view layer/ScrollableMagRangeCache.cpp @ 1118:175d4e15884d spectrogram-minor-refactor

Introduce ScrollableMagRangeCache, plus some tidying etc

/* -*- 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.
*/

#include "ScrollableMagRangeCache.h"

#include <iostream>
using namespace std;

#define DEBUG_SCROLLABLE_MAG_RANGE_CACHE 1

void
ScrollableMagRangeCache::scrollTo(const LayerGeometryProvider *v,
				  sv_frame_t newStartFrame)
{
    if (m_startFrame == newStartFrame) {
	// haven't moved
        return;
    }
	
    int dx = (v->getXForFrame(m_startFrame) -
	      v->getXForFrame(newStartFrame));

#ifdef DEBUG_SCROLLABLE_MAG_RANGE_CACHE
    cerr << "ScrollableMagRangeCache::scrollTo: start frame " << m_startFrame
	 << " -> " << newStartFrame << ", dx = " << dx << endl;
#endif
    
    m_startFrame = newStartFrame;

    if (dx == 0) {
	// haven't moved visibly (even though start frame may have changed)
	return;
    }
	
    int w = int(m_ranges.size());

    if (dx <= -w || dx >= w) {
	// scrolled entirely off
	invalidate();
	return;
    }
	
    // dx is in range, cache is scrollable

    if (dx < 0) {
	// The new start frame is to the left of the old start
	// frame. We need to add some empty ranges at the left (start)
	// end and clip the right end. Assemble -dx new values, then
	// w+dx old values starting at index 0.

	auto newRanges = vector<MagnitudeRange>(-dx);
	newRanges.insert(newRanges.end(),
			 m_ranges.begin(), m_ranges.begin() + w + dx);
	m_ranges = newRanges;
	
    } else {
	// The new start frame is to the right of the old start
	// frame. We want to clip the left (start) end and add some
	// empty ranges at the right end. Assemble w-dx old values
	// starting at index dx, then dx new values.

	auto newRanges = vector<MagnitudeRange>(dx);
	newRanges.insert(newRanges.begin(),
			 m_ranges.begin() + dx, m_ranges.end());
	m_ranges = newRanges;
    }
}

void
ScrollableMagRangeCache::sampleColumn(const LayerGeometryProvider *v,
				      sv_frame_t frame,
				      const MagnitudeRange &r)
{
    int x = (v->getXForFrame(frame) -
	     v->getXForFrame(m_startFrame));

    if (!in_range_for(m_ranges, x)) {
	cerr << "WARNING: ScrollableMagRangeCache::sampleColumn: column " << x
	     << " arising from frame " << frame << " is out of range for cache "
	     << "of width " << m_ranges.size() << endl;
    } else {
	sampleColumn(x, r);
    }
}