xul/xpcom copy image from string to clipboard

I'm stuck with no clues how to copy image to clipboard. My code looks like this:

var image = "data:image/png;base64,..."

var io         = Components.classes["@mozilla.org/network/io-service;1"].getService(Components.interfaces.nsIIOService);
var chann开发者_高级运维el    = io.newChannel(image, null, null); 
var input      = channel.open();

var trans = Components.classes["@mozilla.org/widget/transferable;1"].createInstance(Components.interfaces.nsITransferable);
trans.addDataFlavor("image/png");
trans.setTransferData("image/png", input, input.available()); 

var clipid = Components.interfaces.nsIClipboard;
var clip   = Components.classes["@mozilla.org/widget/clipboard;1"].getService(clipid);
clip.setData(trans, null, clipid.kGlobalClipboard);

As Neil already noted in the newsgroup, the data expected for an image is an nsIContainer instance rather than a stream. I couldn't find any examples of doing that on the web so I modified your code:

var image = "data:image/png;base64,...";

var io         = Components.classes["@mozilla.org/network/io-service;1"].getService(Components.interfaces.nsIIOService);
var channel    = io.newChannel(image, null, null);
var input      = channel.open();
var imgTools   = Components.classes["@mozilla.org/image/tools;1"].getService(Components.interfaces.imgITools);

var container  = {};
imgTools.decodeImageData(input, channel.contentType, container);

var trans = Components.classes["@mozilla.org/widget/transferable;1"].createInstance(Components.interfaces.nsITransferable);
trans.addDataFlavor("image/png");
trans.setTransferData("image/png", container.value, -1);

var clipid = Components.interfaces.nsIClipboard;
var clip   = Components.classes["@mozilla.org/widget/clipboard;1"].getService(clipid);
clip.setData(trans, null, clipid.kGlobalClipboard);

For me this copies the image to clipboard correctly.