comparison layer/Colour3DPlotRenderer.cpp @ 1216:dc2af6616c83

Merge from branch 3.0-integration

+/* -*- 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.
+*/
+
+#include "Colour3DPlotRenderer.h"
+#include "RenderTimer.h"
+
+#include "base/Profiler.h"
+#include "base/HitCount.h"
+
+#include "data/model/DenseThreeDimensionalModel.h"
+#include "data/model/Dense3DModelPeakCache.h"
+#include "data/model/FFTModel.h"
+
+#include "LayerGeometryProvider.h"
+#include "VerticalBinLayer.h"
+#include "PaintAssistant.h"
+#include "ImageRegionFinder.h"
+
+#include "view/ViewManager.h" // for main model sample rate. Pity
+
+#include <vector>
+
+//#define DEBUG_COLOUR_PLOT_REPAINT 1
+
+using namespace std;
+
+Colour3DPlotRenderer::RenderResult
+Colour3DPlotRenderer::render(const LayerGeometryProvider *v, QPainter &paint, QRect rect)
+{
+    return render(v, paint, rect, false);
+}
+
+Colour3DPlotRenderer::RenderResult
+Colour3DPlotRenderer::renderTimeConstrained(const LayerGeometryProvider *v,
+                                            QPainter &paint, QRect rect)
+{
+    return render(v, paint, rect, true);
+}
+
+QRect
+Colour3DPlotRenderer::getLargestUncachedRect(const LayerGeometryProvider *v)
+{
+    RenderType renderType = decideRenderType(v);
+
+    if (renderType == DirectTranslucent) {
+        return QRect(); // never cached
+    }
+
+    int h = m_cache.getSize().height();
+
+    QRect areaLeft(0, 0, m_cache.getValidLeft(), h);
+    QRect areaRight(m_cache.getValidRight(), 0,
+                    m_cache.getSize().width() - m_cache.getValidRight(), h);
+
+    if (areaRight.width() > areaLeft.width()) {
+        return areaRight;
+    } else {
+        return areaLeft;
+    }
+}
+
+bool
+Colour3DPlotRenderer::geometryChanged(const LayerGeometryProvider *v)
+{
+    RenderType renderType = decideRenderType(v);
+
+    if (renderType == DirectTranslucent) {
+        return true; // never cached
+    }
+
+    if (m_cache.getSize() == v->getPaintSize() &&
+        m_cache.getZoomLevel() == v->getZoomLevel() &&
+        m_cache.getStartFrame() == v->getStartFrame()) {
+        return false;
+    } else {
+        return true;
+    }
+}
+
+Colour3DPlotRenderer::RenderResult
+Colour3DPlotRenderer::render(const LayerGeometryProvider *v,
+                             QPainter &paint, QRect rect, bool timeConstrained)
+{
+    RenderType renderType = decideRenderType(v);
+
+    if (renderType != DrawBufferPixelResolution) {
+        // Rendering should be fast in bin-resolution and direct draw
+        // cases because we are quite well zoomed-in, and the sums are
+        // easier this way. Calculating boundaries later will be
+        // fiddly for partial paints otherwise.
+        timeConstrained = false;
+    }
+
+    int x0 = v->getXForViewX(rect.x());
+    int x1 = v->getXForViewX(rect.x() + rect.width());
+    if (x0 < 0) x0 = 0;
+    if (x1 > v->getPaintWidth()) x1 = v->getPaintWidth();
+
+    sv_frame_t startFrame = v->getStartFrame();
+    
+    m_cache.resize(v->getPaintSize());
+    m_cache.setZoomLevel(v->getZoomLevel());
+
+    m_magCache.resize(v->getPaintSize().width());
+    m_magCache.setZoomLevel(v->getZoomLevel());
+    
+    if (renderType == DirectTranslucent) {
+        MagnitudeRange range = renderDirectTranslucent(v, paint, rect);
+        return { rect, range };
+    }
+    
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "cache start " << m_cache.getStartFrame()
+         << " valid left " << m_cache.getValidLeft()
+         << " valid right " << m_cache.getValidRight()
+         << endl;
+    SVDEBUG << " view start " << startFrame
+         << " x0 " << x0
+         << " x1 " << x1
+         << endl;
+#endif
+
+    static HitCount count("Colour3DPlotRenderer: image cache");
+    
+    if (m_cache.isValid()) { // some part of the cache is valid
+
+        if (v->getXForFrame(m_cache.getStartFrame()) ==
+            v->getXForFrame(startFrame) &&
+            m_cache.getValidLeft() <= x0 &&
+            m_cache.getValidRight() >= x1) {
+
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+            SVDEBUG << "cache hit" << endl;
+#endif
+            count.hit();
+            
+            // cache is valid for the complete requested area
+            paint.drawImage(rect, m_cache.getImage(), rect);
+
+            MagnitudeRange range = m_magCache.getRange(x0, x1 - x0);
+
+            return { rect, range };
+
+        } else {
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+            SVDEBUG << "cache partial hit" << endl;
+#endif
+            count.partial();
+            
+            // cache doesn't begin at the right frame or doesn't
+            // contain the complete view, but might be scrollable or
+            // partially usable
+            m_cache.scrollTo(v, startFrame);
+            m_magCache.scrollTo(v, startFrame);
+
+            // if we are not time-constrained, then we want to paint
+            // the whole area in one go; we don't return a partial
+            // paint. To avoid providing the more complex logic to
+            // handle painting discontiguous areas, if the only valid
+            // part of cache is in the middle, just make the whole
+            // thing invalid and start again.
