FineUploader scale thumbnails by one dimension (i.e. maxHeight or maxWidth rather than maxSize) - fine-uploader

Question

The library takes a maxSize parameter for scaling, which applies to the longest of both dimensions. It seems that the work-around solution to scale by one dimension would be to manually run scaleImage() in an onSubmitted callback by calculating what the maxSize should be based on the original image size to get a result with the desired height or width, but this has its own hurdles:
It makes sense that using addFiles() inside of a onSubmitted callback would trigger another onSubmitted event; but if I use addFiles() to add the thumbnail, the thumbnail shows up in the UI list, and this triggers another onSubmitted causing another thumbnail to be generated, which keeps going in a loop.
I need to generate a thumbnail retrained by (a maxHeight of 240 pixels and a maxWidth of 320 pixels) and upload the thumbnail to a separate S3 bucket when uploadStoredFiles() is called, without triggering another onSubmitted event and without showing the thumbnail as a "duplicate" entry in the UI file list. What is the best way to do this in Fine-Uploader?
Some sample code:
function makeThumbnail() {
// FIXME to avoid duplicate, put this in the compression success
var thumbnailPromise = uploader.scaleImage(id, {
maxSize: 123,
quality: 45,
customResizer: !qq.ios() && function (resizeInfo) {
return new Promise(function (resolve, reject) {
pica.resizeCanvas(resizeInfo.sourceCanvas, resizeInfo.targetCanvas, {}, resolve)
});
}
});
thumbnailPromise.then(
function (blob) {
console.log(URL.createObjectURL(blob));
uploader.addFiles(blob);
},
function (err) {
}
);
}

Answer 1

Before you pass a scaled Blob into addFiles, simply add a custom property to the Blob object, something like blob.myScaledImage = true. Then, when handling an onSubmitted callback, retrieve the associated Blob using the getFile API method. If the Blob contains your custom property, don't re-scale it.