LovyanGFX ScreenShot ESP32 Sample

screenshotESP32.ino

#define LGFX_AUTODETECT
#include <LovyanGFX.hpp>
#include "SD.h"

static LGFX lcd;

#define TFCARD_CS_PIN 4 // M5Stack(BASIC, GRAY, FIRE, GO, Core2)

void setup() {
  lcd.init();
  lcd.clear(TFT_BLACK);
  SD.begin(TFCARD_CS_PIN, SPI, 20000000);

  lcd.clear(TFT_RED);
  lcd.println("SCREEN SHOT TEST");

  screenshot(&lcd, SD, "/test.bmp");
}

void loop() {
}

void screenshot(LovyanGFX* _lcd, fs::FS &fs, String filename) {
  File file = fs.open(filename, FILE_WRITE);
  if (!file) {
    ESP_LOGW("file not open(%s)\n", filename);
  }

  uint8_t headSize = 66;
  uint16_t width = _lcd->width();
  uint16_t height = _lcd->height();
  uint16_t dataSize = width * height * 2;
  uint16_t fileSize = headSize + dataSize;
  uint16_t rMask = 0b1111100000000000;
  uint16_t gMask = 0b0000011111100000;
  uint16_t bMask = 0b0000000000011111;

  // BMP Header
  file.write('B');
  file.write('M');

  // fileSize
  file.write((uint8_t)(fileSize & 0xff));
  file.write((uint8_t)(fileSize >> 8));
  file.write(0x00);
  file.write(0x00);

  // Reserve
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);

  // headSize
  file.write(headSize);
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);

  // infoSize
  file.write(0x28);
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);

  // width
  file.write((uint8_t)(width & 0xff));
  file.write((uint8_t)(width >> 8));
  file.write(0x00);
  file.write(0x00);

  // height
  file.write((uint8_t)(height & 0xff));
  file.write((uint8_t)(height >> 8));
  file.write(0x00);
  file.write(0x00);

  // plane
  file.write(0x01);
  file.write(0x00);

  // bit/pixel
  file.write(16);
  file.write(0x00);

  // compression
  file.write(0x03);
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);

  // dataSize
  file.write((uint8_t)(dataSize & 0xff));
  file.write((uint8_t)(dataSize >> 8));
  file.write(0x00);
  file.write(0x00);

  // Horizontal resolution
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);

  // Vertical resolution
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);

  // Color Size
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);

  // Number of important colors
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);
  file.write(0x00);

  // R MASK
  file.write((uint8_t)(rMask & 0xff));
  file.write((uint8_t)(rMask >> 8));
  file.write(0x00);
  file.write(0x00);

  // G MASK
  file.write((uint8_t)(gMask & 0xff));
  file.write((uint8_t)(gMask >> 8));
  file.write(0x00);
  file.write(0x00);

  // B MASK
  file.write((uint8_t)(bMask & 0xff));
  file.write((uint8_t)(bMask >> 8));
  file.write(0x00);
  file.write(0x00);

  // DATA
  bool swap = _lcd->getSwapBytes();
  _lcd->setSwapBytes(true);
  for (int y = 0; y < height; y++) {
    uint16_t pl[width];
    _lcd->readRect(0, height - y - 1, width, 1, pl);
    file.write((uint8_t *)pl, width * 2);
  }
  _lcd->setSwapBytes(swap);

  file.close();
}