annotate base/Layer.h @ 6:44bbf5793d84

* 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 _VIEWER_H_
#define _VIEWER_H_

#include "PropertyContainer.h"
#include "XmlExportable.h"

#include <QObject>
#include <QRect>
#include <QXmlAttributes>

class ZoomConstraint;
class Model;
class QPainter;
class View;

/**
 * The base class for visual representations of the data found in a
 * Model.  Layers are expected to be able to draw themselves onto a
 * View, and may also be editable.
 */

class Layer : public QObject,
	      public PropertyContainer,
	      public XmlExportable
{
    Q_OBJECT

public:
    Layer(View *w);
    virtual ~Layer();

    virtual const Model *getModel() const = 0;
    virtual const ZoomConstraint *getZoomConstraint() const { return 0; }
    virtual void paint(QPainter &, QRect) const = 0;   

    enum VerticalPosition {
	PositionTop, PositionMiddle, PositionBottom
    };
    virtual VerticalPosition getPreferredTimeRulerPosition() const {
	return PositionMiddle;
    }
    virtual VerticalPosition getPreferredFrameCountPosition() const {
	return PositionBottom;
    }

    virtual QString getPropertyContainerName() const {
	return objectName();
    }

    virtual int getVerticalScaleWidth(QPainter &) const { return 0; }
    virtual void paintVerticalScale(QPainter &, QRect) const { }

    virtual QRect getFeatureDescriptionRect(QPainter &, QPoint) const {
	return QRect(0, 0, 0, 0);
    }
    virtual void paintLocalFeatureDescription(QPainter &, QRect, QPoint) const {
    }

    /**
     * This should return true if the view can safely be scrolled
     * automatically by the widget (simply copying the existing data
     * and then refreshing the exposed area) without altering its
     * meaning.  For the widget as a whole this is usually not
     * possible because of invariant (non-scrolling) material
     * displayed over the top, but the widget may be able to optimise
     * scrolling better if it is known that individual views can be
     * scrolled safely in this way.
     */
    virtual bool isLayerScrollable() const { return true; }

    /**
     * Return the proportion of background work complete in drawing
     * this view, as a percentage -- in most cases this will be the
     * value returned by pointer from a call to the underlying model's
     * isReady(int *) call.  The widget may choose to show a progress
     * meter if it finds that this returns < 100 at any given moment.
     */
    virtual int getCompletion() const { return 100; }

    virtual void setObjectName(const QString &name);

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

    virtual void setProperties(const QXmlAttributes &) = 0;

signals:
    void modelChanged();
    void modelCompletionChanged();
    void modelChanged(size_t startFrame, size_t endFrame);
    void modelReplaced();

    void layerParametersChanged();
    void layerNameChanged();

protected:
    View *m_view;
};

#endif