From 0fa29e2875043613e5e94e23175be1aed1e5d9cf Mon Sep 17 00:00:00 2001
From: Sean Harmer <sean.harmer@kdab.com>
Date: Sat, 22 Jun 2013 10:58:53 +0100
Subject: Avoid crash when QOpenGLContext is destroyed before the VAO

Change-Id: I19df59453156a95c5075a065268333a74cec2476
Reviewed-by: James Turner <james.turner@kdab.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
---
 src/gui/opengl/qopenglvertexarrayobject.cpp | 27 +++++++++++++++++++++++++--
 src/gui/opengl/qopenglvertexarrayobject.h   |  1 +
 2 files changed, 26 insertions(+), 2 deletions(-)

(limited to 'src/gui')

diff --git a/src/gui/opengl/qopenglvertexarrayobject.cpp b/src/gui/opengl/qopenglvertexarrayobject.cpp
index e450fe708f..eb7a42f749 100644
--- a/src/gui/opengl/qopenglvertexarrayobject.cpp
+++ b/src/gui/opengl/qopenglvertexarrayobject.cpp
@@ -118,6 +118,9 @@ public:
     void destroy();
     void bind();
     void release();
+    void _q_contextAboutToBeDestroyed();
+
+    Q_DECLARE_PUBLIC(QOpenGLVertexArrayObject)
 
     GLuint vao;
 
@@ -141,12 +144,22 @@ public:
 
 bool QOpenGLVertexArrayObjectPrivate::create()
 {
+    if (vao) {
+        qWarning("QOpenGLVertexArrayObject::create() VAO is already created");
+        return false;
+    }
+
+    Q_Q(QOpenGLVertexArrayObject);
+    if (context)
+        QObject::disconnect(context, SIGNAL(aboutToBeDestroyed()), q, SLOT(_q_contextAboutToBeDestroyed()));
+
     QOpenGLContext *ctx = QOpenGLContext::currentContext();
     if (!ctx) {
         qWarning("QOpenGLVertexArrayObject::create() requires a valid current OpenGL context");
         return false;
     }
     context = ctx;
+    QObject::connect(context, SIGNAL(aboutToBeDestroyed()), q, SLOT(_q_contextAboutToBeDestroyed()));
 
 #if defined(QT_OPENGL_ES_2)
     if (ctx->hasExtension("GL_OES_vertex_array_object")) {
@@ -197,8 +210,16 @@ void QOpenGLVertexArrayObjectPrivate::destroy()
     case NotSupported:
         break;
     }
-    vao = 0;
 #endif
+    vao = 0;
+}
+
+/*!
+    \internal
+*/
+void QOpenGLVertexArrayObjectPrivate::_q_contextAboutToBeDestroyed()
+{
+    destroy();
 }
 
 void QOpenGLVertexArrayObjectPrivate::bind()
@@ -327,7 +348,7 @@ QOpenGLVertexArrayObject::~QOpenGLVertexArrayObject()
 
     Q_D(QOpenGLVertexArrayObject);
     QOpenGLContext *oldContext = 0;
-    if (d->context && d->context != ctx) {
+    if (d->context && ctx && d->context != ctx) {
         oldContext = ctx;
         if (d->context->makeCurrent(oldContext->surface())) {
             ctx = d->context;
@@ -471,3 +492,5 @@ void QOpenGLVertexArrayObject::release()
 */
 
 QT_END_NAMESPACE
+
+#include "moc_qopenglvertexarrayobject.cpp"
diff --git a/src/gui/opengl/qopenglvertexarrayobject.h b/src/gui/opengl/qopenglvertexarrayobject.h
index 569aeea730..8369497660 100644
--- a/src/gui/opengl/qopenglvertexarrayobject.h
+++ b/src/gui/opengl/qopenglvertexarrayobject.h
@@ -102,6 +102,7 @@ public:
 private:
     Q_DISABLE_COPY(QOpenGLVertexArrayObject)
     Q_DECLARE_PRIVATE(QOpenGLVertexArrayObject)
+    Q_PRIVATE_SLOT(d_func(), void _q_contextAboutToBeDestroyed())
     QOpenGLVertexArrayObject(QOpenGLVertexArrayObjectPrivate &dd);
 };
 
-- 
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