Refactor renderer thread

gui/fpgaviewwidget.cc

@@ -23,7 +23,6 @@
 #include <QApplication>
 #include <QCoreApplication>
 #include <QMouseEvent>
-#include <QTimer>
 #include <QWidget>
 
 #include "fpgaviewwidget.h"
@@ -242,7 +241,7 @@ void LineShader::draw(const LineShaderData &line, const QColor &color, float thi
 }
 
 FPGAViewWidget::FPGAViewWidget(QWidget *parent)
-        : QOpenGLWidget(parent), lineShader_(this), zoom_(500.f), ctx_(nullptr), rendererData_(new FPGAViewWidget::RendererData), rendererArgs_(new FPGAViewWidget::RendererArgs)
+        : QOpenGLWidget(parent), lineShader_(this), zoom_(500.f), ctx_(nullptr), paintTimer_(this), rendererData_(new FPGAViewWidget::RendererData), rendererArgs_(new FPGAViewWidget::RendererArgs)
 {
     colors_.background  = QColor("#000000");
     colors_.grid = QColor("#333");
@@ -276,16 +275,12 @@ FPGAViewWidget::FPGAViewWidget(QWidget *parent)
         printf("Could not get OpenGL 3.1 context - trying anyway...\n ");
     }
 
-    QTimer *timer = new QTimer(this);
+	connect(&paintTimer_, SIGNAL(timeout()), this, SLOT(update()));
-	connect(timer, SIGNAL(timeout()), this, SLOT(update()));
+	paintTimer_.start(std::chrono::duration<int, std::milli>(1000/20));  // paint GL 20 times per second
-	timer->start(1000/20);
 
-    timer = new QTimer(this);
+    renderRunner_ = std::unique_ptr<PeriodicRunner>(new PeriodicRunner(this, [this] { renderLines(); }));
-	connect(timer, SIGNAL(timeout()), this, SLOT(pokeRenderer()));
+    renderRunner_->start();
-	timer->start(1000/2);
+    renderRunner_->startTimer(std::chrono::duration<int, std::milli>(1000/2));  // render line 2 times per second
-
-    renderThread_ = std::unique_ptr<QThread>(QThread::create([this] { renderLinesWorker(); }));
-    renderThread_->start();
 }
 
 FPGAViewWidget::~FPGAViewWidget() {}
@@ -423,19 +418,7 @@ void FPGAViewWidget::paintGL()
 }
 
 void FPGAViewWidget::pokeRenderer(void) {
-    render_.wakeOne();
+    renderRunner_->poke();
-}
-
-void FPGAViewWidget::renderLinesWorker(void) {
-    for (;;) {
-        QMutex mutex;
-        mutex.lock();
-        render_.wait(&mutex);
-
-        renderLines();
-
-        mutex.unlock();
-    }
 }
 
 void FPGAViewWidget::renderLines(void)

gui/fpgaviewwidget.h

@@ -28,6 +28,7 @@
 #include <QOpenGLVertexArrayObject>
 #include <QOpenGLWidget>
 #include <QPainter>
+#include <QTimer>
 #include <QThread>
 #include <QWaitCondition>
 
@@ -209,6 +210,60 @@ class LineShader
     void draw(const LineShaderData &data, const QColor &color, float thickness, const QMatrix4x4 &projection);
 };
 
+class PeriodicRunner : public QThread
+{
+    Q_OBJECT
+private:
+    QMutex mutex_;
+    QWaitCondition condition_;
+    bool abort_;
+    std::function<void()> target_;
+    QTimer timer_;
+public:
+    explicit PeriodicRunner(QObject *parent, std::function<void()> target) :
+        QThread(parent), abort_(false), target_(target), timer_(this)
+    {
+        connect(&timer_, &QTimer::timeout, this, &PeriodicRunner::poke);
+    }
+
+    void run(void) override
+    {
+        for (;;) {
+            mutex_.lock();
+            condition_.wait(&mutex_);
+
+            if (abort_) {
+                mutex_.unlock();
+                return;
+            }
+
+            target_();
+
+            mutex_.unlock();
+        }
+    }
+
+    void startTimer(std::chrono::milliseconds value)
+    {
+        timer_.start(value);
+    }
+
+    ~PeriodicRunner()
+    {
+        mutex_.lock();
+        abort_ = true;
+        condition_.wakeOne();
+        mutex_.unlock();
+
+        wait();
+    }
+
+    void poke(void)
+    {
+        condition_.wakeOne();
+    }
+};
+
 class FPGAViewWidget : public QOpenGLWidget, protected QOpenGLFunctions
 {
     Q_OBJECT
@@ -245,7 +300,6 @@ class FPGAViewWidget : public QOpenGLWidget, protected QOpenGLFunctions
 
   private:
     void renderLines(void);
-    void renderLinesWorker(void);
 
     QPoint lastPos_;
     LineShader lineShader_;
@@ -261,9 +315,9 @@ class FPGAViewWidget : public QOpenGLWidget, protected QOpenGLFunctions
     const float zoomLvl2_ = 50.0f;
 
     Context *ctx_;
+    QTimer paintTimer_;
 
-    QWaitCondition render_;
+    std::unique_ptr<PeriodicRunner> renderRunner_;
-    std::unique_ptr<QThread> renderThread_;
 
     struct {
         QColor background;