note
	description: "A hardware accelerated picture in memory"
	author: "Louis Marchand"
	date: "Fri, 27 Mar 2015 21:44:07 +0000"
	revision: "2.0"

class interface
	GAME_TEXTURE

create 
	make (a_renderer: GAME_RENDERER; a_pixel_format: GAME_PIXEL_FORMAT_READABLE; a_width, a_height: INTEGER_32)
			-- Initialization for Current of dimension (a_width , `a_height)
			-- for use on a_renderer, having a_pixel_format. Current
			-- can not be locked to be modified (best performance)
		ensure
			error_or_exist: not has_error implies exists
			is_not_shared: not shared

	make_target (a_renderer: GAME_RENDERER; a_pixel_format: GAME_PIXEL_FORMAT_READABLE; a_width, a_height: INTEGER_32)
			-- Initialization for Current of dimension (a_width , `a_height)
			-- for use on a_renderer, having a_pixel_format. Current
			-- can be used as rendering target (see: GAME_RENDERER.render_target)
		ensure
			error_or_exist: not has_error implies exists
			is_not_shared: not shared

	make_from_surface (a_renderer: GAME_RENDERER; a_surface: GAME_SURFACE)
			-- Initialization of Current for use on a_renderer and using
			-- the data of a_surface (pixel format, picture, etc.)
		ensure
			error_or_exist: not has_error implies exists
			is_not_shared: not shared

	make_from_image (a_renderer: GAME_RENDERER; a_image: GAME_IMAGE)
			-- Initialization of Current for use on a_renderer and using
			-- the data of a_image
		require
			image_is_open: a_image.is_open
		ensure
			error_or_exist: not has_error implies exists
			is_not_shared: not shared

	share_from_other (a_other: GAME_TEXTURE)
			-- Initialization of Current sharing the internal data of Current
			-- Note that each modification of Current will affect a_other and
			-- vice versa
		require
			other_exists: a_other.exists
		ensure
			is_created: exists
			is_shared: shared
			other_assign: attached other as la_other and then not la_other.shared

feature -- Initialization

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

	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: internal_item_exists
	
feature -- Access

	additionnal_alpha: NATURAL_8 assign set_additionnal_alpha
			-- Additionnal alpha blend to apply on Current when drawing
		require
			texture_exist: exists

	additionnal_color: GAME_COLOR_READABLE assign set_additionnal_color
			-- Additionnal color to multiply to Current when drawing
		require
			texture_exist: exists

	disable_blending
			-- Disable every blending mode to use for drawing operations.
			-- No blending mode:	dstRGBA = srcRGBA
			-- (from GAME_BLENDABLE)
		require -- from GAME_BLENDABLE
			blendable_is_valid: exists

	enable_additive_blending
			-- Set the additive blending mode to use for drawing operations.
			-- Additive blending:	dstRGB = (srcRGB * srcA) + dstRGB
			--						dstA = dstA
			-- (from GAME_BLENDABLE)
		require -- from GAME_BLENDABLE
			blendable_is_valid: exists

	enable_alpha_blending
			-- Set the alpha blending mode to use for drawing operations.
			-- Alpha blending:	dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA))
			--					dstA = srcA + (dstA * (1-srcA))
			-- (from GAME_BLENDABLE)
		require -- from GAME_BLENDABLE
			blendable_is_valid: exists

	enable_modulate_blending
			-- Set the color modulate blending mode to use for drawing operations.
			-- Color modulate:	dstRGB = srcRGB * dstRGB
			--					dstA = dstA
			-- (from GAME_BLENDABLE)
		require -- from GAME_BLENDABLE
			blendable_is_valid: exists

	generating_type: TYPE [detachable GAME_TEXTURE]
			-- 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
			-- The vertical length of Current
		require
			texture_exist: exists

	is_additive_blending_enabled: BOOLEAN
			-- True if the blending mode for drawing operation is additive blending.
			-- Additive blending:	dstRGB = (srcRGB * srcA) + dstRGB
			--						dstA = dstA
			-- (from GAME_BLENDABLE)
		require -- from GAME_BLENDABLE
			blendable_is_valid: exists

