annotate base/ZoomConstraint.h @ 1429:48e9f538e6e9

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author Chris Cannam
date Thu, 01 Mar 2018 18:02:22 +0000
parents 12f3b48668d4
children 710e6250a401 a7485c1bdba5
rev   line source
Chris@49 1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
Chris@0 2
Chris@0 3 /*
Chris@52 4 Sonic Visualiser
Chris@52 5 An audio file viewer and annotation editor.
Chris@52 6 Centre for Digital Music, Queen Mary, University of London.
Chris@52 7 This file copyright 2006 Chris Cannam.
Chris@0 8
Chris@52 9 This program is free software; you can redistribute it and/or
Chris@52 10 modify it under the terms of the GNU General Public License as
Chris@52 11 published by the Free Software Foundation; either version 2 of the
Chris@52 12 License, or (at your option) any later version. See the file
Chris@52 13 COPYING included with this distribution for more information.
Chris@0 14 */
Chris@0 15
Chris@0 16 #ifndef _ZOOM_CONSTRAINT_H_
Chris@0 17 #define _ZOOM_CONSTRAINT_H_
Chris@0 18
Chris@0 19 #include <stdlib.h>
Chris@0 20
Chris@0 21 /**
Chris@0 22 * ZoomConstraint is a simple interface that describes a limitation on
Chris@0 23 * the available zoom sizes for a view, for example based on cache
Chris@0 24 * strategy or a (processing) window-size limitation.
Chris@0 25 *
Chris@12 26 * The default ZoomConstraint imposes no actual constraint except for
Chris@12 27 * a nominal maximum.
Chris@0 28 */
Chris@0 29
Chris@0 30 class ZoomConstraint
Chris@0 31 {
Chris@0 32 public:
Chris@27 33 virtual ~ZoomConstraint() { }
Chris@27 34
Chris@0 35 enum RoundingDirection {
Chris@1429 36 RoundDown,
Chris@1429 37 RoundUp,
Chris@1429 38 RoundNearest
Chris@0 39 };
Chris@0 40
Chris@0 41 /**
Chris@0 42 * Given the "ideal" block size (frames per pixel) for a given
Chris@0 43 * zoom level, return the nearest viable block size for this
Chris@0 44 * constraint.
Chris@0 45 *
Chris@0 46 * For example, if a block size of 1523 frames per pixel is
Chris@0 47 * requested but the underlying model only supports value
Chris@0 48 * summaries at powers-of-two block sizes, return 1024 or 2048
Chris@0 49 * depending on the rounding direction supplied.
Chris@0 50 */
Chris@928 51 virtual int getNearestBlockSize(int requestedBlockSize,
Chris@1429 52 RoundingDirection = RoundNearest)
Chris@1429 53 const
Chris@0 54 {
Chris@1429 55 if (requestedBlockSize > getMaxZoomLevel()) return getMaxZoomLevel();
Chris@1429 56 else return requestedBlockSize;
Chris@0 57 }
Chris@12 58
Chris@160 59 /**
Chris@160 60 * Return the maximum zoom level within range for this constraint.
Chris@1102 61 * This is quite large -- individual views will probably want to
Chris@1102 62 * limit how far a user might reasonably zoom out based on other
Chris@1102 63 * factors such as the duration of the file.
Chris@160 64 */
Chris@1102 65 virtual int getMaxZoomLevel() const { return 4194304; } // 2^22, arbitrarily
Chris@0 66 };
Chris@0 67
Chris@0 68 #endif
Chris@0 69