indexing
	description: "General notion of a device context."
	legal: "See notice at end of class."
	status: "See notice at end of class."
	date: "$Date: 2007-08-23 14:55:50 -0700 (Thu, 23 Aug 2007) $"
	revision: "$Revision: 70106 $"

deferred class interface
	WEL_DC


feature -- Access

	bitmap: WEL_BITMAP
			-- Current bitmap selected.

	brush: WEL_BRUSH
			-- Current brush selected.

	font: WEL_FONT
			-- Current font selected.

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)
		ensure -- from ANY
			generating_type_not_void: Result /= Void
			generating_type_not_empty: not Result.is_empty

	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

	item: POINTER
			-- Generic Windows handle or structure pointer.
			-- Can be a HWND, HICON, RECT *, WNDCLASS *, etc...
			-- (from WEL_ANY)

	palette: WEL_PALETTE
			-- Current palette selected.

	pen: WEL_PEN
			-- Current pen selected.

	region: WEL_REGION
			-- Current region selected.
	
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 (other /= Void and then 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 is_deep_equal (other: WEL_DC): 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: WEL_DC): 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: WEL_DC): 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

	background_color: WEL_COLOR_REF
			-- Current color of the background.
		require
			exists: exists
		ensure
			result_not_void: Result /= Void

	bitmap_selected: BOOLEAN
			-- Is a bitmap selected?

	brush_selected: BOOLEAN
			-- Is a brush selected?

	char_abc_widths (first_char_index, last_char_index: NATURAL_32): ARRAYED_LIST [WEL_ABC_STRUCT]
			-- `Result' is a list of Windows ABC structures corresponding to the currently
			-- selected truetype font, with an entry for each character contained within the
			-- indices `first_char_index', `last_char_index'.
		require
			indexes_valid: first_char_index >= 1 and last_char_index >= first_char_index
			valid_range: (last_char_index - first_char_index) <= {INTEGER_32}.max_value.to_natural_32
		ensure
			result_not_void: Result /= Void

	character_size (c: CHARACTER_8): WEL_SIZE
			-- Size of the string `s' using the selected font.
		require
			exists: exists
		ensure
			result_exists: Result /= Void
			positive_width: Result.width >= 0
			positive_height: Result.height >= 0

	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

	device_caps (capability: INTEGER_32): INTEGER_32
			-- Give device-specific information about
			-- the current display device.
			-- See class WEL_CAPABILITIES_CONSTANTS for
			-- `capability' values and results.
		require
			exists: exists

	exists: BOOLEAN
			-- Does the item exist?
			-- (from WEL_ANY)
		require -- from  WEL_REFERENCE_TRACKABLE
			True
		ensure -- from WEL_ANY
			Result = (item /= default_pointer)

	font_selected: BOOLEAN
			-- Is a font selected?

	height: INTEGER_32
			-- Height of screen (in raster lines).
		require
			exists: exists

	is_opaque: BOOLEAN
			-- Is the background mode opaque?
		require
			exists: exists

	is_transparent: BOOLEAN
			-- Is the background mode transparent?
		require
			exists: exists

	map_mode: INTEGER_32
			-- Current mapping mode
			-- See class WEL_MM_CONSTANTS for values.
		require
			exists: exists
		ensure
			valid_map_mode: valid_map_mode_constant (Result)

	mask_blt_supported: BOOLEAN is True
			-- It is since we only support Windows NT or greater.

	palette_selected: BOOLEAN
			-- Is a palette selected?

	pen_selected: BOOLEAN
			-- Is a pen selected?

	pixel_color (x, y: INTEGER_32): WEL_COLOR_REF
			-- Color located at `x', `y' position.
		require
			exists: exists
		ensure
			result_not_void: Result /= Void

	polygon_fill_mode: INTEGER_32
			-- Current polygon fill mode
			-- See class WEL_POLYGON_FILL_MODE_CONSTANTS for values.
		require
			exists: exists
		ensure
			valid_polygon_fill_mode: valid_polygon_fill_mode_constant (Result)

	position: WEL_POINT
			-- Current position in logical coordinates.
		require
			exists: exists
		ensure
			result_exists: Result /= Void

	region_selected: BOOLEAN
			-- Is a region selected?

	rop2: INTEGER_32
			-- Current drawing mode.
		require
			exists: exists
		ensure
			valid_result: valid_rop2_constant (Result)

	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))

	shared: BOOLEAN
			-- Is item shared by another object?
			-- If False (by default), item will
			-- be destroyed by destroy_item.
			-- If True, item will not be destroyed.
			-- (from WEL_ANY)

	stretch_blt_mode: INTEGER_32
			-- Current stretching mode. The stretching mode
			-- defines how color data is added to or removed from
			-- bitmaps that are stretched or compressed when
			-- stretch_blt is called.
		require
			exists: exists
		ensure
			valid_stretch_mode: valid_stretch_mode_constant (Result)

	string_height (s: STRING_GENERAL): INTEGER_32
			-- Height of the string `s' using the selected font.
		require
			exists: exists
			s_exists: s /= Void
		ensure
			positive_result: Result >= 0

	string_size (s: STRING_GENERAL): WEL_SIZE
			-- Size of the string `s' using the selected font.
		require
			exists: exists
			s_exists: s /= Void
		ensure
			result_exists: Result /= Void
			positive_width: Result.width >= 0
			positive_height: Result.height >= 0

	string_width (s: STRING_GENERAL): INTEGER_32
			-- Width of the string `s' using the selected font.
		require
			exists: exists
			s_exists: s /= Void
		ensure
			positive_result: Result >= 0

	tabbed_text_height (text: STRING_GENERAL): INTEGER_32
			-- Height of a tabbed `text'.
		require
			exists: exists
			text_not_void: text /= Void
		ensure
			positive_height: Result >= 0

	tabbed_text_size (text: STRING_GENERAL): WEL_SIZE
			-- Size of a tabbed `text'.
		require
			exists: exists
			text_not_void: text /= Void
		ensure
			result_not_void: Result /= Void
			positive_width: Result.width >= 0
			positive_height: Result.height >= 0

	tabbed_text_size_with_tabulation (text: STRING_GENERAL; tabulations: ARRAY [INTEGER_32]): WEL_SIZE
			-- Size of a tabbed `text', with `tabulations' as
			-- tabulation positions.
		require
			exists: exists
			text_not_void: text /= Void
			tabulations_not_void: tabulations /= Void
		ensure
			result_not_void: Result /= Void
			positive_width: Result.width >= 0
			positive_height: Result.height >= 0

	tabbed_text_width (text: STRING_GENERAL): INTEGER_32
			-- Width of a tabbed `text'.
		require
			exists: exists
			text_not_void: text /= Void
		ensure
			positive_width: Result >= 0

	text_alignment: INTEGER_32
			-- Current text alignment flags.
		require
			exists: exists

	text_color: WEL_COLOR_REF
			-- Current color of the text.
		require
			exists: exists
		ensure
			result_not_void: Result /= Void

	text_face: STRING_GENERAL
			-- Typeface name of the font that is currently selected.
		require
			exists: exists
		ensure
			result_not_void: Result /= Void

	valid_dib_colors_constant (c: INTEGER_32): BOOLEAN
			-- Is `c' a valid dib colors constant?
			-- (from WEL_DIB_COLORS_CONSTANTS)

	valid_extent_map_mode (mode: INTEGER_32): BOOLEAN
			-- Is `mode' a valid window or viewport extent map mode?
		require
			valid_map_mode: valid_map_mode_constant (mode)

	valid_htext_alignment_constant (c: INTEGER_32): BOOLEAN
			-- Is `c' a valid text alignment constant for horizontal positioning?
			-- (from WEL_TA_CONSTANTS)

	valid_map_mode_constant (c: INTEGER_32): BOOLEAN
			-- Is `c' a valid map mode constant?
			-- (from WEL_MM_CONSTANTS)

