Wednesday, October 15, 2014

Dead to Me! Trapdoor, Prototyping web-based desktop applications

This is the inaugural post in my Dead to Me! series which I announced.

I’m not gonna lie. I’m pretty proud of this one. To say Trapdoor was ahead of the times might be a stretch, but really only a small stretch.


My project README explains


Trapdoor is a web-based desktop framework. Confused yet? The idea is to leverage how much energy is put into the web today and make developing a desktop application fun again. Again? For the first time?


Trapdoor was an exploration of how to utilize web development skillsets to build desktop tools. I wanted to experiment with how this idea would play out and if it really made any sense. I was never planning Trapdoor to become are solution. I just wanted to play with the idea, but I do think I played with the idea pretty early on and that it was an extremely successful experiment.


At the time I was still a KDE user and had been learning a little bit of Qt via the Python bindings PyQt4. I knew that Qt had a WebKit widget and quickly found that PyQt4 exposed this pretty easily.





This was a simple demo I built with Trapdoor. We have a web-app built, for this simple example, all in Javascript dumping a few simple controls to the DOM. The JS is responsible for window creation and gets access to the DOM in the new window, where it can construct an interface in HTML and use jQuery to wire it up.


What I was most proud of is that, recognizing this would only be useful if the desktop applications being built could do anything a normal desktop app could do, I made it really easy to extend the Javascript APIs with new things.


The Calculator class defined in the above calculator.py file above and registered in the manifest is able to expose methods to the Javascript API it injects into the application. Otherwise, it is just regular everyday Python and can do anything and can use any Python libraries.


I only worked on Trapdoor for three days. Vaguely I recall wondering if I could write an extension that used PyOpenGL to render 3D graphics in my web-based desktop application, a good year before the WebGL spec landed and three and a half years before work would begin on Node Webkit. Trapdoor won’t be worked on by me and shouldn’t be picked up by anyone else, probably. It will continue to sit in my Github for a while, but it stay forever among my favorite personal projects.

Check it out, if you’re curious.

2 comments:

Anonymous said...

How to run examples?

trapdoor$ ./run-trapdoor demos.helloworld

just hangs

Calvin Spealman said...

Sorry I have not touched this code in 4 years, and I don't have an environment with the dependencies right now (I only ever tested it on Linux and I use Mac/Windows mostly now). I am really happy to see someone trying to use it, but I can't say why it would be hanging. I have not tried it on any modern version of Qt, either.

I write here about programming, how to program better, things I think are neat and are related to programming. I might write other things at my personal website.

I am happily employed by the excellent Caktus Group, located in beautiful and friendly Carrboro, NC, where I work with Python, Django, and Javascript.

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