cogl-gst: Add some documentation

Adds documentation comments to CoglGstVideoSink and makes it generate
a separate manual to contain it.

One thing that I wasn't able to figure out with this was how to get
the documentation to have correct references to the main Cogl docs.
You can pass arguments to gtkdoc-fixxref to point to other manuals,
but presumably this needs the installed locations and when the
Cogl-Gst documentation is generated the Cogl docs may not have been
installed yet.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 5acdf8db47311893a9cf9ea04a66a287b657b8b0)

.gitignore

@@ -60,6 +60,19 @@ depcomp
 /doc/reference/cogl2/cogl2-docs.xml
 /doc/reference/cogl2/*.stamp
 /doc/reference/cogl2/*.bak
+/doc/reference/cogl-gst/cogl-gst-*.txt
+!/doc/reference/cogl-gst/cogl-gst-sections.txt
+/doc/reference/cogl-gst/html
+/doc/reference/cogl-gst/tmpl
+/doc/reference/cogl-gst/xml
+/doc/reference/cogl-gst/cogl-gst.args
+/doc/reference/cogl-gst/cogl-gst.hierarchy
+/doc/reference/cogl-gst/cogl-gst.interfaces
+/doc/reference/cogl-gst/cogl-gst.prerequisites
+/doc/reference/cogl-gst/cogl-gst.signals
+/doc/reference/cogl-gst/cogl-gst-docs.xml
+/doc/reference/cogl-gst/*.stamp
+/doc/reference/cogl-gst/*.bak
 /examples/cogl-crate
 /examples/cogl-gles2-context
 /examples/cogl-gles2-gears

cogl-gst/cogl-gst-video-sink.h

@@ -37,6 +37,46 @@
 #include <gst/base/gstbasesink.h>
 #include <cogl/cogl.h>
 
+/**
+ * SECTION:cogl-gst-video-sink
+ * @short_description: A video sink for integrating a GStreamer
+ *   pipeline with a Cogl pipeline.
+ *
+ * #CoglGstVideoSink is a subclass of #GstBaseSink which can be used to
+ * create a #CoglPipeline for rendering the frames of the video.
+ *
+ * To create a basic video player, an application can create a
+ * #GstPipeline as normal using gst_pipeline_new() and set the
+ * sink on it to one created with cogl_gst_video_sink_new(). The
+ * application can then listen for the #CoglGstVideoSink::new-frame
+ * signal which will be emitted whenever there are new textures ready
+ * for rendering. For simple rendering, the application can just call
+ * cogl_gst_video_sink_get_pipeline() in the signal handler and use
+ * the returned pipeline to paint the new frame.
+ *
+ * An application is also free to do more advanced rendering by
+ * customizing the pipeline. In that case it should listen for the
+ * #CoglGstVideoSink::pipeline-ready signal which will be emitted as
+ * soon as the sink has determined enough information about the video
+ * to know how it should be rendered. In the handler for this signal,
+ * the application can either make modifications to a copy of the
+ * pipeline returned by cogl_gst_video_sink_get_pipeline() or it can
+ * create its own pipeline from scratch and ask the sink to configure
+ * it with cogl_gst_video_sink_setup_pipeline(). If a custom pipeline
+ * is created using one of these methods then the application should
+ * call cogl_gst_video_sink_attach_frame() on the pipeline before
+ * rendering in order to update the textures on the pipeline's layers.
+ *
+ * If the %COGL_FEATURE_ID_GLSL feature is available then the pipeline
+ * used by the sink will have a shader snippet with a function in it
+ * called cogl_gst_sample_video0 which takes a single vec2 argument.
+ * This can be used by custom snippets set the by the application to
+ * sample from the video. The vec2 argument represents the normalised
+ * coordinates within the video.
+ *
+ * Since: 1.16
+ */
+
 G_BEGIN_DECLS
 
