Chris@0: /* -*- c-basic-offset: 4 -*-  vi:set ts=8 sts=4 sw=4: */
Chris@0: 
Chris@0: /*
Chris@0:     A waveform viewer and audio annotation editor.
Chris@2:     Chris Cannam, Queen Mary University of London, 2005-2006
Chris@0:     
Chris@0:     This is experimental software.  Not for distribution.
Chris@0: */
Chris@0: 
Chris@0: #ifndef _ZOOM_CONSTRAINT_H_
Chris@0: #define _ZOOM_CONSTRAINT_H_
Chris@0: 
Chris@0: #include <stdlib.h>
Chris@0: 
Chris@0: /**
Chris@0:  * ZoomConstraint is a simple interface that describes a limitation on
Chris@0:  * the available zoom sizes for a view, for example based on cache
Chris@0:  * strategy or a (processing) window-size limitation.
Chris@0:  *
Chris@12:  * The default ZoomConstraint imposes no actual constraint except for
Chris@12:  * a nominal maximum.
Chris@0:  */
Chris@0: 
Chris@0: class ZoomConstraint
Chris@0: {
Chris@0: public:
Chris@0:     enum RoundingDirection {
Chris@0: 	RoundDown,
Chris@0: 	RoundUp,
Chris@0: 	RoundNearest
Chris@0:     };
Chris@0: 
Chris@0:     /**
Chris@0:      * Given the "ideal" block size (frames per pixel) for a given
Chris@0:      * zoom level, return the nearest viable block size for this
Chris@0:      * constraint.
Chris@0:      *
Chris@0:      * For example, if a block size of 1523 frames per pixel is
Chris@0:      * requested but the underlying model only supports value
Chris@0:      * summaries at powers-of-two block sizes, return 1024 or 2048
Chris@0:      * depending on the rounding direction supplied.
Chris@0:      */
Chris@0:     virtual size_t getNearestBlockSize(size_t requestedBlockSize,
Chris@0: 				       RoundingDirection = RoundNearest)
Chris@0: 	const
Chris@0:     {
Chris@12: 	if (requestedBlockSize > getMaxZoomLevel()) return getMaxZoomLevel();
Chris@12: 	else return requestedBlockSize;
Chris@0:     }
Chris@12: 
Chris@12:     virtual size_t getMaxZoomLevel() const { return 262144; }
Chris@0: };
Chris@0: 
Chris@0: #endif
Chris@0: