iOS: Enable threaded OpenGL.

This change activates ThreadedOpenGL and ThreadedPixmaps capabilities
in the iOS integration. QIOSContext is expanded with a support for
a shared context.

Change-Id: I56615c870a24e17850ad2748421c54e015de3ab2
Reviewed-by: Ian Dean <ian@mediator-software.com>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>

src/plugins/platforms/ios/qioscontext.h

@@ -66,10 +66,14 @@ public:
     GLuint defaultFramebufferObject(QPlatformSurface *) const;
     QFunctionPointer getProcAddress(const QByteArray &procName);
 
+    bool isSharing() const Q_DECL_OVERRIDE;
+    bool isValid() const Q_DECL_OVERRIDE;
+
 private Q_SLOTS:
     void windowDestroyed(QObject *object);
 
 private:
+    QIOSContext *m_sharedContext;
     EAGLContext *m_eaglContext;
     QSurfaceFormat m_format;
 

src/plugins/platforms/ios/qioscontext.mm

@@ -51,7 +51,10 @@
 
 QIOSContext::QIOSContext(QOpenGLContext *context)
     : QPlatformOpenGLContext()
-    , m_eaglContext([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2])
+    , m_sharedContext(static_cast<QIOSContext *>(context->shareHandle()))
+    , m_eaglContext([[EAGLContext alloc]
+        initWithAPI:kEAGLRenderingAPIOpenGLES2
+        sharegroup:m_sharedContext ? [m_sharedContext->m_eaglContext sharegroup] : nil])
     , m_format(context->format())
 {
     m_format.setRenderableType(QSurfaceFormat::OpenGLES);
@@ -203,5 +206,15 @@ QFunctionPointer QIOSContext::getProcAddress(const QByteArray& functionName)
     return QFunctionPointer(dlsym(RTLD_DEFAULT, functionName.constData()));
 }
 
+bool QIOSContext::isValid() const
+{
+    return m_eaglContext;
+}
+
+bool QIOSContext::isSharing() const
+{
+    return m_sharedContext;
+}
+
 #include "moc_qioscontext.cpp"
 

src/plugins/platforms/ios/qiosintegration.mm

@@ -102,6 +102,9 @@ bool QIOSIntegration::hasCapability(Capability cap) const
 {
     switch (cap) {
     case OpenGL:
+    case ThreadedOpenGL:
+        return true;
+    case ThreadedPixmaps:
         return true;
     case MultipleWindows:
         return true;