When a user clicks on a Help icon, the browser requests the following 2 URLs.
http://[TVH_IP]:9981/markdown/class/[TVH_CLASS]?_dc=[??TIMESTAMP??]
http://[TVH_IP]:9981/markdown/toc?_dc=[??TIMESTAMP??]
Both of these URLs return markdown content. The first URL consists of the md file that matches the URL’s class as well as all of the contents of all of the <tvh_include> files present in the main file followed by an Items section containing a description of the properties of the URL’s class.
The second URL contains the static table-of-contents in md format from /docs/markdown/toc.md.
The markdown data is converted into HTML using the third party marked library. This is called from the tvheadend.mdhelp() method in src/webui/static/app/tvheadend.js.
The script support/doc/md_to_c.py is called from the Makefile to create the C file src/docs_inc.c. This script is called multiple times for multiple md file locations with all being centralised into a single src/docs_inc.c file.
Each md file (including the toc) is converted to a C const char array. Each element of the array is a line from the source md files and is wrapped in an i18n translation function. The file names from the <tvh_include> lines are extracted and prefixed with the string \xff\x04 via a the MDINCLUDE compiler preprocessor instruction and added to the array.
At the end of src/docs_inc.c, all of the above arrays are then indexed in a structure called tvh_doc_page.
In src/webui/webui.c’ the /markdown URL path is configured to be handled by page_markdown() in src/webui/doc_md.c. There are various functions that are called within this module, however, the \xff\x04 sequence is interpreted by the function md_render() where the <tvh_include> text is inserted into the content to be returned.
Once the text from the md files has been assembled, the md_props() function in src/webui/doc_md.c appends the Items markdown to the content to be returned.
A typical finally assembled result may look like this:
[Content from first include file]
Some text or seperator.
[Content from second include file]
Main body of the md file
[Content from third include file]
[Content from the internal object class definition]
All text returned to the browser is passed through the C i18n process (JS has its own i18n process) and is capable of being rendered line-by-line into any language supported by TVH provided that a translation for that text exists.