Make the formats dynamic so that plugins can register new seek/query formats

Original commit message from CVS:
Make the formats dynamic so that plugins can register new seek/query
formats

gst/Makefile.am

@@ -64,6 +64,7 @@ libgstreamer_la_SOURCES =		\
 	gstelementfactory.c	\
 	gstevent.c		\
 	gstextratypes.c		\
+	gstformat.c		\
 	gstinfo.c		\
 	gstmemchunk.c		\
 	gstpad.c		\

gst/gst.c

@@ -351,6 +351,7 @@ init_post (void)
   GST_INFO (GST_CAT_GST_INIT, "Initializing GStreamer Core Library version %s %s",
             GST_VERSION, _gst_use_threads?"":"(no threads)");
   
+  _gst_format_initialize ();
   gst_object_get_type ();
   gst_pad_get_type ();
   gst_real_pad_get_type ();

gst/gstformat.c

@@ -0,0 +1,161 @@
+/* GStreamer
+ * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
+ *                    2000 Wim Taymans <wim.taymans@chello.be>
+ *
+ * gstformat.c: GstFormat registration
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * 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 GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gstlog.h"
+
+#include "gstformat.h"
+
+static GList *_gst_formats = NULL;
+static gint  _n_values = 1; /* we start from 1 because 0 reserved for UNDEFINED */
+
+typedef struct _GstFormatDefinition GstFormatDefinition;
+
+struct _GstFormatDefinition 
+{
+  GstFormat  value;
+  gchar     *nick;
+  gchar     *description;
+};
+
+static GstFormatDefinition standard_definitions[] = {
+  { GST_FORMAT_DEFAULT, "default", "Default" },
+  { GST_FORMAT_BYTES,   "bytes",   "Bytes" },
+  { GST_FORMAT_TIME, 	"time",    "Time" }, 
+  { GST_FORMAT_BUFFERS, "buffers", "Buffers" },
+  { GST_FORMAT_PERCENT, "percent", "Percent" },
+  { GST_FORMAT_UNITS,   "units",   "Units as defined by the media type" },
+  { 0, NULL, NULL }
+};
+
+void		
+_gst_format_initialize (void)
+{
+  GstFormatDefinition *standards = standard_definitions;
+
+  while (standards->nick) {
+    _gst_formats = g_list_prepend (_gst_formats, standards);
+    standards++;
+  }
+}
+
+/**
+ * gst_format_register:
+ * @nick: The nick of the new format
+ * @description: The description of the new format
+ *
+ * Create a new GstFormat based on the nick or return an
+ * allrady registered format with that nick
+ *
+ * Returns: A new GstFormat or an already registered format
+ * with the same nick.
+ */
+GstFormat
+gst_format_register (const gchar *nick, const gchar *description)
+{
+  GstFormatDefinition *format;
+  GstFormat query;
+  
+  g_return_val_if_fail (nick != NULL, 0);
+  g_return_val_if_fail (description != NULL, 0);
+
+  query = gst_format_get_by_nick (nick);
+  if (query != GST_FORMAT_UNDEFINED)
+    return query;
+  
+  format = g_new0 (GstFormatDefinition, 1);
+  format->value = _n_values;
+  format->nick = g_strdup (nick);
+  format->description = g_strdup (description);
+
+  _gst_formats = g_list_prepend (_gst_formats, format);
+
+  _n_values++;
+  
+  return format->value;
+}
+
+/**
+ * gst_format_get_by_nick:
+ * @nick: The nick of the format
+ *
+ * Return the format registered with the given nick. 
+ *
+ * Returns: The format with @nick or GST_FORMAT_UNDEFINED
+ * if the format was not registered.
+ */
+GstFormat
+gst_format_get_by_nick (const gchar *nick)
+{
+  GList *walk;
+  GstFormatDefinition *format;
+  
+  g_return_val_if_fail (nick != NULL, 0);
+
+  walk = _gst_formats;
+
+  while (walk) {
+    format = (GstFormatDefinition *) walk->data;
+    
+    if (!strcmp (format->nick, nick))
+      return format->value;
+
+    walk = g_list_next (walk);
+  }
+
+  return GST_FORMAT_UNDEFINED;
+}
+
+/**
+ * gst_format_get_details:
+ * @format: The format to get details of
+ * @nick: The nick of the format
+ * @description: The description of the format
+ *
+ * Get details about the given format.
+ *
+ * Returns: TRUE if the format was registered, FALSE otherwise
+ */
+gboolean
+gst_format_get_details (GstFormat format, const gchar **nick, const gchar **description)
+{
+  GList *walk;
+  GstFormatDefinition *walk_format;
+
+  g_return_val_if_fail (nick != NULL, FALSE);
+  g_return_val_if_fail (description != NULL, FALSE);
+
+  walk = _gst_formats;
+
+  while (walk) {
+    walk_format = (GstFormatDefinition *) walk->data;
+    
+    if (walk_format->value == format) {
+      *nick = walk_format->nick;
+      *description = walk_format->description;
+
+      return TRUE;
+    }
+
+    walk = g_list_next (walk);
+  }
+  return FALSE;
+}

gst/gstformat.h

@@ -2,7 +2,8 @@
  * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
  *                    2000 Wim Taymans <wim.taymans@chello.be>
  *
- * gstformat.h: Header for GstFormat types of offset
+ * gstformat.h: Header for GstFormat types used in queries and
+ *              seeking.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -29,14 +30,14 @@
 G_BEGIN_DECLS
 
 typedef enum {
-  GST_FORMAT_NONE   	= 0,
+  GST_FORMAT_UNDEFINED 	=  0,
-  GST_FORMAT_DEFAULT   	= 1,
+  GST_FORMAT_DEFAULT   	=  1,
-  GST_FORMAT_BYTES   	= 2,
+  GST_FORMAT_BYTES   	=  2,
-  GST_FORMAT_TIME 	= 3,
+  GST_FORMAT_TIME 	=  3,
-  GST_FORMAT_BUFFERS	= 4,
+  GST_FORMAT_BUFFERS	=  4,
-  GST_FORMAT_PERCENT	= 5,
+  GST_FORMAT_PERCENT	=  5,
   /* samples for audio, frames/fields for video */
-  GST_FORMAT_UNITS 	= 6,
+  GST_FORMAT_UNITS 	=  6,
 } GstFormat;
 
 #define GST_FORMATS_FUNCTION(functionname, a...)     \
@@ -50,6 +51,16 @@ functionname (GstPad *pad)                           \
   return formats;                                    \
 }
 
+void		_gst_format_initialize		(void);
+
+/* register a new format */
+GstFormat	gst_format_register		(const gchar *nick, const gchar *description);
+
+GstFormat	gst_format_get_by_nick		(const gchar *nick);
+
+/* query for format details */
+gboolean	gst_format_get_details		(GstFormat format, const gchar **nick, const gchar **description);
+
 
 G_END_DECLS