indexing

	description: "[

		If you need performance information use an EM_FRAME_COUNTER.
		A EM_FRAME_COUNTER draws the current frame rate to a surface.

	]"
	date: "$Date$"
	revision: "$Revision$"

class EM_FRAME_COUNTER

inherit

	EM_TIME_SINGLETON
		undefine
			default_create
		end

	EM_DRAWABLE
		redefine
			draw_part
		end

	EM_SHARED_STANDARD_FONTS
		export {NONE} all end

create

	make

feature {NONE} -- Initialization

	make is
			-- Initialise default values.
		local
			font: EM_FONT
		do
			default_create
			font := standard_bmp_fonts.small_font
			create str.make("??.? fps",font)
			set_visible (True)
		ensure
			is_visible: is_visible
		end

feature -- Commands

	draw (a_surface: EM_SURFACE) is
			-- Draws `current' to `a_surface'
		do
			if is_visible then
				update_fps
				str.set_x (x)
				str.set_y (y)
				str.draw (a_surface)
			end
		end

	draw_part (rect: EM_BLITTING_RECTANGLE; a_surface: EM_SURFACE) is
			-- Draws rectangular part of `current' defined by `rect' to `a_surface'
		do
			if is_visible then
				update_fps
				str.set_x (x)
				str.set_y (y)
				str.draw_part (rect, a_surface)
			end
		end

feature -- Status report

	width: INTEGER is
			-- Width of `Current'
		do
			result := str.width
		end

	height: INTEGER is
			-- Height of `Current'
		do
			result := str.height
		end

feature {NONE} -- Implementation

	str: EM_STRING
		-- The string containing the correctly formatted frame per second information

	count: INTEGER
		-- The number of calls to draw

	last_call: INTEGER
		-- The last call of draw in millisecond

	update_fps is
			-- Recalculates actual frame rate and saves it in `str'.
		local
			fps: STRING
		do
			count := count + 1
			if count\\10 = 0 then
				fps := (10000 / ( time.ticks - last_call )).out
				fps.keep_head (4)
				fps := fps + " fps"
				last_call := time.ticks
				str.set_value(fps)
			end
		end

end