	is_alpha_blending_enabled: BOOLEAN
			-- True if the blending mode for drawing operation is alpha blending.
			-- Alpha blending:	dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA))
			--					dstA = srcA + (dstA * (1-srcA))
			-- (from GAME_BLENDABLE)
		require -- from GAME_BLENDABLE
			blendable_is_valid: exists

	is_blending_disabled: BOOLEAN
			-- True if no blending mode is used for drawing operations.
			-- No blending mode:	dstRGBA = srcRGBA
			-- (from GAME_BLENDABLE)
		require -- from GAME_BLENDABLE
			blendable_is_valid: exists

	is_locked: BOOLEAN
			-- Current is locked to access pixels. Current cannot be used until unlock is called.

	is_modulate_blending_enabled: BOOLEAN
			-- True if the blending mode for drawing operation is color modulate blending.
			-- Color modulate:	dstRGB = srcRGB * dstRGB
			--					dstA = dstA
			-- (from GAME_BLENDABLE)
		require -- from GAME_BLENDABLE
			blendable_is_valid: exists

	is_streamable: BOOLEAN
			-- Can Current be modified by locking
		require
			texture_exist: exists

	is_targetable: BOOLEAN
			-- Can Current be use as render target
		require
			texture_exist: exists

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

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

	pixel_format: GAME_PIXEL_FORMAT_READABLE
			-- Informations about the internal representation of pixels in Current
		require
			texture_exist: exists

	set_additionnal_alpha (a_additionnal_alpha: NATURAL_8)
			-- Assign additionnal_alpha with the value of a_additionnal_alpha
		require
			texture_exist: exists
		ensure
			is_set: additionnal_alpha = a_additionnal_alpha

	set_additionnal_color (a_additionnal_color: GAME_COLOR_READABLE)
			-- Assign additionnal_color with the value of a_additionnal_color
		require
			texture_exist: exists
		ensure
			is_set: additionnal_color.is_equal_ignore_alpha (a_additionnal_color)

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

	shared: BOOLEAN
			-- Is current memory area shared with others?

	update_pixels (a_pixels: GAME_PIXEL_BUFFER)
			-- Modify the pixels colors in the section of Current starting at a_x,a_y using data in a_pixels
		require
			is_format_valid: a_pixels.pixel_format ~ pixel_format
			is_dimension_valid: width ~ a_pixels.width and height ~ a_pixels.height

	update_pixels_with_rect (a_x, a_y: INTEGER_32; a_pixels: GAME_PIXEL_BUFFER)
			-- Modify the pixels colors in the section of Current starting at a_x,a_y using data in a_pixels
		require
			is_format_valid: a_pixels.pixel_format ~ pixel_format
			is_dimension_valid: width >= a_x + a_pixels.width and height >= a_y + a_pixels.height

	width: INTEGER_32
			-- The horizontal length of Current
		require
			texture_exist: exists
	
feature -- Measurement

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

	is_equal (other: GAME_TEXTURE): 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 ~ Current
			consistent: standard_is_equal (other) implies Result

	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_TEXTURE): 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)
		require -- from  GAME_BLENDABLE
			True

	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_TEXTURE)
			-- 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_TEXTURE)
			-- 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_TEXTURE
			-- 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_TEXTURE)
			-- 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_TEXTURE
			-- 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_TEXTURE
			-- 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_TEXTURE
			-- 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

	dispose
			-- Action to be executed just before garbage collection
			-- reclaims an object.
			-- Effect it in descendants to perform specific dispose
			-- actions. Those actions should only take care of freeing
			-- external resources; they should not perform remote calls
			-- on other objects since these may also be dead and reclaimed.
	
feature -- Output

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

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		ensure -- from ANY
			out_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 internal_item_exists implies managed_pointer /= Void
	internal_item_valid: internal_item_exists implies internal_item /= default_pointer

end -- class GAME_TEXTURE

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