下载画布作为chrome扩展程序中的图像

Question

This code work for me for downloading a canvas as an image in a custom html page:

var save = function() {
            var x= document.getElementById("output-canvas");
            var dt = x.toDataURL('image/png');
            this.href = dt;
};
downloadLink.addEventListener('click', save, false);

but it doesn't work (without any errors) for canvas in popup.html in a chrome plugin which i am developing.

Could anybody help me with a solution for downloading canvas items in a chrome plugin?

Edited:

This is my manifest file:

{
  ...
  "permissions": [ "contextMenus", "tabs", "http://*/*", "https://*/*", "activeTab", "storage"],
  ...
}

Answer 1

Checklist:

1. The image URLs you draw on canvas should be allowed in manifest.json "permissions" :

    "permissions": [ "activeTab", "https://i.imgur.com/*" ], 

2. The link element should have a download attribute that contains a name of the file to save:

    <a download="test.png" href="...">Save me</a> 

   or

    var link = document.createElement('a'); link.download = 'test.png'; link.href = canvas.toDataURL('image/png'); document.body.appendChild(link);