Chris@49: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@0: 
Chris@0: /*
Chris@52:     Sonic Visualiser
Chris@52:     An audio file viewer and annotation editor.
Chris@52:     Centre for Digital Music, Queen Mary, University of London.
Chris@52:     This file copyright 2006 Chris Cannam.
Chris@0:     
Chris@52:     This program is free software; you can redistribute it and/or
Chris@52:     modify it under the terms of the GNU General Public License as
Chris@52:     published by the Free Software Foundation; either version 2 of the
Chris@52:     License, or (at your option) any later version.  See the file
Chris@52:     COPYING included with this distribution for more information.
Chris@0: */
Chris@0: 
Chris@1528: #ifndef SV_ZOOM_CONSTRAINT_H
Chris@1528: #define SV_ZOOM_CONSTRAINT_H
Chris@0: 
Chris@0: #include <stdlib.h>
Chris@0: 
Chris@1532: #include "ZoomLevel.h"
Chris@1324: 
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@27:     virtual ~ZoomConstraint() { }
Chris@27: 
Chris@0:     enum RoundingDirection {
Chris@1429:         RoundDown,
Chris@1429:         RoundUp,
Chris@1429:         RoundNearest
Chris@0:     };
Chris@0: 
Chris@0:     /**
Chris@1324:      * Given an "ideal" zoom level (frames per pixel or pixels per
Chris@1324:      * frame) for a given zoom level, return the nearest viable block
Chris@1324:      * size for this 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@1324:     virtual ZoomLevel getNearestZoomLevel(ZoomLevel requestedZoomLevel,
Chris@1324:                                           RoundingDirection = RoundNearest)
Chris@1429:         const
Chris@0:     {
Chris@1552:         // canonicalise
Chris@1552:         if (requestedZoomLevel.level == 1) {
Chris@1552:             requestedZoomLevel.zone = ZoomLevel::FramesPerPixel;
Chris@1552:         }
Chris@1324:         if (getMaxZoomLevel() < requestedZoomLevel) return getMaxZoomLevel();
Chris@1324: 	else return requestedZoomLevel;
Chris@0:     }
Chris@12: 
Chris@160:     /**
Chris@1324:      * Return the minimum zoom level within range for this constraint.
Chris@1324:      * Individual views will probably want to limit this, for example
Chris@1324:      * in order to ensure that at least one or two samples fit in the
Chris@1324:      * current window size, or in order to save on interpolation cost.
Chris@1324:      */
Chris@1324:     virtual ZoomLevel getMinZoomLevel() const {
Chris@1543:         return { ZoomLevel::PixelsPerFrame, 512 };
Chris@1324:     }
Chris@1324:     
Chris@1324:     /**
Chris@160:      * Return the maximum zoom level within range for this constraint.
Chris@1102:      * This is quite large -- individual views will probably want to
Chris@1102:      * limit how far a user might reasonably zoom out based on other
Chris@1102:      * factors such as the duration of the file.
Chris@160:      */
Chris@1324:     virtual ZoomLevel getMaxZoomLevel() const {
Chris@1324:         return { ZoomLevel::FramesPerPixel, 4194304 }; // 2^22, arbitrarily
Chris@1324:     }
Chris@0: };
Chris@0: 
Chris@0: #endif
Chris@0: