Turn the canvas generated image or signature background transparent into a white background

Turn the canvas generated image or signature background transparent into a white background

toWhite () {
    
    
      var imageData = this.context.getImageData(0, 0, w, h)
      for (var i = 0; i < imageData.data.length; i += 4) {
    
    
        // 当该像素是透明的，则设置成白色
        if (imageData.data[i + 3] === 0) {
    
    
          imageData.data[i] = 255
          imageData.data[i + 1] = 255
          imageData.data[i + 2] = 255
          imageData.data[i + 3] = 255
        }
      }
      this.context.putImageData(imageData, 0, 0)
    },