[BUG] GFX line drawing mishandles start/end values

[cxz]

When drawing lines of equal start and end x, y coordinates the GFX library shall draw a rectangle with thickness applied. If the value of the opposing axis has a start value greater than the end value this results in a line drawn in the opposite direction. Tested with nRF5 SDK 15.0.0 a53641a.

Here is a patch which uses MIN() for drawing the rectangle (line):

--- components/libraries/gfx/nrf_gfx.c	2018-03-22 15:25:07.608481800 +0100
+++ components/libraries/gfx/nrf_gfx.c	2018-03-22 15:25:07.608481800 +0100
@@ -265,8 +265,8 @@
     if ((p_line->x_start == p_line->x_end) || (p_line->y_start == p_line->y_end))
     {
         rect_draw(p_instance,
-                  p_line->x_start,
-                  p_line->y_start,
+                  MIN(p_line->x_start, p_line->x_end),
+                  MIN(p_line->y_start, p_line->y_end),
                   abs(p_line->x_end - p_line->x_start) + x_thick,
                   abs(p_line->y_end - p_line->y_start) + y_thick,
                   color);

[Susheel Nuguru]

Thanks for letting us know about this. 

Your fix seems logical, I will forward this to the team to take a look at and possibly fix it in the next release. For your reference, our internal tracking number for this is NRFFOETT-2083

[cxz]

Thanks Aryan.