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87 lines
3 KiB
C
87 lines
3 KiB
C
/* GStreamer
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* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#ifndef __GST_EXAMPLE_H__
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#define __GST_EXAMPLE_H__
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#include <gst/gst.h>
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G_BEGIN_DECLS
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/* This is the definition of the element's object structure. */
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typedef struct _GstExample GstExample;
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/* The structure itself is derived from GstElement, as can be seen by the
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* fact that there's a complete instance of the GstElement structure at
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* the beginning of the object. This allows the element to be cast to
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* an Element or even an Object.
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*/
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struct _GstExample {
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GstElement element;
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/* We need to keep track of our pads, so we do so here. */
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GstPad *sinkpad,*srcpad;
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/* We'll use this to decide whether to do anything to the data we get. */
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gboolean active;
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};
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/* The other half of the object is its class. The class also derives from
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* the same parent, though it must be the class structure this time.
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* Function pointers for polymophic methods and signals are placed in this
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* structure. */
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typedef struct _GstExampleClass GstExampleClass;
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struct _GstExampleClass {
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GstElementClass parent_class;
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/* signals */
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void (*asdf) (GstElement *element, GstExample *example);
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};
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/* Five standard preprocessing macros are used in the GLib object system.
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* The first uses the object's _get_type function to return the GType
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* of the object.
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*/
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#define GST_TYPE_EXAMPLE \
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(gst_example_get_type())
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/* The second is a checking cast to the correct type. If the object passed
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* is not the right type, a warning will be generated on stderr.
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*/
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#define GST_EXAMPLE(obj) \
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(G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_EXAMPLE,GstExample))
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/* The third is a checking cast of the class instead of the object. */
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#define GST_EXAMPLE_CLASS(klass) \
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(G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_EXAMPLE,GstExampleClass))
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/* The last two simply check to see if the passed pointer is an object or
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* class of the correct type. */
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#define GST_IS_EXAMPLE(obj) \
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(G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_EXAMPLE))
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#define GST_IS_EXAMPLE_CLASS(obj) \
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(G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_EXAMPLE))
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/* This is the only prototype needed, because it is used in the above
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* GST_TYPE_EXAMPLE macro.
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*/
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GType gst_example_get_type(void);
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G_END_DECLS
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#endif /* __GST_EXAMPLE_H__ */
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