feat: add runtime display rotation setting for e-ink builds

Adds Settings > Display > Rotation (0°/90°/180°/270°) that persists to
NodePrefs and is applied on startup. Falls back to compile-time
DISPLAY_ROTATION when the field is missing from an older prefs file.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/companion_radio/DataStore.cpp

@@ -289,7 +289,18 @@ void DataStore::loadPrefsInt(const char *filename, NodePrefs& _prefs, double& no
                                     file.read((uint8_t *)&_prefs.clock_12h, sizeof(_prefs.clock_12h));
                                     if (file.available()) {
                                       file.read((uint8_t *)&_prefs.use_lemon_font, sizeof(_prefs.use_lemon_font));
+                                      if (file.available()) {
+                                        file.read((uint8_t *)&_prefs.display_rotation, sizeof(_prefs.display_rotation));
+                                      } else {
+#ifdef DISPLAY_ROTATION
+                                        _prefs.display_rotation = DISPLAY_ROTATION;
+#endif
+                                      }
                                     }
+                                  } else {
+#ifdef DISPLAY_ROTATION
+                                    _prefs.display_rotation = DISPLAY_ROTATION;
+#endif
                                   }
                                 }
                               }
@@ -383,6 +394,7 @@ void DataStore::savePrefs(const NodePrefs& _prefs, double node_lat, double node_
     file.write((uint8_t *)&_prefs.auto_lock, sizeof(_prefs.auto_lock));
     file.write((uint8_t *)&_prefs.clock_12h, sizeof(_prefs.clock_12h));
     file.write((uint8_t *)&_prefs.use_lemon_font, sizeof(_prefs.use_lemon_font));
+    file.write((uint8_t *)&_prefs.display_rotation, sizeof(_prefs.display_rotation));
 
     file.close();
   }

examples/companion_radio/NodePrefs.h

@@ -78,5 +78,6 @@ struct NodePrefs {  // persisted to file
   struct DmMelodyEntry { uint8_t prefix[4]; uint8_t slot; }; // slot: 0=global,1=melody1,2=melody2
   static const int DM_MELODY_TABLE_MAX = 16;
   DmMelodyEntry dm_melody[DM_MELODY_TABLE_MAX];
-  uint8_t  use_lemon_font;  // 0=default Adafruit font, 1=Lemon font (Unicode, pixel-accurate wrap)
+  uint8_t  use_lemon_font;      // 0=default Adafruit font, 1=Lemon font (Unicode, pixel-accurate wrap)
+  uint8_t  display_rotation;    // 0-3; only used on e-ink displays
 };

examples/companion_radio/ui-new/SettingsScreen.h

@@ -15,6 +15,9 @@ class SettingsScreen : public UIScreen {
     CLOCK_SECONDS,
     CLOCK_FORMAT,
     FONT,
+#if defined(EINK_DISPLAY_MODEL)
+    ROTATION,
+#endif
     // Sound section
     SECTION_SOUND,
     BUZZER,
@@ -321,6 +324,14 @@ class SettingsScreen : public UIScreen {
       display.print("Font");
       display.setCursor(VAL_X, y);
       display.print((p && p->use_lemon_font) ? "Lemon" : "Default");
+#if defined(EINK_DISPLAY_MODEL)
+    } else if (item == ROTATION) {
+      display.print("Rotation");
+      display.setCursor(VAL_X, y);
+      { static const char* ROT_LABELS[] = { "0deg", "90deg", "180deg", "270deg" };
+        uint8_t r = p ? (p->display_rotation & 3) : 0;
+        display.print(ROT_LABELS[r]); }
+#endif
     } else if (item == DM_FILTER) {
       display.print("DM");
       display.setCursor(VAL_X, y);
@@ -517,6 +528,14 @@ public:
       _dirty = true;
       return true;
     }
+#if defined(EINK_DISPLAY_MODEL)
+    if (_selected == ROTATION && p && (left || right || enter)) {
+      p->display_rotation = (p->display_rotation + (left ? 3 : 1)) & 3;
+      _task->applyRotation();
+      _dirty = true;
+      return true;
+    }
+#endif
     if (_selected == DM_FILTER && p && (left || right || enter)) {
       p->dm_show_all = p->dm_show_all ? 0 : 1;
       _dirty = true;

examples/companion_radio/ui-new/UITask.cpp

@@ -817,6 +817,7 @@ void UITask::begin(DisplayDriver* display, SensorManager* sensors, NodePrefs* no
 
   applyBrightness();
   applyFont();
+  applyRotation();
 }
 
 void UITask::gotoSettingsScreen() {
@@ -1565,6 +1566,13 @@ void UITask::applyFont() {
   }
 }
 
+void UITask::applyRotation() {
+  if (_display != NULL && _node_prefs != NULL) {
+    _display->setDisplayRotation(_node_prefs->display_rotation);
+    _next_refresh = 0;
+  }
+}
+
 void UITask::setBrightnessLevel(uint8_t level) {
   if (_node_prefs == NULL) return;
   if (level > 4) level = 4;

examples/companion_radio/ui-new/UITask.h

@@ -159,6 +159,7 @@ public:
   void applyTxPower();
   void applyGPSInterval();
   void applyFont();
+  void applyRotation();
   uint32_t autoOffMillis() const {
     if (!_node_prefs || _node_prefs->auto_off_secs == 0) return 0;
     return (uint32_t)_node_prefs->auto_off_secs * 1000UL;

src/helpers/ui/DisplayDriver.h

@@ -7,6 +7,7 @@ class DisplayDriver {
   int _w, _h;
 protected:
   DisplayDriver(int w, int h) { _w = w; _h = h; }
+  void setDimensions(int w, int h) { _w = w; _h = h; }
 public:
   enum Color { DARK=0, LIGHT, RED, GREEN, BLUE, YELLOW, ORANGE }; // on b/w screen, colors will be !=0 synonym of light
 
@@ -196,5 +197,6 @@ public:
   }
   
   virtual void setBrightness(uint8_t level) { }  // level 0-4 (min to max), no-op default
+  virtual void setDisplayRotation(uint8_t rot) { }  // 0-3, no-op for fixed-orientation displays
   virtual void endFrame() = 0;
 };

src/helpers/ui/GxEPDDisplay.cpp

@@ -150,6 +150,12 @@ uint16_t GxEPDDisplay::getTextWidth(const char* str) {
   return w;
 }
 
+void GxEPDDisplay::setDisplayRotation(uint8_t rot) {
+  display.setRotation(rot & 3);
+  setDimensions(display.width(), display.height());
+  last_display_crc_value = -1;  // force redraw on next endFrame
+}
+
 void GxEPDDisplay::endFrame() {
   uint32_t crc = display_crc.finalize();
   if (crc != last_display_crc_value) {

src/helpers/ui/GxEPDDisplay.h

@@ -84,5 +84,6 @@ public:
   void drawRect(int x, int y, int w, int h) override;
   void drawXbm(int x, int y, const uint8_t* bits, int w, int h) override;
   uint16_t getTextWidth(const char* str) override;
+  void setDisplayRotation(uint8_t rot) override;
   void endFrame() override;
 };