Building API documentation for frameworks

[Nicolas Fella]

Hi,

Frameworks 6.15 will contain an important change that affects how 
distributions build offline API documentation. Frameworks are now using 
qdoc instead of doxygen for generating the documentation.

The end result is still qch files, but the build process changes a bit. 
It now works as followed:

1. Download https://invent.kde.org/sdk/kde-qdoc-common

2. Set the KDE_DOCS environment variable to point to where it's downloaded.

3. For the project where documentation should be built, run CMake as usual

4. Build the 'prepare_docs' Make target

5. Build the 'generate_docs' Make target

6. Build the 'install_html_docs' Make target to install the generated 
HTML files

7. Build the 'generate_qch' Make target to create the qch files

8. Build the 'install_qch_docs' Make target to install the qch files

See https://api.kde.org/ecm/module/ECMGenerateQDoc.html

To make sure that cross-linking between modules works you want the 
.index files of the module's dependencies available during the generate 
phase.

kde-qdoc-common contains two things:

1) files that are included from the modules qdocconf files

2) A CMake project that is to be built according to the steps above that 
generates and installs additional documentation files

Let me know if you have any questions on this.

Cheers

Nico