indexing

	description: "[

		An EM_DRAWABLE_CONTAINER is a DS_LINKED_LIST of EM_DRAWABLE. The EM_DRAWABLE_CONTAINER
		itself is an EM_DRAWABLE. If an EM_DRAWABLE_CONTAINER is drawn to an EM_SURFACE
		all containing EM_DRAWABLEs are drawn to the surface. First element in the LIST
		is drawn first, last element is drawn last.
		
		An EM_DRAWABLE_CONTAINER is a new coordinate system for all its elements. All the
		contained elements are drawn to an EM_SURFACE relative to the x and y position of the
		EM_DRAWABLE_CONTAINER and clipped to its `width' and `height' which is calculated from
		contained objects such as to enclose them.

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

class EM_DRAWABLE_CONTAINER [G -> EM_DRAWABLE]

inherit

	EM_DRAWABLE
	 	undefine
	 		copy, is_equal
	 	redefine
	 		publish_mouse_event,
	 		initialize_events
		end

 	DS_BILINKED_LIST [G]
	 	rename
	 		put_last as extend,
	 		extend as extend_with_list
	 	redefine
	 		make
	 	end

	EM_SHARED_BITMAP_FACTORY
		export
			{NONE} all
		undefine
			default_create,
			is_equal, copy
		end

create

	make

feature {NONE} -- Initialization

	make is
			-- Create an empty drawable container.
		do
			Precursor
			create part_rect.make (0, 0, 0, 0)
			initialize_events
			set_visible (True)
		ensure then
			is_visible: is_visible
		end

	initialize_events is
			-- Initialize all events.
		do
			Precursor
			create mouse_motion_on_item_event
			create mouse_button_up_on_item_event
			create mouse_button_down_on_item_event
		end

feature -- Commands

	draw (a_surface: EM_SURFACE) is
			-- Draw `Current' to `a_surface'
		local
			cursor: DS_LINKED_LIST_CURSOR [G]
			translation: EM_VECTOR_2D
			old_clipping_area, clipping_area: EM_RECTANGLE
		do
			if is_visible then
					
				-- Translate coordinate system for drawing all contained objects.
				create translation.make (x, y)
				a_surface.translate_coordinates (translation)

				-- Change clipping area to clip all objects to container boundaries.
				old_clipping_area := a_surface.coordinate_area
				create clipping_area.make_from_coordinates (0, 0, width, height)
				clipping_area := clipping_area.intersection (old_clipping_area)
				a_surface.clip_coordinates (clipping_area)

				-- Draw all contained objects.
				cursor := new_cursor
				from
					cursor.start
				until
					cursor.off
				loop
					a_surface.draw_object (cursor.item)
					cursor.forth
				end

				-- Reset coordinate system.
				a_surface.clip_coordinates (old_clipping_area)
				a_surface.translate_coordinates (- translation)
			end
		end

feature -- Status

	height: INTEGER is
			-- Height of `Current'
		local
			cursor: DS_LINKED_LIST_CURSOR [G]
		do
			create cursor.make (current)
			from
				cursor.start
			until
				cursor.off
			loop
				if cursor.item.y + cursor.item.height > result then
					result := cursor.item.y + cursor.item.height
				end
				cursor.forth
			end
		end

	width: INTEGER is
			-- Width of `Current'
		local
			cursor: DS_LINKED_LIST_CURSOR [G]
		do
			create cursor.make (current)
			from
				cursor.start
			until
				cursor.off
			loop
				if cursor.item.x + cursor.item.width > result then
					result := cursor.item.x + cursor.item.width
				end
				cursor.forth
			end
		end

feature -- Mouse Events

	publish_mouse_event (a_mouse_event: EM_MOUSE_EVENT) is
			-- Publish mouse event when `a_mouse_event' occured on `Current'.
			-- Descendants should redefine this feature
			-- for only publishing their mouse events when mouse pointer
			-- is realy inside object or for
			-- distributing mouse events to child objects.
		local
			cursor: DS_BILINKED_LIST_CURSOR [G]
			transformed_mouse_event: EM_MOUSE_EVENT
			translation: EM_VECTOR_2D
		do
			if bounding_box.has (a_mouse_event.proportional_position) then

				-- Transform `a_mouse_event' into `Current' coordinate system.
				transformed_mouse_event := a_mouse_event.twin
				transformed_mouse_event.set_caught (False)
				create translation.make (x, y)
				transformed_mouse_event.set_proportional_position (a_mouse_event.proportional_position - translation)

				-- First publish mouse events of `Current'.
				dispatch_mouse_event (transformed_mouse_event)

				-- Publish `transformed_mouse_event' to all children.
				-- (in top to bottom order until `caught')
				cursor := new_cursor
				from
					cursor.finish
				until
					cursor.before or transformed_mouse_event.caught
				loop
					cursor.item.publish_mouse_event (transformed_mouse_event)
					cursor.back
				end

				-- Publish item mouse event with drawable object that caught the event.
				if transformed_mouse_event.caught then
					cursor.forth
					dispatch_mouse_on_item_event (cursor.item, transformed_mouse_event)

					-- Propagate to caller if event was caught.
					a_mouse_event.set_caught (True)
				end

			end
		end

	mouse_button_down_on_item_event: EM_EVENT_CHANNEL [TUPLE [G]]
			-- Mouse button down on item event,
			-- gets published when the mouse button event
			-- is caught by an item inside `Current',
			-- item is passed as first argument to subscribers,
			-- an EM_MOUSEBUTTON_EVENT is passed
			-- as optional second argument

	mouse_button_up_on_item_event: EM_EVENT_CHANNEL [TUPLE [G]]
			-- Mouse button up on item event,
			-- gets published when the mouse button event
			-- is caught by an item inside `Current',
			-- item is passed as first argument to subscribers,
			-- an EM_MOUSEBUTTON_EVENT is passed
			-- as optional second argument

	mouse_motion_on_item_event: EM_EVENT_CHANNEL [TUPLE [G]]
			-- Mouse motion on item event,
			-- gets published when the mouse motion event
			-- is caught by an item inside `Current',
			-- item is passed as first argument to subscribers,
			-- an EM_MOUSEBUTTON_EVENT is passed
			-- as optional second argument

feature {NONE} -- implementation

	dispatch_mouse_on_item_event (an_item: G; a_mouse_event: EM_MOUSE_EVENT) is
			-- Dispatch mouse on item event.
		require
			an_item_not_void: an_item /= Void
			a_mouse_event_not_void: a_mouse_event /= Void
		do
			-- Only dispatch when events are initialized.
			if events_initialized then
				inspect
					a_mouse_event.type
				when Em_mousemotion_event then
					mouse_motion_on_item_event.publish ([an_item, a_mouse_event])
				when Em_mouse_button_down_event then
					mouse_button_down_on_item_event.publish ([an_item, a_mouse_event])
				when Em_mouse_button_up_event	then
					mouse_button_up_on_item_event.publish ([an_item, a_mouse_event])
				end
			end
		end

	part_rect: EM_BLITTING_RECTANGLE
			-- The rectangular part to be drawed

end