Ben's changes to the logscale. Low end is now better represented, thanks!

git-svn-id: svn://localhost/ardour2/trunk@1131 d708f5d6-7413-0410-9779-e7cbd77b26cf

diff --git a/gtk2_ardour/fft_graph.cc b/gtk2_ardour/fft_graph.cc
index 367dc54b7c11acb55234194dbd4140fdb64c6a23..5d2f383a806d733154030c844b1a09b961c8a796 100644 (file)
--- a/gtk2_ardour/fft_graph.cc
+++ b/gtk2_ardour/fft_graph.cc
@@ -123,8 +123,9 @@ FFTGraph::setWindowSize_internal(int windowSize)
        }
        
        _logScale = (int *) malloc(sizeof(int) * _dataSize);
+       float count = 0;
        for (int i = 0; i < _dataSize; i++) {
-               _logScale[i] = (int)floor(log10( 1.0 + i * 9.0 / (double)_dataSize) * (double)scaleWidth);
+               _logScale[i] = 0;
        }
        _plan = fftwf_plan_r2r_1d(_windowSize, _in, _out, FFTW_R2HC, FFTW_ESTIMATE);
 }
@@ -241,8 +242,11 @@ FFTGraph::draw_scales(Glib::RefPtr<Gdk::Window> window)
                int rate_at_pos = (int)((double)(SR/2) * (double)logscale_pos / (double)_dataSize);
                
                char buf[32];
-               snprintf(buf,32,"%dhz",rate_at_pos);
-               
+               if (rate_at_pos < 1000)
+                       snprintf(buf,32,"%dHz",rate_at_pos);
+               else
+                       snprintf(buf,32,"%dk",(int)floor( (float)rate_at_pos/(float)1000) );
+
                std::string label = buf;
                
                layout->set_text(label);
@@ -371,12 +375,22 @@ FFTGraph::on_size_request(Gtk::Requisition* requisition)
        if (_logScale != 0) {
                free(_logScale);
        }
-
        _logScale = (int *) malloc(sizeof(int) * _dataSize);
-       //cerr << "LogScale: " << endl;
+
+       float SR = 44100;
+       float FFT_START = SR/(double)_dataSize;
+       float FFT_END = SR/2.0;
+       float FFT_RANGE = log( FFT_END / FFT_START);
+       float pixel = 0;
        for (int i = 0; i < _dataSize; i++) {
-               _logScale[i] = (int)floor(log10( 1.0 + i * 9.0 / (double)_dataSize) * (double)scaleWidth);
-               //cerr << i << ":\t" << _logScale[i] << endl;
+               float freq_at_bin = (SR/2.0) * ((double)i / (double)_dataSize);
+               float freq_at_pixel = FFT_START * exp( FFT_RANGE * pixel / (double)scaleWidth );
+               while (freq_at_bin > freq_at_pixel) {
+                       pixel++;
+                       freq_at_pixel = FFT_START * exp( FFT_RANGE * pixel / (double)scaleWidth );
+               }
+               _logScale[i] = floor(pixel);
+//printf("logscale at %d = %3.3f, freq_at_pixel %3.3f, freq_at_bin %3.3f, scaleWidth %d\n", i, pixel, freq_at_pixel, freq_at_bin, scaleWidth);
        }
 
        requisition->width  = width;;