export async function getTextColorOnImage(url) {
  let canvas
  const width = 100
  const height = 50
  try {
    // 1. 创建离屏Canvas
    canvas = wx.createOffscreenCanvas({ type: '2d', width, height })
    const ctx = canvas.getContext('2d')

    // 2. 加载图片
    const img = canvas.createImage()
    await new Promise((resolve) => {
      img.onload = resolve
      img.src = url
    })

    // 3. 绘制并分析图像
    ctx.drawImage(img, 0, 0, width, height)

    // TODO: 增加取样，提高精确性
    const pixelData = ctx.getImageData(10, 10, 1, 1).data

    // 4. 计算文字颜色
    const brightness = (pixelData[0] * 2126 + pixelData[1] * 7152 + pixelData[2] * 722) / 10000
    return { textColor: brightness > 128 ? 'black' : 'white' }
  } finally {
    // 释放资源
    if (canvas) {
      canvas.width = 0;
      canvas.height = 0;
    }
  }
}