GStreamer documentation notes
-IMPORTANT
-=========
-
-Please make sure you've read and understood everything in this file
-before you try changing documentation.
-
-Some of the docbook-related bits in this README might be out of date now that
-quite a bit of the documentation has moved into the gst-docs repository.
-
OVERVIEW
========
-GStreamer has two sets of documentation that we maintain:
-* API references, using gtk-doc (gstreamer, gstreamer-libs)
+Our documentation uses hotdoc, you should usually refer to the
+[hotdoc documentation](http://hotdoc.github.io/).
+
+GStreamer has two sets of documentation but both are controlled and aggregated in
+the `gst-docs` module:
+
+* API references, using hotdoc (gstreamer, gstreamer-libs) - maintained
+ in each GStreamer modules repository
* FAQ / Application Development Manual / Plugin Writer's Guide / Tutorials -
these are maintained in markdown format and live in the gst-docs repository.
-DOCBOOK NOTES
-=============
+To build the full documentation you should make sure to have `hotdoc` installed and
+build [gst-build](https://cgit.freedesktop.org/gstreamer/gst-build/) configuring it with:
-OK, I've grown so tired of having to coax the docs to build every time I
-get round to it that I've decided to note down some of the things that
-are important to know.
+```
+meson -Ddoc=enabled build/
+```
-OVERVIEW
---------
-* Our documentation should all be Docbook/XML. No SGML.
-* The source for the documentation is:
- - one or more .xml files, with the main one being gstreamer-(whatever).xml
- - image files
- - in .svg
- - in .png (and maybe others)
-* We want to generate docs in HTML, PS and PDF
-* We want to use xml to to generate these
-
-CONVENTIONS
------------
-We stick to some simple conventions for writing docbook documentation.
-* id names:
- - all id's start with chapter-, part-, section-, or misc-
- - verify this is the case by looking at the generated file names in html/
- - sections should also include the chapter name;
- for example in a chapter called chapter-example, a section would be
- called section-example-hello-world
-
-HOW IMAGES ARE HANDLED
-----------------------
-* the format of images used is:
- - PNG for html
- - EPS for ps
- - PDF for pdf
-
-* images may need to be converted from their source format to the end format
-
-* a file called image.entities is generated that provides two entities:
- ℑ and ℑ
- ℑ is the file extension (png, ps, pdf)
-* all generated images will be put in images/
-
-HOW THE BUILD WORKS FOR EACH FORMAT
------------------------------------
-* HTML:
- - xmlto html gstreamer-whatever.xml should produce the html docs.
- - We do this in the html subdir of the doc builddir.
- - images are copied to (builddir)/html/images
- - PNGS should be set to all of the png's referenced for html, both
- already there and auto-generated
-
-* PS :
- - images are converted to .ps files in EPS format. Generated images are
- put in images/
- - xmlto ps gstreamer-whatever.xml generates the ps file
-
-* PDF :
- There are two ways:
- - ps2pdf is the easiest
- - we specify ps, PS as the image type, but using xmlto the build will fail
- because it uses ps2pdf internally and it fails to generate the images
- By hand-generating .pdf images before xmlto we can make the build succeed.
- (This is why image-pdf has file ext pdf but type EPS; this tricks xmlto in
- doing the right thing)
- xmlto pdf gstreamer-whatever.xml generates pdf (but seems to fail on the
- FAQ, so for now we use ps2pdf)
+And building the documentation:
+
+```
+ninja -C build/ subprojects/gst-docs/GStreamer-doc`, this will result in two documentation sets:
+```
+
+This will generate two outputs:
+
+ - the html in `build/subprojects/gst-docs/GStreamer-doc/html`
+ - the [devhelp](https://wiki.gnome.org/Apps/Devhelp) in `build/subprojects/gst-docs/GStreamer-doc/devhelp`
HOW THE BUILD SYSTEM IS SET UP
------------------------------
-* make all should build html, ps, and pdf
-* html is built in a subdir, with the png/ps images copied there
-* ps and pdf are built in the current dir, in one file
+Hotdoc build targets are generated for each documentation 'components' (ie. hotdoc
+subprojects). This includes libraries documentation and one target per GStreamer plugin.
