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significant commenting of the example plugin

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Original commit message from CVS:
significant commenting of the example plugin
This commit is contained in:
Erik Walthinsen 2001-02-22 01:34:25 +00:00
parent b48585ce6c
commit 2324ea92c8
4 changed files with 392 additions and 68 deletions
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198
examples/plugins/example.c
View file

@ -17,9 +17,14 @@
* Boston, MA 02111-1307, USA.
*/
/* First, include the header file for the plugin, to bring in the
* object definition and other useful things.
*/
#include "example.h"
/* elementfactory information */
/* The ElementDetails structure gives a human-readable description
* of the plugin, as well as author and version data.
*/
static GstElementDetails example_details = {
"An example plugin",
"Example",
@ -29,30 +34,47 @@ static GstElementDetails example_details = {
"(C) 2000",
};
/* Example signals and args */
/* These are the signals that this element can fire. They are zero-
* based because the numbers themselves are private to the object.
* LAST_SIGNAL is used for initialization of the signal array.
*/
enum {
ASDF,
/* FILL ME */
LAST_SIGNAL
};
/* Arguments are identified the same way, but cannot be zero, so you
* must leave the ARG_0 entry in as a placeholder.
*/
enum {
ARG_0,
ARG_ACTIVE
ARG_ACTIVE,
/* FILL ME */
};
/* The PadFactory structures describe what pads the element has or
* can have. They can be quite complex, but for this example plugin
* they are rather simple.
*/
static GstPadFactory sink_factory = {
"sink", /* the name of the pads */
GST_PAD_FACTORY_SINK, /* type of the pad */
GST_PAD_FACTORY_ALWAYS, /* ALWAYS/SOMETIMES */
GST_PAD_FACTORY_CAPS(
"example_sink", /* the name of the caps */
"unknown/unknown", /* the mime type of the caps */
"something", GST_PROPS_INT (1), /* a property */
"foo", GST_PROPS_BOOLEAN (TRUE) /* another property */
"sink", /* The name of the pad */
GST_PAD_FACTORY_SINK, /* Direction of the pad */
GST_PAD_FACTORY_ALWAYS, /* The pad exists for every instance */
GST_PAD_FACTORY_CAPS( /* This factory has specific capabilities */
"example_sink", /* The name of the caps */
"unknown/unknown", /* The overall MIME/type */
"foo", GST_PROPS_INT (1), /* An integer property */
"bar", GST_PROPS_BOOLEAN (TRUE) /* A boolean */
"baz", GST_PROPS_LIST ( /* A list of values for */
GST_PROPS_INT (1),
GST_PROPS_INT (3),
),
),
NULL
NULL /* All factories must be NULL-terminated */
};
/* This factory is much simpler, and defines the source pad. */
static GstPadFactory src_factory = {
"src",
GST_PAD_FACTORY_SRC,
@ -65,19 +87,35 @@ static GstPadFactory src_factory = {
};
static void gst_example_class_init (GstExampleClass *klass);
static void gst_example_init (GstExample *example);
/* A number of functon prototypes are given so we can refer to them later. */
static void gst_example_class_init (GstExampleClass *klass);
static void gst_example_init (GstExample *example);
static void gst_example_chain (GstPad *pad, GstBuffer *buf);
static void gst_example_chain (GstPad *pad, GstBuffer *buf);
static void gst_example_set_arg (GtkObject *object,GtkArg *arg,guint id);
static void gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id);
static void gst_example_set_arg (GtkObject *object,GtkArg *arg,guint id);
static void gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id);
GstPadTemplate *src_template, *sink_template;
/* These hold the constructed pad templates, which are created during
* plugin load, and used during element instantiation.
*/
static GstPadTemplate *src_template, *sink_template;
/* The parent class pointer needs to be kept around for some object
* operations.
*/
static GstElementClass *parent_class = NULL;
//static guint gst_example_signals[LAST_SIGNAL] = { 0 };
/* This array holds the ids of the signals registered for this object.
* The array indexes are based on the enum up above.
*/
static guint gst_example_signals[LAST_SIGNAL] = { 0 };
/* This function is used to register and subsequently return the type
* identifier for this object class. On first invocation, it will
* register the type, providing the name of the class, struct sizes,
* and pointers to the various functions that define the class.