+            if (!timeConstrained) {
+                if (m_cache.getValidLeft() > x0 &&
+                    m_cache.getValidRight() < x1) {
+                    m_cache.invalidate();
+                }
+            }
+        }
+    } else {
+        // cache is completely invalid
+        count.miss();
+        m_cache.setStartFrame(startFrame);
+        m_magCache.setStartFrame(startFrame);
+    }
+
+    bool rightToLeft = false;
+
+    int reqx0 = x0;
+    int reqx1 = x1;
+    
+    if (!m_cache.isValid() && timeConstrained) {
+        // When rendering the whole area, in a context where we might
+        // not be able to complete the work, start from somewhere near
+        // the middle so that the region of interest appears
+        // first. But only if we aren't using a peak cache, as
+        // rendering from peak cache is usually (not always) quick and
+        // looks odd if we make a habit of jumping back after reaching
+        // the end.
+        if (x0 == 0 && x1 == v->getPaintWidth()) {
+            int peakCacheIndex = -1, binsPerPeak = -1;
+            getPreferredPeakCache(v, peakCacheIndex, binsPerPeak);
+            if (peakCacheIndex == -1) { // no peak cache
+                x0 = int(x1 * 0.3);
+            }
+        }
+    }
+
+    if (m_cache.isValid()) {
+            
+        // When rendering only a part of the cache, we need to make
+        // sure that the part we're rendering is adjacent to (or
+        // overlapping) a valid area of cache, if we have one. The
+        // alternative is to ditch the valid area of cache and render
+        // only the requested area, but that's risky because this can
+        // happen when just waving the pointer over a small part of
+        // the view -- if we lose the partly-built cache every time
+        // the user does that, we'll never finish building it.
+        int left = x0;
+        int width = x1 - x0;
+        bool isLeftOfValidArea = false;
+        m_cache.adjustToTouchValidArea(left, width, isLeftOfValidArea);
+        x0 = left;
+        x1 = x0 + width;
+
+        // That call also told us whether we should be painting
+        // sub-regions of our target region in right-to-left order in
+        // order to ensure contiguity
+        rightToLeft = isLeftOfValidArea;
+    }
+    
+    // Note, we always paint the full height to cache. We want to
+    // ensure the cache is coherent without having to worry about
+    // vertical matching of required and valid areas as well as
+    // horizontal.
+
+    if (renderType == DrawBufferBinResolution) {
+
+        renderToCacheBinResolution(v, x0, x1 - x0);
+
+    } else { // must be DrawBufferPixelResolution, handled DirectTranslucent earlier
+
+        renderToCachePixelResolution(v, x0, x1 - x0, rightToLeft, timeConstrained);
+    }
+
+    QRect pr = rect & m_cache.getValidArea();
+    paint.drawImage(pr.x(), pr.y(), m_cache.getImage(),
+                    pr.x(), pr.y(), pr.width(), pr.height());
+
+    if (!timeConstrained && (pr != rect)) {
+        cerr << "WARNING: failed to render entire requested rect "
+             << "even when not time-constrained" << endl;
+    }
+
+    MagnitudeRange range = m_magCache.getRange(reqx0, reqx1 - reqx0);
+    
+    return { pr, range };
+}
+
+Colour3DPlotRenderer::RenderType
+Colour3DPlotRenderer::decideRenderType(const LayerGeometryProvider *v) const
+{
+    const DenseThreeDimensionalModel *model = m_sources.source;
+    if (!model || !v || !(v->getViewManager())) {
+        return DrawBufferPixelResolution; // or anything
+    }
+
+    int binResolution = model->getResolution();
+    int zoomLevel = v->getZoomLevel();
+    sv_samplerate_t modelRate = model->getSampleRate();
+
+    double rateRatio = v->getViewManager()->getMainModelSampleRate() / modelRate;
+    double relativeBinResolution = binResolution * rateRatio;
+
+    if (m_params.binDisplay == BinDisplay::PeakFrequencies) {
+        // no alternative works here
+        return DrawBufferPixelResolution;
+    }
+
+    if (!m_params.alwaysOpaque && !m_params.interpolate) {
+
+        // consider translucent option -- only if not smoothing & not
+        // explicitly requested opaque & sufficiently zoomed-in
+        
+        if (model->getHeight() * 3 < v->getPaintHeight() &&
+            relativeBinResolution >= 3 * zoomLevel) {
+            return DirectTranslucent;
+        }
+    }
+
+    if (relativeBinResolution > zoomLevel) {
+        return DrawBufferBinResolution;
+    } else {
+        return DrawBufferPixelResolution;
+    }
+}
+
+ColumnOp::Column
+Colour3DPlotRenderer::getColumn(int sx, int minbin, int nbins,
+                                int peakCacheIndex) const
+{
+    Profiler profiler("Colour3DPlotRenderer::getColumn");
+    
+    // order:
+    // get column -> scale -> normalise -> record extents ->
+    // peak pick -> distribute/interpolate -> apply display gain
+
+    // we do the first bit here:
+    // get column -> scale -> normalise
+
+    ColumnOp::Column column;
+                
+    if (m_params.colourScale.getScale() == ColourScaleType::Phase &&
+        m_sources.fft) {
+
+        ColumnOp::Column fullColumn = m_sources.fft->getPhases(sx);
+
+        column = vector<float>(fullColumn.data() + minbin,
+                               fullColumn.data() + minbin + nbins);
+
+    } else {
+
+        ColumnOp::Column fullColumn =
+            (peakCacheIndex >= 0 ?
