Optimizations

I feel like there could be some optimizations concerning the image update.

1. We should draw binary data directly on the canvas using:

context.putImageData(binary_data);

instead of creating a Blob that is png encoded. That would also allow the back-end to not waste time encoding into png (if that is possible).

2. I feel like the "diff" computation should actually be slower than sending the full image, as it needs an extra computation of "which pixels actually needs a redraw?": https://github.com/matplotlib/matplotlib/blob/5fc44eea64a57ab1c6d236cf7c71906c9d40e6f6/lib/matplotlib/backends/backend_webagg_core.py#L190-L195.
   Plus, we are still sending a full image. Maybe the png encoding does some compression if lots of pixels are transparent? If that is not the case, we are still sending the same amount of data.

从所引用的 matplotlib/backends/backend_webagg_core.py 图像更新代码开始，追踪 ipympl 中对应的 canvas 更新入口点。将提议的二进制数据路径与当前的 PNG 和 diff 路径进行比较，并在修改任一侧之前定义基准测试和验收标准。