finished prototype of nodes providing a texture to a viewer

app/node/processor/renderer/rendererthread.cpp

@@ -0,0 +1,106 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2019 Olive Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "rendererthread.h"
+
+#include <QDebug>
+
+RendererThread::RendererThread() :
+  cancelled_(false)
+{
+}
+
+bool RendererThread::Queue(Node *n, const rational& time)
+{
+  // If the thread is inactive, tryLock() will succeed
+  if (mutex_.tryLock()) {
+
+    // The mutex is locked in the calling thread now, so we can change the active Node
+    node_ = n;
+    time_ = time;
+
+    // We can now wake up our main thread
+    wait_cond_.wakeAll();
+    mutex_.unlock();
+
+    // Wait for thread to start before returning
+    caller_mutex_.lock();
+    caller_mutex_.unlock();
+
+    return true;
+  }
+
+  return false;
+}
+
+void RendererThread::Cancel()
+{
+  // Escape main loop
+  cancelled_ = true;
+
+  // Wait until thread is finished before returning
+  wait();
+}
+
+void RendererThread::run()
+{
+  // Create OpenGL context (automatically destroys any existing if there is one)
+  if (!ctx_.create()) {
+    qWarning() << tr("Failed to create OpenGL context in thread %1").arg(reinterpret_cast<quintptr>(this));
+    return;
+  }
+
+  // Create offscreen surface
+  surface_.create();
+
+  // Make context current on that surface
+  if (!ctx_.makeCurrent(&surface_)) {
+    qWarning() << tr("Failed to makeCurrent() on offscreen surface in thread %1").arg(reinterpret_cast<quintptr>(this));
+    surface_.destroy();
+    return;
+  }
+
+  // Lock mutex for main loop
+  mutex_.lock();
+
+  // Main loop (use Cancel() to exit it)
+  while (!cancelled_) {
+    // Lock the caller mutex (used in Queue() for thread synchronization)
+    caller_mutex_.lock();
+
+    // Main waiting condition
+    wait_cond_.wait(&mutex_);
+
+    // Unlock the caller mutex
+    caller_mutex_.unlock();
+
+    // Process the Node
+    node_->Process(time_);
+  }
+
+  // Release OpenGL context
+  ctx_.doneCurrent();
+
+  // Destroy offscreen surface
+  surface_.destroy();
+
+  // Unlock mutex before exiting
+  mutex_.unlock();
+}