+             m_sources.peakCaches[peakCacheIndex] :
+             m_sources.source)
+            ->getColumn(sx);
+                
+        column = vector<float>(fullColumn.data() + minbin,
+                               fullColumn.data() + minbin + nbins);
+
+        column = ColumnOp::applyGain(column, m_params.scaleFactor);
+
+        column = ColumnOp::normalize(column, m_params.normalization);
+    }
+
+    return column;
+}
+
+MagnitudeRange
+Colour3DPlotRenderer::renderDirectTranslucent(const LayerGeometryProvider *v,
+                                              QPainter &paint,
+                                              QRect rect)
+{
+    Profiler profiler("Colour3DPlotRenderer::renderDirectTranslucent");
+
+    MagnitudeRange magRange;
+    
+    QPoint illuminatePos;
+    bool illuminate = v->shouldIlluminateLocalFeatures
+        (m_sources.verticalBinLayer, illuminatePos);
+
+    const DenseThreeDimensionalModel *model = m_sources.source;
+    
+    int x0 = rect.left();
+    int x1 = rect.right() + 1;
+
+    int h = v->getPaintHeight();
+
+    sv_frame_t modelStart = model->getStartFrame();
+    sv_frame_t modelEnd = model->getEndFrame();
+    int modelResolution = model->getResolution();
+
+    double rateRatio =
+        v->getViewManager()->getMainModelSampleRate() / model->getSampleRate();
+
+    // the s-prefix values are source, i.e. model, column and bin numbers
+    int sx0 = int((double(v->getFrameForX(x0)) / rateRatio - double(modelStart))
+                  / modelResolution);
+    int sx1 = int((double(v->getFrameForX(x1)) / rateRatio - double(modelStart))
+                  / modelResolution);
+
+    int sh = model->getHeight();
+
+    const int buflen = 40;
+    char labelbuf[buflen];
+
+    int minbin = m_sources.verticalBinLayer->getIBinForY(v, h);
+    if (minbin >= sh) minbin = sh - 1;
+    if (minbin < 0) minbin = 0;
+    
+    int nbins  = m_sources.verticalBinLayer->getIBinForY(v, 0) - minbin + 1;
+    if (minbin + nbins > sh) nbins = sh - minbin;
+
+    int psx = -1;
+
+    vector<float> preparedColumn;
+
+    int modelWidth = model->getWidth();
+
+    for (int sx = sx0; sx <= sx1; ++sx) {
+
+        if (sx < 0 || sx >= modelWidth) {
+            continue;
+        }
+
+        if (sx != psx) {
+
+            // order:
+            // get column -> scale -> normalise -> record extents ->
+            // peak pick -> distribute/interpolate -> apply display gain
+
+            // this does the first three:
+            preparedColumn = getColumn(sx, minbin, nbins, false);
+            
+            magRange.sample(preparedColumn);
+
+            if (m_params.binDisplay == BinDisplay::PeakBins) {
+                preparedColumn = ColumnOp::peakPick(preparedColumn);
+            }
+
+            // Display gain belongs to the colour scale and is
+            // applied by the colour scale object when mapping it
+
+            psx = sx;
+        }
+
+	sv_frame_t fx = sx * modelResolution + modelStart;
+
+	if (fx + modelResolution <= modelStart || fx > modelEnd) continue;
+
+        int rx0 = v->getXForFrame(int(double(fx) * rateRatio));
+	int rx1 = v->getXForFrame(int(double(fx + modelResolution + 1) * rateRatio));
+
+	int rw = rx1 - rx0;
+	if (rw < 1) rw = 1;
+
+	bool showLabel = (rw > 10 &&
+			  paint.fontMetrics().width("0.000000") < rw - 3 &&
+			  paint.fontMetrics().height() < (h / sh));
+        
+	for (int sy = minbin; sy < minbin + nbins; ++sy) {
+
+            int ry0 = m_sources.verticalBinLayer->getIYForBin(v, sy);
+            int ry1 = m_sources.verticalBinLayer->getIYForBin(v, sy + 1);
+
+            if (m_params.invertVertical) {
+                ry0 = h - ry0 - 1;
