renderer: re-use the same opengl instance for all background rendering

Previously the OpenGL instance was tied to each render/cache task,
creating and destroying it each time one started and stopped. This was
completely unnecessary since the instance holds no state and can be
shared by all of the render tasks without having to expensively start
a new one.

app/render/backend/opengl/openglbackend.cpp

@@ -27,38 +27,17 @@ OLIVE_NAMESPACE_ENTER
 OpenGLBackend::OpenGLBackend(QObject* parent) :
   RenderBackend(parent)
 {
-  proxy_ = new OpenGLProxy();
 
-  QThread* proxy_thread = new QThread();
-  proxy_thread->start(QThread::IdlePriority);
-  proxy_->moveToThread(proxy_thread);
-
-  if (!proxy_->Init()) {
-    ClearProxy();
-  }
 }
 
 OpenGLBackend::~OpenGLBackend()
 {
   Close();
-
-  ClearProxy();
 }
 
 RenderWorker *OpenGLBackend::CreateNewWorker()
 {
-  return new OpenGLWorker(this, proxy_);
-}
-
-void OpenGLBackend::ClearProxy()
-{
-  if (proxy_) {
-    proxy_->thread()->quit();
-    proxy_->thread()->wait();
-    proxy_->thread()->deleteLater();
-    proxy_->deleteLater();
-    proxy_ = nullptr;
-  }
+  return new OpenGLWorker(this);
 }
 
 OLIVE_NAMESPACE_EXIT

app/render/backend/opengl/openglbackend.h

@@ -36,11 +36,6 @@ public:
 protected:
   virtual RenderWorker* CreateNewWorker() override;
 
-private:
-  void ClearProxy();
-
-  OpenGLProxy* proxy_;
-
 };
 
 OLIVE_NAMESPACE_EXIT

app/render/backend/opengl/openglproxy.cpp

@@ -33,6 +33,8 @@
 
 OLIVE_NAMESPACE_ENTER
 
+OpenGLProxy* OpenGLProxy::instance_ = nullptr;
+
 OpenGLProxy::OpenGLProxy(QObject *parent) :
   QObject(parent),
   ctx_(nullptr),
@@ -48,6 +50,30 @@ OpenGLProxy::~OpenGLProxy()
   surface_.destroy();
 }
 
+void OpenGLProxy::CreateInstance()
+{
+  instance_ = new OpenGLProxy();
+
+  QThread* proxy_thread = new QThread();
+  proxy_thread->start(QThread::IdlePriority);
+  instance_->moveToThread(proxy_thread);
+
+  if (!instance_->Init()) {
+    DestroyInstance();
+  }
+}
+
+void OpenGLProxy::DestroyInstance()
+{
+  if (instance_) {
+    instance_->thread()->quit();
+    instance_->thread()->wait();
+    instance_->thread()->deleteLater();
+    instance_->deleteLater();
+    instance_ = nullptr;
+  }
+}
+
 bool OpenGLProxy::Init()
 {
   // Create context object

app/render/backend/opengl/openglproxy.h

@@ -41,6 +41,15 @@ public:
 
   virtual ~OpenGLProxy() override;
 
+  static void CreateInstance();
+
+  static void DestroyInstance();
+
+  static OpenGLProxy* instance()
+  {
+    return instance_;
+  }
+
   /**
    * @brief Initialize OpenGL instance in whatever thread this object is a part of
    *
@@ -101,6 +110,8 @@ private:
 
   OpenGLTextureCache texture_cache_;
 
+  static OpenGLProxy* instance_;
+
 private slots:
   void FinishInit();
 

app/render/backend/opengl/openglworker.cpp

@@ -22,15 +22,14 @@
 
 OLIVE_NAMESPACE_ENTER
 
-OpenGLWorker::OpenGLWorker(RenderBackend *parent, OpenGLProxy* proxy) :
-  RenderWorker(parent),
-  proxy_(proxy)
+OpenGLWorker::OpenGLWorker(RenderBackend *parent) :
+  RenderWorker(parent)
 {
 }
 
 void OpenGLWorker::TextureToFrame(const QVariant &texture, FramePtr frame, const QMatrix4x4& mat) const
 {
-  QMetaObject::invokeMethod(proxy_,
+  QMetaObject::invokeMethod(OpenGLProxy::instance(),
                             "TextureToBuffer",
                             Qt::BlockingQueuedConnection,
                             Q_ARG(const QVariant&, texture),
@@ -42,7 +41,7 @@ QVariant OpenGLWorker::FootageFrameToTexture(StreamPtr stream, FramePtr frame) c
 {
   QVariant value;
 
-  QMetaObject::invokeMethod(proxy_,
+  QMetaObject::invokeMethod(OpenGLProxy::instance(),
                             "FrameToValue",
                             Qt::BlockingQueuedConnection,
                             Q_RETURN_ARG(QVariant, value),
@@ -58,7 +57,7 @@ QVariant OpenGLWorker::CachedFrameToTexture(FramePtr frame) const
 {
   QVariant value;
 
-  QMetaObject::invokeMethod(proxy_,
+  QMetaObject::invokeMethod(OpenGLProxy::instance(),
                             "PreCachedFrameToValue",
                             Qt::BlockingQueuedConnection,
                             Q_RETURN_ARG(QVariant, value),
@@ -71,7 +70,7 @@ QVariant OpenGLWorker::ProcessShader(const Node *node, const TimeRange &range, c
 {
   QVariant value;
 
-  QMetaObject::invokeMethod(proxy_,
+  QMetaObject::invokeMethod(OpenGLProxy::instance(),
                             "RunNodeAccelerated",
                             Qt::BlockingQueuedConnection,
                             Q_RETURN_ARG(QVariant, value),

app/render/backend/opengl/openglworker.h

@@ -29,7 +29,7 @@ OLIVE_NAMESPACE_ENTER
 class OpenGLWorker : public RenderWorker
 {
 public:
-  OpenGLWorker(RenderBackend* parent, OpenGLProxy* proxy);
+  OpenGLWorker(RenderBackend* parent);
 
 protected:
   virtual void TextureToFrame(const QVariant& texture, FramePtr frame, const QMatrix4x4 &mat) const override;
@@ -42,9 +42,6 @@ protected:
 
   virtual bool TextureHasAlpha(const QVariant& v) const override;
 
-private:
-  OpenGLProxy* proxy_;
-
 };
 
 OLIVE_NAMESPACE_EXIT