gstreamer/gst/autoplug/gstsearchfuncs.c

/* GStreamer
 * Copyright (C) 1999-2002 Erik Walthinsen <omega@cse.ogi.edu>
 *               2000-2002 Wim Taymans <wtay@chello.be>
 *
 * gstsearchfuncs.c: functions needed when doing searches while
 *                   autoplugging
 *
 * 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 "gstsearchfuncs.h"

/* function that really misses in GLib
 */
void
g_list_free_list_and_elements (GList *list)
{
	GList *walk = list;
	
	while (walk)
	{
		g_free (walk->data);
		walk = g_list_next (walk);
	}
	g_list_free (list);
}

/**
 * gst_autoplug_can_connect_src:
 * @fac: factory to connect to
 * @src: caps to check
 *
 * Checks if a factory's sink can connect to the given caps
 *
 * Return: TRUE, if a connection can be established.
 */
GstPadTemplate *
gst_autoplug_can_connect_src (GstElementFactory *fac, GstCaps *src)
{
	GList *templs;
	
	templs = fac->padtemplates;
	
	while (templs)
	{
		if ((GST_PADTEMPLATE_DIRECTION (templs->data) == GST_PAD_SINK) && gst_caps_check_compatibility(src, GST_PADTEMPLATE_CAPS (templs->data)))
		{
			return GST_PADTEMPLATE (templs->data);
		}
    templs = g_list_next (templs);
	}
	
	return NULL;	
}
/**
 * gst_autoplug_can_connect_sink:
 * @fac: factory to connect to
 * @src: caps to check
 *
 * Checks if a factory's src can connect to the given caps
 *
 * Return: TRUE, if a connection can be established.
 */
GstPadTemplate *
gst_autoplug_can_connect_sink (GstElementFactory *fac, GstCaps *sink)
{
	GList *templs;
	
	templs = fac->padtemplates;
	
	while (templs)
	{
		if ((GST_PADTEMPLATE_DIRECTION (templs->data) == GST_PAD_SRC) && gst_caps_check_compatibility(GST_PADTEMPLATE_CAPS (templs->data), sink))
		{
			return GST_PADTEMPLATE (templs->data);
		}
    templs = g_list_next (templs);
	}
	
	return NULL;	
}
GstPadTemplate *
gst_autoplug_can_match (GstElementFactory *src, GstElementFactory *dest)
{
  GList *srctemps, *desttemps;

  srctemps = src->padtemplates;

  while (srctemps) {
    GstPadTemplate *srctemp = (GstPadTemplate *)srctemps->data;

    desttemps = dest->padtemplates;

    while (desttemps) {
      GstPadTemplate *desttemp = (GstPadTemplate *)desttemps->data;

      if (srctemp->direction == GST_PAD_SRC &&
          desttemp->direction == GST_PAD_SINK) {
          if (gst_caps_check_compatibility (gst_padtemplate_get_caps (srctemp), 
              gst_padtemplate_get_caps (desttemp))) {
            GST_DEBUG (GST_CAT_AUTOPLUG_ATTEMPT,
                       "factory \"%s\" can connect with factory \"%s\"\n", 
								       GST_OBJECT_NAME (src), GST_OBJECT_NAME (dest));
            return desttemp;
	       }
      }

      desttemps = g_list_next (desttemps);
    }
    srctemps = g_list_next (srctemps);
  }
  GST_DEBUG (GST_CAT_AUTOPLUG_ATTEMPT,
		         "factory \"%s\" cannot connect with factory \"%s\"\n", 
	           GST_OBJECT_NAME (src), GST_OBJECT_NAME (dest));
  return NULL;
}

