76 lines
2.5 KiB
C++
76 lines
2.5 KiB
C++
/*
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GRID.hpp - time scale grid abstraction
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Copyright (C) Lumiera.org
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2011, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef LIB_TIME_GRID_H
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#define LIB_TIME_GRID_H
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#include "lib/time/timevalue.hpp"
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#include <tr1/memory>
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namespace lib {
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namespace time {
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/**
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* Abstraction of a value alignment grid.
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* Such a grid has an underlying scale (origin and measurement)
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* and is comprised of distinct grid intervals, which can be addressed
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* by a ordering number, centred at origin with interval number zero.
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* The typical example is a 25fps time frame grid, but indeed the
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* spacing of the intervals is not necessarily constant. An entity
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* defining such a grid provides functions to calculate the
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* grid coordinates and to convert back to plain values.
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* This includes a way of rounding to the next lower
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* grid point, usable for grid aligning values.
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*
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* \par usage
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* For one there is the lib::time::Quantiser, which directly
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* implements this interface and plays a central role when it comes
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* to converting continuous time into any kind of frame based timecode.
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* Besides that, the session stores asset::TimeGrid definitions, which
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* can be used to create a Quantiser suitable for some specific output
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* bus or rendering target format.
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*
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* @todo WIP-WIP-WIP
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* @todo maybe abstract this from Time altogether?
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*/
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class Grid
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{
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public:
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virtual ~Grid(); ///< this is an Interface
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virtual int64_t gridPoint (TimeValue const& raw) const =0;
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virtual TimeValue gridAlign (TimeValue const& raw) const =0;
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virtual TimeValue timeOf (int64_t gridPoint) const =0;
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virtual TimeValue timeOf (FSecs, int =0) const =0;
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};
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typedef std::tr1::shared_ptr<const Grid> PGrid;
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}} // lib::time
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#endif
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