Added lvgl support to generate images. Made basic example, grayscale background + text displayed everytime we call /api/display/image.png

Provider/main/lv_setup.cpp

@@ -0,0 +1,106 @@
+#include "lv_setup.hpp"
+#include "esp_heap_caps.h"
+#include "esp_log.h"
+#include "esp_timer.h"
+#include "freertos/task.h"
+#include "types.hpp"
+
+internal const char *kTagLvgl = "LVGL";
+
+SemaphoreHandle_t g_LvglMutex = nullptr;
+lv_display_t *g_LvglDisplay = nullptr;
+uint8_t *g_LvglDrawBuffer = nullptr;
+
+internal void lvgl_tick_task(void *arg)
+{
+    while (true)
+    {
+        vTaskDelay(pdMS_TO_TICKS(10));
+
+        if (xSemaphoreTake(g_LvglMutex, portMAX_DELAY) == pdTRUE)
+        {
+            lv_timer_handler();
+            xSemaphoreGive(g_LvglMutex);
+        }
+    }
+}
+
+internal uint32_t my_tick_get_cb()
+{
+    return (uint32_t)(esp_timer_get_time() / 1000);
+}
+
+internal void lv_dummy_flush_cb(lv_display_t *disp, const lv_area_t *area, uint8_t *px_map)
+{
+    // Headless display, so we don't actually flush to SPI/I2C.
+    // We just tell LVGL that the "flush" is completed so it unblocks wait_for_flushing.
+    lv_display_flush_ready(disp);
+}
+
+internal void lv_draw_sample_ui()
+{
+    lv_obj_t *scr = lv_screen_active();
+    // Default background to white for the grayscale PNG
+    lv_obj_set_style_bg_color(scr, lv_color_white(), 0);
+
+    lv_obj_t *label = lv_label_create(scr);
+    lv_label_set_text(label, "Calendink Provider\nLVGL Headless Renderer");
+    lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
+}
+
+void setup_lvgl()
+{
+    ESP_LOGI(kTagLvgl, "Initializing LVGL");
+
+    g_LvglMutex = xSemaphoreCreateMutex();
+
+    lv_init();
+    lv_tick_set_cb(my_tick_get_cb);
+
+    uint32_t width = CONFIG_CALENDINK_DISPLAY_WIDTH;
+    uint32_t height = CONFIG_CALENDINK_DISPLAY_HEIGHT;
+
+    // Create a virtual display
+    g_LvglDisplay = lv_display_create(width, height);
+    lv_display_set_flush_cb(g_LvglDisplay, lv_dummy_flush_cb);
+
+    // Initialize LodePNG custom bump allocator
+    lodepng_allocator_init();
+
+    // Allocate draw buffers in PSRAM
+    // Using LV_COLOR_FORMAT_L8 (1 byte per pixel)
+    size_t buf_size = LV_DRAW_BUF_SIZE(width, height, LV_COLOR_FORMAT_L8);
+    
+    // Fallback to MALLOC_CAP_DEFAULT if we can't get SPIRAM (for debugging without it)
+    void *buf1 = heap_caps_malloc(buf_size, MALLOC_CAP_SPIRAM);
+    if (!buf1)
+    {
+        ESP_LOGW(kTagLvgl, "Failed to allocate LVGL draw buffer in PSRAM, falling back to internal RAM");
+        buf1 = heap_caps_malloc(buf_size, MALLOC_CAP_DEFAULT);
+    }
+    
+    if (!buf1)
+    {
+        ESP_LOGE(kTagLvgl, "Failed to allocate LVGL draw buffer entirely.");
+        return;
+    }
+
+    g_LvglDrawBuffer = (uint8_t *)buf1;
+
+    lv_display_set_buffers(g_LvglDisplay, buf1, nullptr, buf_size, LV_DISPLAY_RENDER_MODE_FULL);
+    
+    // Explicitly set the color format of the display if it's set in sdkconfig/driver
+    lv_display_set_color_format(g_LvglDisplay, LV_COLOR_FORMAT_L8);
+
+    // Create the background task for the LVGL timer
+    xTaskCreate(lvgl_tick_task, "LVGL Tick", 4096, nullptr, 5, nullptr);
+
+    // Draw the sample UI
+    if (xSemaphoreTake(g_LvglMutex, portMAX_DELAY) == pdTRUE)
+    {
+        lv_draw_sample_ui();
+        xSemaphoreGive(g_LvglMutex);
+    }
+
+    ESP_LOGI(kTagLvgl, "LVGL fully initialized. Display %lux%lu created.", width, height);
+}