Improve build script and LVGL emulator

build_and_run.sh: clear the build directory when the cached CMake generator or CMAKE_BUILD_TYPE no longer matches the desired values, and choose RelWithDebInfo for local runs (Debug for CI). Introduce BUILD_TYPE and pass it to CMake so generator/build-type mismatches are handled cleanly. emulator_display.cpp: align the LVGL draw buffer to 4 bytes to satisfy LV_DRAW_BUF_ALIGN (avoids LVGL v9 assert) and call lv_timer_handler() repeatedly before lv_refr_now to drain timers/deferred layout work so the first render doesn't block.

Author: zjwhitehead

test/test_screenshots/build_and_run.sh

@@ -85,24 +85,30 @@ fi
 
 mkdir -p "$BUILD_DIR"
 
-# Switching to --local with Ninja: clear a Unix Makefiles (or other) cache once.
-if [ "$LOCAL_BUILD" = 1 ] && [ "${#CMAKE_GEN_ARGS[@]}" -gt 0 ]; then
-  if [ -f "$BUILD_DIR/CMakeCache.txt" ]; then
-    if ! grep -q '^CMAKE_GENERATOR:INTERNAL=Ninja$' "$BUILD_DIR/CMakeCache.txt" 2>/dev/null; then
-      echo "Local build: clearing $BUILD_DIR to switch CMake generator to Ninja..."
-      rm -rf "$BUILD_DIR"
-      mkdir -p "$BUILD_DIR"
-    fi
+# If the cached generator or build type no longer matches, clear the build dir once.
+if [ -f "$BUILD_DIR/CMakeCache.txt" ]; then
+  cached_gen=$(grep '^CMAKE_GENERATOR:INTERNAL=' "$BUILD_DIR/CMakeCache.txt" 2>/dev/null | cut -d= -f2)
+  cached_type=$(grep '^CMAKE_BUILD_TYPE:STRING=' "$BUILD_DIR/CMakeCache.txt" 2>/dev/null | cut -d= -f2)
+  want_gen="Unix Makefiles"
+  [ "${#CMAKE_GEN_ARGS[@]}" -gt 0 ] && want_gen="Ninja"
+  if [ "$cached_gen" != "$want_gen" ] || [ "$cached_type" != "$BUILD_TYPE" ]; then
+    echo "Clearing $BUILD_DIR (generator/build type changed: ${cached_gen}/${cached_type} -> ${want_gen}/${BUILD_TYPE})..."
+    rm -rf "$BUILD_DIR"
+    mkdir -p "$BUILD_DIR"
   fi
 fi
 
 cd "$BUILD_DIR"
 
 echo ""
 echo "--- Configuring CMake ---"
+# --local uses RelWithDebInfo: optimized binary (5-10x faster renderer) with debug symbols.
+# CI keeps Debug for faithful failure diagnostics.
+BUILD_TYPE="Debug"
+[ "$LOCAL_BUILD" = 1 ] && BUILD_TYPE="RelWithDebInfo"
 # shellcheck disable=SC2086
 cmake "$SCRIPT_DIR" \
-  -DCMAKE_BUILD_TYPE=Debug \
+  -DCMAKE_BUILD_TYPE="$BUILD_TYPE" \
   "${CMAKE_GEN_ARGS[@]}" \
   "${CMAKE_CCACHE_ARGS[@]}" \
   ${LVGL_DIR:+-DLVGL_DIR="$LVGL_DIR"} \

test/test_screenshots/emulator_display.cpp

@@ -12,8 +12,9 @@
 // Full-screen framebuffer: 160 x 128 pixels, RGB565
 static uint16_t framebuffer[SCREEN_WIDTH * SCREEN_HEIGHT];
 
-// LVGL draw buffers (full-screen for complete frame capture)
-static uint8_t lvgl_buf1[SCREEN_WIDTH * SCREEN_HEIGHT * 2];
+// LVGL draw buffer - must be aligned to LV_DRAW_BUF_ALIGN (4 bytes).
+// LVGL v9 asserts on misaligned buffers and spins in while(1) on failure.
+static uint8_t lvgl_buf1[SCREEN_WIDTH * SCREEN_HEIGHT * 2] __attribute__((aligned(4)));
 
 // Define globals declared in lvgl_core.h
 lv_display_t* main_display = nullptr;
@@ -81,9 +82,14 @@ lv_display_t* emulator_init_display(bool darkMode) {
 }
 
 void emulator_render_frame() {
-  // Tick LVGL forward to process any pending timers/animations
+  // Tick LVGL forward so any time-dependent layout/animation work is scheduled.
   lv_tick_inc(100);
-  // Force a full refresh
+  // Drain LVGL's internal timer queue before forcing the refresh.  Without
+  // this the first render on a freshly-created screen can block waiting for
+  // deferred layout passes that are only triggered by lv_timer_handler().
+  for (int i = 0; i < 64; i++) {
+    lv_timer_handler();
+  }
   lv_refr_now(main_display);
 }