diff layer/Colour3DPlotLayer.cpp @ 1220:2954e9952b78

Fix #1781 Running CQ Chromagram spits out stacks of "bin index out of range" warnings

--- a/layer/Colour3DPlotLayer.cpp	Mon Jan 16 10:00:19 2017 +0000
+++ b/layer/Colour3DPlotLayer.cpp	Thu Jan 26 10:41:50 2017 +0000
@@ -761,11 +761,15 @@
     getDisplayExtents(mn, mx);
     double h = v->getPaintHeight();
     if (m_binScale == BinScale::Linear) {
-        bin = mn + ((h - y) * (mx - mn)) / h;
+        // Arrange that the first bin (mn) appears as the exact result
+        // for the first pixel (which is pixel h-1) and the first
+        // out-of-range bin (mx) would appear as the exact result for
+        // the first out-of-range pixel (which would be pixel -1)
+        bin = mn + ((h - y - 1) * (mx - mn)) / h;
     } else {
         double logmin = mn + 1, logmax = mx + 1;
         LogRange::mapRange(logmin, logmax);
-        bin = LogRange::unmap(logmin + ((h - y) * (logmax - logmin)) / h) - 1;
+        bin = LogRange::unmap(logmin + ((h - y - 1) * (logmax - logmin)) / h) - 1;
     }
     return bin;
 }