It should be quite obvious: drawing requires constant visual feedback. Why is it then that we still draw with code in so many situations? Of course it’s because the low-level APIs always come first, and design tools are built after and on top of those. Existing design tools also don’t typically include complex UI elements such as buttons.

When we launched our Touch Display module for Netduino Go!, we naturally built APIs that made it easy to draw on the screen from code, but very soon, we felt the limitations and tedium of drawing in code. In particular, any modification requires a modification of the code, followed by compilation and deployment. When trying to set-up buttons at pixel precision, the process is not optimal.

On the other hand, code is irreplaceable as a way to automate repetitive tasks. While tools like Illustrator have ways to repeat graphical elements, they do so in a way that is a little alien and counter-intuitive to my developer mind. From these reflections, I knew that I wanted a design tool that would be structurally code-centric but that would still enable immediate feedback and mouse adjustments.

While thinking about the best way to achieve this goal, I saw this fantastic video by Bret Victor:

The key to the magic in all these demos is permanent execution of the code being edited. Whenever a parameter is being modified, everything is re-executed immediately so that the impact of the modification is instantaneously visible. If you do this all the time, the code and the result of its execution fuse in the mind of the user into dual representations of a single object. All mental barriers disappear. It’s like magic.

The tool I built, Nutshell, is just another implementation of this principle. It manipulates a list of graphical operations on the screen. Each operation has a nice editor, and translates into a bit of code. Any modification to the parameters of the operation will modify the bit of generated code and trigger a re-execution of the whole program. This happens so fast that it feels like the drawing reacts instantaneously to all changes.

The order of the operations is also the order in which the code gets executed. So if you want to bring objects to the front, move them down in the list, and up if you want to move them to the back:

But where it gets really fun is when you start applying code constructs such as loops to the design tool. The elements that you put inside of a loop can use the loop counter in expressions, enabling crazy scenarios while retaining the real-time edition features.

When you’re done building, you can just deploy the code to the device and see it run in its native environment:

This works thanks to two code generators. The first code generator is building JavaScript that is executed in the browser to build the canvas view in the web page hosting the tool. The second code generator is building the C# code that will run on the Netduino Go! microcontroller and that will drive the display module.

The possibilities are fascinating, even if you don’t care about driving small touch screens from microcontrollers: it is now possible, within a reasonable budget, to build specialized design tools for very vertical applications. Direct feedback is a powerful ally in many domains. Code generation driven by visual designers has become more approachable than ever thanks to extraordinary JavaScript libraries and to the powerful development platform that modern browsers provide.

I encourage you to tinker with Nutshell and let it open your eyes to new possibilities that you may not have considered before. It’s open source. And of course, my company, Nwazet, can help you develop your own custom browser-based direct feedback design tools. This is real visual programming…