+
+One can build a specific documentation target by explicitely building the target,
+for example to build the GStreamer core library documentation (adapt the paths if you
+are using `gst-build`):
+
+ ninja docs/libgstreamer-doc
+
+Then the documentation will be avalaible in `docs/libgstreamer-doc/html/`.
SPELL CHECKING
--------------
-* with aspell
- * aspell -b -c --mode=sgml --lang=en <file>.xml
- unfortunately the curses-ui of aspell (0.50.5) has problems with the xml tags
+FILL ME.
-GTK-DOC NOTES
+HOTDOC NOTES
=============
* files under revision control:
- - Makefile.am
- - gstreamer-sections.txt
- describes which symbols later appear on one api-doc page
- configure which symbols are shown/invisible/private
- - gstreamer.types
- the types file lists all get_type() functions that register the GObject types
- - gstreamer-docs.sgml
- defines the overall structure of the api documentation
- - tmpl/
- - only add the file to CVS if you have at least filled the short description
- (filename corresponds to the <FILE> tag in the sections file)
- - document as much as possible in the source (*.c files)
+ - sitemap.txt: defines the overall structure of the documentation
+ - gst_plugins_cache.json: Automatically generated information about plugins
* what to do when adding a new piece of API:
- - add both an entity and use the entity in gstreamer-docs.sgml
- - add a new <SECTION> to gstreamer-sections.txt in the correct alphabetical
- position related to the other sections (so that it is easier to locate)
- - add all documented symbols to gstreamer-sections.txt in the proper section
- (default),<SUBSECTION Standard>,<SUBSECTION Private>
- - document at least the Short_Description in tmpl/.sgml
- - document symbols where they are defined, so that when one changes the
- definition, the chaces are good that docs are updated.
- - document functions, signals in the .c files
- - document structs, typedefs, enums in the .h files
-
-* checklist:
- - make sure *-sections.txt has a <TITLE> set for each <FILE>
- - add only *one* <TITLE> to each file, when you have multiple classes in one
- source-file, create one <FILE> section for each class
- - the <TITLE> *must* be named like the type of the GType, when it gets
- registered (otherwise gtkdoc introspection fails)
- - for clarity name the <FILE> like the <TITLE>, but all lowercase
+ - Just let hotdoc generate the documentation and decide where to put it
+ - Make sure to add a `SECTION` documentation section in the file where
+ the documentation should land (hotdoc will use that to create its
+ "smart index" and list symbols from other files that should land
+ on that page in that section.
+ - document functions, signals in the .c files
+ - document structs, typedefs, enums in the .h files
* what to do when trying to improve the docs
- compare the output of
grep "_get_type" gstreamer-sections.txt | sort
with the types in XXX.types to detect entries that
are maybe missing
- - gtk docs does not warns about empty member docs!, run
+ - hotdoc does not warns about empty member docs!, run
find . -name "*.[c,h]" -exec egrep -Hn "^ +\* +@.*: *$" {} \;
in the project root to find them
- - gtk docs does not warns about empty Returns: docs!, run
+ - hotdoc does not warns about empty Returns: docs!, run
find . -name "*.[c,h]" -exec egrep -Hn "^ +\* +@Returns: *$" {} \;
in the project root to find them
-* what happens during a gtk-doc build ?
- - Scan step:
- - based on a $(MODULE).types file:
- - gtkdoc-scangobj creates a gtkdoc-scan binary
- - using CC, LD, CFLAGS, LDFLAGS env var
- - using --type-init-func and --module parameters
- - gtkdoc-scan creates
- - $MODULE.signals.new
- - $MODULE.hierarchy.new
- - $MODULE.interfaces.new
- - $MODULE.prerequisites.new
- - $MODULE.args.new
- - generated source and objects get deleted
- - gtkdoc-scangobj merges changes into the original files
- - gtkdoc-scan
- - extracts decls of functions, macros, enums, structs, unions from headers
- - generates
- - $MODULE-decl.txt
- - $MODULE-decl-list.txt
- - $MODULE-decl-list.txt then should get copied to $MODULE-sections.txt
- - scan-build.stamp gets created
-
- - Template generation step:
- - gtkdoc-mktmpl --module=$MODULE
- - reads in tmpl/*.sgml
- - moves them to tmpl/*.sgml.bak
- - recreates tmpl/*.sgml according to $MODULE-sections.txt
- - moves unused stuff to $MODULE-unused.txt
- - tmpl-build.stamp gets generated
-
-* Possible errors and how to fix them
- - Warning: multiple "IDs" for constraint linkend: gst-tag-register.
