os: define ALPHA8 pixel format

repos/os/include/os/pixel_alpha8.h

@@ -0,0 +1,39 @@
+/*
+ * \brief  Template specializations for the ALPHA8 pixel format
+ * \author Norman Feske
+ * \date   2014-09-10
+ */
+
+/*
+ * Copyright (C) 2014 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _INCLUDE__OS__PIXEL_ALPHA8_H_
+#define _INCLUDE__OS__PIXEL_ALPHA8_H_
+
+#include <os/pixel_rgba.h>
+
+namespace Genode {
+
+	typedef Genode::Pixel_rgba<unsigned char, Genode::Surface_base::ALPHA8,
+	                           0, 0, 0, 0, 0, 0, 0xff, 0>
+	        Pixel_alpha8;
+
+
+	/*
+	 * The second pixel parameter is ignored. It can be of any pixel type.
+	 */
+	template <>
+	template <typename PT>
+	inline Pixel_alpha8 Pixel_alpha8::mix(Pixel_alpha8 p1, PT, int alpha)
+	{
+		Pixel_alpha8 res;
+		res.pixel = p1.pixel + (((255 - p1.pixel)*alpha) >> 8);
+		return res;
+	}
+}
+
+#endif /* _INCLUDE__OS__PIXEL_ALPHA8_H_ */

repos/os/include/os/surface.h

@@ -37,7 +37,7 @@ class Genode::Surface_base
 		typedef Genode::Rect<>  Rect;
 		typedef Genode::Color   Color;
 
-		enum Pixel_format { UNKNOWN, RGB565, RGB888 };
+		enum Pixel_format { UNKNOWN, RGB565, RGB888, ALPHA8 };
 
 		struct Flusher
 		{