*/
GtkType
gst_example_get_type(void)
{
@ -90,8 +128,8 @@ gst_example_get_type(void)
sizeof(GstExampleClass),
(GtkClassInitFunc)gst_example_class_init,
(GtkObjectInitFunc)gst_example_init,
(GtkArgSetFunc)gst_example_set_arg,
(GtkArgGetFunc)gst_example_get_arg,
(GtkArgSetFunc)NULL, /* These last three are depracated */
(GtkArgGetFunc)NULL,
(GtkClassInitFunc)NULL,
};
example_type = gtk_type_unique(GST_TYPE_ELEMENT,&example_info);
@ -99,70 +137,151 @@ gst_example_get_type(void)
return example_type;
}
/* In order to create an instance of an object, the class must be
* initialized by this function. GtkObject will take care of running
* it, based on the pointer to the function provided above.
*/
static void
gst_example_class_init (GstExampleClass *klass)
{
/* Class pointers are needed to supply pointers to the private
* implementations of parent class methods.
*/
GtkObjectClass *gtkobject_class;
GstElementClass *gstelement_class;
/* Since the example class contains the parent classes, you can simply
* cast the pointer to get access to the parent classes.
*/
gtkobject_class = (GtkObjectClass*)klass;
gstelement_class = (GstElementClass*)klass;
/* The parent class is needed for class method overrides. */
parent_class = gtk_type_class(GST_TYPE_ELEMENT);
/* Here we add an argument to the object. This argument is an integer,
* and can be both read and written.
*/
gtk_object_add_arg_type("GstExample::active", GTK_TYPE_INT,
GTK_ARG_READWRITE, ARG_ACTIVE);
/* The last thing is to provide the functions that implement get and set
* of arguments.
*/
gtkobject_class->set_arg = gst_example_set_arg;
gtkobject_class->get_arg = gst_example_get_arg;
}
/* This function is responsible for initializing a specific instance of
* the plugin.
*/
static void
gst_example_init(GstExample *example)
{
/* First we create the sink pad, which is the input to the element.
* We will use the sink_template constructed in the plugin_init function
* (below) to quickly generate the pad we need.
*/
example->sinkpad = gst_pad_new_from_template (sink_template, "sink");
gst_element_add_pad(GST_ELEMENT(example),example->sinkpad);
/* Setting the chain function allows us to supply the function that will
* actually be performing the work. Without this, the element would do
* nothing, with undefined results (assertion failures and such).
*/
gst_pad_set_chain_function(example->sinkpad,gst_example_chain);
/* We then must add this pad to the element's list of pads. The base
* element class manages the list of pads, and provides accessors to it.
*/
gst_element_add_pad(GST_ELEMENT(example),example->sinkpad);
/* The src pad, the output of the element, is created and registered
* in the same way, with the exception of the chain function. Source
* pads don't have chain functions, because they can't accept buffers,
* they only produce them.
*/
example->srcpad = gst_pad_new_from_template (src_template, "src");
gst_element_add_pad(GST_ELEMENT(example),example->srcpad);
/* Initialization of element's private variables. */
example->active = FALSE;
}
/* The chain function is the heart of the element. It's where all the
* work is done. It is passed a pointer to the pad in question, as well
* as the buffer provided by the peer element.
*/
static void
gst_example_chain (GstPad *pad, GstBuffer *buf)
{
GstExample *example;
GstBuffer *outbuf;
/* Some of these checks are of dubious value, since if there were not
* already true, the chain function would never be called.
*/
g_return_if_fail(pad != NULL);
g_return_if_fail(GST_IS_PAD(pad));
g_return_if_fail(buf != NULL);
//g_return_if_fail(GST_IS_BUFFER(buf));
g_return_if_fail(GST_IS_BUFFER(buf));
/* We need to get a pointer to the element this pad belogs to. */
example = GST_EXAMPLE(gst_pad_get_parent (pad));
/* A few more sanity checks to make sure that the element that owns
* this pad is the right kind of element, in case something got confused.
