note
	description: "A mode (width, height, refresh rate, etc.) of a GAME_DISPLAY (screen)"
	author: "Louis Marchand"
	date: "Thu, 02 Apr 2015 02:40:10 +0000"
	revision: "2.0"

class interface
	GAME_DISPLAY_MODE

create 
	make (a_width, a_height: INTEGER_32)
			-- Initialization for Current using only a_width and a_height.
		require
			display_mode_make_width_valid: a_width > 0
			display_mode_make_height_valid: a_height > 0

	make_with_refresh_rate (a_width, a_height, a_refresh_rate: INTEGER_32)
			-- Initialization for Current using a_width, a_height and a_refresh_rate.
		require
			display_mode_make_refresh_rate_valid: a_refresh_rate >= 0
			display_mode_make_width_valid: a_width > 0
			display_mode_make_height_valid: a_height > 0


create {GAME_SDL_ANY}
	own_from_pointer (a_mode: POINTER)
			-- Initialization for Current using a_mode pointer.
			-- Note that the a_mode pointer is owned by Current. The client does not have to free it.
		require
			display_mode_own_pointer_not_null: not a_mode.is_default_pointer

	shared_from_pointer (a_mode: POINTER)
			-- Initialization for Current using a_mode pointer.
			-- Note that the a_mode will not be free by Current.
		require
			display_mode_own_pointer_not_null: not a_mode.is_default_pointer
		ensure
			display_mode_own_internal_pointer_not_null: not item.is_default_pointer

feature -- Initialization

	make_structure
			-- Initialize current with given structure_size.
			-- (from MEMORY_STRUCTURE)
		ensure -- from MEMORY_STRUCTURE
			not_shared: not shared

	make_by_pointer (a_ptr: POINTER)
			-- Initialize current with a_ptr.
			-- (from MEMORY_STRUCTURE)
		require -- from MEMORY_STRUCTURE
			a_ptr_not_null: a_ptr /= default_pointer
		ensure -- from MEMORY_STRUCTURE
			shared: shared
	
feature -- Access

	generating_type: TYPE [detachable GAME_DISPLAY_MODE]
			-- Type of current object
			-- (type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generating_type_not_void: Result /= Void

	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

	has_error: BOOLEAN
			-- Is the library has generate an error
			-- (from GAME_ERROR_MANAGER)

	height: INTEGER_32 assign set_height
			-- The height of `Current
		require
			pointer_exists: exists
		ensure
			display_mode_width_not_changed: width = old width
			display_mode_height_not_changed: height = old height
			display_mode_refresh_rate_not_changed: refresh_rate = old refresh_rate
			display_mode_pixel_format_not_changed: pixel_format ~ old pixel_format

	is_equal (a_other: like Current): BOOLEAN
			-- Is other attached to an object considered
			-- equal to current object?
		require -- from ANY
			other_not_void: a_other /= Void
		require else
			pointer_exists: exists
		ensure -- from ANY
			symmetric: Result implies a_other ~ Current
			consistent: standard_is_equal (a_other) implies Result

	item: POINTER
			-- Access to memory area.
			-- (from MEMORY_STRUCTURE)

	last_error: READABLE_STRING_GENERAL
			-- The last error generate by the library
			-- (from GAME_SDL_ANY)

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
		require -- from  ANY
			True
		require else
			pointer_exists: exists
		ensure -- from ANY
			out_not_void: Result /= Void

	pixel_format: GAME_PIXEL_FORMAT_READABLE assign set_pixel_format
			-- The internal format of the pixel representation in memory.
		require
			pointer_exists: exists

	refresh_rate: INTEGER_32 assign set_refresh_rate
			-- The frame_rate of Current
		require
			pointer_exists: exists
		ensure
			display_mode_width_not_changed: width = old width
			display_mode_height_not_changed: height = old height
			display_mode_refresh_rate_not_changed: refresh_rate = old refresh_rate
			display_mode_pixel_format_not_changed: pixel_format ~ old pixel_format