- - check if gst_tag_register is listed more than once in -sections.txt
-
-STYLE GUIDE FOR GTK-DOC
+* what happens during a hotdoc build ?
+ - Read the GIR and scan the sources files for the docstrings and
+ generate the documentation laying out pages the way they are documented.
+ - The meson build definition is set in a way that makes it so all plugins
+ in `plugins_doc` are introspected and documented
+
+STYLE GUIDE FOR HOTDOC
=======================
- this is in addition to gtk-doc's style-guide.txt
-- when documenting signals, use "the #Gst..." for the object receiving the
- signal; no trailing dot, and no "that received the signal"
- function/macro descriptions are descriptive, not imperative
ie, it uses the third person verb
- synopsis and description should have most-used/application functions at the
"Caller owns returned value" for other types (iterators, ..)
- we do this because, in contrast with GLib/GTK, we are more explicit
about threadsafety and related issues
-- link to signals from the description like this:
- * The <link linkend="GstBin-element-added">element-added</link> signal
WEBSITE DOCUMENTATION
=====================
-Updating the online documentation is pretty simple.
-Make sure that you
-a) have a working freedesktop.org account
-b) $HOME/.ssh/config set up so that it has the right User for the Host
- (for example, I have:
-Host freedesktop.org
- User thomasvs
-c) verify this works by doing ssh freedesktop.org and being logged in without
- a password prompt
-d) have verified your changes build documentation locally.
-
-Then, after updating any of the docs, run "make upload" from that directory.
-Or, run "make upload" from this (docs) directory.
+Updating the online documentation is done from with the `gst-docs` repository
DOCUMENTING ELEMENTS
====================
-As of september 2005 we have some system to document plugins and elements
-in the various plugin packages.
-
-- in a submodule, docs go in docs/plugins
-- template can be copied from gst-plugins-base
-- to add plugins documentation:
- - create docs/plugins
- - create Makefile.am and friends, add to configure.ac
- - create docs/version.entities.in, add to configure.ac
- - in docs/plugins:
- - create $(module)-plugins.types with #include <gst/gst.h>
- - run make
- - edit the -docs.sgml
- - add to cvs:
- cvs add *-plugins-docs.sgml *-plugins.args *-plugins.hierarchy *-plugins.interfaces *-plugins.prerequisites *-plugins.signals *-plugins.types inspect-build.stamp inspect.stamp scanobj-build.stamp
- cvs add inspect
- cvs add inspect/*.xml
- - Additional types can be added to the documentation by placing them in
- the .types file like this:
- type:GstPlayBaseBin
- This is useful for documenting plugin-private types that implement
- signals or properties. The GType is looked up by name after all the
- element classes have been printed - so this is only useful for types
- that are created as a consequence of loading plugins and registering
- the element(s).
+A hotdoc plugin is provided by GStreamer to document GStreamer plugins.
- to add a plugin to be documented:
- - make sure inspect/ has generated a inspect/plugin-xxx.xml file for it.
- - if it has not, make sure you have pygst installed and run 'make update'.
- and add it to CVS.
- - add an xi:include in -docs.sgml in the Plugins chapter for that plugin
-
+ - make sure the plugin is added to the `plugins_doc` variable in meson
- to add an element to be documented:
- - add an xi:include in the Elements chapter for the element
- in the main -docs.sgml
- - add a section for it in -sections.txt with
- <SECTION>
- <FILE>element-(element)</FILE>
- <TITLE>(element)</TITLE>
- GstXxx
- <SUBSECTION Standard>
- GstXxxClass
- GST_XXX
- GST_XXX_CLASS
- GST_IS_XXX
- GST_IS_XXX_CLASS
- GST_TYPE_XXX
- gst_xxx_get_type
- </SECTION>
- add a gtk-doc section to the source code like:
/**
* SECTION:element-multifdsink
- and fill it with documentation about the element, preferably inside
- a <refsect2> docbook container.