+                ry1 = h - ry1 - 1;
+            }
+                    
+            QRect r(rx0, ry1, rw, ry0 - ry1);
+
+            float value = preparedColumn[sy - minbin];
+            QColor colour = m_params.colourScale.getColour(value,
+                                                           m_params.colourRotation);
+
+            if (rw == 1) {
+                paint.setPen(colour);
+                paint.setBrush(Qt::NoBrush);
+                paint.drawLine(r.x(), r.y(), r.x(), r.y() + r.height() - 1);
+                continue;
+            }
+
+	    QColor pen(255, 255, 255, 80);
+	    QColor brush(colour);
+
+            if (rw > 3 && r.height() > 3) {
+                brush.setAlpha(160);
+            }
+
+	    paint.setPen(Qt::NoPen);
+	    paint.setBrush(brush);
+
+	    if (illuminate) {
+		if (r.contains(illuminatePos)) {
+		    paint.setPen(v->getForeground());
+		}
+	    }
+            
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+//            SVDEBUG << "rect " << r.x() << "," << r.y() << " "
+//                      << r.width() << "x" << r.height() << endl;
+#endif
+
+	    paint.drawRect(r);
+
+	    if (showLabel) {
+                double value = model->getValueAt(sx, sy);
+                snprintf(labelbuf, buflen, "%06f", value);
+                QString text(labelbuf);
+                PaintAssistant::drawVisibleText
+                    (v,
+                     paint,
+                     rx0 + 2,
+                     ry0 - h / sh - 1 + 2 + paint.fontMetrics().ascent(),
+                     text,
+                     PaintAssistant::OutlinedText);
+	    }
+	}
+    }
+
+    return magRange;
+}
+
+void
+Colour3DPlotRenderer::getPreferredPeakCache(const LayerGeometryProvider *v,
+                                            int &peakCacheIndex,
+                                            int &binsPerPeak) const
+{
+    peakCacheIndex = -1;
+    binsPerPeak = -1;
+
+    const DenseThreeDimensionalModel *model = m_sources.source;
+    if (!model) return;
+    
+    int zoomLevel = v->getZoomLevel();
+    int binResolution = model->getResolution();
+    
+    for (int ix = 0; in_range_for(m_sources.peakCaches, ix); ++ix) {
+        int bpp = m_sources.peakCaches[ix]->getColumnsPerPeak();
+        int equivZoom = binResolution * bpp;
+        if (zoomLevel >= equivZoom) {
+            // this peak cache would work, though it might not be best
+            if (bpp > binsPerPeak) {
+                // ok, it's better than the best one we've found so far
+                peakCacheIndex = ix;
+                binsPerPeak = bpp;
+            }
+        }
+    }
+
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "getPreferredPeakCache: zoomLevel = " << zoomLevel
+            << ", binResolution " << binResolution 
+            << ", binsPerPeak " << binsPerPeak
+            << ", peakCacheIndex " << peakCacheIndex
+            << ", peakCaches " << m_sources.peakCaches.size()
+            << endl;
+#endif
+}
+
+void
+Colour3DPlotRenderer::renderToCachePixelResolution(const LayerGeometryProvider *v,
+                                                   int x0, int repaintWidth,
+                                                   bool rightToLeft,
+                                                   bool timeConstrained)
+{
+    Profiler profiler("Colour3DPlotRenderer::renderToCachePixelResolution");
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "renderToCachePixelResolution" << endl;
+#endif
+    
+    // Draw to the draw buffer, and then copy from there. The draw
+    // buffer is at the same resolution as the target in the cache, so
+    // no extra scaling needed.
