cbgfx: coreboot graphics library

This change introduces cbgfx, a graphics library, which provides APIs for
drawing basic shapes, texts, graphic data, etc. on a screen.

BUG=chrome-os-partner:43444
BRANCH=tot
TEST=Drew boxes by draw command of depthcharge cli on Samus

Change-Id: I6019e5998e65dca3ab4785a90669b5db02463d2e
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Original-Commit-Id: 5b3ebce8eae91be742e4f977d3407d24e1537580
Original-Reviewed-on: https://chromium-review.googlesource.com/290301
Original-Reviewed-by: Stefan Reinauer <reinauer@google.com>
Original-Change-Id: I10db27715cb907bdc451a33ed99d257e3af241b7
Original-Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/291065
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/11408
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

payloads/libpayload/include/cbgfx.h

@@ -0,0 +1,66 @@
+/*
+ * This file is part of the libpayload project.
+ *
+ * Copyright (C) 2015 Google, Inc.
+ */
+
+#include <stdint.h>
+
+/*
+ * API error codes
+ */
+#define CBGFX_SUCCESS		0
+/* unknown error */
+#define CBGFX_ERROR_UNKNOWN	1
+/* failed to initialize cbgfx library */
+#define CBGFX_ERROR_INIT	2
+/* drawing beyond canvas boundary */
+#define CBGFX_ERROR_BOUNDARY	3
+
+struct vector {
+	union {
+		uint32_t x;
+		uint32_t width;
+	};
+	union {
+		uint32_t y;
+		uint32_t height;
+	};
+};
+
+struct rgb_color {
+	uint8_t red;
+	uint8_t green;
+	uint8_t blue;
+};
+
+/*
+ * Resolution of scale parameters used to describe height, width, coordinate,
+ * etc. relative to the canvas. For example, if it's 100, scales range from 0 to
+ * 100%.
+ */
+#define CANVAS_SCALE		100
+
+/*
+ * The coordinate system is expected to have (0, 0) at top left corner with
+ * y values increasing towards bottom of screen.
+ */
+
+/*
+ * draw a box filled with a color on screen
+ *
+ * top_left_rel: coordinate of top left corner of the box, relative to canvas.
+ * (0 - CANVAS_SCALE).
+ * size_rel: width and height of the box, relative to canvas. (0 - CANVAS_SCALE)
+ * rgb: RGB color of the box.
+ *
+ * return: CBGFX_* error codes
+ */
+int draw_box(const struct vector *top_left_rel,
+	     const struct vector *size_rel,
+	     const struct rgb_color *rgb);
+
+/*
+ * Clear the canvas
+ */
+int clear_canvas(struct rgb_color *rgb);