+ and fill it with documentation about the element
- add an example:
- - either a few pipelines, inside <programlisting>
- - or a piece of code:
- - create an example program (element)-example.c in the plugin dir
- - add the full path (starting with $(top_srcdir)) for this example
- to the EXAMPLE_CFILES variable in Makefile.am
- - add an xinclude of a file named "element-(element)-example.xml"
- to the docbook documentation piece in the element source code
- - add the header to EXTRA_HFILES in Makefile.am to be able to document
- signals and args; in that case, the object struct needs to be in
- -sections.txt outside of the Standard Subsection (which is annoying,
- but ...)
- (FIXME: are we sure we can both do the xinclude from the tmpl/ sgml,
- as well as an override from the source itself ? maybe we should just
- make sure the xinclude is in the source itself instead ?)
- - if the plugin has no public header, don't add the c-file, add entries to the
- -overrides.txt file (see playbin docs in plugins-base).
- - to rebuild the docs, do:
- make clean
- make update
- make
- - examples will only show up using gtk-doc 1.4 or later - it relies on
- merging stuff from .sgml with inline docs. We might want to change
- this to only get stuff from the source.
- - you need to commit resulting files to git:
- - changes to *.signals and *.args
- - new files for your plugin created in inspect/
- - if you get this warning:
- " Documentation in template xxx for ./tmpl/element-yyy:Short_Description
- being overridden by inline comments"
- per-default the description from the GST_ELEMENT_DETAILS is put to the
- Short_Description. This warning mean you have a different one in the section
- docs as "@short_description:".
-
-- the plugin-doc-list on the gstreamer homepage is updated along with other
- web site updates.
-
-- maintainer tricks:
- - in gst-plugins-foo/docs/plugins/, run
- make check-inspected-versions
- to show plugins whose inspect information is not up-to-date (which is
- usually either because they have been moved to a different module or
- because they are not built on the maintainer's machine for some reason).
- Whether it really makes sense to update the version number is debatable
- (after all, the inspected information may be outdated and things may have
- changed, in which case it would be bad to change the version number)
- - find files that have docs
- for file in `find . -name "*.c" -exec grep -l " * SECTION:element-" {} \; | sort`; do if [ -e ${file/.c/.h} ]; then echo ${file/.c/.h}; else echo "no header for $file"; fi; done
- for file in `find . -name "*.cc" -exec grep -l " * SECTION:element-" {} \; | sort`; do if [ -e ${file/.cc/.h} ]; then echo ${file/.cc/.h}; else echo "no header for $file"; fi; done
- - add those .h files to EXTRA_HFILES in Makefile.am
- - update gst-plugins-xxx-docs.sgml
- cd docs/plugins
- ls -1 xml/plugin-*.xml | sort | sed -e "s/\(.*\)/ \<xi:include href=\"\1\" \/\>/"
- ls -1 xml/element-*.xml | grep -v -- "-details.xml" | sort | sed -e "s/\(.*\)/ \<xi:include href=\"\1\" \/\>/"
- - maybe we can generate these lists after "make update" and just xi:include
- them in gst-plugins-xxx-docs.sgml. They should be committed to the vcs.
-
-- possible errors:
- - "multiple constraints for linkend ID":
- check if each section in -sections.txt actually starts and ends with
- <SECTION> and </SECTION>
- - if a plugin does not show up:
- - check inspect/plugin-xxx.xml and tmpl/elements-
-
-RANDOM THINGS I'VE LEARNED
-==========================
-
-* for clean builddir != srcdir separation, I wanted to use xmlto --searchpath
- so the source xml could find the built entity file.
- But xmlto --searchpath is (right now) for TeX input, not xml input.
- xsltproc has a --path option (that xmlto doesn't use yet), but it
- resolves single files to $(specified_path)/$(srcdir)/$(file)
- For now, we need to hack around it by copying xml to the build dir.
+ - either a few pipelines, inside a codeblock
+ - or a piece of code inside a codeblock or in `tests/examples/(pluginname)`
+ - to build the doc for a plugin, do:
+ `ninja docs/(pluginname)-doc`
DEVHELP INTEGRATION
-------------------
Check https://wiki.gnome.org/Apps/Devhelp
It's a really nice development app allowing you to look up API stuff
-from various gtk-doc'd libraries. GStreamer is one of these ;)
+from various hotdoc/gtk-doc'd libraries. GStreamer is one of these ;)
-gtk-doc generates both html API docs and the matching .devhelp(2) books.
+hotdoc generates both html API docs and the matching .devhelp(2) books.
IMAGES
------
projects / platform / upstream / gstreamer.git / commitdiff