+
+    const DenseThreeDimensionalModel *model = m_sources.source;
+    if (!model || !model->isOK() || !model->isReady()) {
+	throw std::logic_error("no source model provided, or model not ready");
+    }
+
+    int h = v->getPaintHeight();
+
+    clearDrawBuffer(repaintWidth, h);
+
+    vector<int> binforx(repaintWidth);
+    vector<double> binfory(h);
+    
+    int binResolution = model->getResolution();
+
+    for (int x = 0; x < repaintWidth; ++x) {
+        sv_frame_t f0 = v->getFrameForX(x0 + x);
+        double s0 = double(f0 - model->getStartFrame()) / binResolution;
+        binforx[x] = int(s0 + 0.0001);
+    }
+
+    int peakCacheIndex = -1;
+    int binsPerPeak = -1;
+
+    if (m_params.colourScale.getScale() != ColourScaleType::Phase) {
+        getPreferredPeakCache(v, peakCacheIndex, binsPerPeak);
+    }
+    
+    for (int y = 0; y < h; ++y) {
+        binfory[y] = m_sources.verticalBinLayer->getBinForY(v, h - y - 1);
+    }
+
+    int attainedWidth;
+
+    if (m_params.binDisplay == BinDisplay::PeakFrequencies) {
+        attainedWidth = renderDrawBufferPeakFrequencies(v,
+                                                        repaintWidth,
+                                                        h,
+                                                        binforx,
+                                                        binfory,
+                                                        rightToLeft,
+                                                        timeConstrained);
+
+    } else {
+        attainedWidth = renderDrawBuffer(repaintWidth,
+                                         h,
+                                         binforx,
+                                         binfory,
+                                         peakCacheIndex,
+                                         rightToLeft,
+                                         timeConstrained);
+    }
+
+    if (attainedWidth == 0) return;
+
+    // draw buffer is pixel resolution, no scaling factors or padding involved
+    
+    int paintedLeft = x0;
+    if (rightToLeft) {
+        paintedLeft += (repaintWidth - attainedWidth);
+    }
+
+    m_cache.drawImage(paintedLeft, attainedWidth,
+                      m_drawBuffer,
+                      paintedLeft - x0, attainedWidth);
+
+    for (int i = 0; in_range_for(m_magRanges, i); ++i) {
+        m_magCache.sampleColumn(i, m_magRanges.at(i));
+    }
+}
+
+QImage
+Colour3DPlotRenderer::scaleDrawBufferImage(QImage image,
+                                           int targetWidth,
+                                           int targetHeight) const
+{
+    int sourceWidth = image.width();
+    int sourceHeight = image.height();
+
+    // We can only do this if we're making the image larger --
+    // otherwise peaks may be lost. So this should be called only when
+    // rendering in DrawBufferBinResolution mode. Whenever the bin
+    // size is smaller than the pixel size, in either x or y axis, we
+    // should be using DrawBufferPixelResolution mode instead
+    
+    if (targetWidth < sourceWidth || targetHeight < sourceHeight) {
+        throw std::logic_error("Colour3DPlotRenderer::scaleDrawBufferImage: Can only use this function when making the image larger; should be rendering DrawBufferPixelResolution instead");
+    }
+
+    if (sourceWidth <= 0 || sourceHeight <= 0) {
+        throw std::logic_error("Colour3DPlotRenderer::scaleDrawBufferImage: Source image is empty");
+    }
+
+    if (targetWidth <= 0 || targetHeight <= 0) {
+        throw std::logic_error("Colour3DPlotRenderer::scaleDrawBufferImage: Target image is empty");
+    }        
+
+    // This function exists because of some unpredictable behaviour
+    // from Qt when scaling images with FastTransformation mode. We
+    // continue to use Qt's scaler for SmoothTransformation but let's
+    // bring the non-interpolated version "in-house" so we know what
+    // it's really doing.
+    
+    if (m_params.interpolate) {
+        return image.scaled(targetWidth, targetHeight,
+                            Qt::IgnoreAspectRatio,
+                            Qt::SmoothTransformation);
+    }
+    
+    // Same format as the target cache
+    QImage target(targetWidth, targetHeight, QImage::Format_ARGB32_Premultiplied);
+
+    for (int y = 0; y < targetHeight; ++y) {
+
+        QRgb *targetLine = reinterpret_cast<QRgb *>(target.scanLine(y));
+        
+        int sy = int((uint64_t(y) * sourceHeight) / targetHeight);
+        if (sy == sourceHeight) --sy;
+
+        for (int x = 0; x < targetWidth; ++x) {
+
+            int sx = int((uint64_t(x) * sourceWidth) / targetWidth);
+            if (sx == sourceWidth) --sx;
+            
+            targetLine[x] = image.pixel(sx, sy);
+        }
+    }
+
+    return target;
+}
+
+void
+Colour3DPlotRenderer::renderToCacheBinResolution(const LayerGeometryProvider *v,
+                                                 int x0, int repaintWidth)
+{
+    Profiler profiler("Colour3DPlotRenderer::renderToCacheBinResolution");
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "renderToCacheBinResolution" << endl;
+#endif
+    
+    // Draw to the draw buffer, and then scale-copy from there. Draw
+    // buffer is at bin resolution, i.e. buffer x == source column
+    // number. We use toolkit smooth scaling for interpolation.
+
+    const DenseThreeDimensionalModel *model = m_sources.source;
+    if (!model || !model->isOK() || !model->isReady()) {
+	throw std::logic_error("no source model provided, or model not ready");
+    }
+
+    // The draw buffer will contain a fragment at bin resolution. We
+    // need to ensure that it starts and ends at points where a
+    // time-bin boundary occurs at an exact pixel boundary, and with a
+    // certain amount of overlap across existing pixels so that we can
+    // scale and draw from it without smoothing errors at the edges.
+
+    // If (getFrameForX(x) / increment) * increment ==
+    // getFrameForX(x), then x is a time-bin boundary.  We want two
+    // such boundaries at either side of the draw buffer -- one which
+    // we draw up to, and one which we subsequently crop at.
