Function tryGetCanvas

pmcaptcha/pmcaptcha.ts:510–555

()

  } catch {}

  if (_canvasInstalling) {
    const deadline = Date.now() + 60_000;
    while (_canvasInstalling && Date.now() < deadline) {
      if (!(await generationDelay(500))) return false;
    }
    return _canvas ?? false;
  }

  _canvasInstalling = true;
  log(LogLevel.INFO, "canvas not found — auto installing (npm install canvas)…");

  try {
    execSync("npm install canvas", { stdio: "pipe" });
    log(LogLevel.INFO, "canvas installed successfully");
  } catch (e) {
    log(LogLevel.ERROR, "canvas install failed", e);
    _canvas = false;
    _canvasInstalling = false;
    return false;
  }

  try {
    const canvasId = require.resolve("canvas");
    if (require.cache[canvasId]) delete require.cache[canvasId];
  } catch {}

  try {
    _canvas = await import("canvas");
    log(LogLevel.INFO, "canvas dynamically loaded after install");
  } catch (e) {
    log(LogLevel.ERROR, "canvas load failed after install", e);
    _canvas = false;
  }

  _canvasInstalling = false;
  return _canvas ?? false;
}

async function generateImageCaptcha(
  digitOnly: boolean
): Promise<{ buffer: Buffer; answer: string } | null> {
  const cv = await tryGetCanvas();
  if (!cv) return null;

  const CHARSET_DIGIT = "0123456789";
  const CHARSET_MIXED = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789";

  const charset = digitOnly ? CHARSET_DIGIT : CHARSET_MIXED;
  const LENGTH  = 5;