field and playlist provisional implementations

[melted] / src / framework / mlt_field.c

diff --git a/src/framework/mlt_field.c b/src/framework/mlt_field.c
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+/*
+ * mlt_field.c -- A field for planting multiple transitions and filters
+ * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
+ * Author: Charles Yates <charles.yates@pandora.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include "mlt_field.h"
+#include "mlt_service.h"
+#include "mlt_filter.h"
+#include "mlt_transition.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+/** Private structures.
+*/
+
+struct mlt_field_s
+{
+       // We extending service here
+       struct mlt_service_s parent;
+
+       // This is the producer we're connected to
+       mlt_service producer;
+};
+
+/** Forward declarations
+*/
+
+static int service_get_frame( mlt_service service, mlt_frame_ptr frame, int index );
+
+/** Constructor. This service needs to know its producer at construction.
+
+       When the first filter or transition is planted, we connect it immediately to
+       the producer of the field, and all subsequent plants are then connected to the
+       previous plant. This immediate connection requires the producer prior to the first
+       plant.
+       
+       It's a kind of arbitrary decsion - we could generate a dummy service here and 
+       then connect the dummy in the normal connect manner. Behaviour may change in the
+       future (say, constructing a dummy when producer service is NULL). However, the
+       current solution is quite clean, if slightly out of sync with the rest of the
+       mlt framework.
+*/
+
+mlt_field mlt_field_init( mlt_service producer )
+{
+       // Initialise the field
+       mlt_field this = calloc( sizeof( struct mlt_field_s ), 1 );
+
+       // Get the service
+       mlt_service service = &this->parent;
+
+       // Initialise the service
+       mlt_service_init( service, this );
+
+       // Override the get_frame method
+       service->get_frame = service_get_frame;
+
+       // Connect to the producer immediately
+       if ( mlt_service_connect_producer( service, producer, 0 ) == 0 )
+               this->producer = producer;
+
+       // Return this
+       return this;
+}
+
+/** Get the service associated to this field.
+*/
+
+mlt_service mlt_field_service( mlt_field this )
+{
+       return &this->parent;
+}
+
+/** Get the properties associated to this field.
+*/
+
+mlt_properties mlt_field_properties( mlt_field this )
+{
+       return mlt_service_properties( &this->parent );
+}
+
+/** Plant a filter.
+*/
+
+int mlt_field_plant_filter( mlt_field this, mlt_filter that, int track )
+{
+       // Connect the filter to the last producer
+       int result = mlt_filter_connect( that, this->producer, track );
+
+       // If sucessful, then we'll use this for connecting in the future
+       if ( result == 0 )
+       {
+               // Update last
+               this->producer = mlt_filter_service( that );
+       }
+
+       return result;
+}
+
+/** Plant a transition.
+*/
+
+int mlt_field_plant_transition( mlt_field this, mlt_transition that, int a_track, int b_track )
+{
+       // Connect the transition to the last producer
+       int result = mlt_transition_connect( that, this->producer, a_track, b_track );
+
+       // If sucessful, then we'll use this for connecting in the future
+       if ( result == 0 )
+       {
+               // Update last
+               this->producer = mlt_transition_service( that );
+       }
+
+       return 0;
+}
+
+/** Get a frame.
+*/
+
+static int service_get_frame( mlt_service service, mlt_frame_ptr frame, int index )
+{
+       mlt_field this = service->child;
+       return mlt_service_get_frame( this->producer, frame, index );
+}
+
+/** Close the field.
+*/
+
+void mlt_field_close( mlt_field this )
+{
+       mlt_service_close( &this->parent );
+       free( this );
+}
+