From f1e4e73833d1215bfacaea4993d630b16b521556 Mon Sep 17 00:00:00 2001
From: Damian Kowalski <s464894@labs.wmi.amu.edu.pl>
Date: Sat, 6 Apr 2024 21:28:58 +0200
Subject: [PATCH] histogram

---
 src/core/histogram.cpp | 53 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 44 insertions(+), 9 deletions(-)

diff --git a/src/core/histogram.cpp b/src/core/histogram.cpp
index 1287666..bef28e1 100644
--- a/src/core/histogram.cpp
+++ b/src/core/histogram.cpp
@@ -22,21 +22,56 @@ Histogram::~Histogram()
     delete L;
 }
 
-void Histogram::generate(QImage* image)
-{
-    qDebug() << Q_FUNC_INFO << "Not implemented yet!";
+void Histogram::generate(QImage* image) {
+    R->clear();
+    G->clear();
+    B->clear();
+    L->clear();
+
+    if (image == nullptr) {
+        qDebug() << "Invalid image provided.";
+        return;
+    }
+
+    for (int y = 0; y < image->height(); ++y) {
+        for (int x = 0; x < image->width(); ++x) {
+            QColor pixelColor = image->pixelColor(x, y);
+
+            R->insert(pixelColor.red(), R->value(pixelColor.red()) + 1);
+            G->insert(pixelColor.green(), G->value(pixelColor.green()) + 1);
+            B->insert(pixelColor.blue(), B->value(pixelColor.blue()) + 1);
+
+            int luminance = qRound(0.299 * pixelColor.red() + 0.587 * pixelColor.green() + 0.114 * pixelColor.blue());
+            L->insert(luminance, L->value(luminance) + 1);
+        }
+    }
 }
 
-/** Returns the maximal value of the histogram in the given channel */
-int Histogram::maximumValue(Channel selectedChannel = RGB)
+int Histogram::maximumValue(Channel selectedChannel)
 {
-    qDebug() << Q_FUNC_INFO << "Not implemented yet!";
+    int maxVal = 0;
 
-    return 0;
+    if (selectedChannel == RGB) {
+        int maxR = maximumValue(RChannel);
+        int maxG = maximumValue(GChannel);
+        int maxB = maximumValue(BChannel);
+        maxVal = std::max(maxR, std::max(maxG, maxB));
+    }
+    else {
+        QHash<int, int>* hist = get(selectedChannel);
+
+        QHash<int, int>::const_iterator cit = hist->constBegin();
+        while (cit != hist->constEnd()) {
+            if (cit.value() > maxVal) {
+                maxVal = cit.value();
+            }
+            ++cit;
+        }
+    }
+
+    return maxVal;
 }
 
-
-/** Returns a pointer to the given channel QHash<int, int> */
 QHash<int, int>* Histogram::get(Channel channel = LChannel)
 {
     if (channel==LChannel) return L;