+
+    sv_frame_t leftBoundaryFrame = -1, leftCropFrame = -1;
+    sv_frame_t rightBoundaryFrame = -1, rightCropFrame = -1;
+
+    int drawBufferWidth;
+    int binResolution = model->getResolution();
+
+    for (int x = x0; ; --x) {
+        sv_frame_t f = v->getFrameForX(x);
+        if ((f / binResolution) * binResolution == f) {
+            if (leftCropFrame == -1) leftCropFrame = f;
+            else if (x < x0 - 2) {
+                leftBoundaryFrame = f;
+                break;
+            }
+        }
+    }
+    for (int x = x0 + repaintWidth; ; ++x) {
+        sv_frame_t f = v->getFrameForX(x);
+        if ((f / binResolution) * binResolution == f) {
+            if (rightCropFrame == -1) rightCropFrame = f;
+            else if (x > x0 + repaintWidth + 2) {
+                rightBoundaryFrame = f;
+                break;
+            }
+        }
+    }
+    drawBufferWidth = int
+        ((rightBoundaryFrame - leftBoundaryFrame) / binResolution);
+    
+    int h = v->getPaintHeight();
+
+    // For our purposes here, the draw buffer needs to be exactly our
+    // target size (so we recreate always rather than just clear it)
+    
+    recreateDrawBuffer(drawBufferWidth, h);
+
+    vector<int> binforx(drawBufferWidth);
+    vector<double> binfory(h);
+    
+    for (int x = 0; x < drawBufferWidth; ++x) {
+        binforx[x] = int(leftBoundaryFrame / binResolution) + x;
+    }
+
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "[BIN] binResolution " << binResolution << endl;
+#endif
+    
+    for (int y = 0; y < h; ++y) {
+        binfory[y] = m_sources.verticalBinLayer->getBinForY(v, h - y - 1);
+    }
+
+    int attainedWidth = renderDrawBuffer(drawBufferWidth,
+                                         h,
+                                         binforx,
+                                         binfory,
+                                         -1,
+                                         false,
+                                         false);
+
+    if (attainedWidth == 0) return;
+
+    int scaledLeft = v->getXForFrame(leftBoundaryFrame);
+    int scaledRight = v->getXForFrame(rightBoundaryFrame);
+
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "scaling draw buffer from width " << m_drawBuffer.width()
+            << " to " << (scaledRight - scaledLeft) << " (nb drawBufferWidth = "
+            << drawBufferWidth << ")" << endl;
+#endif
+
+    QImage scaled = scaleDrawBufferImage
+        (m_drawBuffer, scaledRight - scaledLeft, h);
+            
+    int scaledLeftCrop = v->getXForFrame(leftCropFrame);
+    int scaledRightCrop = v->getXForFrame(rightCropFrame);
+    
+    int targetLeft = scaledLeftCrop;
+    if (targetLeft < 0) {
+        targetLeft = 0;
+    }
+    
+    int targetWidth = scaledRightCrop - targetLeft;
+    if (targetLeft + targetWidth > m_cache.getSize().width()) {
+        targetWidth = m_cache.getSize().width() - targetLeft;
+    }
+    
+    int sourceLeft = targetLeft - scaledLeft;
+    if (sourceLeft < 0) {
+        sourceLeft = 0;
+    }
+    
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "repaintWidth = " << repaintWidth
+            << ", targetWidth = " << targetWidth << endl;
+#endif
+    
+    if (targetWidth > 0) {
+        // we are copying from an image that has already been scaled,
+        // hence using the same width in both geometries
+        m_cache.drawImage(targetLeft, targetWidth,
+                          scaled,
+                          sourceLeft, targetWidth);
+    }
+    
+    for (int i = 0; i < targetWidth; ++i) {
+        // but the mag range vector has not been scaled
+        int sourceIx = int((double(i + sourceLeft) / scaled.width())
+                           * int(m_magRanges.size()));
+        if (in_range_for(m_magRanges, sourceIx)) {
+            m_magCache.sampleColumn(i, m_magRanges.at(sourceIx));
+        }
+    }
+}
+
+int
+Colour3DPlotRenderer::renderDrawBuffer(int w, int h,
+                                       const vector<int> &binforx,
+                                       const vector<double> &binfory,
+                                       int peakCacheIndex,
+                                       bool rightToLeft,
+                                       bool timeConstrained)
+{
+    // Callers must have checked that the appropriate subset of
+    // Sources data members are set for the supplied flags (e.g. that
+    // peakCache corresponding to peakCacheIndex exists)
+    
+    RenderTimer timer(timeConstrained ?
