+ Stencil Renderables and small refactoring

source/base/video-colors.ads

@@ -10,6 +10,11 @@ package Video.Colors with Pure is
 	-- Universal definition for color component (like R, G, B channels or Alpha)
 	-- defined to cover the best color resolution required (e. g. 8 bit in true color systems)
 
+	subtype Opacity is Color_Component;
+
+	Opaque      : constant Opacity;
+	Transparent : constant Opacity;
+
 	subtype Color_Component_1_Bit is Integer range 0 .. 1;
 	subtype Color_Component_4_Bit is Integer range 0 .. 2**4 - 1;
 	subtype Color_Component_5_Bit is Integer range 0 .. 2**5 - 1;
@@ -43,7 +48,7 @@ package Video.Colors with Pure is
 		R : Color_Component;
 		G : Color_Component;
 		B : Color_Component;
-		A : Color_Component := From_8_Bit (2**Color_Component_Bits - 1);
+		A : Opacity := From_8_Bit (2**Color_Component_Bits - 1);
 	end record;
 
 	function RGB_8 (
@@ -61,4 +66,7 @@ package Video.Colors with Pure is
 private
 	type Color_Component is range 0 .. 2**Color_Component_Bits - 1;
 
+	Opaque      : constant Opacity := Color_Component'Last;
+	Transparent : constant Opacity := Color_Component'First;
+
 end Video.Colors;

source/base/video-renderables-color-stencil.ads

@@ -0,0 +1,4 @@
+with Video.Stencils;
+
+package Video.Renderables.Color.Stencil
+is new Renderables.Color.Generic_Stencil (Stencil_Type => Video.Stencils.Stencil'Class);

source/base/video-renderables-generic_sprite.ads

@@ -1,14 +0,0 @@
---
--- Base interface for rendering image (sprite) to image (renderable)
---
-generic
-	type Sprite (<>) is limited private;
-package Video.Renderables.Generic_Sprite is
-	type Sprite_Renderable is limited interface and Root_Renderable;
-
-	procedure Paste (
-		Target   : in out Sprite_Renderable;
-		A        :        Integer_Geometry.Point;
-		Source   :        Sprite) is abstract;
-
-end Video.Renderables.Generic_Sprite;

source/base/video-renderables-image.ads

@@ -1,4 +1,3 @@
 with Video.Images;
-with Video.Renderables.Generic_Sprite;
 
-package Video.Renderables.Image is new Video.Renderables.Generic_Sprite (Images.Image'Class);
+package Video.Renderables.Image is new Video.Renderables.Generic_Image (Images.Image'Class);

source/base/video-renderables.ads

@@ -61,6 +61,33 @@ package Video.Renderables with Pure is
 			Bounds : in     Box;
 			Paint  : in     Paint_Type) is abstract;
 
+		generic
+			type Stencil_Type (<>) is limited private;
+		package Generic_Stencil is
+			type Stencil_Renderable is limited interface and Root_Renderable;
+
+			procedure Fill (
+				Target : in out Stencil_Renderable;
+				A      : in     Point;
+				Shape  : in     Stencil_Type;
+				Paint  : in     Paint_Type) is abstract;
+		end Generic_Stencil;
+
 	end Paint_Renderables;
 
+	--
+	-- Base interface for rendering image (sprite) to image (renderable)
+	--
+	generic
+		type Image_Type (<>) is limited private;
+	package Generic_Image is
+		type Image_Renderable is limited interface and Root_Renderable;
+
+		procedure Paste (
+			Target   : in out Image_Renderable;
+			A        :        Integer_Geometry.Point;
+			Source   :        Image_Type) is abstract;
+
+	end Generic_Image;
+
 end Video.Renderables;

source/base/video-stencils.ads

@@ -0,0 +1,31 @@
+with Video.Integer_Geometry, Video.Colors;
+use  Video.Integer_Geometry, Video.Colors;
+
+package Video.Stencils is
+
+	type Stencil is interface;
+
+	function Bounding_Box (
+		Source  : Stencil)
+		return    Box is abstract;
+	-- Stencil bounds in native (whatever it means) resolution
+
+	function Pixel (
+		Source  : Stencil;
+		A       : Point)
+		return    Opacity is abstract;
+
+	type Raster_Stencil is interface and Stencil;
+
+	generic
+		type Pixel_Type is private;
+	package Generic_Raster is
+		type Stencil is interface and Raster_Stencil;
+
+		function Pixel (
+			Source : Stencil;
+			A      : Point)
+			return Pixel_Type is abstract;
+	end Generic_Raster;
+
+end Video.Stencils;