 #define COGL_GST_TYPE_VIDEO_SINK cogl_gst_video_sink_get_type()
@@ -77,53 +117,234 @@ typedef struct _CoglGstVideoSink CoglGstVideoSink;
 typedef struct _CoglGstVideoSinkClass CoglGstVideoSinkClass;
 typedef struct _CoglGstVideoSinkPrivate CoglGstVideoSinkPrivate;
 
+/**
+ * CoglGstVideoSink:
+ *
+ * The #CoglGstVideoSink structure contains only private data and
+ * should be accessed using the provided API.
+ *
+ * Since: 1.16
+ */
 struct _CoglGstVideoSink
 {
+  /*< private >*/
   GstBaseSink parent;
   CoglGstVideoSinkPrivate *priv;
 };
 
+/**
+ * CoglGstVideoSinkClass:
+ * @new_frame: handler for the #CoglGstVideoSink::new-frame signal
+ * @pipeline_ready: handler for the #CoglGstVideoSink::pipeline-ready signal
+ *
+ * Since: 1.16
+ */
+
+/**
+ * CoglGstVideoSink::new-frame:
+ * @sink: the #CoglGstVideoSink
+ *
+ * The sink will emit this signal whenever there are new textures
+ * available for a new frame of the video. After this signal is
+ * emitted, an application can call cogl_gst_video_sink_get_pipeline()
+ * to get a pipeline suitable for rendering the frame. If the
+ * application is using a custom pipeline it can alternatively call
+ * cogl_gst_video_sink_attach_frame() to attach the textures.
+ *
+ * Since: 1.16
+ */
+
+/**
+ * CoglGstVideoSink::pipeline-ready:
+ * @sink: the #CoglGstVideoSink
+ *
+ * The sink will emit this signal as soon as it has gathered enough
+ * information from the video to configure a pipeline. If the
+ * application wants to do some customized rendering, it can setup its
+ * pipeline after this signal is emitted. The application's pipeline
+ * will typically either be a copy of the one returned by
+ * cogl_gst_video_sink_get_pipeline() or it can be a completely custom
+ * pipeline which is setup using cogl_gst_video_sink_setup_pipeline().
+ *
+ * Note that it is an error to call either of those functions before
+ * this signal is emitted. The #CoglGstVideoSink::new-frame signal
+ * will only be emitted after the pipeline is ready so the application
+ * could also create its pipeline in the handler for that.
+ *
+ * Since: 1.16
+ */
+
 struct _CoglGstVideoSinkClass
 {
+  /*< private >*/
   GstBaseSinkClass parent_class;
 
+  /*< public >*/
   void (* new_frame) (CoglGstVideoSink *sink);
   void (* pipeline_ready) (CoglGstVideoSink *sink);
 
+  /*< private >*/
   void *_padding_dummy[8];
 };
 
 GType
 cogl_gst_video_sink_get_type (void) G_GNUC_CONST;
 
+/**
+ * cogl_gst_video_sink_new:
+ * @ctx: The #CoglContext
+ *
+ * Creates a new #CoglGstVideoSink which will create resources for use
+ * with the given context.
+ *
+ * Return value: a new #CoglGstVideoSink
+ * Since: 1.16
+ */
 CoglGstVideoSink *
 cogl_gst_video_sink_new (CoglContext *ctx);
 
+/**
+ * cogl_gst_video_sink_get_pipeline:
+ * @vt: The #CoglGstVideoSink
+ *
+ * Returns a pipeline suitable for rendering the current frame of the
+ * given video sink. The pipeline will already have the textures for
+ * the frame attached. For simple rendering, an application will
+ * typically call this function immediately before it paints the
+ * video. It can then just paint a rectangle using the returned
+ * pipeline.
+ *
+ * An application is free to make a copy of this
+ * pipeline and modify it for custom rendering.
+ *
+ * Note: it is considered an error to call this function before the
+ * #CoglGstVideoSink::pipeline-ready signal is emitted.
+ *
+ * Return value: the pipeline for rendering the current frame
+ * Since: 1.16
+ */
 CoglPipeline *
 cogl_gst_video_sink_get_pipeline (CoglGstVideoSink *vt);
 
+/**
+ * cogl_gst_video_sink_set_context:
+ * @vt: The #CoglGstVideoSink
+ * @ctx: The #CoglContext for the sink to use
+ *
+ * Sets the #CoglContext that the video sink should use for creating
+ * any resources. This function would normally only be used if the
+ * sink was constructed via gst_element_factory_make() instead of
+ * cogl_gst_video_sink_new().
+ *
+ * Since: 1.16
+ */
 void
 cogl_gst_video_sink_set_context (CoglGstVideoSink *vt,
                                  CoglContext *ctx);
 
+/**
+ * cogl_gst_video_sink_get_free_layer:
+ * @sink: The #CoglGstVideoSink
+ *
+ * This can be used when doing specialised rendering of the video by
+ * customizing the pipeline. #CoglGstVideoSink may use up to three
+ * private layers on the pipeline in order to attach the textures of
+ * the video frame. This function will return the index of the next
+ * available unused layer after the sink's internal layers. This can
+ * be used by the application to add additional layers, for example to
+ * blend in another color in the fragment processing.
+ *
+ * Return value: the index of the next available layer after the
+ *   sink's internal layers.
+ * Since: 1.16
+ */
 int
 cogl_gst_video_sink_get_free_layer (CoglGstVideoSink *sink);
 
+/**
+ * cogl_gst_video_sink_attach_frame:
+ * @sink: The #CoglGstVideoSink
+ * @pln: A #CoglPipeline
+ *
+ * Updates the given pipeline with the textures for the current frame.
+ * This can be used if the application wants to customize the
+ * rendering using its own pipeline. Typically this would be called in
+ * response to the #CoglGstVideoSink::new-frame signal which is
+ * emitted whenever the new textures are available. The application
+ * would then make a copy of its template pipeline and call this to
+ * set the textures.
+ *
+ * Return value: the next free layer after the sink's internal private
+ *   layers. This is the same value that is returned by
+ *   cogl_gst_video_sink_get_free_layer().
+ * Since: 1.16
+ */
 int
 cogl_gst_video_sink_attach_frame (CoglGstVideoSink *sink,
                                   CoglPipeline *pln);
 
+/**
+ * cogl_gst_video_sink_set_first_layer:
+ * @sink: The #CoglGstVideoSink
+ * @first_layer: The new first layer
+ *
+ * Sets the index of the first layer that the sink will use for its
+ * rendering. This is useful if the application wants to have custom
+ * layers that appear before the layers added by the sink. In that
+ * case by default the sink's layers will be modulated with the result
+ * of the application's layers that come before @first_layer.
+ *
+ * Note that if this function is called then the name of the function
+ * to call in the shader snippets to sample the video will also
+ * change. For example, if @first_layer is three then the function
+ * will be cogl_gst_sample_video3.
+ *
+ * Since: 1.16
+ */
 void
 cogl_gst_video_sink_set_first_layer (CoglGstVideoSink *sink,
                                      int first_layer);
 
+/**
+ * cogl_gst_video_sink_set_default_sample:
+ * @sink: The #CoglGstVideoSink
+ * @default_sample: Whether to add the default sampling
+ *
+ * By default the pipeline generated by
+ * cogl_gst_video_sink_setup_pipeline() and
+ * cogl_gst_video_sink_get_pipeline() will have a layer with a shader
+ * snippet that automatically samples the video. If the application
+ * wants to sample the video in a completely custom way using its own
+ * shader snippet it can set @default_sample to %FALSE to avoid this
+ * default snippet being added. In that case the application's snippet
+ * can call cogl_gst_sample_video0 to sample the texture itself.
+ *
+ * Since: 1.16
+ */
 void
 cogl_gst_video_sink_set_default_sample (CoglGstVideoSink *sink,
                                         CoglBool default_sample);
 
