All kinds of prefetching and caching techniques went into the scrollbar alone.Ĭarousel is also a view into both the local photo gallery and the photos stored into the cloud. This sounds simple but when you have thousands of pictures going across the screen, even decoding the JPEG becomes a bottleneck. One of the nice features of Carousel is that I can quickly scroll through my entire photo library to look at my old photos. In a nutshell, the two technical aspects of Carousel I was most impressed by are the performance and the handling of edge cases. There’s a series of 3 blog posts describing the engineering behind Carousel that reveal the magic behind the scenes. From doing it to doing it wellĪ photo gallery app sounds mundane, but as I learned more about its functionality and dove into the codebase, I quickly realized that Carousel was far from “just a photo gallery”. Those projects were interesting exercises in understanding the distinction between doing something and doing it well, and I learned that the culture at Dropbox leans strongly towards doing it well. If all the images were the same size, then events that only have a few images would be left with whitespace. Furthermore, why download the full-image if the user just zooms into a portion of the screen? Therefore, I split the image into tiles and fetched the tiles on a per-need basis.Īmong other projects, I also helped ship Carousel for iPad by maximizing the usage of the screen real estate. In a mobile app, bandwidth is a limited resource.

However, the full image could be arbitrarily large and downloading the entire file could be very bandwidth intensive. The simple approach would be to download just the higher resolution image and display it. This was an interesting project because I got to design and implement the entire feature while keeping in mind the many practical constraints that go into doing it well. My first project would be high-resolution zooming on images stored in the cloud, as the app originally displayed only a screen-size thumbnail.

In a nutshell, Carousel is a photo gallery app that auto-uploads your photos to the cloud and allows quick access to any of your photo stored in Dropbox. In my first internship at Dropbox, I was assigned to work on the Carousel iPhone app. Read more about my second internship, maximizing signal in interviews and the social, cultural and business aspects. This is one of four blog posts on my experiences interning at Dropbox in Fall 2014 and Summer 2015.

Dropbox developer internship