indexing
	description: "[
					Representation of a typeface.
					Appearance is specified in terms of font family, height, shape and
					weight. The local system font closest to the specification will be
					displayed. A specific font name may optionally be specified. See `set_preferred_face'"
		
					There are two available queries for a font height, height and height_in_points.
					Changing one, changes the other accordingly. height is given in pixels while
					height_in_points is in points or 1/72 of an inch. Using height_in_points ensures
					that on different screen resolutions `Current' has the same physical size, although
					the pixel height may differ to achieve this.
	]"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	keywords: "character, face, height, family, weight, shape, bold, italic"
	date: "$Date: 2006-03-22 23:29:03 -0800 (Wed, 22 Mar 2006) $"
	revision: "$Revision: 57641 $"

class interface
	EV_FONT

create 
	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

	make_with_values (a_family, a_weight, a_shape, a_height: INTEGER_32)
			-- Create with `a_family', `a_weight', `a_shape' and `a_height'.
		require
			a_family_valid: valid_family (a_family)
			a_weight_valid: valid_weight (a_weight)
			a_shape_valid: valid_shape (a_shape)
			a_height_bigger_than_zero: a_height > 0
		ensure
			a_family_set: family = a_family
			a_weight_set: weight = a_weight
			a_shape_set: shape = a_shape
			a_height_set: height = a_height

feature -- Access

	char_set: INTEGER_32
			-- Charset of the font.
			-- Only meaningful on windows.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.char_set

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

	family: INTEGER_32
			-- Font category. Can be any of the Family_* constants
			-- defined in EV_FONT_CONSTANTS.
			-- Default: Family_sans
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.family

	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)

	height: INTEGER_32
			-- Preferred font height in pixels.
			-- Default: 8
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.height

	height_in_points: INTEGER_32
			-- Preferred font height in points.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.height_in_points

	preferred_families: EV_ACTIVE_LIST [STRING_32]
			-- Preferred familys. The first one in the list
			-- will be tried first. If it does not exists on
			-- the system, the second will be tried, etc.
			--
			-- Overrides family if found on current system.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.preferred_families
			result_not_void: Result /= Void

	shape: INTEGER_32
			-- Preferred font slant. Can be any of the Shape_*
			-- constants defined in EV_FONT_CONSTANTS.
			-- Default: Shape_regular
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.shape

	weight: INTEGER_32
			-- Preferred font thickness. Can be any of the Weight_*
			-- constants defined in EV_FONT_CONSTANTS.
			-- Default: Weight_regular
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.weight
	
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))

	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

	ascent: INTEGER_32
			-- Vertical distance from the origin of the drawing
			-- operation to the top of the drawn character.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.ascent

	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

	descent: INTEGER_32
			-- Vertical distance from the origin of the drawing
			-- operation to the bottom of the drawn character.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.descent

	horizontal_resolution: INTEGER_32
			-- Horizontal resolution of screen for which the font is designed.
			-- Measured in dots per inch. If return value is zero, the
			-- resolution is not known.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.horizontal_resolution

	is_proportional: BOOLEAN
			-- Can characters in the font have different widths?
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.is_proportional

	maximum_width: INTEGER_32
			-- Width of the biggest character in the font.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.maximum_width

	minimum_width: INTEGER_32
			-- Width of the smallest character in the font.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.minimum_width

	name: STRING_32
			-- Face name chosen by toolkit.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result.is_equal (implementation.name)

	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))

	string_size (a_string: STRING_GENERAL): TUPLE [INTEGER_32, INTEGER_32, INTEGER_32, INTEGER_32]
			-- [width, height, left_offset, right_offset] in pixels of `a_string' in the current font,
			-- taking into account line breaks ('%N').
			-- width and height correspond to the rectange used to bound `a_string', and
			-- should be used when placing strings next to each as part of a text.
			-- On some fonts, characters may extend outside of the bounds given by width and height,
			-- for example certain italic letters may overhang other letters. Use `left_offset' and
			-- `right_offset' to determine if there is any overhang for `a_string'. a negative `left_offset'
			-- indicates overhang to the left, while a positive `right_offset' indicates an overhang to the right.
			-- To determine the complete bounding rectangle for `a_string' add negative `left_offset'
			-- and positive `right_offset' to width.
		require
			not_destroyed: not is_destroyed
			a_string_not_void: a_string /= Void
		ensure
			result_not_void: Result /= Void
			bridge_ok: Result.item (1).is_equal (implementation.string_size (a_string).item (1)) and Result.item (2).is_equal (implementation.string_size (a_string).item (2))

