The easy way out: draw one, dummy. Then choose it in your profile settings.

Those of you who have keen eyes may note that my profile picture has transparency. Those of you who are worth your salt will know that you can't draw transparency on DSi Paint. Good luck finding that glass crayon.

So how did I do it?

The answer is surprisingly simple.

I sent a request to the server that asked it to save an image to its server. Then I can use that image as my profile picture.

Now how can you do it?

The secret ingredient is crime JS. And some Java. The two languages which I am the most familiar with. (HTML doesn't count.)

The first step is to convert the image into a format known as Base 64. For context, it looks something like this:

data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAUgAA

and so on for thousands of characters. It essentially encodes an image into a big, messy string. But why Base 64? I'll get to that in a bit.

Doing this in Java isn't that hard. I followed Baeldung's guide on converting images to Base 64. Once the program converted the image to Base 64, it wrote the data to a file for safekeeping. Here's the code that I used. My code does have dependencies, but handling dependencies is way, waaay outside of the scope of this blog.

(I did this in Java since that's the language I'm most familiar with. However, you could probably do the same thing with C++ or Kotlin or, god forbid, Rust. You can't use JS and HTML here since HTML canvases can't store transparency data.)

Alright, so you have the data of the image in one massive string. Now what? Now we send it over.

Sending it over was the harder part to figure out for me, but, thankfully, the code of DSi Paint is well-formatted and concise (despite its quality), so once I knew where to look it wasn't hard to find out. (Please note I said DSi Paint, not 3DS Paint. I'm not sure if this would work on 3DS Paint, but I'm optimistic that it would.)

It turns out that, like most of the rest of DSi Paint, the painting app operates on XMLHttpRequests. These requests allow the client to send data to the server without refreshing the page, making it a very powerful tool. Sending images over an XMLHttpRequest is hard, however. There's multiple ways to do it, but converting the image into a string of characters is likely the simplest way to do it since transmitting a message full of letters and numbers is trivial. Clever.

Cool, but how do you go about sending these XMLHttpRequests? You need to open the developer console on a major modern web browser.

First navigate to DSi Paint's DSi Paint. Then paste this script into the dev console. On Chrome, you can easily open this by hitting "Ctrl + Shift + I" and then navigating to the "Console" tab. Of course, replace the first string with your Base 64 image data. Once the script has been run (by pressing Enter) and the bottom reads "Image saved to gallery.", you're set.

Now cruise over to your user settings and select that image as your new profile picture. What's cool is that the image is saved as a legitimate DSi Paint image, so it saves there forever. Unless you delete it. But why would you ever do that?

Also, this blog is dedicated to banjo, who guessed first try who my profile picture is. Absolute madlad. Shoutouts to Pop and CM as well since they guessed in the right neck of the woods.

Have fun making custom profile pictures!

On behalf of the entire community, please don't patch this. Not that it breaks anything. But if you do, I want to figure out how since I can't think of how you would do it.