	set_height (a_height: INTEGER_32)
			-- Assign height with the value of a_height.
		require
			pointer_exists: exists
		ensure
			display_mode_width_not_changed: width = old width
			display_mode_height_changed: height = a_height
			display_mode_refresh_rate_not_changed: refresh_rate = old refresh_rate
			display_mode_pixel_format_not_changed: pixel_format ~ old pixel_format

	set_pixel_format (a_pixel_format: like pixel_format)
			-- Assign the pixel_format of the pixel representation in memory to the value of a_pixel_format.
		require
			pointer_exists: exists

	set_refresh_rate (a_refresh_rate: INTEGER_32)
			-- Assign refresh_rate with the value of a_refresh_rate.
		require
			pointer_exists: exists
		ensure
			display_mode_width_not_changed: width = old width
			display_mode_height_not_changed: height = old height
			display_mode_refresh_rate_changed: refresh_rate = a_refresh_rate
			display_mode_pixel_format_not_changed: pixel_format ~ old pixel_format

	set_width (a_width: INTEGER_32)
			-- Assign width with the value of a_width.
		require
			pointer_exists: exists
		ensure
			display_mode_width_changed: width = a_width
			display_mode_height_not_changed: height = old height
			display_mode_refresh_rate_not_changed: refresh_rate = old refresh_rate
			display_mode_pixel_format_not_changed: pixel_format ~ old pixel_format

	shared: BOOLEAN
			-- Is current memory area shared with others?
			-- (from MEMORY_STRUCTURE)

	width: INTEGER_32 assign set_width
			-- The width of Current
		require
			pointer_exists: exists
		ensure
			display_mode_width_not_changed: width = old width
			display_mode_height_not_changed: height = old height
			display_mode_refresh_rate_not_changed: refresh_rate = old refresh_rate
			display_mode_pixel_format_not_changed: pixel_format ~ old pixel_format
	
feature -- Comparison

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

	frozen equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.is_equal (b))

	frozen is_deep_equal alias "≡≡≡" (other: GAME_DISPLAY_MODE): 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)

	frozen standard_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b 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
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.standard_is_equal (b))

	frozen standard_is_equal alias "≜" (other: GAME_DISPLAY_MODE): 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

	exists: BOOLEAN
			-- Is allocated memory still allocated?
			-- (from MEMORY_STRUCTURE)

	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 -- Duplication

	copy (other: GAME_DISPLAY_MODE)
			-- 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: Current ~ other

	frozen deep_copy (other: GAME_DISPLAY_MODE)
			-- 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: GAME_DISPLAY_MODE
			-- 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: GAME_DISPLAY_MODE)
			-- 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: GAME_DISPLAY_MODE
			-- 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: GAME_DISPLAY_MODE
			-- New object equal to Current
			-- twin calls copy; to change copying/twinning semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result ~ Current
	
feature -- Basic operations

	frozen default: detachable GAME_DISPLAY_MODE
			-- 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)
		ensure -- from ANY
			instance_free: class

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

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
	
feature -- Implementation

	structure_size: INTEGER_32
			-- Size to allocate (in bytes).
		ensure -- from MEMORY_STRUCTURE
			is_class: class
			positive_result: Result > 0
	
feature -- Output

	Io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			io_not_void: Result /= Void

	print (o: detachable ANY)
			-- Write terse external representation of o
			-- on standard output.
			-- (from ANY)
		ensure -- from ANY
			instance_free: class

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		ensure -- from ANY
			tagged_out_not_void: Result /= Void
	
feature -- Platform

	Operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
		ensure -- from ANY
			instance_free: class
			operating_environment_not_void: Result /= Void
	
invariant
		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

		-- from MEMORY_STRUCTURE
	managed_pointer_valid: not shared implies managed_pointer /= Void
	internal_item_valid: shared implies internal_item /= default_pointer

end -- class GAME_DISPLAY_MODE

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