HTML5: Masking file inputs with CSS3

This morning, I was implimenting an AJAX “profile photo uploader” using the new HTML5 File object. With the new File object, you’re able to do a file upload using an AJAX request instead of requiring a form submission to upload the file.

This works great with the caveat that there still needs to be a <input type="file" /> on the page in order for the user to select a file. This presents a UI/UX issue because there isn’t much leway in styling HTML file inputs and consequently the input was looking out of place on our form.

After poking around for a bit I ran across jQuery File Upload which seems to solve this problem. Inspecting the CSS, the CSS “masks” the file input by using a CSS3 “transform” and then setting the opacity value to 0 so the input is visually hidden.

Implimenting the transform+opacity trick was pretty straightforward but the issue I ran into was that I couldn’t get the mouse cursor being displayed to appear as a “hand”, I kept seeing the “text selector” cursor. I had changed the transform being used and unfortunately the jQuery File Upload CSS didn’t have any comments explaining what it was actually doing to get the cursor part of the CSS to work.

It turns out what you want to do is use the CSS3 “transform” function to skew the file input so that the “Browse” button is covering the element that you want to use to trigger the “select file” behavior and then just set the opacity to 0 to make the file input invisible.

You can see the progression here The first container has no styling applied on the file input, the second one has the “Browse” button skewed into the right spot and finally the last one has the opacity set to 0. If you change the “cursor” CSS directive on the file input you’ll notice that in the 2nd and 3rd examples the cursor will change wherever your mouse is in the container. Also, you’ll notice that if you click anywhere in the container the “select a file” dialog will get triggered as expected.

Anyway, as always comments/feedback/questions are welcome!