+                      RenderTimer::FastRender :
+                      RenderTimer::NoTimeout);
+
+    Profiler profiler("Colour3DPlotRenderer::renderDrawBuffer");
+    
+    int divisor = 1;
+    const DenseThreeDimensionalModel *sourceModel = m_sources.source;
+    if (peakCacheIndex >= 0) {
+        divisor = m_sources.peakCaches[peakCacheIndex]->getColumnsPerPeak();
+        sourceModel = m_sources.peakCaches[peakCacheIndex];
+    }
+
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "renderDrawBuffer: w = " << w << ", h = " << h
+            << ", peakCacheIndex = " << peakCacheIndex << " (divisor = "
+            << divisor << "), rightToLeft = " << rightToLeft
+            << ", timeConstrained = " << timeConstrained << endl;
+    SVDEBUG << "renderDrawBuffer: normalization = " << int(m_params.normalization)
+            << ", binDisplay = " << int(m_params.binDisplay)
+            << ", binScale = " << int(m_params.binScale)
+            << ", alwaysOpaque = " << m_params.alwaysOpaque
+            << ", interpolate = " << m_params.interpolate << endl;
+#endif
+    
+    int sh = sourceModel->getHeight();
+    
+    int minbin = int(binfory[0] + 0.0001);
+    if (minbin >= sh) minbin = sh - 1;
+    if (minbin < 0) minbin = 0;
+
+    int nbins  = int(binfory[h-1] + 0.0001) - minbin + 1;
+    if (minbin + nbins > sh) nbins = sh - minbin;
+
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "minbin = " << minbin << ", nbins = " << nbins << ", last binfory = "
+         << binfory[h-1] << " (rounds to " << int(binfory[h-1]) << ") (model height " << sh << ")" << endl;
+#endif
+    
+    int psx = -1;
+
+    int start = 0;
+    int finish = w;
+    int step = 1;
+
+    if (rightToLeft) {
+        start = w-1;
+        finish = -1;
+        step = -1;
+    }
+
+    int columnCount = 0;
+    
+    vector<float> preparedColumn;
+
+    int modelWidth = sourceModel->getWidth();
+
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "modelWidth " << modelWidth << ", divisor " << divisor << endl;
+#endif
+    
+    for (int x = start; x != finish; x += step) {
+
+        // x is the on-canvas pixel coord; sx (later) will be the
+        // source column index
+        
+        ++columnCount;
+        
+        if (binforx[x] < 0) continue;
+
+        int sx0 = binforx[x] / divisor;
+        int sx1 = sx0;
+        if (x+1 < w) sx1 = binforx[x+1] / divisor;
+        if (sx0 < 0) sx0 = sx1 - 1;
+        if (sx0 < 0) continue;
+        if (sx1 <= sx0) sx1 = sx0 + 1;
+
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+//        SVDEBUG << "x = " << x << ", binforx[x] = " << binforx[x] << ", sx range " << sx0 << " -> " << sx1 << endl;
+#endif
+
+        vector<float> pixelPeakColumn;
+        MagnitudeRange magRange;
+        
+        for (int sx = sx0; sx < sx1; ++sx) {
+
+            if (sx < 0 || sx >= modelWidth) {
+                continue;
+            }
+
+            if (sx != psx) {
+                
+                // order:
+                // get column -> scale -> normalise -> record extents ->
+                // peak pick -> distribute/interpolate -> apply display gain
+
+                // this does the first three:
+                ColumnOp::Column column = getColumn(sx, minbin, nbins,
+                                                    peakCacheIndex);
+
+                magRange.sample(column);
+
+                if (m_params.binDisplay == BinDisplay::PeakBins) {
+                    column = ColumnOp::peakPick(column);
+                }
+
+                preparedColumn =
+                    ColumnOp::distribute(column,
+                                         h,
+                                         binfory,
+                                         minbin,
+                                         m_params.interpolate);
+
+                // Display gain belongs to the colour scale and is
+                // applied by the colour scale object when mapping it
+                
+                psx = sx;
+            }
+
+            if (sx == sx0) {
+                pixelPeakColumn = preparedColumn;
+            } else {
+                for (int i = 0; in_range_for(pixelPeakColumn, i); ++i) {
+                    pixelPeakColumn[i] = std::max(pixelPeakColumn[i],
+                                                  preparedColumn[i]);
+                }
+            }
+        }
+
+        if (!pixelPeakColumn.empty()) {
+
+            for (int y = 0; y < h; ++y) {
+                int py;
+                if (m_params.invertVertical) {
+                    py = y;
+                } else {
+                    py = h - y - 1;
+                }
+                m_drawBuffer.setPixel
+                    (x,
+                     py,
+                     m_params.colourScale.getPixel(pixelPeakColumn[y]));
+            }
+            
+            m_magRanges.push_back(magRange);
+        }
+
+        double fractionComplete = double(columnCount) / double(w);
+        if (timer.outOfTime(fractionComplete)) {
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+            SVDEBUG << "out of time" << endl;
+#endif
+            return columnCount;
+        }
+    }
+
+    return columnCount;
+}
+
+int
+Colour3DPlotRenderer::renderDrawBufferPeakFrequencies(const LayerGeometryProvider *v,
+                                                      int w, int h,
+                                                      const vector<int> &binforx,
+                                                      const vector<double> &binfory,
+                                                      bool rightToLeft,
+                                                      bool timeConstrained)
+{
+    // Callers must have checked that the appropriate subset of
+    // Sources data members are set for the supplied flags (e.g. that
+    // fft model exists)
+    
+    RenderTimer timer(timeConstrained ?
