Improve critical border flashing and LVGL buffer usage

Switch critical border visibility logic from hidden flag to border opacity for smoother flashing and more reliable redraws. Increase LVGL buffer size to full screen to reduce partial update issues. Adjust UI task refresh rate from 25 Hz to 20 Hz for better performance.

Author: zjwhitehead

inc/sp140/lvgl/lvgl_core.h

@@ -13,8 +13,8 @@
 #define SCREEN_HEIGHT 128
 
 // LVGL buffer size - optimize for our display
-// Use 1/4 of the screen size to balance memory usage and performance
-#define LVGL_BUFFER_SIZE (SCREEN_WIDTH * (SCREEN_HEIGHT / 4))
+// Use half screen size for single flush to balance performance and memory usage
+#define LVGL_BUFFER_SIZE (SCREEN_WIDTH * SCREEN_HEIGHT / 2)
 
 // LVGL refresh time in ms - match the config file setting
 #define LVGL_REFRESH_TIME 40

src/sp140/lvgl/lvgl_main_screen.cpp

@@ -624,7 +624,7 @@ void setupMainScreen(bool darkMode) {
     lv_obj_set_style_border_color(critical_border, LVGL_RED, LV_PART_MAIN);
     lv_obj_set_style_bg_opa(critical_border, LV_OPA_0, LV_PART_MAIN);  // Transparent background
     lv_obj_set_style_radius(critical_border, 0, LV_PART_MAIN);  // Sharp corners
-    lv_obj_add_flag(critical_border, LV_OBJ_FLAG_HIDDEN);  // Initially hidden
+    lv_obj_set_style_border_opa(critical_border, LV_OPA_0, LV_PART_MAIN);  // Initially invisible border
     // Move border to front so it's visible over all other elements
     lv_obj_move_foreground(critical_border);
   }

src/sp140/lvgl/lvgl_updates.cpp

@@ -179,23 +179,23 @@ void startArmFailIconFlash() {
 static void critical_border_flash_timer_cb(lv_timer_t* timer) {
   // This callback runs within the LVGL task handler, so no mutex needed here.
   if (critical_border != NULL) {
-    // Toggle visibility: 300ms on, 700ms off
-    bool is_on = !lv_obj_has_flag(critical_border, LV_OBJ_FLAG_HIDDEN);
-    if (is_on) {
-      lv_obj_add_flag(critical_border, LV_OBJ_FLAG_HIDDEN);
-      // Invalidate the border area to ensure clean redraw
-      lv_obj_invalidate(critical_border);
+    // Toggle opacity: 300ms on (opaque), 700ms off (transparent)
+    uint8_t current_opa = lv_obj_get_style_border_opa(critical_border, LV_PART_MAIN);
+    if (current_opa == LV_OPA_100) {
+      lv_obj_set_style_border_opa(critical_border, LV_OPA_0, LV_PART_MAIN);
       lv_timer_set_period(timer, 700); // Off duration
+      // Invalidate entire screen when hiding to ensure clean removal of border pixels
+      lv_obj_invalidate(lv_scr_act());
     } else {
-      lv_obj_clear_flag(critical_border, LV_OBJ_FLAG_HIDDEN);
-      // Invalidate the border area to ensure clean redraw
-      lv_obj_invalidate(critical_border);
+      lv_obj_set_style_border_opa(critical_border, LV_OPA_100, LV_PART_MAIN);
       lv_timer_set_period(timer, 300); // On duration
 
       // Trigger vibration pulse in sync with border "on"
       if (ENABLE_VIBE) {
         pulseVibration(300, 200); // 300ms pulse, intensity 200
       }
+      // Invalidate the border area when showing
+      lv_obj_invalidate(critical_border);
     }
     // Force immediate refresh to minimize tearing
     lv_refr_now(lv_disp_get_default());
@@ -206,7 +206,7 @@ void startCriticalBorderFlash() {
   if (xSemaphoreTake(lvglMutex, pdMS_TO_TICKS(50)) == pdTRUE) {
     if (critical_border != NULL && !isFlashingCriticalBorder) {
       isFlashingCriticalBorder = true;
-      lv_obj_clear_flag(critical_border, LV_OBJ_FLAG_HIDDEN); // Start visible
+      lv_obj_set_style_border_opa(critical_border, LV_OPA_100, LV_PART_MAIN); // Start visible
       critical_border_flash_timer = lv_timer_create(critical_border_flash_timer_cb, 300, NULL);
     }
     xSemaphoreGive(lvglMutex);
@@ -220,7 +220,9 @@ void stopCriticalBorderFlash() {
       critical_border_flash_timer = NULL;
     }
     if (critical_border != NULL) {
-      lv_obj_add_flag(critical_border, LV_OBJ_FLAG_HIDDEN);
+      lv_obj_set_style_border_opa(critical_border, LV_OPA_0, LV_PART_MAIN);
+      // Invalidate entire screen to ensure clean removal
+      lv_obj_invalidate(lv_scr_act());
     }
     isFlashingCriticalBorder = false;
     xSemaphoreGive(lvglMutex);
@@ -235,7 +237,7 @@ bool isCriticalBorderFlashing() {
 void startCriticalBorderFlashDirect() {
   if (critical_border != NULL && !isFlashingCriticalBorder) {
     isFlashingCriticalBorder = true;
-    lv_obj_clear_flag(critical_border, LV_OBJ_FLAG_HIDDEN); // Start visible
+    lv_obj_set_style_border_opa(critical_border, LV_OPA_100, LV_PART_MAIN); // Start visible
     lv_obj_invalidate(critical_border); // Ensure clean initial draw
     critical_border_flash_timer = lv_timer_create(critical_border_flash_timer_cb, 300, NULL);
     // Force immediate refresh for clean start
@@ -249,8 +251,8 @@ void stopCriticalBorderFlashDirect() {
     critical_border_flash_timer = NULL;
   }
   if (critical_border != NULL) {
-    lv_obj_add_flag(critical_border, LV_OBJ_FLAG_HIDDEN);
-    lv_obj_invalidate(critical_border); // Ensure clean removal
+    lv_obj_set_style_border_opa(critical_border, LV_OPA_0, LV_PART_MAIN);
+    lv_obj_invalidate(lv_scr_act()); // Ensure clean removal of border
     // Force immediate refresh for clean stop
     lv_refr_now(lv_disp_get_default());
   }

src/sp140/sp140.ino

@@ -497,7 +497,7 @@ void monitoringTask(void *pvParameters) {
 // UI task: fixed 25 Hz refresh and snapshot publish
 void uiTask(void *pvParameters) {
   TickType_t lastWake = xTaskGetTickCount();
-  const TickType_t uiTicks = pdMS_TO_TICKS(40); // 25 Hz
+  const TickType_t uiTicks = pdMS_TO_TICKS(50);  // 20 Hz
   for (;;) {
     refreshDisplay();
     pushTelemetrySnapshot();