Random colors via JSON API in Segment object like "col":["r","r","r"] #4996 (#5000)

Add support for random colors via JSON API in Segment object like col=["r","r","r"] #4996

Author: AlexeyMal

wled00/json.cpp

@@ -209,7 +209,7 @@ static bool deserializeSegment(JsonObject elem, byte it, byte presetId = 0)
         // JSON "col" array can contain the following values for each of segment's colors (primary, background, custom):
         // "col":[int|string|object|array, int|string|object|array, int|string|object|array]
         //   int = Kelvin temperature or 0 for black
-        //   string = hex representation of [WW]RRGGBB
+        //   string = hex representation of [WW]RRGGBB or "r" for random color
         //   object = individual channel control {"r":0,"g":127,"b":255,"w":255}, each being optional (valid to send {})
         //   array = direct channel values [r,g,b,w] (w element being optional)
         int rgbw[] = {0,0,0,0};
@@ -233,6 +233,9 @@ static bool deserializeSegment(JsonObject elem, byte it, byte presetId = 0)
               if (kelvin == 0) seg.setColor(i, 0);
               if (kelvin >  0) colorKtoRGB(kelvin, brgbw);
               colValid = true;
+            } else if (hexCol[0] == 'r' && hexCol[1] == '\0') { // Random colors via JSON API in Segment object like col=["r","r","r"] · Issue #4996
+              setRandomColor(brgbw);
+              colValid = true;
             } else { //HEX string, e.g. "FFAA00"
               colValid = colorFromHexString(brgbw, hexCol);
             }