*/
g_return_if_fail(example != NULL);
g_return_if_fail(GST_IS_EXAMPLE(example));
/* If we are supposed to be doing something, here's where it happens. */
if (example->active) {
/* DO STUFF */
}
/* In this example we're going to copy the buffer to another one,
* so we need to allocate a new buffer first.
outbuf = gst_buffer_new();
gst_pad_push(example->srcpad,buf);
/* We need to copy the size and offset of the buffer at a minimum. */
GST_BUFFER_SIZE (outbuf) = GST_BUFFER_SIZE (buf);
GST_BUFFER_OFFSET (outbuf) = GST_BUFFER_OFFSET (buf);
/* Then allocate the memory for the new buffer */
GST_BUFFER_DATA (outbuf) = (guchar *)g_malloc (GST_BUFFER_SIZE (outbuf));
/* Then copy the data in the incoming buffer into the new buffer. */
memcpy (GST_BUFFER_DATA (outbuf), GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (outbuf));
/* When we're done with the buffer, we push it on to the next element
* in the pipeline, through the element's source pad, which is stored
* in the element's structure.
*/
gst_pad_push(example->srcpad,outbuf);
/* If we're not doing something, just send the original incoming buffer. */
} else {
gst_pad_push(example->srcpad,buf);
}
}
/* Arguments are part of the Gtk+ object system, and these functions
* enable the element to respond to various arguments.
*/
static void
gst_example_set_arg (GtkObject *object,GtkArg *arg,guint id)
{
GstExample *example;
/* it's not null if we got it, but it might not be ours */
/* It's not null if we got it, but it might not be ours */
g_return_if_fail(GST_IS_EXAMPLE(object));
/* Get a pointer of the right type. */
example = GST_EXAMPLE(object);
switch(id) {
/* Check the argument id to see which argument we're setting. */
switch (id) {
case ARG_ACTIVE:
/* Here we simply copy the value of the argument to our private
* storage. More complex operations can be done, but beware that
* they may occur at any time, possibly even while your chain function
* is running, if you are using threads.
*/
example->active = GTK_VALUE_INT(*arg);
g_print("example: set active to %d\n",example->active);
break;
@ -171,12 +290,13 @@ gst_example_set_arg (GtkObject *object,GtkArg *arg,guint id)
}
}
/* The set function is simply the inverse of the get fuction. */
static void
gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id)
{
GstExample *example;
/* it's not null if we got it, but it might not be ours */
/* It's not null if we got it, but it might not be ours */
g_return_if_fail(GST_IS_EXAMPLE(object));
example = GST_EXAMPLE(object);
@ -190,25 +310,45 @@ gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id)
}
}
/* This is the entry into the plugin itself. When the plugin loads,
* this function is called to register everything that the plugin provides.
*/
GstPlugin*
plugin_init (GModule *module)
{
GstPlugin *plugin;
GstElementFactory *factory;
/* First we try to create a new Plugin structure. */
plugin = gst_plugin_new("example");
/* If we get a NULL back, chances are we're already loaded. */
g_return_val_if_fail(plugin != NULL, NULL);
/* We need to create an ElementFactory for each element we provide.
* This consists of the name of the element, the GtkType identifier,
* and a pointer to the details structure at the top of the file.
*/
factory = gst_elementfactory_new("example", GST_TYPE_EXAMPLE, &example_details);
g_return_val_if_fail(factory != NULL, NULL);
/* The pad templates can be easily generated from the factories above,
* and then added to the list of padtemplates for the elementfactory.
* Note that the generated padtemplates are stored in static global
* variables, for the gst_example_init function to use later on.
*/
sink_template = gst_padtemplate_new (&sink_factory);
gst_elementfactory_add_padtemplate (factory, sink_template);
src_template = gst_padtemplate_new (&src_factory);
gst_elementfactory_add_padtemplate (factory, src_template);
/* The very last thing is to register the elementfactory with the plugin. */
gst_plugin_add_factory (plugin, factory);
/* Now we can return the pointer to the newly created Plugin object. */
return plugin;
/* At this point, the GStreamer core registers the plugin, its
* elementfactories, padtemplates, etc., for use in you application.
