Check if Canvas is blank in Fabric.js

问题

I want to check every 5 seconds if my Canvas element is blank.

I followed the solution from the link below, but its not working.

how-to-check-if-a-canvas-is-blank

The above link works for plain canvas element BUT NOT for the one that fabric.js creates.

Here is the Fiddle that works without Fabric.js

Here is my Fiddle that DOES NOT WORK when Fabric.js creates the canvas.

回答1:

it is because you have given background color as white, if you remove that it works

来源：https://stackoverflow.com/questions/36660743/check-if-canvas-is-blank-in-fabric-js