annotate layer/Colour3DPlotRenderer.h @ 1614:c6f5c822b10d

Fix potential divide-by-zero (depending on a race elsewhere)

/* -*- 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 2006-2016 Chris Cannam and QMUL.
    
    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 COLOUR_3D_PLOT_RENDERER_H
#define COLOUR_3D_PLOT_RENDERER_H

#include "ColourScale.h"
#include "ScrollableImageCache.h"
#include "ScrollableMagRangeCache.h"

#include "base/ColumnOp.h"
#include "base/MagnitudeRange.h"

#include "data/model/Model.h"

#include <QRect>
#include <QPainter>
#include <QImage>

class LayerGeometryProvider;
class VerticalBinLayer;
class RenderTimer;
class Dense3DModelPeakCache;
class DenseThreeDimensionalModel;

enum class BinDisplay {
    AllBins,
    PeakBins,
    PeakFrequencies
};

enum class BinScale {
    Linear,
    Log
};

class Colour3DPlotRenderer
{
public:
    struct Sources {
        Sources() : verticalBinLayer(0) { }
        
        // These must all outlive this class
        const VerticalBinLayer *verticalBinLayer; // always
        ModelId source; // always; a DenseThreeDimensionalModel
        ModelId fft; // optionally; an FFTModel; used for phase/peak-freq modes
        std::vector<ModelId> peakCaches; // zero or more
    };        

    struct Parameters {
        Parameters() :
            colourScale(ColourScale::Parameters()),
            normalization(ColumnNormalization::None),
            binDisplay(BinDisplay::AllBins),
            binScale(BinScale::Linear),
            alwaysOpaque(false),
            interpolate(false),
            invertVertical(false),
            showDerivative(false),
            scaleFactor(1.0),
            colourRotation(0) { }

        /** A complete ColourScale object by value, used for colour
         *  map conversion. Note that the final display gain setting is
         *  also encapsulated here. */
        ColourScale colourScale;

        /** Type of column normalization. */
        ColumnNormalization normalization;

        /** Selection of bins to display. */
        BinDisplay binDisplay;

        /** Scale for vertical bin spacing (linear or logarithmic). */
        BinScale binScale;

        /** Whether cells should always be opaque. If false, then
         *  large cells (when zoomed in a long way) will be rendered
         *  translucent in order not to obscure anything in a layer
         *  beneath. */
        bool alwaysOpaque;

        /** Whether to apply smoothing when rendering cells at more
         *  than one pixel per cell.  !!! todo: decide about separating
         *  out x-interpolate and y-interpolate as the spectrogram
         *  actually does (or used to)
         */
        bool interpolate;

        /** Whether to render the whole caboodle upside-down. */
        bool invertVertical;

        /** Whether to show the frame-to-frame difference instead of
         *  the actual value */
        bool showDerivative;

        /** Initial scale factor (e.g. for FFT scaling). This factor
         *  is applied to all values read from the underlying model
         *  *before* magnitude ranges are calculated, in contrast to
         *  the display gain found in the ColourScale parameter. */
        double scaleFactor;

        /** Colourmap rotation, in the range 0-255. */
        int colourRotation;
    };
    
    Colour3DPlotRenderer(Sources sources, Parameters parameters) :
        m_sources(sources),
        m_params(parameters),
        m_secondsPerXPixel(0.0),
        m_secondsPerXPixelValid(false)
    { }

    struct RenderResult {
        /**
         * The rect that was actually rendered. May be equal to the
         * rect that was requested to render, or may be smaller if
         * time ran out and the complete flag was not set.
         */
        QRect rendered;

        /**
         * The magnitude range of the data in the rendered area, after
         * initial scaling (parameters.scaleFactor) and normalisation,
         * for use in displaying colour scale etc. (Note that the
         * magnitude range *before* normalisation would not be very
         * meaningful for this purpose, as the scale would need to be
         * different for every column if column or hybrid
         * normalisation was in use.)
         */
        MagnitudeRange range;
    };

    /**
     * Render the requested area using the given painter, obtaining
     * geometry (e.g. start frame) from the given
     * LayerGeometryProvider.
     *
     * The whole of the supplied rect will be rendered and the
     * returned QRect will be equal to the supplied QRect. (See
     * renderTimeConstrained for an alternative that may render only
     * part of the rect in cases where obtaining source data is slow
     * and retaining responsiveness is important.)
     *
     * Note that Colour3DPlotRenderer retains internal cache state
     * related to the size and position of the supplied
     * LayerGeometryProvider. Although it is valid to call render()
     * successively on the same Colour3DPlotRenderer with different
     * LayerGeometryProviders, it will be much faster to use a
     * dedicated Colour3DPlotRenderer for each LayerGeometryProvider.
     *
     * If the model to render from is not ready, this will throw a
     * std::logic_error exception. The model must be ready and the
     * layer requesting the render must not be dormant in its view, so
     * that the LayerGeometryProvider returns valid results; it is the
     * caller's responsibility to ensure these.
     */
    RenderResult render(const LayerGeometryProvider *v,
                        QPainter &paint, QRect rect);
    
