gr-fosphor/qt: Qt5 - Associate GL context to the worker thread

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

lib/QGLSurface.cc

@@ -19,6 +19,8 @@
  */
 
 #include <QtEvents>
+#include <QThread>
+
 #include "QGLSurface.h"
 #include "qt_sink_c_impl.h"
 
@@ -30,7 +32,10 @@ namespace gr {
 QGLSurface::QGLSurface(QWidget *parent, qt_sink_c_impl *block)
   : QGLWidget(parent), d_block(block)
 {
-	this->doneCurrent();
+	/* Save the pointer to the main GUI thread */
+	this->d_gui_thread = this->thread();
+
+	/* QWidget policies */
 	this->setFocusPolicy(Qt::StrongFocus);
 	this->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
 }
@@ -102,5 +107,33 @@ QGLSurface::keyPressEvent(QKeyEvent *ke)
 	}
 }
 
+
+void
+QGLSurface::grabContext()
+{
+	QMetaObject::invokeMethod(
+		this,
+		"giveContext",
+		Qt::BlockingQueuedConnection,
+		Q_ARG(QThread*, QThread::currentThread())
+	);
+
+	this->makeCurrent();
+}
+
+void
+QGLSurface::releaseContext()
+{
+	this->doneCurrent();
+	this->context()->moveToThread(this->d_gui_thread);
+}
+
+void
+QGLSurface::giveContext(QThread *thread)
+{
+	this->doneCurrent();
+	this->context()->moveToThread(thread);
+}
+
   } /* namespace fosphor */
 } /* namespace gr */

lib/QGLSurface.h

@@ -23,6 +23,8 @@
 
 #include <QGLWidget>
 
+class QThread;
+
 namespace gr {
   namespace fosphor {
 
@@ -33,14 +35,21 @@ namespace gr {
       Q_OBJECT
 
       qt_sink_c_impl *d_block;
+      QThread *d_gui_thread;
 
      protected:
       void paintEvent(QPaintEvent *pe);
       void resizeEvent(QResizeEvent *re);
       void keyPressEvent(QKeyEvent *ke);
 
+     private slots:
+      void giveContext(QThread *thread);
+
      public:
       QGLSurface(QWidget *parent, qt_sink_c_impl *d_block);
+
+      void grabContext();
+      void releaseContext();
     };
 
   } // namespace fosphor

lib/qt_sink_c_impl.cc

@@ -64,7 +64,7 @@ qt_sink_c_impl::qt_sink_c_impl(QWidget *parent)
 void
 qt_sink_c_impl::glctx_init()
 {
-	this->d_gui->makeCurrent();
+	this->d_gui->grabContext();
 	this->d_gui->setFocus();
 }
 
@@ -83,7 +83,7 @@ qt_sink_c_impl::glctx_poll()
 void
 qt_sink_c_impl::glctx_fini()
 {
-	this->d_gui->doneCurrent();
+	this->d_gui->releaseContext();
 }
 
 void

lib/qt_sink_c_impl.h

@@ -26,11 +26,11 @@
 
 #include "base_sink_c_impl.h"
 
-class QGLWidget;
-
 namespace gr {
   namespace fosphor {
 
+    class QGLSurface;
+
     /*!
      * \brief Qt version of fosphor sink (implementation)
      * \ingroup fosphor
@@ -40,7 +40,7 @@ namespace gr {
      friend class QGLSurface;
 
      private:
-      QGLWidget *d_gui;
+      QGLSurface *d_gui;
 
      protected:
       /* Delegated implementation of GL context management */