*/
}

32
examples/plugins/example.h
View file

@ -28,36 +28,58 @@ extern "C" {
#endif /* __cplusplus */
/* Definition of structure storing data for this element. */
/* This is the definition of the element's object structure. */
typedef struct _GstExample GstExample;
/* The structure itself is derived from GstElement, as can be seen by the
* fact that there's a complete instance of the GstElement structure at
* the beginning of the object. This allows the element to be cast to
* an Element or even an Object.
*/
struct _GstExample {
GstElement element;
/* We need to keep track of our pads, so we do so here. */
GstPad *sinkpad,*srcpad;
gint8 active;
/* We'll use this to decide whether to do anything to the data we get. */
gboolean active;
};
/* Standard definition defining a class for this element. */
/* The other half of the object is its class. The class also derives from
* the same parent, though it must be the class structure this time.
* Function pointers for polymophic methods and signals are placed in this
* structure. */
typedef struct _GstExampleClass GstExampleClass;
struct _GstExampleClass {
GstElementClass parent_class;
};
/* Standard macros for defining types for this element. */
/* Five standard preprocessing macros are used in the Gtk+ object system.
* The first uses the object's _get_type function to return the GtkType
* of the object.
*/
#define GST_TYPE_EXAMPLE \
(gst_example_get_type())
/* The second is a checking cast to the correct type. If the object passed
* is not the right type, a warning will be generated on stderr.
*/
#define GST_EXAMPLE(obj) \
(GTK_CHECK_CAST((obj),GST_TYPE_EXAMPLE,GstExample))
/* The third is a checking cast of the class instead of the object. */
#define GST_EXAMPLE_CLASS(klass) \
(GTK_CHECK_CLASS_CAST((klass),GST_TYPE_EXAMPLE,GstExample))
/* The last two simply check to see if the passed pointer is an object or
* class of the correct type. */
#define GST_IS_EXAMPLE(obj) \
(GTK_CHECK_TYPE((obj),GST_TYPE_EXAMPLE))
#define GST_IS_EXAMPLE_CLASS(obj) \
(GTK_CHECK_CLASS_TYPE((klass),GST_TYPE_EXAMPLE))
/* Standard function returning type information. */
/* This is the only prototype needed, because it is used in the above
* GST_TYPE_EXAMPLE macro.
*/
GtkType gst_example_get_type(void);

198
tests/old/examples/plugins/example.c
View file

@ -17,9 +17,14 @@
* Boston, MA 02111-1307, USA.
*/
/* First, include the header file for the plugin, to bring in the
* object definition and other useful things.
*/
#include "example.h"
/* elementfactory information */
/* The ElementDetails structure gives a human-readable description
* of the plugin, as well as author and version data.
*/
static GstElementDetails example_details = {
"An example plugin",
"Example",
@ -29,30 +34,47 @@ static GstElementDetails example_details = {
"(C) 2000",
};
/* Example signals and args */
/* These are the signals that this element can fire. They are zero-
* based because the numbers themselves are private to the object.
* LAST_SIGNAL is used for initialization of the signal array.
*/
enum {
ASDF,
/* FILL ME */
LAST_SIGNAL
};
/* Arguments are identified the same way, but cannot be zero, so you
* must leave the ARG_0 entry in as a placeholder.
*/
enum {
ARG_0,
ARG_ACTIVE
ARG_ACTIVE,
/* FILL ME */
};
/* The PadFactory structures describe what pads the element has or
* can have. They can be quite complex, but for this example plugin
* they are rather simple.