+/**
+ * cogl_gst_video_sink_setup_pipeline:
+ * @sink: The #CoglGstVideoSink
+ * @pipeline: A #CoglPipeline
+ *
+ * Configures the given pipeline so that will be able to render the
+ * video for the @sink. This should only be used if the application
+ * wants to perform some custom rendering using its own pipeline.
+ * Typically an application will call this in response to the
+ * #CoglGstVideoSink::pipeline-ready signal.
+ *
+ * Note: it is considered an error to call this function before the
+ * #CoglGstVideoSink::pipeline-ready signal is emitted.
+ *
+ * Since: 1.16
+ */
 void
 cogl_gst_video_sink_setup_pipeline (CoglGstVideoSink *sink,
                                     CoglPipeline *pipeline);
+
 G_END_DECLS
 
 #endif

configure.ac

@@ -516,6 +516,10 @@ AS_IF([test "x$enable_cogl_gst" = "xyes"],
   dnl define location of gstreamer plugin directory
   plugindir="\$(libdir)/gstreamer-$GST_MAJORMINOR"
   AC_SUBST(plugindir)
+
+  dnl For the gtk doc generation
+  GSTREAMER_PREFIX="`$PKG_CONFIG --variable=prefix gstreamer-1.0`"
+  AC_SUBST(GSTREAMER_PREFIX)
       ]
 )
 
@@ -1441,6 +1445,8 @@ doc/reference/cogl/Makefile
 doc/reference/cogl/cogl-docs.xml
 doc/reference/cogl-2.0-experimental/Makefile
 doc/reference/cogl-2.0-experimental/cogl-2.0-experimental-docs.xml
+doc/reference/cogl-gst/Makefile
+doc/reference/cogl-gst/cogl-gst-docs.xml
 examples/Makefile
 tests/Makefile
 tests/config.env

doc/reference/Makefile.am

@@ -1 +1,5 @@
 SUBDIRS = cogl cogl-2.0-experimental
+
+if BUILD_COGL_GST
+SUBDIRS += cogl-gst
+endif

