view layer/WaveformLayer.h @ 11:2d5005f2b3d9

* Rework handling of layer properties in file I/O -- we now get the individual
  layers to load and save them rather than doing it via generic property lists
  in the base class, so as to ensure we read and write meaningful values rather
  than generic int values requiring conversion.

/* -*- 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 _WAVEFORM_VIEW_H_
#define _WAVEFORM_VIEW_H_

#include <QRect>
#include <QColor>

#include "base/Layer.h"

#include "model/RangeSummarisableTimeValueModel.h"

class View;
class QPainter;
class QPixmap;

class WaveformLayer : public Layer
{
    Q_OBJECT

public:
    WaveformLayer(View *w);
    ~WaveformLayer();

    virtual const ZoomConstraint *getZoomConstraint() const { return m_model; }
    virtual const Model *getModel() const { return m_model; }
    virtual void paint(QPainter &paint, QRect rect) const;

    virtual int getVerticalScaleWidth(QPainter &) const;
    virtual void paintVerticalScale(QPainter &paint, QRect rect) const;

    void setModel(const RangeSummarisableTimeValueModel *model);

    virtual PropertyList getProperties() const;
    virtual PropertyType getPropertyType(const PropertyName &) const;
    virtual QString getPropertyGroupName(const PropertyName &) const;
    virtual int getPropertyRangeAndValue(const PropertyName &,
					   int *min, int *max) const;
    virtual QString getPropertyValueLabel(const PropertyName &,
					  int value) const;
    virtual void setProperty(const PropertyName &, int value);

    /**
     * Set the gain multiplier for sample values in this view.
     *
     * The default is 1.0.
     */
    void setGain(float gain);
    float getGain() const { return m_gain; }

    /**
     * Set the basic display colour for waveforms.
     *
     * The default is black.
     *!!! NB should default to white if the associated View !hasLightBackground()
     */
    void setBaseColour(QColor);
    QColor getBaseColour() const { return m_colour; }

    /**
     * Set whether to display mean values as a lighter-coloured area
     * beneath the peaks.  Rendering will be slightly faster without
     * but arguably prettier with.
     *
     * The default is to display means.
     */
    void setShowMeans(bool);
    bool getShowMeans() const { return m_showMeans; }

    /**
     * Set whether to use shades of grey (or of the base colour) to
     * provide additional perceived vertical resolution (i.e. using
     * half-filled pixels to represent levels that only just meet the
     * pixel unit boundary).  This provides a small improvement in
     * waveform quality at a small cost in rendering speed.
     * 
     * The default is to use greyscale.
     */
    void setUseGreyscale(bool);
    bool getUseGreyscale() const { return m_greyscale; }


    enum ChannelMode { SeparateChannels, MergeChannels };

    /**
     * Specify whether multi-channel audio data should be displayed
     * with a separate axis per channel (SeparateChannels), or with a
     * single synthetic axis showing channel 0 above the axis and
     * channel 1 below (MergeChannels).
     * 
     * MergeChannels does not work for files with more than 2
     * channels.
     * 
     * The default is SeparateChannels.
     */
    void setChannelMode(ChannelMode);
    ChannelMode getChannelMode() const { return m_channelMode; }


    /**
     * Specify the channel to use from the source model.  A value of
     * -1 means to show all available channels (laid out to the
     * channel mode). The default is -1.
     */
    void setChannel(int);
    int getChannel() const { return m_channel; }


    enum Scale { LinearScale, MeterScale, dBScale };

    /**
     * Specify the vertical scale for sample levels.  With LinearScale,
     * the scale is directly proportional to the raw [-1, +1)
     * floating-point audio sample values.  With dBScale the
     * vertical scale is proportional to dB level (truncated at
     * -50dB).  MeterScale provides a hybrid variable scale based on
     * IEC meter scale, intended to provide a clear overview at
     * relatively small heights.
     *
     * Note that the effective gain (see setGain()) is applied before
     * vertical scaling.
     *
     * The default is LinearScale.
     */
    void setScale(Scale);
    Scale getScale() const { return m_scale; }

    /**
     * Enable or disable aggressive pixmap cacheing.  If enabled,
     * waveforms will be rendered to an off-screen pixmap and
     * refreshed from there instead of being redrawn from the peak
     * data each time.  This may be faster if the data and zoom level
     * do not change often, but it may be slower for frequently zoomed
     * data and it will only work if the waveform is the "bottom"
     * layer on the displayed widget, as each refresh will erase
     * anything beneath the waveform.
     *
     * This is intended specifically for a panner widget display in
     * which the waveform never moves, zooms, or changes, but some
     * graphic such as a panner outline is frequently redrawn over the
     * waveform.  This situation would necessitate a lot of waveform
     * refresh if the default cacheing strategy was used.
     *
     * The default is not to use aggressive cacheing.
     */
    void setAggressiveCacheing(bool);
    bool getAggressiveCacheing() const { return m_aggressive; }

    virtual int getCompletion() const;

    virtual QString getPropertyContainerIconName() const { return "waveform"; }

    virtual QString toXmlString(QString indent = "",
				QString extraAttributes = "") const;

    void setProperties(const QXmlAttributes &attributes);

protected:
    int dBscale(float sample, int m) const;

    const RangeSummarisableTimeValueModel *m_model; // I do not own this

    /// Return value is number of channels displayed
    size_t getChannelArrangement(size_t &min, size_t &max, bool &merging) const;

    float        m_gain;
    QColor       m_colour;
    bool         m_showMeans;
    bool         m_greyscale;
    ChannelMode  m_channelMode;
    int          m_channel;
    Scale        m_scale;
    bool         m_aggressive;

    mutable QPixmap *m_cache;
    mutable bool m_cacheValid;
    mutable int m_cacheZoomLevel;
};

#endif