How to begin developing Add-ons?

I need to develop a add-on that will display ePubs as I have NO budget for development due to being an independent developer.

I can not find ANY documentation on how to do this, not even bundled with Xojo itself!


why a plugin ? pretty sure you can do it with a canvas.

Because ePubs are ZIP files under the hood and therefore need to be extracted first and my attempts to convert the C source code of Info-Zip’s Unzip to rb have not been successful so far.

I google’d “xojo zip” and the first result was Thom’s library (which is exactly what I was looking for):

Using the MUCH easier ZipFolderItem class REQUIRES a $35 license and, as mentioned up front, I have no budget.

Hi Bryan,
I don’t know what your knowledge are.
If you are skilled in C you can use any free development environment to develop Xojo plugin or external dll.
In the “Extras\PluginSDK” directory installed with Xojo you can find documentation and some basic plugin examples.

I prefer to use and develop dll, not Xojo plugins: this let me use many other facilities not available in the Xojo framework.

I’m pretty sure you can extract without using the ZipFolderItem or license-required functions.

Ah. You want to use free solutions and NOT have to put in any effort. You should have said, then I could simply have ignored this thread.

Note: the other‘s are VERY helpful. I on the other hand have far less patience because in my book there‘s a fine line between being useful and being used.

I need my app to run on Mac, Win, and (ideally) iOS. So an add-on/plugin is my only option.

I don’t mind putting in a little effort, but his plugin lacks iOS support as well.

I don’t want to discourage you but aren’t you starting with a bigger than usual goal?
A free epub reader already exists for these platforms.

… and also open source…

FWIW, there’s no plugin support on iOS.

There’s nothing wrong with free software. Heck, most of the paid zip-compression solutions for Xojo are based on a free and open source library, zlib.

(And considering how expensive Xojo is, it’s odd that something as basic, useful, and x-plat friendly as zip support isn’t built-in.)

In any case, a plugin or paid solution is not required. Here’s an open-souce Xojo/zlib wrapper that supports extracting/listing zip archives.

The RAD needs to be a main focus in 2018 IMO.

Excel xlsx files are also zip files, and I read them without any plugin.
you can call command lines unzip on the mac, on windows an OLEobject, on iOS I don’t know
but as there are no plugin on iOS, going with xojo native is easier than a plugin IMHO.

see more here :

I would start with a reachable goal. Use one of the linked solutions in this thread to get Mac and Windows running first. Once you have Mac and Windows running you can consider the amount of work that it will take to get ZIP on iOS working, and plan your next steps.

Version 2 isnt $35 , its ‘donationware’ if I recall.

But even $35 is nothing if it saves you 2 hours work.

I have NO budget for development due to being an independent developer.[/quote]

So is Thomas.