    /**
     * Render the requested area using the given painter, obtaining
     * geometry (e.g. start frame) from the stored
     * LayerGeometryProvider.
     *
     * As much of the rect will be rendered as can be managed given
     * internal time constraints (using a RenderTimer object
     * internally). The returned QRect (the rendered field in the
     * RenderResult struct) will contain the area that was
     * rendered. Note that we always render the full requested height,
     * it's only width that is time-constrained.
     *
     * Note that Colour3DPlotRenderer retains internal cache state
     * related to the size and position of the supplied
     * LayerGeometryProvider. Although it is valid to call render()
     * successively on the same Colour3DPlotRenderer with different
     * LayerGeometryProviders, it will be much faster to use a
     * dedicated Colour3DPlotRenderer for each LayerGeometryProvider.
     *
     * If the model to render from is not ready, this will throw a
     * std::logic_error exception. The model must be ready and the
     * layer requesting the render must not be dormant in its view, so
     * that the LayerGeometryProvider returns valid results; it is the
     * caller's responsibility to ensure these.
     */
    RenderResult renderTimeConstrained(const LayerGeometryProvider *v,
                                       QPainter &paint, QRect rect);

    /**
     * Return the area of the largest rectangle within the entire area
     * of the cache that is unavailable in the cache. This is only
     * valid in relation to a preceding render() call which is
     * presumed to have set the area, start frame, and zoom level for
     * the cache. It could be used to establish a suitable region for
     * a subsequent paint request (because if an area is not in the
     * cache, it cannot have been rendered since the cache was
     * cleared).
     *
     * Returns an empty QRect if the cache is entirely valid.
     */
    QRect getLargestUncachedRect(const LayerGeometryProvider *v);

    /**
     * Return true if the provider's geometry differs from the cache,
     * or if we are not using a cache. i.e. if the cache will be
     * regenerated for the next render, or the next render performed
     * from scratch.
     */
    bool geometryChanged(const LayerGeometryProvider *v);
    
    /**
     * Return true if the rendering will be opaque. This may be used
     * by the calling layer to determine whether it can scroll
     * directly without regard to any other layers beneath.
     */
    bool willRenderOpaque(const LayerGeometryProvider *v) {
        return decideRenderType(v) != DirectTranslucent;
    }
    
    /**
     * Return the colour corresponding to the given value.
     * \see ColourScale::getPixel
     * \see ColourScale::getColour
     */
    QColor getColour(double value) const {
        return m_params.colourScale.getColour(value, m_params.colourRotation);
    }

    /**
     * Return the enclosing rectangle for the region of similar colour
     * to the given point within the cache. Return an empty QRect if
     * this is not possible. \see ImageRegionFinder
     */
    QRect findSimilarRegionExtents(QPoint point) const;
    
private:
    Sources m_sources;
    Parameters m_params;

    // Draw buffer is the target of each partial repaint. It is always
    // at view height (not model height) and is cleared and repainted
    // on each fragment render. The only reason it's stored as a data
    // member is to avoid reallocation.
    QImage m_drawBuffer;

    // A temporary store of magnitude ranges per-column, used when
    // rendering to the draw buffer. This always has the same length
    // as the width of the draw buffer, and the x coordinates of the
    // two containers are equivalent.
    std::vector<MagnitudeRange> m_magRanges;
    
    // The image cache is our persistent record of the visible
    // area. It is always the same size as the view (i.e. the paint
    // size reported by the LayerGeometryProvider) and is scrolled and
    // partially repainted internally as appropriate. A render request
    // is carried out by repainting to cache (via the draw buffer) any
    // area that is being requested but is not valid in the cache, and
    // then repainting from cache to the requested painter.
    ScrollableImageCache m_cache;

    // The mag range cache is our record of the column magnitude
    // ranges for each of the columns in the cache. It always has the
    // same start frame and width as the image cache, and the column
    // indices match up across both. Our cache update mechanism
    // guarantees that every valid column in the image cache has a
    // valid range in the magnitude cache, but not necessarily vice
    // versa (as the image cache is limited to contiguous ranges).
    ScrollableMagRangeCache m_magCache;

    double m_secondsPerXPixel;
    bool m_secondsPerXPixelValid;
    
    RenderResult render(const LayerGeometryProvider *v,
                        QPainter &paint, QRect rect, bool timeConstrained);

    MagnitudeRange renderDirectTranslucent(const LayerGeometryProvider *v,
                                           QPainter &paint, QRect rect);
    
    void renderToCachePixelResolution(const LayerGeometryProvider *v, int x0,
                                      int repaintWidth, bool rightToLeft,
                                      bool timeConstrained);

    void renderToCacheBinResolution(const LayerGeometryProvider *v, int x0,
                                    int repaintWidth);

    int renderDrawBuffer(int w, int h,
                         const std::vector<int> &binforx,
                         const std::vector<double> &binfory,
                         int peakCacheIndex, // -1 => don't use a peak cache
                         bool rightToLeft,
                         bool timeConstrained);

    int renderDrawBufferPeakFrequencies(const LayerGeometryProvider *v,
                                        int w, int h,
                                        const std::vector<int> &binforx,
                                        const std::vector<double> &binfory,
                                        bool rightToLeft,
                                        bool timeConstrained);
    
    void recreateDrawBuffer(int w, int h);
    void clearDrawBuffer(int w, int h);

    enum RenderType {
        DrawBufferPixelResolution,
        DrawBufferBinResolution,
        DirectTranslucent
    };

    RenderType decideRenderType(const LayerGeometryProvider *) const;

    QImage scaleDrawBufferImage(QImage source, int targetWidth, int targetHeight)
        const;
    
    ColumnOp::Column getColumn(int sx, int minbin, int nbins,
                               std::shared_ptr<DenseThreeDimensionalModel> source) const;
    ColumnOp::Column getColumnRaw(int sx, int minbin, int nbins,
                                  std::shared_ptr<DenseThreeDimensionalModel> source) const;

    void getPreferredPeakCache(const LayerGeometryProvider *,
                               int &peakCacheIndex, int &binsPerPeak) const;

    void updateTimings(const RenderTimer &timer, int xPixelCount);
};

#endif