Force user to crop/upload an image to a certain size? Preferably using filepicker - ruby-on-rails

Question

I have users uploading images using filepicker, but I want them to have to upload an image of a certain size (and crop if the image is too big). I could cut it myself, but then it won't look good. Ideally, the user would crop it themselves.
I've tried this page: https://www.filepicker.com/documentation/file-ingestion/widgets/pick?v=v2 and I've tried various options but nothing seems to work quite well.
data-fp-image-min doesn't prevent users from uploading smaller images. data-fp-crop-force along with data-fp-crop-max and data-fp-crop-min doesn't do the trick either.
I'm open to using other image uploading libraries, but I like using filepicker. Seems like this is something other people would have run into.
I'm using rails btw.

Answer 1

From the docs:
data-fp-image-min - Images smaller than the specified dimensions will be upscaled to the minimum size.
So it doesn't really prevent users from uploading smaller images.
data-fp-crop-max and data-fp-crop-min specifies the maximum and minimum dimensions of the crop area so it won't give you specific dimensions.
I would recommend you to:
Set data-fp-crop-ratio - Specify the crop area height to width ratio. User will be able to adjust the crop area for each photo with desired ratio.
Set data-fp-crop-force="true" - User could not skip cropping image.
Then resize image to specific height or width.
This will result, you will always get the image with the desired dimensions.
Example for 150 x 200 image output:
Html widget:
<input type="filepicker"
data-fp-crop-ratio="3/4"
data-fp-crop-force="true"
mimetype="image/*"
onchange="window.upload(event)"
data-fp-apikey="APUGwDkkSvqNr9Y3KD4tAz" />
Javascript:
window.upload = function(event){
console.log(JSON.stringify(event.fpfile));
var listElem = document.createElement("li");
var image = document.createElement("img");
/*
set w=150 (width) conversion option
so all images would be 150x200
and crop_first option to make sure the image is cropped
before any other conversion parameters are executed.
*/
image.setAttribute('src', event.fpfile.url + '&w=150&crop_first=true');
listElem.appendChild(image);
document.getElementById('results').appendChild(listElem);
};
Here is working solution: http://jsfiddle.net/krystiangw/9o9ebddL/