	string_width (a_string: STRING_GENERAL): INTEGER_32
			-- Width in pixels of `a_string' in the current font.
		require
			not_destroyed: not is_destroyed
			a_string_not_void: a_string /= Void
		ensure
			bridge_ok: Result = implementation.string_width (a_string)
			positive: Result >= 0

	vertical_resolution: INTEGER_32
			-- Vertical resolution of screen for which the font is designed.
			-- Measured in dots per inch. If return value is zero, the
			-- resolution is not known.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.vertical_resolution

	width: INTEGER_32
			-- Character width of current fixed-width font.
			-- If font is proportional, returns the average width.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.width
	
feature -- Element change

	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_family (a_family: INTEGER_32)
			-- Assign  `a_family' to family.
		require
			not_destroyed: not is_destroyed
			a_family_valid: valid_family (a_family)
		ensure
			family_assigned: family = a_family

	set_height (a_height: INTEGER_32)
			-- Set `a_height' to height.
			-- height_in_points changes accordingly based on screen resolution.
		require
			not_destroyed: not is_destroyed
			a_height_bigger_than_zero: a_height > 0
		ensure
			height_assigned: height = a_height

	set_height_in_points (a_height: INTEGER_32)
			-- Set height_in_points to `a_height'.
			-- height changes accordingly based on screen resolution.
		require
			not_destroyed: not is_destroyed
			a_height_bigger_than_zero: a_height > 0
		ensure
			height_assigned: height_in_points = a_height

	set_shape (a_shape: INTEGER_32)
			-- Set `a_shape' to shape.
		require
			not_destroyed: not is_destroyed
			a_shape_valid: valid_shape (a_shape)
		ensure
			shape_assigned: shape = a_shape

	set_weight (a_weight: INTEGER_32)
			-- Set `a_weight' to weight.
		require
			not_destroyed: not is_destroyed
			a_weight_valid: valid_weight (a_weight)
		ensure
			weight_assigned: weight = a_weight
	
feature -- Duplication

	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

	copy (other: like Current)
			-- Update `Current' with all attributes of `other'.
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: is_equal (other)

	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)

	is_equal (other: like Current): BOOLEAN
			-- Does `other' have same appearance?
		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
	
feature -- Command

	destroy
			-- Destroy underlying native toolkit object.
			-- Render `Current' unusable.
			-- (from EV_ANY)
		ensure -- from EV_ANY
			is_destroyed: is_destroyed
	
feature {ANY} -- Contract support

	valid_family (a_family: INTEGER_32): BOOLEAN
			-- Is `a_family' a valid family value.
			-- (from EV_FONT_CONSTANTS)

	valid_shape (a_shape: INTEGER_32): BOOLEAN
			-- Is `a_shape' a valid shape value.
			-- (from EV_FONT_CONSTANTS)

	valid_weight (a_weight: INTEGER_32): BOOLEAN
			-- Is `a_weight' a valid weight value.
			-- (from EV_FONT_CONSTANTS)
	
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
	family_valid: is_initialized implies valid_family (family)
	weight_valid: is_initialized implies valid_weight (weight)
	shape_valid: is_initialized implies valid_shape (shape)
	height_positive: is_initialized implies height > 0
	height_in_points_positive: is_initialized implies height_in_points > 0
	ascent_not_negative: is_initialized implies ascent >= 0
	descent_not_negative: is_initialized implies descent >= 0
	width_of_empty_string_equals_zero: is_initialized implies string_width ("") = 0
	horizontal_resolution_non_negative: is_initialized implies horizontal_resolution >= 0
	vertical_resolution_non_negative: is_initialized implies vertical_resolution >= 0

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

		-- 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_FONT