fix prev/next mode for RGBW

lib/MiLight/RgbwPacketFormatter.cpp

@@ -29,7 +29,13 @@ void RgbwPacketFormatter::modeSpeedUp() {
 }
 
 void RgbwPacketFormatter::nextMode() {
-  command(RGBW_DISCO_MODE, 0);
+  lastMode = (lastMode + 1) % RGBW_NUM_MODES;
+  updateMode(lastMode);
+}
+
+void RgbwPacketFormatter::previousMode() {
+  lastMode = (lastMode - 1) % RGBW_NUM_MODES;
+  updateMode(lastMode);
 }
 
 void RgbwPacketFormatter::updateMode(uint8_t mode) {

lib/MiLight/RgbwPacketFormatter.h

@@ -37,11 +37,13 @@ enum MiLightRgbwButton {
 #define RGBW_COMMAND_INDEX 5
 #define RGBW_BRIGHTNESS_GROUP_INDEX 4
 #define RGBW_COLOR_INDEX 3
+#define RGBW_NUM_MODES 9
 
 class RgbwPacketFormatter : public PacketFormatter {
 public:
   RgbwPacketFormatter()
-    : PacketFormatter(7)
+    : PacketFormatter(7),
+      lastMode(0)
   { }
 
   virtual void updateStatus(MiLightStatus status, uint8_t groupId);
@@ -55,10 +57,14 @@ public:
   virtual void modeSpeedDown();
   virtual void modeSpeedUp();
   virtual void nextMode();
+  virtual void previousMode();
   virtual void updateMode(uint8_t mode);
   virtual void enableNightMode();
 
   virtual void initializePacket(uint8_t* packet);
+
+protected:
+  uint8_t lastMode;
 };
 
 #endif