Add a method for checking if context was successfully created

Now it is possible to check after graph construction if the graph
is actually usable in environments where the OpenGL support might
not be sufficient.

Task-number: QTRD-3748
Change-Id: Ia68b4e51386859f6d0c7b09cb44e50a74730ca55
Reviewed-by: Titta Heikkala <titta.heikkala@theqtcompany.com>

1 files changed, 28 insertions, 5 deletions

diff --git a/src/datavisualization/engine/qabstract3dgraph.cpp b/src/datavisualization/engine/qabstract3dgraph.cpp
index 2f3caccd..bc40fbf9 100644
--- a/src/datavisualization/engine/qabstract3dgraph.cpp
+++ b/src/datavisualization/engine/qabstract3dgraph.cpp
@@ -189,7 +189,11 @@ QAbstract3DGraph::QAbstract3DGraph(QAbstract3DGraphPrivate *d, const QSurfaceFor
 
     d_ptr->m_context->setFormat(requestedFormat());
     d_ptr->m_context->create();
-    d_ptr->m_context->makeCurrent(this);
+    bool makeSuccess = d_ptr->m_context->makeCurrent(this);
+
+    // If we fail to get context, just abort
+    if (!makeSuccess || !QOpenGLContext::currentContext())
+        return;
 
     initializeOpenGLFunctions();
 
@@ -208,6 +212,8 @@ QAbstract3DGraph::QAbstract3DGraph(QAbstract3DGraphPrivate *d, const QSurfaceFor
             qFatal("GLSL version must be 1.20 or higher. Try installing latest display drivers.");
     }
 
+    d_ptr->m_initialized = true;
+
     d_ptr->renderLater();
 
 #if defined(Q_OS_OSX)
@@ -872,6 +878,20 @@ qreal QAbstract3DGraph::margin() const
 }
 
 /*!
+ * \return \c{true} if the OpenGL context of the graph has been successfully initialized.
+ * Trying to use a graph when the context initialization has failed typically results in a crash.
+ * A common reason for a context initialization failure is lack of sufficient platform support
+ * for OpenGL.
+ */
+bool QAbstract3DGraph::hasContext() const
+{
+    if (d_ptr->m_initialized)
+        return true;
+    else
+        return false;
+}
+
+/*!
  * \internal
  */
 bool QAbstract3DGraph::event(QEvent *event)
@@ -898,9 +918,11 @@ void QAbstract3DGraph::resizeEvent(QResizeEvent *event)
 {
     Q_UNUSED(event);
 
-    Q3DScene *scene = d_ptr->m_visualController->scene();
-    scene->d_ptr->setWindowSize(QSize(width(), height()));
-    scene->d_ptr->setViewport(QRect(0, 0, width(), height()));
+    if (d_ptr->m_visualController) {
+        Q3DScene *scene = d_ptr->m_visualController->scene();
+        scene->d_ptr->setWindowSize(QSize(width(), height()));
+        scene->d_ptr->setViewport(QRect(0, 0, width(), height()));
+    }
 }
 
 /*!
@@ -968,7 +990,8 @@ QAbstract3DGraphPrivate::QAbstract3DGraphPrivate(QAbstract3DGraph *q)
       m_updatePending(false),
       m_visualController(0),
       m_devicePixelRatio(1.f),
-      m_offscreenSurface(0)
+      m_offscreenSurface(0),
+      m_initialized(false)
 {
 }