Merge pull request #1465 from pbolduc/bug/1431

Fixes an issue where switching effects causes crash

wled00/FX.h

@@ -317,9 +317,31 @@ class WS2812FX {
         WS2812FX::_usedSegmentData -= _dataLen;
         _dataLen = 0;
       }
-      void reset(){next_time = 0; step = 0; call = 0; aux0 = 0; aux1 = 0; deallocateData();}
+
+      /** 
+       * If reset of this segment was request, clears runtime
+       * settings of this segment.
+       * Must not be called while an effect mode function is running
+       * because it could access the data buffer and this method 
+       * may free that data buffer.
+       */
+      void resetIfRequired() {
+        if (_requiresReset) {
+          next_time = 0; step = 0; call = 0; aux0 = 0; aux1 = 0; 
+          deallocateData();
+          _requiresReset = false;
+        }
+      }
+
+      /** 
+       * Flags that before the next effect is calculated,
+       * the internal segment state should be reset. 
+       * Call resetIfRequired before calling the next effect function.
+       */
+      void reset() { _requiresReset = true; }
       private:
         uint16_t _dataLen = 0;
+        bool _requiresReset = false;
     } segment_runtime;
 
     WS2812FX() {

wled00/FX_fcn.cpp

@@ -76,6 +76,11 @@ void WS2812FX::service() {
   for(uint8_t i=0; i < MAX_NUM_SEGMENTS; i++)
   {
     _segment_index = i;
+
+    // reset the segment runtime data if needed, called before isActive to ensure deleted
+    // segment's buffers are cleared
+    SEGENV.resetIfRequired();
+
     if (SEGMENT.isActive())
     {
       if(nowUp > SEGENV.next_time || _triggered || (doShow && SEGMENT.mode == 0)) //last is temporary