class
	EL_FONT_IMP

inherit
	EL_FONT_I
		undefine
			string_size, copy_font
		redefine
			interface
		end

	EV_FONT_IMP
		redefine
			interface, height, is_proportional, set_height, wel_font
		end

	EL_MODULE_LOG

	EL_MODULE_WINDOWS_VERSION

	EL_MODULE_SCREEN

create
	make

feature -- Access

	height: INTEGER
			-- Preferred font height measured in screen pixels.
		local
			height_proportion: DOUBLE
		do
			height_proportion := wel_font.height / (Screen.height * Pixels_to_points_factor)
			Result := (Screen.height * height_proportion).rounded
		end

feature -- Status query

	is_proportional: BOOLEAN
			-- Can characters in the font have different sizes?
		do
			Result := wel_font.is_proportional
		end

feature -- Element change

	set_height (a_height: INTEGER)
			-- Set `a_height' as preferred font size in pixels.
		do
			Wel_log_font.update_by_font (wel_font)
			Wel_log_font.set_height (pixels_to_logical_pixels_y (a_height).opposite)
			wel_font.set_indirect (Wel_log_font)
		end

feature {NONE} -- Implementation

	pixels_to_logical_pixels_y (a_height: INTEGER): INTEGER
			-- Scale to approx. the same size as GTK implementation font height and adjust for user selected DPI
			-- Rendering 4.5 cm Verdana font
			-- 	On GTK 		'A' is 40 mm high
			-- 	On Windows	'A' is 44 mm high
		local
			height_proportion: DOUBLE
		do
			height_proportion := a_height / Screen.height
			Result := (Screen.height * height_proportion * Pixels_to_points_factor).rounded
		end

feature {NONE} -- Internal attributes

	interface: detachable EL_FONT note option: stable attribute end;

	wel_font: EL_WEL_FONT
		-- Basic WEL font.

feature {NONE} -- Constants

	Pixels_to_points_factor: DOUBLE = 1.212

end