fix the peak trace line running out of sync with the waterfall due to 793df68b

src/ui/Application.cpp

@@ -316,6 +316,10 @@ void Application::processAudio() {
 
         // Push ALL new spectra to the waterfall so that the scroll rate
         // is determined by the audio sample rate, not the display refresh.
+        int curCh = std::clamp(ui_.waterfallChannel, 0, nSpec - 1);
+        const auto& traceHist = audio_.getWaterfallHistory(curCh);
+        int traceHistSz = static_cast<int>(traceHist.size());
+
         if (ui_.waterfallMultiCh && nSpec > 1) {
             // For multi-channel: replay the last spectraThisFrame entries
             // from channel 0's history to get per-step data.  Other
@@ -353,16 +357,22 @@ void Application::processAudio() {
                     }
                 }
                 waterfall_.pushLineMulti(wfSpectra, wfInfo, ui_.minDB, ui_.maxDB);
+
+                // Push peak trace entry synchronized with each waterfall line.
+                int tIdx = std::max(0, traceHistSz - (histSz - si));
+                measurements_.pushPeakTrace(traceHist[tIdx],
+                                            settings.sampleRate, settings.isIQ, settings.fftSize);
             }
         } else {
-            int wfCh = std::clamp(ui_.waterfallChannel, 0, nSpec - 1);
-            const auto& hist = audio_.getWaterfallHistory(wfCh);
+            const auto& hist = audio_.getWaterfallHistory(curCh);
             int histSz = static_cast<int>(hist.size());
             int start = std::max(0, histSz - spectraThisFrame);
-            for (int si = start; si < histSz; ++si)
+            for (int si = start; si < histSz; ++si) {
                 waterfall_.pushLine(hist[si], ui_.minDB, ui_.maxDB);
+                measurements_.pushPeakTrace(hist[si],
+                                            settings.sampleRate, settings.isIQ, settings.fftSize);
+            }
         }
-        int curCh = std::clamp(ui_.waterfallChannel, 0, nSpec - 1);
         cursors_.update(audio_.getSpectrum(curCh),
                        settings.sampleRate, settings.isIQ, settings.fftSize);
         measurements_.update(audio_.getSpectrum(curCh),

src/ui/Measurements.cpp

@@ -61,24 +61,18 @@ void Measurements::findPeaks(const std::vector<float>& spectrumDB, int maxN,
     }
 }
 
-void Measurements::update(const std::vector<float>& spectrumDB,
+void Measurements::pushPeakTrace(const std::vector<float>& spectrumDB,
                                   double sampleRate, bool isIQ, int fftSize) {
-    lastSampleRate_ = sampleRate;
-    // Always track global peak (for the readout label).
-    if (!spectrumDB.empty()) {
-        auto it = std::max_element(spectrumDB.begin(), spectrumDB.end());
-        int bin = static_cast<int>(std::distance(spectrumDB.begin(), it));
-        globalPeak_.bin = bin;
-        globalPeak_.dB = *it;
-        globalPeak_.freq = binToFreq(bin, sampleRate, isIQ, fftSize);
+    if (spectrumDB.empty()) return;
 
-        // Push into peak history circular buffer (with optional freq range filter)
     constexpr int kMaxHistory = 4096;
     if (static_cast<int>(peakHistBins_.size()) < kMaxHistory)
         peakHistBins_.resize(kMaxHistory, -1);
 
-        // Find peak within the trace frequency range
-        int traceBin = bin;
+    auto it = std::max_element(spectrumDB.begin(), spectrumDB.end());
+    int traceBin = static_cast<int>(std::distance(spectrumDB.begin(), it));
+
+    // Optionally restrict to a frequency range.
     int bins = static_cast<int>(spectrumDB.size());
     if (traceMinFreq > 0.0f || traceMaxFreq > 0.0f) {
         double fMin = isIQ ? -sampleRate / 2.0 : 0.0;
@@ -99,6 +93,18 @@ void Measurements::update(const std::vector<float>& spectrumDB,
     if (peakHistLen_ < kMaxHistory) ++peakHistLen_;
 }
 
+void Measurements::update(const std::vector<float>& spectrumDB,
+                           double sampleRate, bool isIQ, int fftSize) {
+    lastSampleRate_ = sampleRate;
+    // Always track global peak (for the readout label).
+    if (!spectrumDB.empty()) {
+        auto it = std::max_element(spectrumDB.begin(), spectrumDB.end());
+        int bin = static_cast<int>(std::distance(spectrumDB.begin(), it));
+        globalPeak_.bin = bin;
+        globalPeak_.dB = *it;
+        globalPeak_.freq = binToFreq(bin, sampleRate, isIQ, fftSize);
+    }
+
     if (!enabled) { peaks_.clear(); return; }
 
     findPeaks(spectrumDB, maxPeaks, minPeakDist, peakThreshold);

src/ui/Measurements.h

@@ -18,6 +18,10 @@ public:
     void update(const std::vector<float>& spectrumDB,
                 double sampleRate, bool isIQ, int fftSize);
 
+    // Push a single peak trace entry for this spectrum (call once per waterfall line).
+    void pushPeakTrace(const std::vector<float>& spectrumDB,
+                       double sampleRate, bool isIQ, int fftSize);
+
     // Draw markers on the spectrum display area.
     void draw(const SpectrumDisplay& specDisplay,
               float posX, float posY, float sizeX, float sizeY,