indexing

	description: "[

		A delegate of an EM_WIDGET which can draw the widget and handle layout requests.
		
		Custom subclasses of EM_WIDGET should provide their own delegate to draw the widget.

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

deferred class EM_WIDGET_DELEGATE

inherit

	EM_SHARED_STANDARD_FONTS
		export {NONE} all end

	EM_SHARED_THEME
		export {NONE} all end

feature -- Initialisation

	install (widget: EM_WIDGET) is
			-- Install style on `widget'.
			-- Set up all default values for background, border, font and colors.
		require
			widget_not_void: widget /= Void
		do
			widget.set_font (theme_fonts.default_text_font)
			widget.set_foreground_color (theme_colors.standard_text)
			widget.set_background_color (theme_colors.window_background)
			if widget.surface /= Void then
				install_surface (widget)
			end
		end

	install_surface (widget: EM_WIDGET) is
			-- Install style on `widget's surface
			-- This will be called for every resize of the widget.
		require
			a_widget_not_void: widget /= Void
		do
		end

feature -- Measurement

	contains (widget: EM_WIDGET; a_x, a_y: INTEGER): BOOLEAN is
			-- Does `widget' contain `a_x' `a_y'.
		require
			widget_not_void: widget /= Void
			a_x_in_bounds: 0 <= a_x and a_x <= widget.width
			a_y_in_bounds: 0 <= a_y and a_y <= widget.height
		do
			Result := True
		end

	optimal_width (widget: EM_WIDGET): INTEGER is
			-- Optimal width of `widget'
		require
			widget_not_void: widget /= Void
		do
			Result := 0
		ensure
			result_not_negative: Result >= 0
		end

	optimal_height (widget: EM_WIDGET): INTEGER is
			-- Optimal height of `widget'
		require
			widget_not_void: widget /= Void
		do
			Result := 0
		ensure
			result_not_negative: Result >= 0
		end

feature -- Drawing

	draw_body (widget: EM_WIDGET) is
			-- Draw body of `widget'.
		require
			widget_not_void: widget /= Void
		do
		end

end