comparison 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);
+    }
+}
+