gst/gstutils.h

   1 /* GStreamer
   2  * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
   3  *                    2000 Wim Taymans <wtay@chello.be>
   4  *
   5  * gstutils.h: Header for various utility functions
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Library General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Library General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Library General Public
  18  * License along with this library; if not, write to the
  19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20  * Boston, MA 02111-1307, USA.
  21  */
  22
  23
  24 #ifndef __GST_UTILS_H__
  25 #define __GST_UTILS_H__
  26
  27 #include <glib.h>
  28 #include <gst/gstelement.h>
  29
  30 G_BEGIN_DECLS
  31
  32 void            gst_util_set_value_from_string  (GValue *value, const gchar *value_str);
  33 void            gst_util_set_object_arg         (GObject *object, const gchar *name, const gchar *value);
  34
  35 void            gst_util_dump_mem               (guchar *mem, guint size);
  36
  37 void            gst_print_pad_caps              (GString *buf, gint indent, GstPad *pad);
  38 void            gst_print_element_args          (GString *buf, gint indent, GstElement *element);
  39
  40
  41 /* Macros for defining classes.  Ideas taken from Bonobo, which took theirs
  42    from Nautilus and GOB. */
  43
  44 /* Define the boilerplate type stuff to reduce typos and code size.  Defines
  45    the get_type method and the parent_class static variable.
  46    void additional_initializations (GType type) is for initializing interfaces
  47    and stuff like that */
  48
  49 #define GST_BOILERPLATE_FULL(type, type_as_function, parent_type,               \
  50     parent_type_macro, additional_initializations)                              \
  51                                                                                 \
  52 static void type_as_function ## _base_init     (gpointer      g_class);         \
  53 static void type_as_function ## _class_init    (type ## Class *g_class);        \
  54 static void type_as_function ## _init          (type          *object);         \
  55 static parent_type ## Class *parent_class = NULL;                               \
  56 static void                                                                     \
  57 type_as_function ## _class_init_trampoline (gpointer g_class,                   \
  58                                             gpointer data)                      \
  59 {                                                                               \
  60   parent_class = (parent_type ## Class *) g_type_class_peek_parent (g_class);   \
  61   type_as_function ## _class_init ((type ## Class *)g_class);                   \
  62 }                                                                               \
  63                                                                                 \
  64 GType                                                                           \
  65 type_as_function ## _get_type (void)                                            \
  66 {                                                                               \
  67   static GType object_type = 0;                                                 \
  68   if (object_type == 0) {                                                       \
  69     static const GTypeInfo object_info = {                                      \
  70       sizeof (type ## Class),                                                   \
  71       type_as_function ## _base_init,                                           \
  72       NULL,               /* base_finalize */                                   \
  73       type_as_function ## _class_init_trampoline,                               \
  74       NULL,               /* class_finalize */                                  \
  75       NULL,               /* class_data */                                      \
  76       sizeof (type),                                                            \
  77       0,                  /* n_preallocs */                                     \
  78       (GInstanceInitFunc) type_as_function ## _init                             \
  79     };                                                                          \
  80     object_type = g_type_register_static (parent_type_macro, #type,             \
  81         &object_info, 0);                                                       \
  82     additional_initializations (object_type);                                   \
  83   }                                                                             \
  84   return object_type;                                                           \
  85 }
  86
  87 #define __GST_DO_NOTHING(type)  /* NOP */
  88 #define GST_BOILERPLATE(type,type_as_function,parent_type,parent_type_macro)    \
  89   GST_BOILERPLATE_FULL (type, type_as_function, parent_type, parent_type_macro, \
  90       __GST_DO_NOTHING)
  91
  92 /* Just call the parent handler.  This assumes that there is a variable
  93  * named parent_class that points to the (duh!) parent class.  Note that
  94  * this macro is not to be used with things that return something, use
  95  * the _WITH_DEFAULT version for that */
  96 #define GST_CALL_PARENT(parent_class_cast, name, args)                          \
  97         ((parent_class_cast(parent_class)->name != NULL) ?                      \
  98          parent_class_cast(parent_class)->name args : (void) 0)
  99
 100 /* Same as above, but in case there is no implementation, it evaluates
 101  * to def_return */
 102 #define GST_CALL_PARENT_WITH_DEFAULT(parent_class_cast, name, args, def_return) \
 103         ((parent_class_cast(parent_class)->name != NULL) ?                      \
 104          parent_class_cast(parent_class)->name args : def_return)
 105
 106
 107 G_END_DECLS
 108
 109 #endif /* __GST_UTILS_H__ */