Refactor battery color calculation logic into BatteryIcon::ColorFromPercentage().

Author: JF002

src/displayapp/screens/BatteryIcon.cpp

@@ -3,6 +3,7 @@
 #include "displayapp/screens/Symbols.h"
 #include "displayapp/icons/battery/batteryicon.c"
 #include "displayapp/InfiniTimeTheme.h"
+#include <lvgl/src/lv_misc/lv_color.h>
 
 using namespace Pinetime::Applications::Screens;
 
@@ -51,3 +52,12 @@ const char* BatteryIcon::GetPlugIcon(bool isCharging) {
   else
     return "";
 }
+
+lv_color_t BatteryIcon::ColorFromPercentage(int batteryPercent) {
+  // HSV color model has red at 0° and green at 120°.
+  // We lock saturation and brightness at 100% and traverse the cylinder
+  // between red and green, thus avoiding the darker RGB on medium battery
+  // charges and giving us a much nicer color range.
+  const uint8_t hue = batteryPercent * 120 / 100;
+  return lv_color_hsv_to_rgb(hue, 100, 100);
+}

src/displayapp/screens/BatteryIcon.h

@@ -16,6 +16,7 @@ namespace Pinetime {
 
         static const char* GetUnknownIcon();
         static const char* GetPlugIcon(bool isCharging);
+        static lv_color_t ColorFromPercentage(int batteryPercent);
 
       private:
         lv_obj_t* batteryImg;

src/displayapp/screens/WatchFaceTerminal.cpp

@@ -123,12 +123,10 @@ void WatchFaceTerminal::Refresh() {
   powerPresent = batteryController.IsPowerPresent();
   batteryPercentRemaining = batteryController.PercentRemaining();
   if (batteryPercentRemaining.IsUpdated() || powerPresent.IsUpdated()) {
-    // HSV color model has red at 0° and green at 120°.
-    // We lock satuation and brightness at 100% and traverse the cilinder
-    // between red and green, thus avoiding the darker RGB on medium battery
-    // charges and giving us a much nicer color range.
-    uint8_t hue = batteryPercentRemaining.Get() * 120 / 100;
-    lv_obj_set_style_local_text_color(batteryValue, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, lv_color_hsv_to_rgb(hue, 100, 100));
+    lv_obj_set_style_local_text_color(batteryValue,
+                                      LV_LABEL_PART_MAIN,
+                                      LV_STATE_DEFAULT,
+                                      BatteryIcon::ColorFromPercentage(batteryPercentRemaining.Get()));
     lv_label_set_text_fmt(batteryValue, "#ffffff [BATT]# %d%%", batteryPercentRemaining.Get());
     if (batteryController.IsCharging()) {
       lv_label_ins_text(batteryValue, LV_LABEL_POS_LAST, " Charging");