doc/reference/cogl-gst/Makefile.am

@@ -0,0 +1,106 @@
+## Process this file with automake to produce Makefile.in
+
+# We require automake 1.6 at least.
+AUTOMAKE_OPTIONS = 1.6
+
+# This is a blank Makefile.am for using gtk-doc.
+# Copy this to your project's API docs directory and modify the variables to
+# suit your project. See the GTK+ Makefiles in gtk+/docs/reference for examples
+# of using the various options.
+
+# The name of the module, e.g. 'glib'.
+DOC_MODULE=cogl-gst
+
+# The top-level SGML file. You can change this if you want to.
+DOC_MAIN_SGML_FILE=$(DOC_MODULE)-docs.xml
+
+# The directory containing the source code. Relative to $(srcdir).
+# gtk-doc will search all .c & .h files beneath here for inline comments
+# documenting the functions and macros.
+# e.g. DOC_SOURCE_DIR=../../../gtk
+DOC_SOURCE_DIR=../../../cogl-gst
+
+# Extra options to pass to gtkdoc-scangobj. Not normally needed.
+SCANGOBJ_OPTIONS=--type-init-func="gst_init(NULL, NULL)"
+
+# Extra options to supply to gtkdoc-scan.
+# e.g. SCAN_OPTIONS=--deprecated-guards="GTK_DISABLE_DEPRECATED"
+SCAN_OPTIONS=--deprecated-guards="COGL_DISABLE_DEPRECATED"
+
+# Extra options to supply to gtkdoc-mkdb.
+# e.g. MKDB_OPTIONS=--sgml-mode --output-format=xml
+MKDB_OPTIONS=--sgml-mode --output-format=xml --name-space=cogl_gst
+
+# Extra options to supply to gtkdoc-mktmpl
+# e.g. MKTMPL_OPTIONS=--only-section-tmpl
+MKTMPL_OPTIONS=
+
+# Extra options to supply to gtkdoc-fixref. Not normally needed.
+# e.g. FIXXREF_OPTIONS=--extra-dir=../gdk-pixbuf/html --extra-dir=../gdk/html
+FIXXREF_OPTIONS=\
+	--extra-dir=$(GLIB_PREFIX)/share/gtk-doc/html/glib \
+	--extra-dir=$(GDKPIXBUF_PREFIX)/share/gtk-doc/html/gdk-pixbuf \
+	--extra-dir=$(GSTREAMER_PREFIX)/share/gtk-doc/html/gstreamer-1.0 \
+	--extra-dir=$(GSTREAMER_PREFIX)/share/gtk-doc/html/gstreamer-libs-1.0
+
+# Used for dependencies. The docs will be rebuilt if any of these change.
+# e.g. HFILE_GLOB=$(top_srcdir)/gtk/*.h
+# e.g. CFILE_GLOB=$(top_srcdir)/gtk/*.c
+HFILE_GLOB=\
+	$(top_srcdir)/cogl/*.h \
+	$(top_builddir)/cogl/*.h \
+	$(top_srcdir)/cogl/winsys/*.h \
+	$(top_srcdir)/cogl-gst/*.h
+CFILE_GLOB=$(top_srcdir)/cogl-gst/*.c
+
+IGNORE_HFILES=\
+	$(NULL)
+
+EXTRA_HFILES=
+
+# Images to copy into HTML directory.
+# e.g. HTML_IMAGES=$(top_srcdir)/gtk/stock-icons/stock_about_24.png
+HTML_IMAGES=\
+	$(NULL)
+
+# Extra SGML files that are included by $(DOC_MAIN_SGML_FILE).
+# e.g. content_files=running.sgml building.sgml changes-2.0.sgml
+content_files=\
+	$(NULL)
+
+# SGML files where gtk-doc abbrevations (#GtkWidget) are expanded
+# These files must be listed here *and* in content_files
+# e.g. expand_content_files=running.sgml
+expand_content_files=\
+	$(NULL)
+
+# CFLAGS and LDFLAGS for compiling gtkdoc-scangobj with your library.
+# Only needed if you are using gtkdoc-scangobj to dynamically query widget
+# signals and properties.
+# e.g. AM_CPPFLAGS=-I$(top_srcdir) -I$(top_builddir) $(GTK_DEBUG_FLAGS)
+# e.g. GTKDOC_LIBS=$(top_builddir)/gtk/$(gtktargetlib)
+
+AM_CPPFLAGS=\
+	-I$(top_srcdir) \
+	-I$(top_builddir)/cogl \
+	-DCOGL_ENABLE_EXPERIMENTAL_API \
+	$(COGL_DEP_CFLAGS) \
+	$(COGL_GST_DEP_CFLAGS)
+
+GTKDOC_LIBS=\
+	$(top_builddir)/cogl/libcogl2.la \
+	$(top_builddir)/cogl-gst/libcogl-gst.la \
+	$(COGL_DEP_LIBS) \
+	$(COGL_GST_DEP_LIBS)
+
+# This includes the standard gtk-doc make rules, copied by gtkdocize.
+if BUILD_GTK_DOC
+include $(top_srcdir)/gtk-doc.make
+else
+EXTRA_DIST =
+endif
+
+# Other files to distribute
+# e.g. EXTRA_DIST += version.xml.in
+
+EXTRA_DIST += $(HTML_IMAGES) $(content_files)

