LVGL V9 Download and display PNG on CYD

How-to
1

Hello everybody.
(Sorry for my english I’m a foreigner)
Using Platformio I’m almost able to display whatever widget I want but I’m struggling with a picture.
FYI lodePNG is set to 1 into lvconf.h

What do you want to achieve?

Just want to display a PNG picture provided by a weather forecast website.

What have you tried so far?

Tried to download to LittleFS and display it => no success at all
Tried tu download to a buffer and the display it (code below) all I have is ‘PNG’ displayed like a watermark.

Code to reproduce

#include "main.h"
#include <Arduino.h>
#include <WiFi.h>
#include <esp_wifi.h>
#include <HTTPClient.h>
#include <esp32_smartdisplay.h>
#include <lvgl.h>

// URL de l’image PNG
const char *url_png = "https://prevision-meteo.ch/style/images/icon/faiblement-nuageux-big.png";

// Buffer PNG
std::vector<uint8_t> png_buf;

bool download_png(const char *url)
{
    HTTPClient http;
    WiFiClientSecure client;
    client.setInsecure(); // Pour HTTPS sans certificat

    if (!http.begin(client, url))
    {
        Serial.println("HTTP begin failed");
        return false;
    }

    int httpCode = http.GET();
    if (httpCode != 200)
    {
        Serial.printf("HTTP GET failed, code: %d\n", httpCode);
        http.end();
        return false;
    }

    int len = http.getSize();
    if (len <= 0)
        len = 1024 * 10; // fallback
    Serial.print("image len: ");
    Serial.println(len);
    png_buf.resize(len);
    WiFiClient *stream = http.getStreamPtr();

    int idx = 0;
    while (http.connected() && idx < len)
    {
        while (stream->available())
        {
            png_buf[idx++] = stream->read();
        }
    }
    png_buf.resize(idx); // Ajuste à taille réelle

    http.end();
    return true;
}

void setup()
{
    Serial.begin(115200);
    delay(500);

    // Connexion WiFi
    WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
    Serial.print("Connecting to WiFi");
    while (WiFi.status() != WL_CONNECTED)
    {
        delay(500);
        Serial.print(".");
    }
    Serial.println("\nWiFi connected!");

    // Initialisation SmartDisplay / LVGL
    smartdisplay_init();
    lv_obj_t *scr = lv_scr_act();

    // Création de l'objet image
    lv_obj_t *img = lv_img_create(scr);
    lv_obj_center(img);

    // Téléchargement PNG
    if (!download_png(url_png))
    {
        Serial.println("PNG download failed!");
        return;
    }

    // Affectation du buffer PNG à l'objet image
    lv_img_set_src(img, png_buf.data());
    Serial.print( (const char*)png_buf.data());
    Serial.println("PNG displayed!");
}

void loop()
{
    lv_timer_handler(); // Gestion des tâches LVGL
    delay(5);
}

Screenshot and/or video

unfortunately nono

Environment

  • MCU/MPU/Board: ESP32S3
  • **LVGL version:**9.4

Thanks for your help