*/
static GstPadFactory sink_factory = {
"sink", /* the name of the pads */
GST_PAD_FACTORY_SINK, /* type of the pad */
GST_PAD_FACTORY_ALWAYS, /* ALWAYS/SOMETIMES */
GST_PAD_FACTORY_CAPS(
"example_sink", /* the name of the caps */
"unknown/unknown", /* the mime type of the caps */
"something", GST_PROPS_INT (1), /* a property */
"foo", GST_PROPS_BOOLEAN (TRUE) /* another property */
"sink", /* The name of the pad */
GST_PAD_FACTORY_SINK, /* Direction of the pad */
GST_PAD_FACTORY_ALWAYS, /* The pad exists for every instance */
GST_PAD_FACTORY_CAPS( /* This factory has specific capabilities */
"example_sink", /* The name of the caps */
"unknown/unknown", /* The overall MIME/type */
"foo", GST_PROPS_INT (1), /* An integer property */
"bar", GST_PROPS_BOOLEAN (TRUE) /* A boolean */
"baz", GST_PROPS_LIST ( /* A list of values for */
GST_PROPS_INT (1),
GST_PROPS_INT (3),
),
),
NULL
NULL /* All factories must be NULL-terminated */
};
/* This factory is much simpler, and defines the source pad. */
static GstPadFactory src_factory = {
"src",
GST_PAD_FACTORY_SRC,
@ -65,19 +87,35 @@ static GstPadFactory src_factory = {
};
static void gst_example_class_init (GstExampleClass *klass);
static void gst_example_init (GstExample *example);
/* A number of functon prototypes are given so we can refer to them later. */
static void gst_example_class_init (GstExampleClass *klass);
static void gst_example_init (GstExample *example);
static void gst_example_chain (GstPad *pad, GstBuffer *buf);
static void gst_example_chain (GstPad *pad, GstBuffer *buf);
static void gst_example_set_arg (GtkObject *object,GtkArg *arg,guint id);
static void gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id);
static void gst_example_set_arg (GtkObject *object,GtkArg *arg,guint id);
static void gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id);
GstPadTemplate *src_template, *sink_template;
/* These hold the constructed pad templates, which are created during
* plugin load, and used during element instantiation.
*/
static GstPadTemplate *src_template, *sink_template;
/* The parent class pointer needs to be kept around for some object
* operations.
*/
static GstElementClass *parent_class = NULL;
//static guint gst_example_signals[LAST_SIGNAL] = { 0 };
/* This array holds the ids of the signals registered for this object.
* The array indexes are based on the enum up above.
*/
static guint gst_example_signals[LAST_SIGNAL] = { 0 };
/* This function is used to register and subsequently return the type
* identifier for this object class. On first invocation, it will
* register the type, providing the name of the class, struct sizes,
* and pointers to the various functions that define the class.
*/
GtkType
gst_example_get_type(void)
{
@ -90,8 +128,8 @@ gst_example_get_type(void)
sizeof(GstExampleClass),
(GtkClassInitFunc)gst_example_class_init,
(GtkObjectInitFunc)gst_example_init,
(GtkArgSetFunc)gst_example_set_arg,
(GtkArgGetFunc)gst_example_get_arg,
(GtkArgSetFunc)NULL, /* These last three are depracated */
(GtkArgGetFunc)NULL,
(GtkClassInitFunc)NULL,
};
example_type = gtk_type_unique(GST_TYPE_ELEMENT,&example_info);
@ -99,70 +137,151 @@ gst_example_get_type(void)
return example_type;
}
/* In order to create an instance of an object, the class must be
* initialized by this function. GtkObject will take care of running
* it, based on the pointer to the function provided above.
*/
static void
gst_example_class_init (GstExampleClass *klass)
{
/* Class pointers are needed to supply pointers to the private
* implementations of parent class methods.
*/
GtkObjectClass *gtkobject_class;
GstElementClass *gstelement_class;
/* Since the example class contains the parent classes, you can simply
* cast the pointer to get access to the parent classes.
*/
gtkobject_class = (GtkObjectClass*)klass;
gstelement_class = (GstElementClass*)klass;
/* The parent class is needed for class method overrides. */
parent_class = gtk_type_class(GST_TYPE_ELEMENT);
/* Here we add an argument to the object. This argument is an integer,
* and can be both read and written.
*/
gtk_object_add_arg_type("GstExample::active", GTK_TYPE_INT,
GTK_ARG_READWRITE, ARG_ACTIVE);
/* The last thing is to provide the functions that implement get and set
* of arguments.
*/
gtkobject_class->set_arg = gst_example_set_arg;
gtkobject_class->get_arg = gst_example_get_arg;
}
/* This function is responsible for initializing a specific instance of
* the plugin.
*/
static void
gst_example_init(GstExample *example)
{
/* First we create the sink pad, which is the input to the element.
* We will use the sink_template constructed in the plugin_init function
* (below) to quickly generate the pad we need.
