Always repaint NPB buffer on brightness change

Fix bus re-init causing full brightness (every show() now attempts to set the brightness, bus will ignore this if it stays the same)

wled00/FX_fcn.cpp

@@ -1231,7 +1231,7 @@ void WS2812FX::show(void) {
   #endif
 
   uint8_t newBri = estimateCurrentAndLimitBri();
-  if (newBri < _brightness) busses.setBrightness(newBri, true); // "repaint" all pixels
+  busses.setBrightness(newBri); // "repaints" all pixels if brightness changed
 
   #ifdef WLED_DEBUG
   sumCurrent += micros() - microsStart;
@@ -1245,7 +1245,7 @@ void WS2812FX::show(void) {
   // restore bus brightness to its original value
   // this is done right after show, so this is only OK if LED updates are completed before show() returns
   // or async show has a separate buffer (ESP32 RMT and I2S are ok)
-  if (newBri < _brightness) busses.setBrightness(_brightness, true);
+  if (newBri < _brightness) busses.setBrightness(_brightness);
 
   #ifdef WLED_DEBUG
   sumMicros += micros() - microsStart;
@@ -1328,15 +1328,10 @@ void WS2812FX::setBrightness(uint8_t b, bool direct) {
       seg.freeze = false;
     }
   }
-  if (direct) {
   // setting brightness with NeoPixelBusLg has no effect on already painted pixels,
   // so we need to force an update to existing buffer
-    // that would be dangerous if applied immediately (could exceed ABL), but will not output until the next show()
-    busses.setBrightness(b, true);
-  } else {
-    // setting brightness with NeoPixelBusLg has no effect on already painted pixels,
-    // so we need to redraw whole canvas for the change of brightness to take effect
   busses.setBrightness(b);
+  if (!direct) {
     unsigned long t = millis();
     if (_segments[0].next_time > t + 22 && t - _lastShow > MIN_SHOW_DELAY) trigger(); //apply brightness change immediately if no refresh soon
   }

wled00/bus_manager.cpp

@@ -157,7 +157,7 @@ bool BusDigital::canShow() {
   return PolyBus::canShow(_busPtr, _iType);
 }
 
-void BusDigital::setBrightness(uint8_t b, bool updateNPBBuffer) {
+void BusDigital::setBrightness(uint8_t b) {
   if (_bri == b) return;
   //Fix for turning off onboard LED breaking bus
   #ifdef LED_BUILTIN
@@ -168,7 +168,12 @@ void BusDigital::setBrightness(uint8_t b, bool updateNPBBuffer) {
   uint8_t prevBri = _bri;
   Bus::setBrightness(b);
   PolyBus::setBrightness(_busPtr, _iType, b);
-  if (!_buffering && updateNPBBuffer) {
+
+  if (_buffering) return;
+
+  // must update/repaint every LED in the NeoPixelBus buffer to the new brightness
+  // the only case where repainting is unnecessary is when all pixels are set after the brightness change but before the next show
+  // (which we can't rely on)
   uint16_t hwLen = _len;
   if (_type == TYPE_WS2812_1CH_X3) hwLen = NUM_ICS_WS2812_1CH_3X(_len); // only needs a third of "RGB" LEDs for NeoPixelBus
   for (uint_fast16_t i = 0; i < hwLen; i++) {
@@ -177,7 +182,6 @@ void BusDigital::setBrightness(uint8_t b, bool updateNPBBuffer) {
     PolyBus::setPixelColor(_busPtr, _iType, i, c, 0);
   }
 }
-}
 
 //If LEDs are skipped, it is possible to use the first as a status LED.
 //TODO only show if no new show due in the next 50ms
@@ -583,9 +587,9 @@ void IRAM_ATTR BusManager::setPixelColor(uint16_t pix, uint32_t c) {
   }
 }
 
-void BusManager::setBrightness(uint8_t b, bool updateBuffer) {
+void BusManager::setBrightness(uint8_t b) {
   for (uint8_t i = 0; i < numBusses; i++) {
-    busses[i]->setBrightness(b, updateBuffer);
+    busses[i]->setBrightness(b);
   }
 }
 

wled00/bus_manager.h

@@ -124,7 +124,7 @@ class Bus {
     virtual void     setStatusPixel(uint32_t c)  {}
     virtual void     setPixelColor(uint16_t pix, uint32_t c) = 0;
     virtual uint32_t getPixelColor(uint16_t pix) { return 0; }
-    virtual void     setBrightness(uint8_t b, bool updateBuffer = false) { _bri = b; };
+    virtual void     setBrightness(uint8_t b)    { _bri = b; };
     virtual void     cleanup() = 0;
     virtual uint8_t  getPins(uint8_t* pinArray)  { return 0; }
     virtual uint16_t getLength()                 { return _len; }
@@ -202,7 +202,7 @@ class BusDigital : public Bus {
 
     void show();
     bool canShow();
-    void setBrightness(uint8_t b, bool updateBuffer = false);
+    void setBrightness(uint8_t b);
     void setStatusPixel(uint32_t c);
     void setPixelColor(uint16_t pix, uint32_t c);
     void setColorOrder(uint8_t colorOrder);
@@ -317,7 +317,7 @@ class BusManager {
     bool canAllShow();
     void setStatusPixel(uint32_t c);
     void setPixelColor(uint16_t pix, uint32_t c);
-    void setBrightness(uint8_t b, bool updateBuffer = false);
+    void setBrightness(uint8_t b);
     void setSegmentCCT(int16_t cct, bool allowWBCorrection = false);
     uint32_t getPixelColor(uint16_t pix);