diff layer/SpectrumLayer.cpp @ 1386:fc3d89f88690 spectrogramparam

Use log-frequency rather than log-bin for calculating x coord in spectrum. This has the advantage that frequency positions don't move when we change the window size or oversampling ratio, but it does give us an unhelpfully large amount of space for very low frequencies - to be considered

--- a/layer/SpectrumLayer.cpp	Thu Nov 08 12:55:36 2018 +0000
+++ b/layer/SpectrumLayer.cpp	Mon Nov 12 11:34:34 2018 +0000
@@ -346,26 +346,61 @@
 }
 
 double
+SpectrumLayer::getBinForFrequency(double freq) const
+{
+    if (!m_sliceableModel) return 0;
+    double bin = (freq * getFFTSize()) / m_sliceableModel->getSampleRate();
+    // we assume the frequency of a bin corresponds to the centre of
+    // its visual range
+    bin += 0.5;
+    return bin;
+}
+
+double
+SpectrumLayer::getBinForX(const LayerGeometryProvider *v, double x) const
+{
+    if (!m_sliceableModel) return 0;
+    double bin = getBinForFrequency(getFrequencyForX(v, x));
+    return bin;
+}
+
+double
 SpectrumLayer::getFrequencyForX(const LayerGeometryProvider *v, double x) const
 {
     if (!m_sliceableModel) return 0;
-    double bin = getBinForX(v, x);
+    double freq = getScalePointForX(v, x,
+                                    getFrequencyForBin(m_minbin),
+                                    getFrequencyForBin(m_maxbin));
+    return freq;
+}
+
+double
+SpectrumLayer::getFrequencyForBin(double bin) const
+{
+    if (!m_sliceableModel) return 0;
     // we assume the frequency of a bin corresponds to the centre of
     // its visual range
     bin -= 0.5;
-    return (m_sliceableModel->getSampleRate() * bin) /
-        (m_sliceableModel->getHeight() * 2);
+    double freq = (bin * m_sliceableModel->getSampleRate()) / getFFTSize();
+    return freq;
+}
+
+double
+SpectrumLayer::getXForBin(const LayerGeometryProvider *v, double bin) const
+{
+    if (!m_sliceableModel) return 0;
+    double x = getXForFrequency(v, getFrequencyForBin(bin));
+    return x;
 }
 
 double
 SpectrumLayer::getXForFrequency(const LayerGeometryProvider *v, double freq) const
 {
     if (!m_sliceableModel) return 0;
-    double bin = (freq * m_sliceableModel->getHeight() * 2) /
-        m_sliceableModel->getSampleRate();
-    // we want the centre of the bin range
-    bin += 0.5;
-    return getXForBin(v, bin);
+    double x = getXForScalePoint(v, freq,
+                                 getFrequencyForBin(m_minbin),
+                                 getFrequencyForBin(m_maxbin));
+    return x;
 }
 
 bool