[mythtv] Guide to write a plugin?

Henrik Gammelmark mythtv at geemark.com
Thu Oct 12 17:41:10 UTC 2006

Josh Lefler wrote:
> Henrik,
> I recently wrote my first plugin for myth (Ticket #2482) and had much 
> the same dilemma as you when I got started. Here are a few bits of 
> information that made the process easier for me:
> The menus for MythTV are created from XML files that generally, but not 
> always, end in menu.xml. You can manually modify one of these files to 
> get your plugin to show up in the menu. See Ticket 2475 to see how I 
> modified a few of the menus to replace an old plugin with my new one.
> Secondly, know that the plugin architecture is really pretty simple. 
> Each plugin has three functions that Myth may run - init, run, and 
> config. Init is run whenever mythfrontend starts and should handle 
> things like upgrading gracefully, etc. Run is ran when someone actually 
> selects the menu item for your plugin (with the action defined something 
> like PLUGIN (yourpluginname). Finally, config is ran when someone 
> selects your plugin from within a configuration menu.
> Essentially - the init is always run when mythfrontend starts. You get 
> the other two to run by adding the appropriate menu items in the 
> appropriate places.
> Next, the UI for your plugin itself. Myth has an internal UI system that 
> is pretty easy to use once you grok it. Basically, you define your UI 
> with an XML file. Contained within this UI is the elements that you need 
> to display and interact with from code. Myth parses the XML file and 
> creates the appropriate GUI, then you can use some myth functions to 
> grab handlers for each of the UI elements so you can then interact with 
> them like you would a GUI object in just about any other language.
> Settings: Use gContext->GetSetting and gContext->SaveSetting to save 
> simple bits of data to/from the database. For more complex stuff, 
> interact with the database using Myth's dbcon class.
> I referenced the game class heavily when writing my plugin because it 
> was the most similar to my end-goal.
> I'm available if you have any questions or I can be of any assistance.
> Josh Lefler
> Lefler, Inc.

Thank you very much for your reply. A few more questions:

How do I go about compiling the thing? I should end up with what? A .so 
file? And where do I place this? With what filename?

Regarding the UI xml file, does it need to have a specific name, or do I 
reference it from within my code?

Do you know anything about the i18n folder, containing translations? Is 
that for internal use only, or does mythtv choose the translation etc 

Sorry if I'm asking dumb questions, I haven't yet figured out how things 
play together.

/ Henrik
> Henrik Gammelmark wrote:
>> I have looked around on mythtv.org, but I cannot seem to find any 
>> documentation / howtos / turorials / faqs on how to build a simple 
>> plugin for MythTV.
>> Does anyone know of any such guide or at least some sort of 
>> documentation to use? For starters I wish to create simple Hello World 
>> plugin that appears in the main menu, and responds to a keystroke (or 
>> lirc key) by doing something useless.
>> In #mythtv @ Freenode, I was told that there is no such guide or sample 
>> plugin, and the best way to go about it, is study an existing plugin. So 
>> I started taking apart mythweather, but I quickly got stuck.
>> Any pointers would be helpful - what is the bare minimum of code 
>> required to accomplish the above task, and also, what is the build 
>> procedure? I never used qmake before, and I'm not sure I understand what 
>> it does.
>> Thank you very much in advance
>> / Henrik
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