annotate data/model/Model.h @ 360:ac300d385ab2

* Various fixes to object lifetime management, particularly in the spectrum
  layer and for notification of main model deletion.
  The main purpose of this is to improve the behaviour of the spectrum, but I
  think it may also help with #1840922 Various crashes in Layer Summary window.

/* -*- 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 _MODEL_H_
#define _MODEL_H_

#include <vector>
#include <QObject>

#include "base/XmlExportable.h"

typedef std::vector<float> SampleBlock;

class ZoomConstraint;
class AlignmentModel;

/** 
 * Model is the base class for all data models that represent any sort
 * of data on a time scale based on an audio frame rate.
 */

class Model : public QObject,
	      public XmlExportable
{
    Q_OBJECT

public:
    virtual ~Model();

    /**
     * Return true if the model was constructed successfully.  Classes
     * that refer to the model should always test this before use.
     */
    virtual bool isOK() const = 0;

    /**
     * Return the first audio frame spanned by the model.
     */
    virtual size_t getStartFrame() const = 0;

    /**
     * Return the last audio frame spanned by the model.
     */
    virtual size_t getEndFrame() const = 0;

    /**
     * Return the frame rate in frames per second.
     */
    virtual size_t getSampleRate() const = 0;

    /**
     * Return the frame rate of the underlying material, if the model
     * itself has already been resampled.
     */
    virtual size_t getNativeRate() const { return getSampleRate(); }

    /**
     * Return the "work title" of the model, if known.
     */
    virtual QString getTitle() const;

    /**
     * Return the "artist" or "maker" of the model, if known.
     */
    virtual QString getMaker() const;

    /**
     * Return the location of the data in this model (e.g. source
     * URL).  This should not normally be returned for editable models
     * that have been edited.
     */
    virtual QString getLocation() const;

    /**
     * Return the type of the model.  For display purposes only.
     */
    virtual QString getTypeName() const = 0;

    /**
     * Return a copy of this model.
     *
     * If the model is not editable, this may be effectively a shallow
     * copy.  If the model is editable, however, this operation must
     * properly copy all of the model's editable data.
     *
     * In general this operation is not useful for non-editable dense
     * models such as waveforms, because there may be no efficient
     * copy operation implemented -- for such models it is better not
     * to copy at all.
     *
     * Caller owns the returned value.
     */
    virtual Model *clone() const = 0;
    
    /**
     * Return true if the model has finished loading or calculating
     * all its data, for a model that is capable of calculating in a
     * background thread.  The default implementation is appropriate
     * for a thread that does not background any work but carries out
     * all its calculation from the constructor or accessors.
     *
     * If "completion" is non-NULL, this function should return
     * through it an estimated percentage value showing how far
     * through the background operation it thinks it is (for progress
     * reporting).  If it has no way to calculate progress, it may
     * return the special value COMPLETION_UNKNOWN.
     */
    virtual bool isReady(int *completion = 0) const {
	bool ok = isOK();
	if (completion) *completion = (ok ? 100 : 0);
	return ok;
    }
    static const int COMPLETION_UNKNOWN;

    /**
     * If this model imposes a zoom constraint, i.e. some limit to the
     * set of resolutions at which its data can meaningfully be
     * displayed, then return it.
     */
    virtual const ZoomConstraint *getZoomConstraint() const {
        return 0;
    }

    /**
     * If this model was derived from another, return the model it was
     * derived from.  The assumption is that the source model's
     * alignment will also apply to this model, unless some other
     * property (such as a specific alignment model set on this model)
     * indicates otherwise.
     */
    virtual Model *getSourceModel() const {
        return m_sourceModel;
    }

    /**
     * Set the source model for this model.
     */
    virtual void setSourceModel(Model *model);

    /**
     * Specify an aligment between this model's timeline and that of a
     * reference model.  The alignment model records both the
     * reference and the alignment.  This model takes ownership of the
     * alignment model.
     */
    virtual void setAlignment(AlignmentModel *alignment);

    /**
     * Return the reference model for the current alignment timeline,
     * if any.
     */
    virtual const Model *getAlignmentReference() const;

    /**
     * Return the frame number of the reference model that corresponds
     * to the given frame number in this model.
     */
    virtual size_t alignToReference(size_t frame) const;

    /**
     * Return the frame number in this model that corresponds to the
     * given frame number of the reference model.
     */
    virtual size_t alignFromReference(size_t referenceFrame) const;

    /**
     * Return the completion percentage for the alignment model: 100
     * if there is no alignment model or it has been entirely
     * calculated, or less than 100 if it is still being calculated.
     */
    virtual int getAlignmentCompletion() const;

    virtual void toXml(QTextStream &stream,
                       QString indent = "",
                       QString extraAttributes = "") const;

    virtual QString toDelimitedDataString(QString) const { return ""; }

public slots:
    void aboutToDelete();
    void sourceModelAboutToBeDeleted();

signals:
    /**
     * Emitted when a model has been edited (or more data retrieved
     * from cache, in the case of a cached model that generates slowly)
     */
    void modelChanged();

    /**
     * Emitted when a model has been edited (or more data retrieved
     * from cache, in the case of a cached model that generates slowly)
     */
    void modelChanged(size_t startFrame, size_t endFrame);

    /**
     * Emitted when some internal processing has advanced a stage, but
     * the model has not changed externally.  Views should respond by
     * updating any progress meters or other monitoring, but not
     * refreshing the actual view.
     */
    void completionChanged();

    /**
     * Emitted when the completion percentage changes for the
     * calculation of this model's alignment model.
     */
    void alignmentCompletionChanged();

    /**
     * Emitted when something notifies this model (through calling
     * aboutToDelete() that it is about to delete it.  Note that this
     * depends on an external agent such as a Document object or
     * owning model telling the model that it is about to delete it;
     * there is nothing in the model to guarantee that this signal
     * will be emitted before the actual deletion.
     */
    void aboutToBeDeleted();

protected:
    Model() : m_sourceModel(0), m_alignment(0), m_aboutToDelete(false) { }

    // Not provided.
    Model(const Model &);
    Model &operator=(const Model &); 

    Model *m_sourceModel;
    AlignmentModel *m_alignment;
    bool m_aboutToDelete;
};

#endif