Add histogram

histogram.cpp

@@ -0,0 +1,84 @@
+#include "histogram.h"
+#include <cmath>
+#include <algorithm>
+#include <QPainter>
+#include <QDebug>
+
+Histogram::Histogram(QWidget *parent) : QWidget(parent)
+{
+    setStyleSheet("QWidget { background: white; color: black; } ");
+}
+
+void Histogram::imageLoaded(Image *img)
+{
+    if(img && img->rawImage())
+    {
+        m_histogram = img->rawImage()->imageStats().m_histogram[0];
+        m_points.clear();
+        update();
+    }
+}
+
+void Histogram::paintEvent(QPaintEvent *)
+{
+    QPainter painter(this);
+    painter.fillRect(rect(), Qt::black);
+
+    uint h = height();
+    uint w = width();
+
+    if(m_histogram.size())
+    {
+
+        if(m_points.size() != w)
+        {
+            m_points.clear();
+            for(uint64_t i = 0; i < w; i++)
+            {
+                uint32_t sum = 0;
+                uint64_t start = i * m_histogram.size() / w;
+                uint64_t end =(i+1) * m_histogram.size() / w;
+                for(uint64_t o = start; o < end; o++)
+                    sum += m_histogram[o];
+                m_points.push_back(sum);
+            }
+            float scale = *std::max_element(m_points.begin(), m_points.end());
+            if(m_log)
+            {
+                scale = std::log(scale);
+                std::for_each(m_points.begin(), m_points.end(), [scale](float &x){ x = (x > 0 ? std::log(x) : 0.0f) / scale; });
+            }
+            else
+            {
+                std::for_each(m_points.begin(), m_points.end(), [scale](float &x){ x /= scale; });
+            }
+        }
+        std::vector<QPointF> points;
+        points.push_back(QPointF(0, h));
+        for(size_t i = 0; i < m_points.size(); i++)
+        {
+            points.push_back(QPointF(i, h - m_points[i] * h));
+        }
+        points.push_back(QPoint(w, h));
+        painter.setBrush(Qt::gray);
+        painter.setPen(Qt::white);
+
+        painter.drawPolygon(&points[0], points.size());
+    }
+
+    QStyleOptionButton button;
+    button.initFrom(this);
+    button.state = m_log ? QStyle::State_On : QStyle::State_Off;
+    button.text = tr("Logarithmic scale");
+    button.rect = style()->subElementRect(QStyle::SE_CheckBoxClickRect, &button, this);
+    button.rect.moveTop(0);
+    button.rect.moveRight(w);
+    style()->drawControl(QStyle::CE_CheckBox, &button, &painter, this);
+}
+
+void Histogram::mouseReleaseEvent(QMouseEvent *)
+{
+    m_log = !m_log;
+    m_points.clear();
+    update();
+}