	valid_polygon_fill_mode_constant (c: INTEGER_32): BOOLEAN
			-- Is `c' a valid polygon fill mode constant?
			-- (from WEL_POLYGON_FILL_MODE_CONSTANTS)

	valid_rop2_constant (c: INTEGER_32): BOOLEAN
			-- Is `c' a valid rop2 constant?
			-- (from WEL_DRAWING_CONSTANTS)

	valid_stretch_mode_constant (c: INTEGER_32): BOOLEAN
			-- Is `c' a valid stretch mode constant?
			-- (from WEL_STRETCH_MODE_CONSTANTS)

	valid_text_alignment_constant (c: INTEGER_32): BOOLEAN
			-- Is `c' a valid text alignment constant?
			-- (from WEL_TA_CONSTANTS)

	valid_vtext_alignment_constant (c: INTEGER_32): BOOLEAN
			-- Is `c' a valid text alignment constant for vertical positioning?
			-- (from WEL_TA_CONSTANTS)

	viewport_extent: WEL_SIZE
			-- Retrieve the size of the current viewport for the dc.
		require
			exists: exists
		ensure
			result_not_void: Result /= Void

	viewport_origin: WEL_POINT
			-- Viewport origin for the dc.
		require
			exists: exists
		ensure
			result_not_void: Result /= Void

	width: INTEGER_32
			-- Width of the screen (in pixels).
		require
			exists: exists

	window_extent: WEL_SIZE
			-- Window extent for the dc
		require
			exists: exists
		ensure
			result_not_void: Result /= Void

	window_origin: WEL_POINT
			-- Window origin for the dc.
		require
			exists: exists
		ensure
			result_not_void: Result /= Void
	
feature -- Status setting

	select_bitmap (a_bitmap: WEL_BITMAP)
			-- Select the `a_bitmap' as the current bitmap.
		require
			exists: exists
			a_bitmap_not_void: a_bitmap /= Void
			a_bitmap_exists: a_bitmap.exists
		ensure
			bitmap_set: bitmap = a_bitmap
			bitmap_selected: bitmap_selected

	select_brush (a_brush: WEL_BRUSH)
			-- Select the `a_brush' as the current brush.
		require
			exists: exists
			a_brush_not_void: a_brush /= Void
			a_brush_exists: a_brush.exists
		ensure
			brush_set: brush = a_brush
			brush_selected: brush_selected

	select_font (a_font: WEL_FONT)
			-- Select the `a_font' as the current font.
		require
			exists: exists
			a_font_not_void: a_font /= Void
			a_font_exists: a_font.exists
		ensure
			font_set: font = a_font
			font_selected: font_selected

	select_palette (a_palette: WEL_PALETTE)
			-- Select the `a_palette' as the current palette.
		require
			exists: exists
			a_palette_not_void: a_palette /= Void
			a_palette_exists: a_palette.exists

	select_pen (a_pen: WEL_PEN)
			-- Select the `a_pen' as the current pen.
		require
			exists: exists
			a_pen_not_void: a_pen /= Void
			a_pen_exists: a_pen.exists
		ensure
			pen_set: pen = a_pen
			pen_selected: pen_selected

	select_region (a_region: WEL_REGION)
			-- Select the `a_region' as the current region.
		require
			exists: exists
			a_region_not_void: a_region /= Void
			a_region_exists: a_region.exists
		ensure
			region_set: region = a_region
			region_selected: region_selected

	set_background_color (color: WEL_COLOR_REF)
			-- Set the background_color to `color'.
		require
			exists: exists
			color_not_void: color /= Void
		ensure
			color_set: background_color.item = color.item

	set_background_opaque
			-- Set the background mode to opaque.
		require
			exists: exists
		ensure
			is_opaque: is_opaque

	set_background_transparent
			-- Set the background mode to transparent.
		require
			exists: exists
		ensure
			is_transparent: is_transparent

