			-- `Current' is locked at it's current horizontal offset from
    			-- the left edge of the viewable area of parent.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			is_locked: is_locked
    			locked_position_set: locked_position = virtual_x_position - parent.virtual_x_position

    	lock_at_position (a_position: INTEGER_32)
    			-- Ensure is_locked is `True' with the horizontal offset from
    			-- the left edge of the viewable area of parent set to `a_position'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			is_locked: is_locked
    			locked_position_set: locked_position = a_position

    	required_width_of_item_span (start_row, end_row: INTEGER_32): INTEGER_32
    			-- Result is greatest `required_width' of all items from
    			-- row index `start_row', `end_row'.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void
    			valid_rows: start_row >= 1 and end_row <= parent.row_count and start_row <= end_row
    		ensure
    			result_non_negative: Result >= 0

    	resize_to_content
    			-- Resize `Current' to greatest `required_width' of all items contained.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void
    			shown: is_displayed
    		ensure
    			width_set: width = required_width_of_item_span (1, parent.row_count)

    	show
    			-- Allow column to be displayed when parent is.
    			-- Does not signify that the column will be visible on screen but that it will be visible within its parent.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			is_displayed: is_displayed

    	toggle
    			-- Change is_selected.
    			-- (from EV_DESELECTABLE)
    		require -- from EV_DESELECTABLE
    			not_is_destroyed: not is_destroyed
    			can_be_selected: not is_selected implies is_selectable
    		ensure -- from EV_DESELECTABLE
    			is_selected_changed: is_selected /= old is_selected

    	unlock
    			-- Ensure is_locked is `False'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			not_is_locked: not is_locked

    feature -- Element change

    	clear
    			-- Remove all items from `Current'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    			all_items_may_be_removed: all_items_may_be_removed
    		ensure
    			to_implement_assertion ("EV_GRID_COLUMN.clear - All items positions return `Void'.")

    	redraw
    			-- Force all items within `Current' to be re-drawn when next idle.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void

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

    	set_background_color (a_color: EV_COLOR)
    			-- Set background_color with `a_color'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			background_color_set: background_color = a_color

    	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_foreground_color (a_color: EV_COLOR)
    			-- Set foreground_color with `a_color'.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			foreground_color_set: foreground_color = a_color

    	set_item (i: INTEGER_32; a_item: EV_GRID_ITEM)
    			-- Set item at `i'-th row to be `a_item'.
    			-- If `a_item' is `Void', the current item (if any) is removed.
    		require
    			not_destroyed: not is_destroyed
    			i_positive: i > 0
    			is_parented: parent /= Void
    			item_may_be_added_to_tree_node: a_item /= Void and parent.row (i).is_part_of_tree_structure implies parent.row (i).is_index_valid_for_item_setting_if_tree_node (index)
    			item_may_be_removed_from_tree_node: a_item = Void and then parent.row (i).is_part_of_tree_structure implies parent.row (i).is_index_valid_for_item_removal_if_tree_node (index)
    		ensure
    			item_set: item (i) = a_item

    	set_pixmap (a_pixmap: EV_PIXMAP)
    			-- Display image of `a_pixmap' on `Current' to left of title.
    		require
    			not_destroyed: not is_destroyed
    			pixmap_not_void: a_pixmap /= Void
    		ensure
    			pixmap_set: pixmap = a_pixmap

    	set_title (a_title: like title)
    			-- a_title_not_void: a_title /= Void.
    		require
    			not_destroyed: not is_destroyed
    			is_parented: parent /= Void
    		ensure
    			title_set: title.is_equal (a_title)

    	set_width (a_width: INTEGER_32)
    			-- Assign `a_width' to width.
    		require
    			not_destroyed: not is_destroyed
    			width_non_negative: a_width >= 0
    			is_parented: parent /= Void
    		ensure
    			width_set: width = a_width

    feature -- Duplication

    	copy (other: like Current)
    			-- 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: 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 -- Command

    	destroy
    			-- Destroy underlying native toolkit object.
    			-- Render `Current' unusable.
    			-- (from EV_ANY)
    		ensure -- from EV_ANY
    			is_destroyed: is_destroyed

    feature -- Contract support

    	all_items_may_be_removed: BOOLEAN
    			-- May `Current' have all of its items removed?
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void

    	all_items_may_be_set: BOOLEAN
    			-- May `Current' be set with count items.
    		require
    			not_destroyed: not is_destroyed
    			parented: parent /= Void

    feature -- Markers

    	fixme (comment: STRING_8)
    			-- Mark code that has to be "fixed" with `comment'.
    			-- (from REFACTORING_HELPER)
    		require -- from REFACTORING_HELPER
    			comment_not_void: comment /= Void

    	to_implement (comment: STRING_8)
    			-- Mark code that has to be "implemented" with `comment'.
    			-- (from REFACTORING_HELPER)
    		require -- from REFACTORING_HELPER
    			comment_not_void: comment /= Void

    	to_implement_assertion (comment: STRING_8): BOOLEAN
    			-- Mark assertion that has to be "implemented" with `comment'.
    			-- (from REFACTORING_HELPER)
    		require -- from REFACTORING_HELPER
    			comment_not_void: comment /= Void

    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 -- Status Report

    	is_destroyed: BOOLEAN
    			-- Is `Current' no longer usable?
    			-- (from EV_ANY)
    		ensure -- from EV_ANY
    			bridge_ok: Result = implementation.is_destroyed

    invariant
    	virtual_position_and_virtual_position_unlocked_equal_when_not_locked: not is_locked implies virtual_x_position = virtual_x_position_unlocked

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

    		-- from EV_DESELECTABLE
    	not_selectable_therefore_not_selected: not is_selectable implies not is_selected

    		-- from EV_ANY
    	is_initialized: is_initialized
    	is_coupled: implementation /= Void and then implementation.interface = Current
    	default_create_called: default_create_called

    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_GRID_COLUMN