[lvgl] Revise code generation to allow early widget creation (#7611)

esphome/components/lvgl/lvgl_esphome.cpp

@@ -11,12 +11,6 @@ namespace esphome {
 namespace lvgl {
 static const char *const TAG = "lvgl";
 
-#if LV_USE_LOG
-static void log_cb(const char *buf) {
-  esp_log_printf_(ESPHOME_LOG_LEVEL_INFO, TAG, 0, "%.*s", (int) strlen(buf) - 1, buf);
-}
-#endif  // LV_USE_LOG
-
 static const char *const EVENT_NAMES[] = {
     "NONE",
     "PRESSED",
@@ -383,26 +377,48 @@ void LvglComponent::write_random_() {
   }
 }
 
-void LvglComponent::setup() {
-  ESP_LOGCONFIG(TAG, "LVGL Setup starts");
-#if LV_USE_LOG
-  lv_log_register_print_cb(log_cb);
-#endif
+/**
+ * @class LvglComponent
+ * @brief Component for rendering LVGL.
+ *
+ * This component renders LVGL widgets on a display. Some initialisation must be done in the constructor
+ * since LVGL needs to be initialised before any widgets can be created.
+ *
+ * @param displays a list of displays to render onto. All displays must have the same
+ *                 resolution.
+ * @param buffer_frac the fraction of the display resolution to use for the LVGL
+ *                    draw buffer. A higher value will make animations smoother but
+ *                    also increase memory usage.
+ * @param full_refresh if true, the display will be fully refreshed on every frame.
+ *                     If false, only changed areas will be updated.
+ * @param draw_rounding the rounding to use when drawing. A value of 1 will draw
+ *                      without any rounding, a value of 2 will round to the nearest
+ *                      multiple of 2, and so on.
+ * @param resume_on_input if true, this component will resume rendering when the user
+ *                         presses a key or clicks on the screen.
+ */
+LvglComponent::LvglComponent(std::vector<display::Display *> displays, float buffer_frac, bool full_refresh,
+                             int draw_rounding, bool resume_on_input)
+    : draw_rounding(draw_rounding),
+      displays_(std::move(displays)),
+      buffer_frac_(buffer_frac),
+      full_refresh_(full_refresh),
+      resume_on_input_(resume_on_input) {
   lv_init();
   lv_update_event = static_cast<lv_event_code_t>(lv_event_register_id());
   lv_api_event = static_cast<lv_event_code_t>(lv_event_register_id());
   auto *display = this->displays_[0];
   size_t buffer_pixels = display->get_width() * display->get_height() / this->buffer_frac_;
   auto buf_bytes = buffer_pixels * LV_COLOR_DEPTH / 8;
-  auto *buf = lv_custom_mem_alloc(buf_bytes);  // NOLINT
-  if (buf == nullptr) {
-#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_ERROR
-    ESP_LOGE(TAG, "Malloc failed to allocate %zu bytes", buf_bytes);
-#endif
-    this->mark_failed();
-    this->status_set_error("Memory allocation failure");
-    return;
+  this->rotation = display->get_rotation();
+  if (this->rotation != display::DISPLAY_ROTATION_0_DEGREES) {
+    this->rotate_buf_ = static_cast<lv_color_t *>(lv_custom_mem_alloc(buf_bytes));  // NOLINT
+    if (this->rotate_buf_ == nullptr)
+      return;
   }
+  auto *buf = lv_custom_mem_alloc(buf_bytes);  // NOLINT
+  if (buf == nullptr)
+    return;
   lv_disp_draw_buf_init(&this->draw_buf_, buf, nullptr, buffer_pixels);
   lv_disp_drv_init(&this->disp_drv_);
   this->disp_drv_.draw_buf = &this->draw_buf_;
@@ -410,18 +426,7 @@ void LvglComponent::setup() {
   this->disp_drv_.full_refresh = this->full_refresh_;
   this->disp_drv_.flush_cb = static_flush_cb;
   this->disp_drv_.rounder_cb = rounder_cb;
-  this->rotation = display->get_rotation();
-  if (this->rotation != display::DISPLAY_ROTATION_0_DEGREES) {
-    this->rotate_buf_ = static_cast<lv_color_t *>(lv_custom_mem_alloc(buf_bytes));  // NOLINT
-    if (this->rotate_buf_ == nullptr) {
-#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_ERROR
-      ESP_LOGE(TAG, "Malloc failed to allocate %zu bytes", buf_bytes);
-#endif
-      this->mark_failed();
-      this->status_set_error("Memory allocation failure");
-      return;
-    }
-  }
+  // reset the display rotation since we will handle all rotations
   display->set_rotation(display::DISPLAY_ROTATION_0_DEGREES);
   switch (this->rotation) {
     default:
@@ -435,12 +440,30 @@ void LvglComponent::setup() {
       break;
   }
   this->disp_ = lv_disp_drv_register(&this->disp_drv_);
-  for (const auto &v : this->init_lambdas_)
-    v(this);
+}
+
+void LvglComponent::setup() {
+  if (this->draw_buf_.buf1 == nullptr) {
+    this->mark_failed();
+    this->status_set_error("Memory allocation failure");
+    return;
+  }
+  ESP_LOGCONFIG(TAG, "LVGL Setup starts");
+#if LV_USE_LOG
+  lv_log_register_print_cb([](const char *buf) {
+    auto next = strchr(buf, ')');
+    if (next != nullptr)
+      buf = next + 1;
+    while (isspace(*buf))
+      buf++;
+    esp_log_printf_(LVGL_LOG_LEVEL, TAG, 0, "%.*s", (int) strlen(buf) - 1, buf);
+  });
+#endif
   this->show_page(0, LV_SCR_LOAD_ANIM_NONE, 0);
   lv_disp_trig_activity(this->disp_);
   ESP_LOGCONFIG(TAG, "LVGL Setup complete");
 }
+
 void LvglComponent::update() {
   // update indicators
   if (this->paused_) {
@@ -455,13 +478,6 @@ void LvglComponent::loop() {
   }
   lv_timer_handler_run_in_period(5);
 }
-bool lv_is_pre_initialise() {
-  if (!lv_is_initialized()) {
-    ESP_LOGE(TAG, "LVGL call before component is initialised");
-    return true;
-  }
-  return false;
-}
 
 #ifdef USE_LVGL_ANIMIMG
 void lv_animimg_stop(lv_obj_t *obj) {