	set_di_bits (a_bitmap: WEL_BITMAP; start_scan, scan_lines: INTEGER_32; bits: ARRAY [CHARACTER_8]; bitmap_info: WEL_BITMAP_INFO; usage: INTEGER_32): INTEGER_32
			-- Set device-independent bits of `a_bitmap'.
		require
			exists: exists
			a_bitmap_not_void: a_bitmap /= Void
			a_bitmap_exists: a_bitmap.exists
			positive_start_scan: start_scan >= 0
			positive_scan_lines: scan_lines >= 0
			bitmap_info_not_void: bitmap_info /= Void
			valid_usage: valid_dib_colors_constant (usage)

	set_hv_text_alignment (h, v: INTEGER_32)
			-- Set the text alignment using the horizontal and
			-- vertical components in `h' and `v'.
			-- See class WEL_TA_CONSTANTS for valid alignments.
		require
			exists: exists
			valid_horizontal_alignment: valid_htext_alignment_constant (h)
			valid_vertical_alignment: valid_vtext_alignment_constant (v)
		ensure
			text_alignments_set: flag_set (text_alignment, h) and flag_set (text_alignment, v)

	set_map_mode (mode: INTEGER_32)
			-- Set the mapping mode `mode' of the device context.
			-- See class WEL_MM_CONSTANTS for `mode' values.
		require
			exists: exists
			valid_map_mode: valid_map_mode_constant (mode)
		ensure
			map_mode_set: map_mode = mode

	set_polygon_fill_mode (mode: INTEGER_32)
			-- Set the polygon fill mode polygon_fill_mode with
			-- `mode'.
			-- See class WEL_POLYGON_FILL_MODE_CONSTANTS for
			-- `mode' values.
		require
			exists: exists
			valid_polygon_fill_mode: valid_polygon_fill_mode_constant (mode)
		ensure
			polygon_fill_mode_set: polygon_fill_mode = mode

	set_rop2 (a_rop2: INTEGER_32)
			-- Set the current foreground mix mode. GDI uses the
			-- foreground mix mode to combine pens and interiors of
			-- filled objects with the colors already on the screen.
			-- The foreground mix mode defines how colors from the
			-- brush or pen and the colors in the existing image
			-- are to be combined.
			-- For `a_rop2' values, see class WEL_ROP2_CONSTANTS.
		require
			exists: exists
			valid_rop2_constant: valid_rop2_constant (a_rop2)
		ensure
			rop2_set: rop2 = a_rop2

	set_shared
			-- Set shared to True.
			-- (from WEL_ANY)
		ensure -- from WEL_ANY
			shared: shared

	set_stretch_blt_mode (a_mode: INTEGER_32)
			-- Set the bitmap stretching mode with `a_mode'.
			-- See class WEL_STRETCH_MODE_CONSTANTS for `a_mode'
			-- values.
		require
			exists: exists
			valid_stretch_mode_constant: valid_stretch_mode_constant (a_mode)
		ensure
			stretch_blt_mode_set: stretch_blt_mode = a_mode

	set_text_alignment (an_alignment: INTEGER_32)
			-- Set the text alignment with `an_alignment'.
			-- See class WEL_TA_CONSTANTS for `an_alignment'.
		require
			exists: exists
			valid_alignment: valid_text_alignment_constant (an_alignment)
		ensure
			text_alignment_set: flag_set (text_alignment, an_alignment)

	set_text_color (color: WEL_COLOR_REF)
			-- Set the text_color to `color'.
		require
			exists: exists
			color_not_void: color /= Void
		ensure
			color_set: text_color.item = color.item

	set_unshared
			-- Set shared to False.
			-- (from WEL_ANY)
		ensure -- from WEL_ANY
			unshared: not shared

	set_viewport_extent (x_extent, y_extent: INTEGER_32)
			-- Set the `x_extent' and `y_extent' of the viewport
			-- associated with the device context.
		require
			exists: exists
			valid_current_map_mode: valid_extent_map_mode (map_mode)
		ensure
			x_viewport_extent_set: map_mode /= mm_isotropic implies viewport_extent.width = x_extent
			y_viewport_extent_set: map_mode /= mm_isotropic implies viewport_extent.height = y_extent

