annotate layer/LayerGeometryProvider.h @ 1127:9fb8dfd7ce4c spectrogram-minor-refactor

Fix threshold in spectrogram -- it wasn't working in the last release.
There is a new protocol for this. Formerly the threshold parameter had a
range from -50dB to 0 with the default at -50, and -50 treated internally
as "no threshold". However, there was a hardcoded, hidden internal threshold
for spectrogram colour mapping at -80dB with anything below this being rounded
to zero. Now the threshold parameter has range -81 to -1 with the default
at -80, -81 is treated internally as "no threshold", and there is no hidden
internal threshold. So the default behaviour is the same as before, an
effective -80dB threshold, but it is now possible to change this in both
directions. Sessions reloaded from prior versions may look slightly different
because, if the session says there should be no threshold, there will now
actually be no threshold instead of having the hidden internal one.

Still need to do something in the UI to make it apparent that the -81dB
setting removes the threshold entirely. This is at least no worse than the
previous, also obscured, magic -50dB setting.

/* -*- 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 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 LAYER_GEOMETRY_PROVIDER_H
#define LAYER_GEOMETRY_PROVIDER_H

#include "base/BaseTypes.h"

#include <QMutex>
#include <QMutexLocker>
#include <QPainter>

class ViewManager;
class View;
class Layer;

/**
 * Interface for classes that provide geometry information (such as
 * size, start frame, and a large number of other properties) about
 * the disposition of a layer. The main implementor of this interface
 * is the View class, but other implementations may be used in
 * different circumstances, e.g. as a proxy to handle hi-dpi
 * coordinate mapping.
 *
 * Note it is expected that some implementations of this may be
 * disposable, created on-the-fly for a single use. Code that receives
 * a LayerGeometryProvider pointer as an argument to something should
 * not, in general, store that pointer as it may be invalidated before
 * the next use. Use getId() to instead obtain a persistent identifier
 * for a LayerGeometryProvider, for example to establish whether the
 * same one is being provided in two separate calls.
 */
class LayerGeometryProvider
{
protected:
    static int getNextId() {
        static QMutex idMutex;
        static int nextId = 1;
        static int maxId = INT_MAX;
        QMutexLocker locker(&idMutex);
        int id = nextId;
        if (nextId == maxId) {
            // we don't expect this to happen in the lifetime of a
            // process, but it would be undefined behaviour if it did
            // since we're using a signed int, so we should really
            // guard for it...
            nextId = 1;
        } else {
            nextId++;
        }
        return id;
    }            
    
public:
    LayerGeometryProvider() { }
    
    /**
     * Retrieve the id of this object.
     */
    virtual int getId() const = 0;

    /**
     * Retrieve the first visible sample frame on the widget.
     * This is a calculated value based on the centre-frame, widget
     * width and zoom level.  The result may be negative.
     */
    virtual sv_frame_t getStartFrame() const = 0;

    /**
     * Return the centre frame of the visible widget.  This is an
     * exact value that does not depend on the zoom block size.  Other
     * frame values (start, end) are calculated from this based on the
     * zoom and other factors.
     */
    virtual sv_frame_t getCentreFrame() const = 0;

    /**
     * Retrieve the last visible sample frame on the widget.
     * This is a calculated value based on the centre-frame, widget
     * width and zoom level.
     */
    virtual sv_frame_t getEndFrame() const = 0;

    /**
     * Return the pixel x-coordinate corresponding to a given sample
     * frame (which may be negative).
     */
    virtual int getXForFrame(sv_frame_t frame) const = 0;

    /**
     * Return the closest frame to the given pixel x-coordinate.
     */
    virtual sv_frame_t getFrameForX(int x) const = 0;

    virtual sv_frame_t getModelsStartFrame() const = 0;
    virtual sv_frame_t getModelsEndFrame() const = 0;

    /**
     * Return the closest pixel x-coordinate corresponding to a given
     * view x-coordinate.
     */
    virtual int getXForViewX(int viewx) const = 0;
    
    /**
     * Return the closest view x-coordinate corresponding to a given
     * pixel x-coordinate.
     */
    virtual int getViewXForX(int x) const = 0;
    
    /**
     * Return the (maybe fractional) pixel y-coordinate corresponding
     * to a given frequency, if the frequency range is as specified.
     * This does not imply any policy about layer frequency ranges,
     * but it might be useful for layers to match theirs up if
     * desired.
     *
     * Not thread-safe in logarithmic mode.  Call only from GUI thread.
     */
    virtual double getYForFrequency(double frequency,
                                    double minFreq, double maxFreq, 
                                    bool logarithmic) const = 0;

    /**
     * Return the closest frequency to the given (maybe fractional)
     * pixel y-coordinate, if the frequency range is as specified.
     *
     * Not thread-safe in logarithmic mode.  Call only from GUI thread.
     */
    virtual double getFrequencyForY(double y,
                                    double minFreq, double maxFreq,
                                    bool logarithmic) const = 0;

    virtual int getTextLabelHeight(const Layer *layer, QPainter &) const = 0;

    virtual bool getValueExtents(QString unit, double &min, double &max,
                                 bool &log) const = 0;

    /**
     * Return the zoom level, i.e. the number of frames per pixel
     */
    virtual int getZoomLevel() const = 0;

    /**
     * To be called from a layer, to obtain the extent of the surface
     * that the layer is currently painting to. This may be the extent
     * of the view (if 1x display scaling is in effect) or of a larger
     * cached pixmap (if greater display scaling is in effect).
     */
    virtual QRect getPaintRect() const = 0;

    virtual QSize getPaintSize() const { return getPaintRect().size(); }
    virtual int getPaintWidth() const { return getPaintRect().width(); }
    virtual int getPaintHeight() const { return getPaintRect().height(); }

    virtual bool hasLightBackground() const = 0;
    virtual QColor getForeground() const = 0;
    virtual QColor getBackground() const = 0;

    virtual ViewManager *getViewManager() const = 0;

    virtual bool shouldIlluminateLocalFeatures(const Layer *, QPoint &) const = 0;
    virtual bool shouldShowFeatureLabels() const = 0;

    virtual void drawMeasurementRect(QPainter &p, const Layer *,
                                     QRect rect, bool focus) const = 0;

    virtual void updatePaintRect(QRect r) = 0;
    
    virtual View *getView() = 0;
    virtual const View *getView() const = 0;
};

#endif