BatteryIcon: Change color with charge percentage

Author: vkareh

src/displayapp/screens/BatteryIcon.cpp

@@ -27,15 +27,9 @@ void BatteryIcon::SetBatteryPercentage(uint8_t percentage) {
   lv_obj_set_height(batteryJuice, percentage * 14 / 100);
   lv_obj_realign(batteryJuice);
   if (colorOnLowBattery) {
-    static constexpr int lowBatteryThreshold = 15;
-    static constexpr int criticalBatteryThreshold = 5;
-    if (percentage > lowBatteryThreshold) {
-      SetColor(LV_COLOR_WHITE);
-    } else if (percentage > criticalBatteryThreshold) {
-      SetColor(LV_COLOR_ORANGE);
-    } else {
-      SetColor(Colors::deepOrange);
-    }
+    uint8_t green = percentage * 255 / 100;
+    uint8_t red = 255 - green;
+    SetColor(LV_COLOR_MAKE(red, green, 0x0));
   }
 }