<canvas id="previewCanvas" c type="2d" style="width: {{canvasWidth}}px; height: {{canvasHeight}}px;">
</canvas>

  // {canvasId, width, height, canvasWidth, canvasHeight, path, success}
  drawImageToCanvas: function (config) {
    const query = wx.createSelectorQuery();
    query.select(config.canvasId).fields({
      node: true,
      size: true
    }).exec(e1 => {
      console.log('图像处理', config.canvasId, 'wx.createSelectorQuery', e1);

      const canvas = e1[0].node;
      const ctx = canvas.getContext('2d');

      ctx.clearRect(0, 0, e1[0].width, e1[0].height);
      ctx.mozImageSmoothingEnabled = false;
      ctx.webkitImageSmoothingEnabled = false;
      ctx.msImageSmoothingEnabled = false;
      ctx.imageSmoothingEnabled = false;

      // 必须设置为 canvas 初始化的大小，否则图片会被拉伸
      // 注意，在 html 设置的 width、height 是显示大小，这里设置的是画图大小
      // 如果这里的尺寸比 html 的小，就会放大；否则缩小
      canvas.width = config.canvasWidth;
      canvas.height = config.canvasHeight;

      if (config.backgroundHex) {
        ctx.fillStyle = config.backgroundHex;
        ctx.fillRect(0, 0, config.width, config.height);
      }

      // 如果有图片，才画图
      if (config.path) {
        const img = canvas.createImage();
        img.onload = (e2) => {
          console.log("图像处理", config.canvasId, 'img.onload', e2);

          // 默认把图片全部像素画在目标尺寸上
          ctx.drawImage(img, 0, 0, config.width, config.height);
          if (config.success) config.success(canvas);
        };
        img.src = config.path;
      } else {
        if (config.success) config.success(canvas);
      }
    });

  onLoad: function (options) {
    var that = this;
    var url = "cloud://wxss-brick-0f77b1.7778-wxss-brick-0f77b1-1257336119/images/image1.jpeg";
    wx.getImageInfo({
      src: url,
      success: function (e2) {
        console.log('图像处理', 'getImageInfo', e2);
        that.drawImageToCanvas({
          canvasId: '#previewCanvas',
          width: e2.width,
          height: e2.height,
          canvasWidth: 300,
          canvasHeight: 300,
          path: e2.path,
          success: function () {},
        });
      },
    });
  },

  onLoad: function (options) {
    var that = this;
    var url = "cloud://wxss-brick-0f77b1.7778-wxss-brick-0f77b1-1257336119/images/image1.jpeg";
    wx.getImageInfo({
      src: url,
      success: function (e2) {
        console.log('图像处理', 'getImageInfo', e2);
        that.drawImageToCanvas({
          canvasId: '#previewCanvas',
          width: e2.width,
          height: e2.height,
          canvasWidth: e2.width,
          canvasHeight: e2.height,
          path: e2.path,
          success: function () {},
        });
      },
    });
  },

  onLoad: function (options) {
    var that = this;
    var url = "cloud://wxss-brick-0f77b1.7778-wxss-brick-0f77b1-1257336119/images/image1.jpeg";
    wx.getImageInfo({
      src: url,
      success: function (e2) {
        console.log('图像处理', 'getImageInfo', e2);
        that.drawImageToCanvas({
          canvasId: '#previewCanvas',
          width: 300,
          height: 300,
          canvasWidth: e2.width,
          canvasHeight: e2.height,
          path: e2.path,
          success: function () {},
        });
      },
    });
  },

  onLoad: function (options) {
    var that = this;
    var url = "cloud://wxss-brick-0f77b1.7778-wxss-brick-0f77b1-1257336119/images/image1.jpeg";
    wx.getImageInfo({
      src: url,
      success: function (e2) {
        console.log('图像处理', 'getImageInfo', e2);
        that.drawImageToCanvas({
          canvasId: '#previewCanvas',
          width: 300,
          height: 300,
          canvasWidth: 300,
          canvasHeight: 300,
          path: e2.path,
          success: function () {},
        });
      },
    });
  },