*/
example->sinkpad = gst_pad_new_from_template (sink_template, "sink");
gst_element_add_pad(GST_ELEMENT(example),example->sinkpad);
/* Setting the chain function allows us to supply the function that will
* actually be performing the work. Without this, the element would do
* nothing, with undefined results (assertion failures and such).
*/
gst_pad_set_chain_function(example->sinkpad,gst_example_chain);
/* We then must add this pad to the element's list of pads. The base
* element class manages the list of pads, and provides accessors to it.
*/
gst_element_add_pad(GST_ELEMENT(example),example->sinkpad);
/* The src pad, the output of the element, is created and registered
* in the same way, with the exception of the chain function. Source
* pads don't have chain functions, because they can't accept buffers,
* they only produce them.
*/
example->srcpad = gst_pad_new_from_template (src_template, "src");
gst_element_add_pad(GST_ELEMENT(example),example->srcpad);
/* Initialization of element's private variables. */
example->active = FALSE;
}
/* The chain function is the heart of the element. It's where all the
* work is done. It is passed a pointer to the pad in question, as well
* as the buffer provided by the peer element.
*/
static void
gst_example_chain (GstPad *pad, GstBuffer *buf)
{
GstExample *example;
GstBuffer *outbuf;
/* Some of these checks are of dubious value, since if there were not
* already true, the chain function would never be called.
*/
g_return_if_fail(pad != NULL);
g_return_if_fail(GST_IS_PAD(pad));
g_return_if_fail(buf != NULL);
//g_return_if_fail(GST_IS_BUFFER(buf));
g_return_if_fail(GST_IS_BUFFER(buf));
/* We need to get a pointer to the element this pad belogs to. */
example = GST_EXAMPLE(gst_pad_get_parent (pad));
/* A few more sanity checks to make sure that the element that owns
* this pad is the right kind of element, in case something got confused.
*/
g_return_if_fail(example != NULL);
g_return_if_fail(GST_IS_EXAMPLE(example));
/* If we are supposed to be doing something, here's where it happens. */
if (example->active) {
/* DO STUFF */
}
/* In this example we're going to copy the buffer to another one,
* so we need to allocate a new buffer first.
outbuf = gst_buffer_new();
gst_pad_push(example->srcpad,buf);
/* We need to copy the size and offset of the buffer at a minimum. */
GST_BUFFER_SIZE (outbuf) = GST_BUFFER_SIZE (buf);
GST_BUFFER_OFFSET (outbuf) = GST_BUFFER_OFFSET (buf);
/* Then allocate the memory for the new buffer */
GST_BUFFER_DATA (outbuf) = (guchar *)g_malloc (GST_BUFFER_SIZE (outbuf));
/* Then copy the data in the incoming buffer into the new buffer. */
memcpy (GST_BUFFER_DATA (outbuf), GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (outbuf));
/* When we're done with the buffer, we push it on to the next element
* in the pipeline, through the element's source pad, which is stored
* in the element's structure.
*/
gst_pad_push(example->srcpad,outbuf);
/* If we're not doing something, just send the original incoming buffer. */
} else {
gst_pad_push(example->srcpad,buf);
}
}
/* Arguments are part of the Gtk+ object system, and these functions
* enable the element to respond to various arguments.
*/
static void
gst_example_set_arg (GtkObject *object,GtkArg *arg,guint id)
{
GstExample *example;
/* it's not null if we got it, but it might not be ours */
/* It's not null if we got it, but it might not be ours */
g_return_if_fail(GST_IS_EXAMPLE(object));
/* Get a pointer of the right type. */
example = GST_EXAMPLE(object);
switch(id) {
/* Check the argument id to see which argument we're setting. */
switch (id) {
case ARG_ACTIVE:
/* Here we simply copy the value of the argument to our private
* storage. More complex operations can be done, but beware that
* they may occur at any time, possibly even while your chain function
* is running, if you are using threads.
