From bdb13e88f5ec8b514db50a61839e7410cca40ea1 Mon Sep 17 00:00:00 2001
From: itsmattkc <itsmattkc@gmail.com>
Date: Tue, 21 Apr 2020 01:29:08 +1000
Subject: [PATCH] histogram: implemented histogram widget

---
 app/panel/scope/scope.cpp                |   8 +-
 app/panel/scope/scope.h                  |   5 +
 app/panel/viewer/viewerbase.cpp          |   1 +
 app/widget/scope/histogram/histogram.cpp | 150 ++++++++++++++++++++++-
 app/widget/scope/histogram/histogram.h   |  47 +++++++
 5 files changed, 208 insertions(+), 3 deletions(-)

diff --git a/app/panel/scope/scope.cpp b/app/panel/scope/scope.cpp
index 4073a70af..ef6678311 100644
--- a/app/panel/scope/scope.cpp
+++ b/app/panel/scope/scope.cpp
@@ -57,7 +57,8 @@ ScopePanel::ScopePanel(QWidget* parent) :
   stack_->addWidget(waveform_view_);
 
   // Create histogram
-  stack_->addWidget(new QWidget());
+  histogram_ = new HistogramScope();
+  stack_->addWidget(histogram_);
 
   connect(scope_type_combobox_, static_cast<void(QComboBox::*)(int)>(&QComboBox::currentIndexChanged), stack_, &QStackedWidget::setCurrentIndex);
 
@@ -88,6 +89,11 @@ void ScopePanel::DrewManagedTexture(OpenGLTexture *texture)
   waveform_view_->SetTexture(texture);
 }
 
+void ScopePanel::SetBuffer(Frame *frame)
+{
+  histogram_->SetBuffer(frame);
+}
+
 void ScopePanel::Retranslate()
 {
   SetTitle(tr("Scope"));
diff --git a/app/panel/scope/scope.h b/app/panel/scope/scope.h
index 3256ad1fc..48c63518c 100644
--- a/app/panel/scope/scope.h
+++ b/app/panel/scope/scope.h
@@ -25,6 +25,7 @@
 #include <QStackedWidget>
 
 #include "widget/panel/panel.h"
+#include "widget/scope/histogram/histogram.h"
 #include "widget/scope/waveform/waveform.h"
 
 OLIVE_NAMESPACE_ENTER
@@ -51,6 +52,8 @@ public:
 public slots:
   void DrewManagedTexture(OpenGLTexture* texture);
 
+  void SetBuffer(Frame* frame);
+
 protected:
   virtual void Retranslate() override;
 
@@ -63,6 +66,8 @@ private:
 
   WaveformScope* waveform_view_;
 
+  HistogramScope* histogram_;
+
 };
 
 OLIVE_NAMESPACE_EXIT
diff --git a/app/panel/viewer/viewerbase.cpp b/app/panel/viewer/viewerbase.cpp
index f53bb42bc..937692788 100644
--- a/app/panel/viewer/viewerbase.cpp
+++ b/app/panel/viewer/viewerbase.cpp
@@ -106,6 +106,7 @@ void ViewerPanelBase::CreateScopePanel(ScopePanel::Type type)
 
   // Connect viewer widget texture drawing to scope panel
   connect(vw, &ViewerWidget::DrewManagedTexture, p, &ScopePanel::DrewManagedTexture);
+  connect(vw, &ViewerWidget::LoadedBuffer, p, &ScopePanel::SetBuffer);
 
   if (!scope_panel_count_) {
     vw->SetEmitDrewManagedTextureEnabled(true);
diff --git a/app/widget/scope/histogram/histogram.cpp b/app/widget/scope/histogram/histogram.cpp
index 1f4a13543..a4c9097cd 100644
--- a/app/widget/scope/histogram/histogram.cpp
+++ b/app/widget/scope/histogram/histogram.cpp
@@ -20,23 +20,169 @@
 
 #include "histogram.h"
 
+#include <QPainter>
+#include <QtMath>
+
+#include "common/clamp.h"
+#include "common/functiontimer.h"
+
 OLIVE_NAMESPACE_ENTER
 
 HistogramScope::HistogramScope(QWidget* parent) :
-  QOpenGLWidget(parent)
+  QOpenGLWidget(parent),
+  buffer_(nullptr)
 {
+  connect(&worker_, &HistogramScopeWorker::Finished, this, &HistogramScope::FinishedProcessing, Qt::QueuedConnection);
+  worker_.start(QThread::IdlePriority);
+}
+
+HistogramScope::~HistogramScope()
+{
+  worker_.Cancel();
+  worker_.quit();
+  worker_.wait();
 }
 
 void HistogramScope::SetBuffer(Frame* frame)
 {
+  // We'll be multithreading this, so we make a copy to prevent collisions
   buffer_ = frame;
 