	set_viewport_origin (x_origin, y_origin: INTEGER_32)
			-- Set the `x_origin' and `y_origin' of the viewport
			-- associated with the device context.
		require
			exists: exists
		ensure
			x_viewport_origin_set: viewport_origin.x = x_origin
			y_viewport_origin_set: viewport_origin.y = y_origin

	set_window_extent (x_extent, y_extent: INTEGER_32)
			-- Set the `x_extent' and `y_extent' of the window
			-- associated with the device context.
		require
			exists: exists
			valid_current_map_mode: valid_extent_map_mode (map_mode)
		ensure
			x_window_extent_set: map_mode /= mm_isotropic implies window_extent.width = x_extent
			y_window_extent_set: map_mode /= mm_isotropic implies window_extent.height = y_extent

	set_window_origin (x_origin, y_origin: INTEGER_32)
			-- Set the `x_origin' and `y_origin' of the window
			-- associated with the device context
		require
			exists: exists
		ensure
			x_window_origin_set: window_origin.x = x_origin
			y_window_origin_set: window_origin.y = y_origin

	unselect_all
			-- Deselect all objects and restore the old ones.
		require
			exists: exists
		ensure
			pen_not_selected: not pen_selected
			brush_not_selected: not brush_selected
			region_not_selected: not region_selected
			palette_not_selected: not palette_selected
			font_not_selected: not font_selected
			bitmap_not_selected: not bitmap_selected

	unselect_bitmap
			-- Deselect the bitmap and restore the old one.
		require
			exists: exists
			bitmap_selected: bitmap_selected
		ensure
			bitmap_not_selected: not bitmap_selected

	unselect_brush
			-- Deselect the brush and restore the old one.
		require
			exists: exists
			brush_selected: brush_selected
		ensure
			brush_not_selected: not brush_selected

	unselect_font
			-- Deselect the font and restore the old one.
		require
			exists: exists
			font_selected: font_selected
		ensure
			font_not_selected: not font_selected

	unselect_palette
			-- Deselect the palette and restore the old one.
		require
			exists: exists
			palette_selected: palette_selected
		ensure
			palette_not_selected: not palette_selected

	unselect_pen
			-- Deselect the pen and restore the old one.
		require
			exists: exists
			pen_selected: pen_selected
		ensure
			pen_not_selected: not pen_selected

	unselect_region
			-- Deselect the region and restore the old one.
		require
			exists: exists
			region_selected: region_selected
		ensure
			region_not_selected: not region_selected
	
feature -- Element change

	set_item (an_item: POINTER)
			-- Set item with `an_item'
			-- (from WEL_ANY)
		ensure -- from WEL_ANY
			item_set: item = an_item
	
feature -- Removal

	delete
			-- Destroy inner structure of `Current'.
			-- To be called when Current is no more needed
			-- (from WEL_REFERENCE_TRACKABLE)
		require -- from WEL_REFERENCE_TRACKABLE
			reference_not_tracked: not reference_tracked
		ensure -- from WEL_REFERENCE_TRACKABLE
			destroyed: not shared implies not exists

	dispose
			-- Destroy inner structure of `Current'.
			-- (from WEL_REFERENCE_TRACKABLE)
		require -- from  DISPOSABLE
			True
		ensure then -- from WEL_REFERENCE_TRACKABLE
			internal_object_id_freed: internal_object_id = 0
	
feature -- Duplication

	copy (other: WEL_DC)
			-- 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: WEL_DC)
			-- 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: WEL_DC
			-- 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: WEL_DC)
			-- 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: WEL_DC
			-- 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: WEL_DC
			-- 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

	alpha_blend (a_x_dest, a_y_dest, a_width, a_height: INTEGER_32; a_dc_src: WEL_DC; a_x_src, a_y_src, a_width_src, a_height_src: INTEGER_32; a_blend_function: <