Drag an image from table cell to an iFrame droppable area - image

Question

I have problems to drag an image from one iframe (1) out of a dynamic table to another iframe (2) within a droppable area. I think there is no permission issue, but a "type" issue. The drop area on iframe (2) is working with files from anywhere except form the iframe (1). The iframe (1) is hosted by localhost. The iframe (2) is hosted by a different domain.
Three different functions I found to convert data uri to file or blob were tested. The setData arguments also have been tested with all possibilities, no success by now.
Interestingly, having opened the site with the two iframes on Chrome and firefox, I am able to drag an drop from firefox to Chrome, but the image will be converted to bmp type and renamed! The other way around it is not working.
What are the right arguments for setData / get Data to drop an image
data uri on a drop area?
Do I have to convert data uri to a file
resp. blob object?
If so, again, what arguments will do the job?
Any help would be appreciated very much!
var dataUri;
var file;
function mouseDown(event){
toDataURL(event.target.src, function(dataUrl) {
console.log('RESULT:', dataUrl.replace('data:text/plain;base64,', ''));
dataUri = dataUrl.replace('data:text/plain;base64,', '');
file = urltoFile(dataUrl, 'hello.jpg','image/jpeg')
.then(function(file){ console.log(file);});
})
}
function drag(event) {
// event.stopPropagation();
console.log(file);
console.log(dataUri);
event.dataTransfer.setData("text/plain", file);
//event.dataTransfer.mozSetDataAt("application/x-moz-file", file, 0);
event.dataTransfer.effectAllowed = "move";
}
function drop(event) {
//event.preventDefault();
console.log(file);
console.log(dataUri);
var data = event.dataTransfer.getData("text/plain");
//var data = event.dataTransfer.mozGetDataAt("application/x-moz-file", 0);
event.target.appendChild(document.getElementById(data));
document.getElementsById(data);
console.log(data);
}
function allowDrop(event) {
event.preventDefault();
}
function dataURLtoFile(dataurl, filename) {
var arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
while(n--){
u8arr[n] = bstr.charCodeAt(n);
}
return new File([u8arr], filename, {type:mime});
}
function urltoFile(url, filename, mimeType){
return (fetch(url)
.then(function(res){return res.arrayBuffer();})
.then(function(buf){return new File([buf], filename,{type:mimeType});})
);
}
function dataURItoBlob(dataURI) {
// convert base64 to raw binary data held in a string
// doesn't handle URLEncoded DataURIs - see SO answer #6850276 for code that does this
var byteString = atob(dataURI.split(',')[1]);
// separate out the mime component
var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0];
// write the bytes of the string to an ArrayBuffer
var ab = new ArrayBuffer(byteString.length);
var dw = new DataView(ab);
for(var i = 0; i < byteString.length; i++) {
dw.setUint8(i, byteString.charCodeAt(i));
}
// write the ArrayBuffer to a blob, and you're done
return new Blob([ab], {type: mimeString});
}