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+Some of the docbook-related bits in this README might be out of date now that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)
-* "books", using DocBook/XML (faq, manual, pwg)
+* FAQ / Application Development Manual / Plugin Writer's Guide / Tutorials -
+ these are maintained in markdown format and live in the gst-docs repository.
DOCBOOK NOTES
=============
* The source for the documentation is:
- one or more .xml files, with the main one being gstreamer-(whatever).xml
- image files
- - in .fig
+ - in .svg
- in .png (and maybe others)
* We want to generate docs in HTML, PS and PDF
-* We want to use xmlto to generate these
+* We want to use xml to to generate these
CONVENTIONS
-----------
* 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
+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
+
GTK-DOC NOTES
=============
-* files under CVS control:
+* files under revision control:
- Makefile.am
- - gstreamer-sections.txt, gstreamer.types.in, gstreamer-docs.sgml
+ - 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/
- (FIXME: describe what each of these files do)
+ - 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)
* 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
+ - 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>
+ - 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
+
+* 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
+ find . -name "*.[c,h]" -exec egrep -Hn "^ +\* +@.*: *$" {} \;
+ in the project root to find them
+ - gtk docs does not warns about empty Returns: docs!, run
+ find . -name "*.[c,h]" -exec egrep -Hn "^ +\* +@Returns: *$" {} \;
+ in the project root to find them
* what happens during a gtk-doc build ?
- - headers are scanned based on $(MODULE).types
- $(MODULE)-scan is created
- gtkdoc-scan is called with a sourcedir and a module name,
- where the module name is $(MODULE)
- $(MODULE)-sections.txt is created if it doesn't exist yet (it should),
- as well as $(MODULE)-decl.txt and $(MODULE)-decl-list.txt
-
- and .args, .hierarchy and .signals files are created
- gtkdoc-scan is called
+ - 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
- (FIXME: why is there gstreamer.types.in and gst-plugins.types.in ?)
+* 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
+=======================
+- this is in addition to gtk-doc's style-guide.txt
-WBSITE DOCUMENTATION
-====================
+- 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
+ top
+- functions that can return FALSE/NULL or fail should describe their failure
+ conditions like this:
+ * Returns NULL if no element with the given name is found in the bin, if
+ * the frobble was stuck in the froob, or the frizzle was frazzed.
+- a line with function attributes should be added before Returns:
+ - can contain:
+ "MT safe." - the function is verified to be multithreadingsafe
+ "Caller owns returned reference" for refcounted classes
+ "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
Then, after updating any of the docs, run "make upload" from that directory.
Or, run "make upload" from this (docs) directory.
+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).
+
+- 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
+
+- 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.
+ - 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
==========================
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.
+
+
+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 ;)
+
+gtk-doc generates both html API docs and the matching .devhelp(2) books.
+
+IMAGES
+------
+It's important to keep the original source format for images, to be able
+to change and regenerate later on. Original files go in
+docs/images
projects / platform / upstream / gstreamer.git / blobdiff