*/
example->active = GTK_VALUE_INT(*arg);
g_print("example: set active to %d\n",example->active);
break;
@ -171,12 +290,13 @@ gst_example_set_arg (GtkObject *object,GtkArg *arg,guint id)
}
}
/* The set function is simply the inverse of the get fuction. */
static void
gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id)
{
GstExample *example;
/* it's not null if we got it, but it might not be ours */
/* It's not null if we got it, but it might not be ours */
g_return_if_fail(GST_IS_EXAMPLE(object));
example = GST_EXAMPLE(object);
@ -190,25 +310,45 @@ gst_example_get_arg (GtkObject *object,GtkArg *arg,guint id)
}
}
/* This is the entry into the plugin itself. When the plugin loads,
* this function is called to register everything that the plugin provides.
*/
GstPlugin*
plugin_init (GModule *module)
{
GstPlugin *plugin;
GstElementFactory *factory;
/* First we try to create a new Plugin structure. */
plugin = gst_plugin_new("example");
/* If we get a NULL back, chances are we're already loaded. */
g_return_val_if_fail(plugin != NULL, NULL);
/* We need to create an ElementFactory for each element we provide.
* This consists of the name of the element, the GtkType identifier,
* and a pointer to the details structure at the top of the file.
*/
factory = gst_elementfactory_new("example", GST_TYPE_EXAMPLE, &example_details);
g_return_val_if_fail(factory != NULL, NULL);
/* The pad templates can be easily generated from the factories above,
* and then added to the list of padtemplates for the elementfactory.
* Note that the generated padtemplates are stored in static global
* variables, for the gst_example_init function to use later on.
*/
sink_template = gst_padtemplate_new (&sink_factory);
gst_elementfactory_add_padtemplate (factory, sink_template);
src_template = gst_padtemplate_new (&src_factory);
gst_elementfactory_add_padtemplate (factory, src_template);
/* The very last thing is to register the elementfactory with the plugin. */
gst_plugin_add_factory (plugin, factory);
/* Now we can return the pointer to the newly created Plugin object. */
return plugin;
/* At this point, the GStreamer core registers the plugin, its
* elementfactories, padtemplates, etc., for use in you application.
*/
}

32
tests/old/examples/plugins/example.h
View file

@ -28,36 +28,58 @@ extern "C" {
#endif /* __cplusplus */
/* Definition of structure storing data for this element. */
/* This is the definition of the element's object structure. */
typedef struct _GstExample GstExample;
/* The structure itself is derived from GstElement, as can be seen by the
* fact that there's a complete instance of the GstElement structure at
* the beginning of the object. This allows the element to be cast to
* an Element or even an Object.
*/
struct _GstExample {
GstElement element;
/* We need to keep track of our pads, so we do so here. */
GstPad *sinkpad,*srcpad;
gint8 active;
/* We'll use this to decide whether to do anything to the data we get. */
gboolean active;
};
/* Standard definition defining a class for this element. */
/* The other half of the object is its class. The class also derives from
* the same parent, though it must be the class structure this time.
* Function pointers for polymophic methods and signals are placed in this
* structure. */
typedef struct _GstExampleClass GstExampleClass;
struct _GstExampleClass {
GstElementClass parent_class;
};
/* Standard macros for defining types for this element. */
/* Five standard preprocessing macros are used in the Gtk+ object system.
* The first uses the object's _get_type function to return the GtkType
* of the object.
*/
#define GST_TYPE_EXAMPLE \
(gst_example_get_type())
/* The second is a checking cast to the correct type. If the object passed
* is not the right type, a warning will be generated on stderr.
*/
#define GST_EXAMPLE(obj) \
(GTK_CHECK_CAST((obj),GST_TYPE_EXAMPLE,GstExample))
/* The third is a checking cast of the class instead of the object. */
#define GST_EXAMPLE_CLASS(klass) \
(GTK_CHECK_CLASS_CAST((klass),GST_TYPE_EXAMPLE,GstExample))
/* The last two simply check to see if the passed pointer is an object or
* class of the correct type. */
#define GST_IS_EXAMPLE(obj) \
(GTK_CHECK_TYPE((obj),GST_TYPE_EXAMPLE))
#define GST_IS_EXAMPLE_CLASS(obj) \
(GTK_CHECK_CLASS_TYPE((klass),GST_TYPE_EXAMPLE))
/* Standard function returning type information. */
/* This is the only prototype needed, because it is used in the above
* GST_TYPE_EXAMPLE macro.
*/
GtkType gst_example_get_type(void);