lumiera_/src/steam/mobject/output-designation.hpp

137 lines
4.6 KiB
C++

/*
OUTPUT-DESIGNATION.hpp - specifying a desired output destination
Copyright (C) Lumiera.org
2010, Hermann Vosseler <Ichthyostega@web.de>
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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/** @file output-designation.hpp
** Core abstraction: symbolic representation of some output target.
** An OutputDesignation represents something you might want to connect to
** or towards which you'd like to direct output. It might be _absolute,_ in
** which case it represents an actual output device attached to the system,
** or it might be relative, as a placeholder for further wiring and output routing.
** An example for the latter would be the "master bus".
**
** The concept of an OutputDesignation plays a crucial role to allow flexible connection
** and rearrangement of media content. It allows to build partial structures, which can
** be connected automatically to a suitable output when placed into the appropriate context.
** In the end, the Builder will resolve all output designations, finally leading to a fixed
** set of exit nodes, which can be pulled to deliver content.
*/
#ifndef STEAM_MOBJECT_OUTPUT_DESIGNATION_H
#define STEAM_MOBJECT_OUTPUT_DESIGNATION_H
#include "steam/asset/pipe.hpp"
#include "lib/hash-value.h"
#include "lib/opaque-holder.hpp"
#include "lib/meta/typelist-manip.hpp"
namespace steam {
namespace mobject {
namespace mp = lib::meta;
class MObject;
template<class MX>
class PlacementRef;
typedef PlacementRef<MObject> RefPlacement;
/**
* Descriptor to denote the desired target of produced media data.
* OutputDesignation is always an internal and relative specification
* and boils down to referring an asset::Pipe by ID. In order to become
* actually effective, some object within the model additionally
* needs to _claim_ this pipe-ID, meaning that this object
* states to root and represent this pipe. When the builder
* encounters a pair of (OutputDesignation, OutputClaim),
* an actual stream connection will be wired in the
* processing node network.
*
* @todo couldn't the inline buffer be "downgraded" to InPlaceBuffer or PolymorphicValue??
* Seemingly we never-ever need to re-discover the erased type of the embedded spec.
* Thus for this to work, we'd just need to add an "empty" spec ///////////////////TICKET #723
*
* @see OutputMapping_test
*/
class OutputDesignation
{
public:
using PID = asset::ID<asset::Pipe>;
using PPipe = asset::PPipe;
explicit OutputDesignation (PID explicitTarget);
explicit OutputDesignation (RefPlacement const& indirectTarget);
explicit OutputDesignation (uint relative_busNr =0);
// using default copying
/** retrieve the direct destination
* this descriptor is actually pointing to.
* In case of a target pipe not explicitly specified
* this might involve a resolution step and take the
* current context into account.
* @param origin starting point for figuring out connections
* @return a pipe-ID, which should be used as next connection.
* This might not be the final designation, but the
* directly visible next pipe to connect to
*/
PID
resolve (PPipe origin)
{
return spec_->resolve (origin);
}
//TODO: API to retrieve target stream type
class TargetSpec
{
public:
virtual ~TargetSpec();
virtual PID resolve (PPipe origin) =0;
};
private:
enum
{ VTABLE = sizeof(size_t)
, SPEC_SIZ = VTABLE
+ mp::maxSize<
mp::Types< PID, lumiera_uid, uint>::List>::value
};
typedef lib::OpaqueHolder<TargetSpec, SPEC_SIZ> SpecBuff;
/** Storage to hold the Target Spec inline */
SpecBuff spec_;
};
}} // namespace steam::mobject
#endif /*STEAM_MOBJECT_OUTPUT_DESIGNATION_H*/