Use sprintf_P for color array generation

wled00/json.cpp

@@ -328,39 +328,27 @@ void serializeSegment(JsonObject& root, WS2812FX::Segment& seg, byte id, bool fo
   byte segbri = seg.opacity;
   root["bri"] = (segbri) ? segbri : 255;
 
-	JsonArray colarr = root.createNestedArray("col");
-
-  char colstr[70]; //max len 68 (5 chan, all 255)
-  obuf = colstr; olen = 0;
-  oappend("[");
+  char colstr[70]; colstr[0] = '['; colstr[1] = '\0'; //max len 68 (5 chan, all 255)
 
 	for (uint8_t i = 0; i < 3; i++)
 	{
-    oappend("[");
+    byte segcol[4]; byte* c = segcol;
 
     if (id == strip.getMainSegmentId() && i < 2) //temporary, to make transition work on main segment
     {
-      byte* c = (i == 0)? col:colSec;
-
-      oappendi(c[0]); oappend(",");
-      oappendi(c[1]); oappend(",");
-      oappendi(c[2]);
-      if (strip.isRgbw) {
-        oappend(","); oappendi(c[3]);
-      }
+      c = (i == 0)? col:colSec;
     } else {
-  		oappendi((seg.colors[i] >> 16) & 0xFF); oappend(",");
-  		oappendi((seg.colors[i] >> 8) & 0xFF); oappend(",");
-  		oappendi((seg.colors[i]) & 0xFF);
-  		if (strip.isRgbw) {
-  			oappend(","); oappendi((seg.colors[i] >> 24) & 0xFF);
-      }
+      segcol[0] = (byte)(seg.colors[i] >> 16); segcol[1] = (byte)(seg.colors[i] >> 8);
+      segcol[2] = (byte)(seg.colors[i]);       segcol[3] = (byte)(seg.colors[i] >> 24);
     }
 
-    oappend("]");
-    if (i < 2) oappend(",");
+    char tmpcol[22];
+    if (strip.isRgbw) sprintf_P(tmpcol, PSTR("[%u,%u,%u,%u]"), c[0], c[1], c[2], c[3]);
+    else              sprintf_P(tmpcol, PSTR("[%u,%u,%u]"),   c[0], c[1], c[2]);
+
+    strcat(colstr, i<2 ? strcat(tmpcol,",") : tmpcol);
 	}
-  oappend("]");
+  strcat(colstr,"]");
   root["col"] = serialized(colstr);
 
 	root[F("fx")]  = seg.mode;