/* returns TRUE if the factory has padtemplates with the specified direction */
gboolean
gst_autoplug_factory_has_direction (GstElementFactory *fac, GstPadDirection dir)
{
	GList *templs = fac->padtemplates;
	
	while (templs)
	{
		if (GST_PADTEMPLATE_DIRECTION (templs->data) == dir)
		{
			return TRUE;
		}
		templs = g_list_next (templs);
	}
	
	return FALSE;
}

/* Decisions are based on the padtemplates. 
 * These functions return a new list so be sure to free it.
 */
GList *
gst_autoplug_factories_sinks (GList *factories)
{
	GList *ret = NULL;
	
	while (factories)
	{
		if (gst_autoplug_factory_has_sink (factories->data))
			ret = g_list_prepend (ret, factories->data);
		factories = g_list_next (factories);
  }
	return ret;	
}
GList *
gst_autoplug_factories_srcs (GList *factories)
{
	GList *ret = NULL;
	
	while (factories)
	{
		if (gst_autoplug_factory_has_src (factories->data))
			ret = g_list_prepend (ret, factories->data);
		factories = g_list_next (factories);
  }
	return ret;	
}
GList *	
gst_autoplug_factories_filters (GList *factories)
{
	GList *ret = NULL;
	
	while (factories)
	{
		/* if you want it faster do src/sink check at once, don't call two functions */
		if (gst_autoplug_factory_has_src (factories->data) && gst_autoplug_factory_has_sink (factories->data))
			ret = g_list_prepend (ret, factories->data);
		factories = g_list_next (factories);
  }
	return ret;	
}


/* returns all factories which have sinks with non-NULL caps and srcs with
 * any caps.
 */
GList *
gst_autoplug_factories_filters_with_sink_caps (GList *factories)
{
	GList *ret = NULL;
	
	while (factories)
	{
		GList *templs = ((GstElementFactory *) factories->data)->padtemplates;
		gboolean have_src = FALSE;
		gboolean have_sink = FALSE;
		while (templs)
		{
			if (GST_PADTEMPLATE_DIRECTION (templs->data) == GST_PAD_SRC)
			{
				have_src = TRUE;
			}	
			if ((GST_PADTEMPLATE_DIRECTION (templs->data) == GST_PAD_SINK) && (GST_PADTEMPLATE_CAPS (templs->data) != NULL))
			{
				have_sink = TRUE;
			}
			if (have_src && have_sink)
			{
				ret = g_list_prepend (ret, factories->data);
				break;
			}
			templs = g_list_next (templs);
		}
		factories = g_list_next (factories);
	}
	return ret;
}



/* returns all factories which have a maximum of maxtemplates GstPadTemplates in direction dir
 */
GList *
gst_autoplug_factories_at_most_templates(GList *factories, GstPadDirection dir, guint maxtemplates)
{
	GList *ret = NULL;
	
	while (factories)
	{
		guint count = 0;
		GList *templs = ((GstElementFactory *) factories->data)->padtemplates;

		while (templs)
		{
			if (GST_PADTEMPLATE_DIRECTION (templs->data) == dir)
			{
				count++;
			}
			if (count > maxtemplates)
				break;
			templs = g_list_next (templs);
		}
		if (count <= maxtemplates)
		  ret = g_list_prepend (ret, factories->data);
		
		factories = g_list_next (factories);
	}
	return ret;
}
/*********************************************************************
 *
 * SHORTEST PATH ALGORITHM
 */
/**
 * gst_autoplug_sp:
 * @srccaps: Caps to plug from
 * @sinkcaps: Caps to plug to
 * @factories: GList containing all allowed #GstElementFactory entries
 *
 * main function 
 *
 * Returns: a GList of GstElementFactory items which have to be connected to get
 *          the shortest path.
 */
GList *
gst_autoplug_sp (GstCaps *srccaps, GstCaps *sinkcaps, GList *factories)
{
	GList *factory_nodes = NULL;
	guint curcost = GST_AUTOPLUG_MAX_COST; /* below this cost, there is no path */
	GstAutoplugNode *bestnode = NULL; /* best (unconnected) endpoint currently */
	
