refactor(DisplayDriverTFT): simplify alert rendering logic for better performance

boards/esp32-32e-4/DisplayDriverTFT.cpp

@@ -193,22 +193,32 @@ void DisplayDriverTFT::drawBoot(const ScreenState& st) {
 }
 
 void DisplayDriverTFT::drawAlert(const ScreenState& st) {
-    // Throttle redraws to ~24fps to prevent tearing
-    uint32_t now = millis();
-    if(now - _lastAlertDrawMs < ALERT_DRAW_INTERVAL_MS) {
-        return;
-    }
-    _lastAlertDrawMs = now;
-
+    // Static 2-color pulse - alternate every ~2 seconds
     uint32_t elapsed = millis() - st.alertStartMs;
-    // Slower pulse - divide by 1500 for ~9.4 second cycle (was 300 for ~1.9s)
-    uint8_t pulse = 180 + (uint8_t)(75.0f * sinf(elapsed / 1500.0f));
-    uint16_t bg = _tft.color565(pulse, 0, 0);
+    bool brightPhase = (elapsed / 2000) % 2 == 0;
+
+    // Only redraw when phase changes (timer-based, not every frame)
+    if(brightPhase != _lastAlertPhase) {
+        _lastAlertPhase = brightPhase;
+        uint16_t bg = brightPhase ? TFT_RED : _tft.color565(180, 0, 0);
 
         _tft.fillScreen(bg);
         _tft.setTextColor(TFT_WHITE, bg);
 
-    // Progressive fill hint - draws dark overlay from bottom rising up
+        setTitleFont();
+        _tft.setCursor(10, 28);
+        _tft.print(st.alertTitle.length() > 0 ? st.alertTitle : "ALERT");
+
+        setBodyFont();
+        _tft.setCursor(10, 70);
+        _tft.print(st.alertBody);
+
+        setLabelFont();
+        _tft.setCursor(10, _tft.height() - 10);
+        _tft.print("Hold to silence...");
+    }
+
+    // Progressive fill hint - only redraw when touch state changes
     if(_alertTouchDown) {
         uint32_t touchElapsed = millis() - _alertTouchStartMs;
         float progress = (float)touchElapsed / (float)ALERT_FILL_DURATION_MS;
@@ -218,23 +228,10 @@ void DisplayDriverTFT::drawAlert(const ScreenState& st) {
         int dispH = _tft.height();
         int fillHeight = (int)(dispH * progress);
         if(fillHeight > 0) {
-            // Draw dark overlay from bottom
-            uint16_t overlay = _tft.color565(80, 0, 0); // Dark red
+            uint16_t overlay = _tft.color565(80, 0, 0);
             _tft.fillRect(0, dispH - fillHeight, _tft.width(), fillHeight, overlay);
         }
     }
-
-    setTitleFont();
-    _tft.setCursor(10, 28); // y=28 baseline for ~18px font
-    _tft.print(st.alertTitle.length() > 0 ? st.alertTitle : "ALERT");
-
-    setBodyFont();
-    _tft.setCursor(10, 70); // y adjusted for ~12px body font
-    _tft.print(st.alertBody);
-
-    setLabelFont();
-    _tft.setCursor(10, _tft.height() - 10); // y adjusted for ~9px label font
-    _tft.print("Hold to silence...");
 }
 
 void DisplayDriverTFT::drawDashboard(const ScreenState& st) {

boards/esp32-32e-4/DisplayDriverTFT.h

@@ -44,9 +44,8 @@ private:
     // Touch hint for alert - progressive fill from bottom
     bool _alertTouchDown = false;
     uint32_t _alertTouchStartMs = 0;
-    uint32_t _lastAlertDrawMs = 0;
+    bool _lastAlertPhase = false; // tracks bright/dark phase for 2-color alert
     static constexpr uint32_t ALERT_FILL_DURATION_MS = 3000;
-    static constexpr uint32_t ALERT_DRAW_INTERVAL_MS = 333; // ~3fps
 
     // Touch tracking for press/release detection
     bool _touchWasPressed = false;