How to display custom
images on the GC9A01

#!/usr/bin/env python3
"""
Convert an image to an RGB565 C header for Arduino_GFX_Library.

Usage:
    python3 image_to_rgb565.py <image> <varname>

Example:
    python3 image_to_rgb565.py myface.png myface

Outputs: myface.h in the same folder as the image.
The image will be resized to 240x240 automatically.
"""

import sys
from pathlib import Path
from PIL import Image

def convert(img_path, varname):
    img = Image.open(img_path).convert("RGB")
    img = img.resize((240, 240), Image.LANCZOS)
    raw = img.tobytes()
    pixels = [(raw[i], raw[i+1], raw[i+2]) for i in range(0, len(raw), 3)]

    out_path = Path(img_path).parent / f"{varname}.h"
    with open(out_path, "w") as f:
        f.write(f"// {Path(img_path).name} -> 240x240 RGB565\n")
        f.write(f"#pragma once\n")
        f.write(f"const uint16_t {varname}[57600] = {{\n  ")

        for i, (r, g, b) in enumerate(pixels):
            val = ((r & 0xF8) << 8) | ((g & 0xFC) << 3) | (b >> 3)
            f.write(f"0x{val:04X}")
            if i < len(pixels) - 1:
                f.write(", ")
            if (i + 1) % 12 == 0:
                f.write("\n  ")

        f.write("\n};\n")

    print(f"Done -> {out_path}  (240x240, {240*240*2} bytes)")

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Usage: python3 image_to_rgb565.py <image> <varname>")
        sys.exit(1)
    convert(sys.argv[1], sys.argv[2])

python3 image_to_rgb565.py myface.png myface

/*
 * We stand on the shoulders of giants when we build
 * with knowledge gained from others' efforts.
 * That doesn't make us giants. Be humble.
 * Create with care. Open source is the way.
 *
 * GC9A01 Custom Image Display
 * ---------------------------
 * Displays a custom RGB565 image on a GC9A01 240x240
 * round IPS TFT display via SPI using Arduino_GFX_Library.
 * Image is pre-converted from PNG using image_to_rgb565.py.
 *
 * Board:   ESP32 Dev Board (38-pin)
 * Library: Arduino_GFX_Library by Moon On Our Nation
 *
 * Wiring:
 *   VCC -> 3.3V or 5V   GND -> GND
 *   SCL -> GPIO 18       SDA -> GPIO 23
 *   DC  -> GPIO 27       CS  -> GPIO 5
 *   RST -> GPIO 4
 *
 * Open source - MIT Licence
 * Full guide:
 * https://electroniczoology.com/guides/how-to-display-images-gc9a01-esp32
 *
 * Electronic Zoology - field notes from the garage
 */

#include <Arduino_GFX_Library.h>
#include "myface.h"   // <- change myface to your varname
#define IMAGE myface  // <- change myface to match

#define TFT_DC  27
#define TFT_CS   5
#define TFT_RST  4

Arduino_DataBus *bus = new Arduino_HWSPI(TFT_DC, TFT_CS);
Arduino_GFX *gfx = new Arduino_GC9A01(bus, TFT_RST, 0, true);

void setup() {
  Serial.begin(115200);
  gfx->begin();
  gfx->fillScreen(0x0000);
  gfx->draw16bitRGBBitmap(0, 0, (uint16_t*)IMAGE, 240, 240);
}

void loop() {}