Mercurial > hg > svcore
view base/ZoomConstraint.h @ 1551:4de4284d0596
Merge from branch zoom
author | Chris Cannam |
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date | Wed, 10 Oct 2018 08:44:15 +0100 |
parents | 1f72a44f5638 |
children | 05c3fbaec8ea |
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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */ /* Sonic Visualiser An audio file viewer and annotation editor. Centre for Digital Music, Queen Mary, University of London. This file copyright 2006 Chris Cannam. 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. See the file COPYING included with this distribution for more information. */ #ifndef SV_ZOOM_CONSTRAINT_H #define SV_ZOOM_CONSTRAINT_H #include <stdlib.h> #include "ZoomLevel.h" /** * ZoomConstraint is a simple interface that describes a limitation on * the available zoom sizes for a view, for example based on cache * strategy or a (processing) window-size limitation. * * The default ZoomConstraint imposes no actual constraint except for * a nominal maximum. */ class ZoomConstraint { public: virtual ~ZoomConstraint() { } enum RoundingDirection { RoundDown, RoundUp, RoundNearest }; /** * Given an "ideal" zoom level (frames per pixel or pixels per * frame) for a given zoom level, return the nearest viable block * size for this constraint. * * For example, if a block size of 1523 frames per pixel is * requested but the underlying model only supports value * summaries at powers-of-two block sizes, return 1024 or 2048 * depending on the rounding direction supplied. */ virtual ZoomLevel getNearestZoomLevel(ZoomLevel requestedZoomLevel, RoundingDirection = RoundNearest) const { if (getMaxZoomLevel() < requestedZoomLevel) return getMaxZoomLevel(); else return requestedZoomLevel; } /** * Return the minimum zoom level within range for this constraint. * Individual views will probably want to limit this, for example * in order to ensure that at least one or two samples fit in the * current window size, or in order to save on interpolation cost. */ virtual ZoomLevel getMinZoomLevel() const { return { ZoomLevel::PixelsPerFrame, 512 }; } /** * Return the maximum zoom level within range for this constraint. * This is quite large -- individual views will probably want to * limit how far a user might reasonably zoom out based on other * factors such as the duration of the file. */ virtual ZoomLevel getMaxZoomLevel() const { return { ZoomLevel::FramesPerPixel, 4194304 }; // 2^22, arbitrarily } }; #endif