	GST_INFO (GST_CAT_AUTOPLUG_ATTEMPT, "attempting to autoplug via shortest path");
  GST_DEBUG (GST_CAT_AUTOPLUG_ATTEMPT, "trying to plug %s to %s\n", gst_caps_get_mime (srccaps), gst_caps_get_mime (sinkcaps));
  /* g_print ("trying to plug %s to %s\n", gst_caps_get_mime (srccaps), gst_caps_get_mime (sinkcaps)); */
	/* wrap all factories as GstAutoplugNode 
	 * initialize the cost */
	while (factories)
	{
		GstAutoplugNode *node = g_new0 (GstAutoplugNode, 1);
		node->prev = NULL;
		node->fac = (GstElementFactory *) factories->data;
		node->templ = gst_autoplug_can_connect_src (node->fac, srccaps);
		node->cost = (node->templ ? gst_autoplug_get_cost (node->fac) : GST_AUTOPLUG_MAX_COST);
		node->endpoint = gst_autoplug_can_connect_sink (node->fac, sinkcaps);
		if ((node->endpoint != NULL) && (bestnode == NULL || (node->cost < bestnode->cost)))
		{
			bestnode = node;
		}
		factory_nodes = g_list_prepend (factory_nodes, node);
		/* make curcost the minimum cost of any plugin */
		curcost = node->cost < curcost ? node->cost : curcost;
		factories = g_list_next (factories);
	}
	
	/* check if we even have possible endpoints */
	if (bestnode == NULL)
	{
		GST_DEBUG (GST_CAT_AUTOPLUG_ATTEMPT, "no factory found that could connect to sink caps\n");
		g_list_free_list_and_elements (factory_nodes);
		return NULL;
	}
	
	/* iterate until we found the best path */
	while (curcost < GST_AUTOPLUG_MAX_COST)
	{
		GList *nodes = factory_nodes;
		guint nextcost = GST_AUTOPLUG_MAX_COST; /* next cost to check */
		GST_DEBUG (GST_CAT_AUTOPLUG_ATTEMPT, "iterating at current cost %d, bestnode %s at %d\n", curcost, GST_OBJECT_NAME (bestnode->fac), bestnode->cost);
		/* check if we already have a valid best connection to the sink */
		if (bestnode->cost <= curcost)
		{
			GList *ret;
			GST_DEBUG (GST_CAT_AUTOPLUG_ATTEMPT, "found a way to connect via %s\n", GST_OBJECT_NAME ((GstObject *) bestnode->fac));		
			/* enter all factories into the return list */
			ret = g_list_prepend (NULL, bestnode->fac);
			bestnode = bestnode->prev;
			while (bestnode != NULL)
			{
				ret = g_list_prepend (ret, bestnode->fac);
				bestnode = bestnode->prev;
			}
			g_list_free_list_and_elements (factory_nodes);
			return ret;
		}
		
		/* iterate over all factories we have
		 * if they have the current cost, calculate if this
		 * factory supplies shorter paths to other elements
		 */
		while (nodes)
		{
			if (((GstAutoplugNode *) nodes->data)->cost == curcost)
			{
				/* now check all elements if we got a shorter path */
				GList *sinknodes = factory_nodes;
				GstAutoplugNode *srcnode = (GstAutoplugNode *) nodes->data;
				while (sinknodes)
				{
					GstAutoplugNode *sinknode = (GstAutoplugNode *) sinknodes->data;
					GstPadTemplate *templ;
					if ((sinknode->cost > srcnode->cost + gst_autoplug_get_cost (sinknode->fac)) && (templ = gst_autoplug_can_match(srcnode->fac, sinknode->fac)))
					{
						/* we got a shorter path
						 * now enter that path to that node */
						sinknode->prev = srcnode;
						sinknode->templ = templ;
						sinknode->cost = srcnode->cost + gst_autoplug_get_cost (sinknode->fac);
						/* make sure to set which cost to view next */
						nextcost = (nextcost > sinknode->cost) ? sinknode->cost : nextcost;
						/* did we get a new best node? */
						if (sinknode->endpoint && (sinknode->cost < bestnode->cost))
						{
							bestnode = sinknode;
						}			
					}
					sinknodes = g_list_next (sinknodes);
				}
				/* FIXME: for speed remove the item we just iterated with from the factory_nodes
				 * but don't free it yet and don't forget to free it.
				 */
			}
		  nodes = g_list_next (nodes);
		}
		curcost = nextcost;
	}
	
	GST_DEBUG (GST_CAT_AUTOPLUG_ATTEMPT, "found no path from source caps to sink caps\n");		
	g_list_free_list_and_elements (factory_nodes);
	return NULL;	
}