+  StartUpdate();
+}
+
+void HistogramScope::FinishedProcessing(QVector<double> red, QVector<double> green, QVector<double> blue)
+{
+  red_val_ = red;
+  green_val_ = green;
+  blue_val_ = blue;
+
   update();
 }
 
 void HistogramScope::paintGL()
 {
-  //QPainter p(this);
+  QVector<QLine> red_lines(red_val_.size());
+  QVector<QLine> green_lines(green_val_.size());
+  QVector<QLine> blue_lines(blue_val_.size());
+
+  for (int i=0;i<red_lines.size();i++) {
+    red_lines.replace(i, QLine(i, height() * (1.0 - red_val_.at(i)), i, height()));
+    green_lines.replace(i, QLine(i, height() * (1.0 - green_val_.at(i)), i, height()));
+    blue_lines.replace(i, QLine(i, height() * (1.0 - blue_val_.at(i)), i, height()));
+  }
+
+  QPainter p(this);
+  p.setCompositionMode(QPainter::CompositionMode_Plus);
+
+  p.setPen(Qt::red);
+  p.drawLines(red_lines);
+
+  p.setPen(Qt::green);
+  p.drawLines(green_lines);
+
+  p.setPen(Qt::blue);
+  p.drawLines(blue_lines);
+}
+
+void HistogramScope::resizeEvent(QResizeEvent *e)
+{
+  QOpenGLWidget::resizeEvent(e);
+
+  if (buffer_){
+    StartUpdate();
+  }
+}
+
+void HistogramScope::StartUpdate()
+{
+  worker_.QueueNext(*buffer_, width());
+}
+
+HistogramScopeWorker::HistogramScopeWorker() :
+  cancelled_(false)
+{
+}
+
+void HistogramScopeWorker::run()
+{
+  while (!cancelled_) {
+    next_lock_.lock();
+    while (!next_.is_allocated()) {
+      next_wait_.wait(&next_lock_);
+
+      if (cancelled_){
+        next_lock_.unlock();
+        return;
+      }
+    }
+
+    // Copy values
+    Frame f = next_;
+    int w = next_width_;
+    next_.destroy();
+
+    next_lock_.unlock();
+
+    QVector<int> data(w * kRGBChannels, 0);
+
+    int max_w = w-1;
+
+    for (int x=0;x<f.width();x++) {
+      for (int y=0;y<f.height();y++) {
+        Color c = f.get_pixel(x, y);
+
+        data[qFloor(clamp(c.red(), 0.0f, 1.0f) * max_w)]++;
+        data[qFloor(clamp(c.green(), 0.0f, 1.0f) * max_w) + w]++;
+        data[qFloor(clamp(c.blue(), 0.0f, 1.0f) * max_w) + w * 2]++;
+      }
+    }
+
+    int max_val = 0;
+
+    foreach (const int& i, data) {
+      if (i > max_val) {
+        max_val = i;
+      }
+    }
+
+    if (!max_val) {
+      // Prevent divide by zero
+      return;
+    }
+
+    QVector<double> red_lines(w);
+    QVector<double> green_lines(w);
+    QVector<double> blue_lines(w);
+
+    for (int i=0;i<w;i++) {
+      red_lines.replace(i, static_cast<double>(data.at(i)) / static_cast<double>(max_val));
+      green_lines.replace(i, static_cast<double>(data.at(i + w)) / static_cast<double>(max_val));
+      blue_lines.replace(i, static_cast<double>(data.at(i + w * 2)) / static_cast<double>(max_val));
+    }
+
+    emit Finished(red_lines, green_lines, blue_lines);
+  }
+}
+
+void HistogramScopeWorker::QueueNext(const Frame &f, int width)
+{
+  next_lock_.lock();
+
+  next_ = f;
+  next_width_ = width;
+
+  next_wait_.wakeOne();
+
+  next_lock_.unlock();
+}
+
+void HistogramScopeWorker::Cancel()
+{
+  cancelled_ = true;
+  next_lock_.lock();
+  next_wait_.wakeOne();
+  next_lock_.unlock();
 }
 
 OLIVE_NAMESPACE_EXIT
diff --git a/app/widget/scope/histogram/histogram.h b/app/widget/scope/histogram/histogram.h
index 973bb1f94..b4b94527e 100644
--- a/app/widget/scope/histogram/histogram.h
+++ b/app/widget/scope/histogram/histogram.h
@@ -21,27 +21,74 @@
 #ifndef HISTOGRAMSCOPE_H
 #define HISTOGRAMSCOPE_H
 
+#include <QMutex>
 #include <QOpenGLWidget>
+#include <QThread>
+#include <QWaitCondition>
 
 #include "codec/frame.h"
 
 OLIVE_NAMESPACE_ENTER
 
+class HistogramScopeWorker : public QThread
+{
+  Q_OBJECT
+public:
+  HistogramScopeWorker();
+
+  virtual void run() override;
+
+  // Thread-safe
+  void QueueNext(const Frame& f, int width);
+
+  void Cancel();
+
+signals:
+  void Finished(QVector<double> red, QVector<double> green, QVector<double> blue);
+
+private:
+  QAtomicInt cancelled_;
+
+  QMutex next_lock_;
+  QWaitCondition next_wait_;
+  Frame next_;
+  int next_width_;
+
+};
+
 class HistogramScope : public QOpenGLWidget
 {
   Q_OBJECT
 public:
   HistogramScope(QWidget* parent = nullptr);
 
+  virtual ~HistogramScope() override;
+
 public slots:
   void SetBuffer(Frame* frame);
 
 protected:
+//  virtual void paintEvent(QPaintEvent* e) override;
   virtual void paintGL() override;
 
+  virtual void resizeEvent(QResizeEvent* e) override;
+
 private:
+  void StartUpdate();
+
   Frame* buffer_;
 
+  QVector<double> red_val_;
+
+  QVector<double> green_val_;
+
+  QVector<double> blue_val_;
+
+  HistogramScopeWorker worker_;
+
+private slots:
+  void FinishedProcessing(QVector<double> red, QVector<double> green, QVector<double> blue);
+
 };
 
 OLIVE_NAMESPACE_EXIT