获取图像的平均颜色

function getAverageColor(img) {
  const canvas = document.createElement('canvas');
  const ctx = canvas.getContext('2d');
  const width = canvas.width = img.width;
  const height = canvas.height = img.height;

  ctx.drawImage(img, 0, 0);

  const data = ctx.getImageData(0, 0, width, height).data;
  let r = 0, g = 0, b = 0, count = 0;

  for (let i = 0; i< data.length; i += 4) {
    r += data[i];
    g += data[i + 1];
    b += data[i + 2];
    count++;
  }

  r = Math.floor(r / count);
  g = Math.floor(g / count);
  b = Math.floor(b / count);

  return `rgb(${r}, ${g}, ${b})`;
}