Add the possibility to the screen to handle a touch gesture.

A default action is taken if the current screen doesn't handle it.

src/DisplayApp/Screens/Brightness.cpp

@@ -70,3 +70,23 @@ uint8_t Brightness::LevelToInt(Pinetime::Controllers::BrightnessController::Leve
     default : return 0;
   }
 }
+
+bool Brightness::OnTouchEvent(Pinetime::Applications::TouchEvents event) {
+  switch(event) {
+    case TouchEvents::SwipeLeft:
+      brightness.Lower();
+      SetValue();
+      return true;
+    case TouchEvents::SwipeRight:
+      brightness.Higher();
+      SetValue();
+      return true;
+    default:
+      return false;
+  }
+}
+
+void Brightness::SetValue() {
+  lv_slider_set_value(slider, LevelToInt(brightness.Level()), LV_ANIM_OFF);
+  lv_label_set_text(slider_label, LevelToString(brightness.Level()));
+}

src/DisplayApp/Screens/Brightness.h

@@ -13,6 +13,7 @@ namespace Pinetime {
           ~Brightness() override;
           bool Refresh() override;
           bool OnButtonPushed() override;
+          bool OnTouchEvent(TouchEvents event) override;
 
           void OnValueChanged();
         private:
@@ -25,6 +26,7 @@ namespace Pinetime {
           const char* LevelToString(Controllers::BrightnessController::Levels level);
           uint8_t LevelToInt(Controllers::BrightnessController::Levels level);
           void SetValue(uint8_t value);
+          void SetValue();
       };
     }
   }

src/DisplayApp/Screens/Screen.h

@@ -1,4 +1,5 @@
 #pragma once
+#include "../TouchEvents.h"
 
 namespace Pinetime {
   namespace Applications {
@@ -15,6 +16,9 @@ namespace Pinetime {
           // Return false if the button hasn't been handled by the app, true if it has been handled
           virtual bool OnButtonPushed() { return false; }
 
+          // Return false if the event hasn't been handled by the app, true if it has been handled
+          virtual bool OnTouchEvent(TouchEvents event) { return false; }
+
         protected:
           DisplayApp* app;
       };