Skip json buffer for fxdata

Eliminates size limit on ESP8266.

Author: willmmiles

wled00/json.cpp

@@ -1161,21 +1161,6 @@ void serializePins(JsonObject root)
   }
 }
 
-// deserializes mode data string into JsonArray
-void serializeModeData(JsonArray fxdata)
-{
-  char lineBuffer[256];
-  for (size_t i = 0; i < strip.getModeCount(); i++) {
-    strncpy_P(lineBuffer, strip.getModeData(i), sizeof(lineBuffer)/sizeof(char)-1);
-    lineBuffer[sizeof(lineBuffer)/sizeof(char)-1] = '\0'; // terminate string
-    if (lineBuffer[0] != 0) {
-      char* dataPtr = strchr(lineBuffer,'@');
-      if (dataPtr) fxdata.add(dataPtr+1);
-      else         fxdata.add("");
-    }
-  }
-}
-
 // deserializes mode names string into JsonArray
 // also removes effect data extensions (@...) from deserialised names
 void serializeModeNames(JsonArray arr)
@@ -1249,6 +1234,44 @@ void serveJson(AsyncWebServerRequest* request)
     return;
   }
 
+  if (subJson == json_target::fxdata) {
+    size_t fx_index = 0;
+    request->sendChunked(FPSTR(CONTENT_TYPE_JSON),
+      [fx_index](uint8_t* data, size_t len, size_t) mutable {
+        size_t bytes_written = 0;
+        char lineBuffer[256];
+        while (fx_index < strip.getModeCount() && (len > 5)) {
+          strncpy_P(lineBuffer, strip.getModeData(fx_index), sizeof(lineBuffer)/sizeof(char)-1); // Copy to stack buffer
+          if (lineBuffer[0] != 0) {
+            lineBuffer[sizeof(lineBuffer)/sizeof(char)-1] = '\0'; // terminate string
+            char* dataPtr = strchr(lineBuffer,'@'); // Find '@', if there is one
+            size_t mode_bytes;
+            if (dataPtr) {
+              mode_bytes = snprintf_P((char*) data, len, PSTR(",\"%s\""), dataPtr + 1);
+              if (mode_bytes > len) break;  // didn't fit              
+            } else {
+              strncpy_P((char*)data, PSTR(",\"\""), len);
+              mode_bytes = 3;
+            }
+            if (fx_index == 0) *data = '[';
+            data += mode_bytes;
+            len -= mode_bytes;
+            bytes_written += mode_bytes;
+          }
+          ++fx_index;        
+        }
+
+        if ((fx_index == strip.getModeCount()) && (len >= 1)) {
+          *data = ']';
+          ++bytes_written;
+          ++fx_index; // we're really done
+        }
+
+        return bytes_written;
+    });
+    return;
+  }
+
   if (!requestJSONBufferLock(JSON_LOCK_SERVEJSON)) {
     request->deferResponse();    
     return;
@@ -1272,7 +1295,7 @@ void serveJson(AsyncWebServerRequest* request)
     case json_target::effects:
       serializeModeNames(lDoc); break;
     case json_target::fxdata:
-      serializeModeData(lDoc); break;
+      break;  // handled earlier, should never get here
     case json_target::networks:
       serializeNetworks(lDoc); break;
     case json_target::config: