add display fade logic via a task

Platformio/HAL/Targets/ESP32/display/display.cpp

@@ -58,9 +58,15 @@ void Display::setupTouchScreen(){
     touch.begin(128); // Initialize touchscreen and set sensitivity threshold
 }
 
-void Display::setBrightness(uint8_t brigthness)
+void Display::setBrightness(uint8_t brightness)
 {
-    ledcWrite(LCD_BACKLIGHT_LEDC_CHANNEL, brigthness);
+  mAwakeBrightness = brightness;
+  startFade();
+}
+
+void Display::setCurrentBrightness(uint8_t brightness){
+  mBrightness = brightness;
+  ledcWrite(LCD_BACKLIGHT_LEDC_CHANNEL, mBrightness);
 }
 
 void Display::turnOff()
@@ -102,6 +108,40 @@ void Display::screenInput(lv_indev_drv_t *indev_driver, lv_indev_data_t *data){
   }
 }
 
+void Display::fadeImpl(void* ){
+  bool fadeDone = false;
+  while(!fadeDone){
+    fadeDone = getInstance()->fade();
+    vTaskDelay(3 / portTICK_PERIOD_MS); // 3 miliseconds between steps 
+    // 0 - 255 will take about .75 seconds to fade up. 
+  }
+  vTaskDelete(getInstance()->mDisplayFadeTask);
+  getInstance()->mDisplayFadeTask = nullptr;
+}
+
+bool Display::fade(){
+  //Early return no fade needed. 
+  if (mBrightness == mAwakeBrightness ||
+      isAsleep && mBrightness == 0){return true;} 
+  
+  bool fadeDown = isAsleep || mBrightness > mAwakeBrightness; 
+  if (fadeDown){
+    setCurrentBrightness(mBrightness - 1);
+    auto setPoint = isAsleep ? 0 : mAwakeBrightness;
+    return mBrightness == setPoint;
+  }else{
+    setCurrentBrightness(mBrightness + 1);
+    return mBrightness == mAwakeBrightness;
+  }
+}
+
+void Display::startFade(){
+  if(mDisplayFadeTask != nullptr){// Already have fade task no need to start another.
+    xTaskCreate(&Display::fadeImpl, "Display Fade Task",
+                  1024, nullptr, 5, &mDisplayFadeTask);
+  }
+}
+
 void Display::flushDisplay(lv_disp_drv_t *disp, const lv_area_t *area, lv_color_t *color_p) {
   uint32_t w = (area->x2 - area->x1 + 1);
   uint32_t h = (area->y2 - area->y1 + 1);

Platformio/HAL/Targets/ESP32/display/display.hpp

@@ -22,15 +22,31 @@ class Display: public DisplayAbstract
     public:
         static std::shared_ptr<Display> getInstance();
         
+        /// @brief Set brightness setting and fade to it
+        /// @param brightness 
         virtual void setBrightness(uint8_t brightness) override;
         virtual void turnOff() override;
     
         void onTouch(Notification<TS_Point>::HandlerTy aTouchHandler);
 
+        void wake() {isAsleep = false; startFade();}
+        void sleep() {isAsleep = true; startFade();}
+
     protected:
         virtual void flushDisplay(lv_disp_drv_t *disp, const lv_area_t *area, lv_color_t *color_p);
         virtual void screenInput(lv_indev_drv_t *indev_driver, lv_indev_data_t *data) override;
         
+        /// @brief Fade toward brightness based on isAwake
+        /// @return True - Fade complete
+        ///         False - Fade set point not reached 
+        bool fade();
+        /// @brief Start the Fade task 
+        void startFade();
+        
+        /// @brief Set the actual display brightness right now
+        /// @param brightness 
+        void setCurrentBrightness(uint8_t brightness);
+
     private:
         Display(int backlight_pin, int enable_pin);
         void setupTFT();
@@ -44,4 +60,11 @@ class Display: public DisplayAbstract
         TS_Point touchPoint;
         TS_Point oldPoint;
         Notification<TS_Point> mTouchEvent;
+
+        TaskHandle_t mDisplayFadeTask = nullptr;
+        static void fadeImpl(void* aBrightness);
+
+        uint8_t mBrightness = 0; // Current display brightness
+        uint8_t mAwakeBrightness = 100; // Current setting for brightness when awake
+        bool isAsleep = false;
 };