view base/ZoomConstraint.h @ 10:ec6886f0e673

* Fix update and play limits for play-selection mode when not looping
* Fix playback in loop mode when no selection -- but the GUI update for
  this is still wrong on the flyback
* Various fixes and improvements to making selections, particularly during
  playback
* Draw selection under non-opaque non-scrollable layers, so as to improve
  cacheing
* Show selection limits as text when drawing selection
* Allow user to find missing audio files when loading session
* Cross-fade selections when in play-selection mode -- mostly.  We don't
  cross-fade on a processing block boundary, and unfortunately with short
  selections the selection boundary is quite likely to coincide with a block
  boundary.

/* -*- c-basic-offset: 4 -*-  vi:set ts=8 sts=4 sw=4: */

/*
    A waveform viewer and audio annotation editor.
    Chris Cannam, Queen Mary University of London, 2005-2006
    
    This is experimental software.  Not for distribution.
*/

#ifndef _ZOOM_CONSTRAINT_H_
#define _ZOOM_CONSTRAINT_H_

#include <stdlib.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.
 */

class ZoomConstraint
{
public:
    enum RoundingDirection {
	RoundDown,
	RoundUp,
	RoundNearest
    };

    /**
     * Given the "ideal" block size (frames per pixel) 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 size_t getNearestBlockSize(size_t requestedBlockSize,
				       RoundingDirection = RoundNearest)
	const
    {
	return requestedBlockSize;
    }
};

#endif