doc/reference/cogl-gst/cogl-gst-docs.xml.in

@@ -0,0 +1,105 @@
+<?xml version="1.0"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
+               "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
+<!ENTITY version "@VERSION@">
+]>
+<book id="index" xmlns:xi="http://www.w3.org/2003/XInclude">
+
+  <bookinfo>
+    <title>Cogl GST 2.0 Reference Manual</title>
+    <releaseinfo>for Cogl &version;</releaseinfo>
+
+    <copyright>
+      <year>2013</year>
+      <holder>Intel Corporation</holder>
+    </copyright>
+
+    <legalnotice>
+      <para>
+        Permission is granted to copy, distribute and/or modify this
+        document under the terms of the <citetitle>GNU Free
+        Documentation License</citetitle>, Version 1.1 or any later
+        version published by the Free Software Foundation with no
+        Invariant Sections, no Front-Cover Texts, and no Back-Cover
+        Texts. You may obtain a copy of the <citetitle>GNU Free
+        Documentation License</citetitle> from the Free Software
+        Foundation by visiting <ulink type="http"
+        url="http://www.fsf.org">their Web site</ulink> or by writing
+        to:
+
+        <address>
+          The Free Software Foundation, Inc.,
+          <street>59 Temple Place</street> - Suite 330,
+          <city>Boston</city>, <state>MA</state> <postcode>02111-1307</postcode>,
+          <country>USA</country>
+        </address>
+      </para>
+    </legalnotice>
+
+  </bookinfo>
+
+  <chapter>
+    <title>Cogl GST - a library for integrating GStreamer with Cogl</title>
+
+    <section id="cogl-gst-intro">
+      <title>About Cogl GST</title>
+
+      <para>Cogl GST is a small library which provides a GStreamer
+      sink which can manage a CoglPipeline to render a video within a
+      Cogl scene.</para>
+
+    </section>
+
+    <section id="cogl-gst-general-apis">
+      <title>General APIs</title>
+      <xi:include href="xml/cogl-gst-video-sink.xml"/>
+    </section>
+
+  </chapter>
+
+  <chapter id="coglglossary">
+    <title>Glossaries</title>
+
+    <xi:include href="xml/annotation-glossary.xml"><xi:fallback /></xi:include>
+  </chapter>
+
+  <index>
+    <title>Index of all symbols</title>
+    <xi:include href="xml/api-index-full.xml"><xi:fallback /></xi:include>
+  </index>
+
+  <appendix id="license">
+    <title>License</title>
+
+    <para>
+      This library is free software; you can redistribute it and/or
+      modify it under the terms of the <citetitle>GNU Library General
+      Public License</citetitle> as published by the Free Software
+      Foundation; either version 2 of the License, or (at your option)
+      any later version.
+    </para>
+
+    <para>
+      This library is distributed in the hope that it will be useful,
+      but WITHOUT ANY WARRANTY; without even the implied warranty of
+      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+      <citetitle>GNU Library General Public License</citetitle> for
+      more details.
+    </para>
+
+    <para>
+      You may obtain a copy of the <citetitle>GNU Library General
+      Public License</citetitle> from the Free Software Foundation by
+      visiting <ulink type="http" url="http://www.fsf.org">their Web
+      site</ulink> or by writing to:
+
+      <address>
+        Free Software Foundation, Inc.
+        <street>59 Temple Place</street> - Suite 330
+        <city>Boston</city>, <state>MA</state> <postcode>02111-1307</postcode>
+        <country>USA</country>
+      </address>
+    </para>
+  </appendix>
+
+</book>

doc/reference/cogl-gst/cogl-gst-sections.txt

@@ -0,0 +1,28 @@
+<SECTION>
+<FILE>cogl-gst-video-sink</FILE>
+<TITLE>CoglGstVideoSink</TITLE>
+
+<SUBSECTION>
+CoglGstVideoSink
+CoglGstVideoSinkClass
+cogl_gst_video_sink_new
+cogl_gst_video_sink_set_context
+cogl_gst_video_sink_get_pipeline
+cogl_gst_video_sink_attach_frame
+cogl_gst_video_sink_setup_pipeline
+cogl_gst_video_sink_get_free_layer
+cogl_gst_video_sink_set_first_layer
+cogl_gst_video_sink_set_default_sample
+
+<SUBSECTION Standard>
+COGL_GST_IS_VIDEO_SINK
+COGL_GST_IS_VIDEO_SINK_CLASS
+COGL_GST_VIDEO_SINK
+COGL_GST_VIDEO_SINK_CLASS
+COGL_GST_TYPE_VIDEO_SINK
+COGL_GST_VIDEO_SINK_GET_CLASS
+<SUBSECTION Private>
+CoglGstVideoSinkPrivate
+cogl_gst_video_sink_get_type
+
+</SECTION>

doc/reference/cogl-gst/cogl-gst.types

@@ -0,0 +1,2 @@
+#include <cogl-gst/cogl-gst.h>
+cogl_gst_video_sink_get_type