From f2353464673421bdc3ed66342bf30790999530df Mon Sep 17 00:00:00 2001
From: Filip Leonarski <filip.leonarski@psi.ch>
Date: Fri, 12 Dec 2025 14:43:46 +0100
Subject: [PATCH] Histogram: Add clear()

---
 common/Histogram.h         | 18 ++++++++++--------
 reader/JFJochReaderImage.h |  6 ++++++
 tests/HistogramTest.cpp    | 17 +++++++++++++++++
 3 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/common/Histogram.h b/common/Histogram.h
index dc33d0d8..6f9eb2c3 100644
--- a/common/Histogram.h
+++ b/common/Histogram.h
@@ -52,6 +52,7 @@ public:
 
 class FloatHistogram {
     std::vector<uint64_t> count;
+    int64_t total_count = 0;
     mutable std::mutex m;
     float min;
     float max;
@@ -72,6 +73,13 @@ public:
 
         if (bin < count.size())
             count[bin] += 1;
+        ++total_count;
+    }
+
+    void clear() {
+        std::unique_lock ul(m);
+        for (auto &c: count) c = 0;
+        total_count = 0;
     }
 
     MultiLinePlot GetPlot() const {
@@ -91,9 +99,7 @@ public:
 
     uint64_t TotalCount() const {
         std::unique_lock ul(m);
-        uint64_t total = 0;
-        for (auto c: count) total += c;
-        return total;
+        return total_count;
     }
 
     // Returns the value x such that approximately `percent`% of samples are <= x.
@@ -107,13 +113,9 @@ public:
 
         std::unique_lock ul(m);
 
-        uint64_t total = 0;
-        for (auto c: count) total += c;
-        if (total == 0) return std::nullopt;
-
         // Target rank in [0, total-1]
         const double q = static_cast<double>(percent) / 100.0;
-        const auto target = static_cast<uint64_t>(std::floor(q * static_cast<double>(total - 1)));
+        const auto target = static_cast<uint64_t>(std::floor(q * static_cast<double>(total_count - 1)));
 
         uint64_t cumulative = 0;
         for (size_t i = 0; i < count.size(); i++) {
diff --git a/reader/JFJochReaderImage.h b/reader/JFJochReaderImage.h
index 39719ec0..f82b9467 100644
--- a/reader/JFJochReaderImage.h
+++ b/reader/JFJochReaderImage.h
@@ -13,6 +13,7 @@
 #include "../common/TopPixels.h"
 #include "JFJochReaderDataset.h"
 #include "../common/CrystalLattice.h"
+#include "../common/Histogram.h"
 
 constexpr static int32_t GAP_PXL_VALUE = INT32_MIN + 1;
 constexpr static int32_t ERROR_PXL_VALUE = INT32_MIN;
@@ -38,6 +39,9 @@ class JFJochReaderImage {
     TopPixels top_pixels_acc{20};
     std::vector<std::pair<int32_t, int32_t>> top_pixels;
 
+    // This histogram operates in square root of count from 0 to 10^20
+    FloatHistogram count_histogram{2048, 0.0f, 1000.0};
+
     constexpr static float auto_foreground_range = 0.001f;
     int32_t auto_foreground;
     void CalcAutoContrast();
@@ -66,6 +70,8 @@ public:
     std::shared_ptr<JFJochReaderDataset> CreateMutableDataset();
 
     int32_t GetAutoContrastValue() const;
+
+    MultiLinePlot GetHistogram() const;
 };
 
 #endif //JFJOCH_JFJOCHREADERIMAGE_H
diff --git a/tests/HistogramTest.cpp b/tests/HistogramTest.cpp
index b808a1a4..8672ffe8 100644
--- a/tests/HistogramTest.cpp
+++ b/tests/HistogramTest.cpp
@@ -70,3 +70,20 @@ TEST_CASE("FloatHistogram_Percentile") {
 
     CHECK(h.TotalCount() == 10);
 }
+
+TEST_CASE("FloatHistogram_Clear") {
+    FloatHistogram h(111, 89.5, 200.5);
+    for (int i = 0; i < 8; i++)
+        h.Add(100.0f);
+    h.Add(150.0f);
+    h.Add(200.0f);
+
+    CHECK(h.TotalCount() == 10);
+
+    h.clear();
+
+    CHECK(h.TotalCount() == 0);
+
+    h.Add(200.0f);
+    CHECK(h.TotalCount() == 1);
+}
\ No newline at end of file