libpayload: cbgfx: Support drawing a box with rounded corners

A function draw_rounded_box() is added to draw a box with rounded
corners. In addition, this function is different from draw_box() in 2
ways:
- The position and size arguments are relative to the canvas.
- This function supports drawing only the border of a box (linear time
  complexity when the thickness is fixed).

BRANCH=none
BUG=b:146105976
TEST=emerge-nami libpayload

Change-Id: Ie480410d2fd8316462d5ff874999ae2317de04f9
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37757
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>

payloads/libpayload/include/cbgfx.h

@@ -114,6 +114,25 @@ struct rgb_color {
  */
 int draw_box(const struct rect *box, const struct rgb_color *rgb);
 
+/**
+ * Draw a box with rounded corners on screen.
+ *
+ * @param[in] pos_rel	Coordinate of the top left corner of the box relative to
+ *                      the canvas.
+ * @param[in] dim_rel	Width and height of the image relative to the canvas.
+ * @param[in] rgb       Color of the border of the box.
+ * @param[in] thickness Thickness of the border relative to the canvas. If zero
+ *                      is given, the box will be filled with the rgb color.
+ * @param[in] radius    Radius of the rounded corners relative to the canvas. A
+ *                      zero value indicates sharp corners will be drawn.
+ *
+ * @return CBGFX_* error codes
+ */
+int draw_rounded_box(const struct scale *pos_rel, const struct scale *dim_rel,
+		     const struct rgb_color *rgb,
+		     const struct fraction *thickness,
+		     const struct fraction *radius);
+
 /**
  * Clear the canvas
  */