+                      RenderTimer::FastRender :
+                      RenderTimer::NoTimeout);
+
+    const FFTModel *fft = m_sources.fft;
+
+    int sh = fft->getHeight();
+    
+    int minbin = int(binfory[0] + 0.0001);
+    if (minbin >= sh) minbin = sh - 1;
+    if (minbin < 0) minbin = 0;
+
+    int nbins  = int(binfory[h-1]) - minbin + 1;
+    if (minbin + nbins > sh) nbins = sh - minbin;
+
+    FFTModel::PeakSet peakfreqs;
+
+    int psx = -1;
+    
+    int start = 0;
+    int finish = w;
+    int step = 1;
+
+    if (rightToLeft) {
+        start = w-1;
+        finish = -1;
+        step = -1;
+    }
+    
+    int columnCount = 0;
+    
+    vector<float> preparedColumn;
+
+    int modelWidth = fft->getWidth();
+#ifdef DEBUG_COLOUR_PLOT_REPAINT
+    SVDEBUG << "modelWidth " << modelWidth << endl;
+#endif
+    
+    double minFreq =
+        (double(minbin) * fft->getSampleRate()) / fft->getFFTSize();
+    double maxFreq =
+        (double(minbin + nbins - 1) * fft->getSampleRate()) / fft->getFFTSize();
+
+    bool logarithmic = (m_params.binScale == BinScale::Log);
+    
+    for (int x = start; x != finish; x += step) {
+        
+        // x is the on-canvas pixel coord; sx (later) will be the
+        // source column index
+        
+        ++columnCount;
+        
+        if (binforx[x] < 0) continue;
+
+        int sx0 = binforx[x];
+        int sx1 = sx0;
+        if (x+1 < w) sx1 = binforx[x+1];
+        if (sx0 < 0) sx0 = sx1 - 1;
+        if (sx0 < 0) continue;
+        if (sx1 <= sx0) sx1 = sx0 + 1;
+
+        vector<float> pixelPeakColumn;
+        MagnitudeRange magRange;
+        
+        for (int sx = sx0; sx < sx1; ++sx) {
+
+            if (sx < 0 || sx >= modelWidth) {
+                continue;
+            }
+
+            if (sx != psx) {
+                preparedColumn = getColumn(sx, minbin, nbins, false);
+                magRange.sample(preparedColumn);
+                psx = sx;
+            }
+
+            if (sx == sx0) {
+                pixelPeakColumn = preparedColumn;
+                peakfreqs = fft->getPeakFrequencies(FFTModel::AllPeaks, sx,
+                                                    minbin, minbin + nbins - 1);
+            } else {
+                for (int i = 0; in_range_for(pixelPeakColumn, i); ++i) {
+                    pixelPeakColumn[i] = std::max(pixelPeakColumn[i],
+                                                  preparedColumn[i]);
+                }
+            }
+        }
+
+        if (!pixelPeakColumn.empty()) {
+
+            for (FFTModel::PeakSet::const_iterator pi = peakfreqs.begin();
+                 pi != peakfreqs.end(); ++pi) {
+
+                int bin = pi->first;
+                double freq = pi->second;
+
+                if (bin < minbin) continue;
+                if (bin >= minbin + nbins) break;
+            
+                double value = pixelPeakColumn[bin - minbin];
+            
+                double y = v->getYForFrequency
+                    (freq, minFreq, maxFreq, logarithmic);
+            
+                int iy = int(y + 0.5);
+                if (iy < 0 || iy >= h) continue;
+
+                m_drawBuffer.setPixel
+                    (x,
+                     iy,
+                     m_params.colourScale.getPixel(value));
+            }
+
+            m_magRanges.push_back(magRange);
+        }
+
+        double fractionComplete = double(columnCount) / double(w);
+        if (timer.outOfTime(fractionComplete)) {
+            return columnCount;
+        }
+    }
+
+    return columnCount;
+}
+
+void
+Colour3DPlotRenderer::recreateDrawBuffer(int w, int h)
+{
+    m_drawBuffer = QImage(w, h, QImage::Format_Indexed8);
+
+    for (int pixel = 0; pixel < 256; ++pixel) {
+        m_drawBuffer.setColor
+            ((unsigned char)pixel,
+             m_params.colourScale.getColourForPixel
+             (pixel, m_params.colourRotation).rgb());
+    }
+
+    m_drawBuffer.fill(0);
+    m_magRanges.clear();
+}
+
+void
+Colour3DPlotRenderer::clearDrawBuffer(int w, int h)
+{
+    if (m_drawBuffer.width() < w || m_drawBuffer.height() != h) {
+        recreateDrawBuffer(w, h);
+    } else {
+        m_drawBuffer.fill(0);
+        m_magRanges.clear();
+    }
+}
+
+QRect
+Colour3DPlotRenderer::findSimilarRegionExtents(QPoint p) const
+{
+    QImage image = m_cache.getImage();
+    ImageRegionFinder finder;
+    QRect rect = finder.findRegionExtents(&image, p);
+    return rect;
+}