QOpenGLVAO: refactor the helper class and export it

It is useful in other places, for instance in QtQuick, to avoid
duplicating the same resolver logic.

Change-Id: I9748a420a0abeb07cc84f948965b1e0321a95ca2
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

src/gui/opengl/qopenglvertexarrayobject.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Klaralvdalens Datakonsult AB (KDAB).
+** Copyright (C) 2014 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Sean Harmer <sean.harmer@kdab.com>
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtGui module of the Qt Toolkit.
@@ -49,69 +49,48 @@
 #include <QtGui/qopenglfunctions_3_0.h>
 #include <QtGui/qopenglfunctions_3_2_core.h>
 
+#include <private/qopenglvertexarrayobject_p.h>
+
 QT_BEGIN_NAMESPACE
 
 class QOpenGLFunctions_3_0;
 class QOpenGLFunctions_3_2_Core;
 
-class QVertexArrayObjectHelper
+void qtInitializeVertexArrayObjectHelper(QOpenGLVertexArrayObjectHelper *helper, QOpenGLContext *context)
 {
-public:
+    Q_ASSERT(helper);
-    QVertexArrayObjectHelper(QOpenGLContext *context)
-    {
     Q_ASSERT(context);
+
     bool tryARB = true;
 
     if (context->isOpenGLES()) {
 #ifdef QT_OPENGL_ES_3
-            GenVertexArrays = ::glGenVertexArrays;
+        helper->GenVertexArrays = ::glGenVertexArrays;
-            DeleteVertexArrays = ::glDeleteVertexArrays;
+        helper->DeleteVertexArrays = ::glDeleteVertexArrays;
-            BindVertexArray = ::glBindVertexArray;
+        helper->BindVertexArray = ::glBindVertexArray;
         tryARB = false;
 #else
         if (context->hasExtension(QByteArrayLiteral("GL_OES_vertex_array_object"))) {
-                GenVertexArrays = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLsizei , GLuint *)>(context->getProcAddress(QByteArrayLiteral("glGenVertexArraysOES")));
+            helper->GenVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_GenVertexArrays_t>(context->getProcAddress(QByteArrayLiteral("glGenVertexArraysOES")));
-                DeleteVertexArrays = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLsizei , const GLuint *)>(context->getProcAddress(QByteArrayLiteral("glDeleteVertexArraysOES")));
+            helper->DeleteVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_DeleteVertexArrays_t>(context->getProcAddress(QByteArrayLiteral("glDeleteVertexArraysOES")));
-                BindVertexArray = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLuint )>(context->getProcAddress(QByteArrayLiteral("glBindVertexArrayOES")));
+            helper->BindVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_BindVertexArray_t>(context->getProcAddress(QByteArrayLiteral("glBindVertexArrayOES")));
             tryARB = false;
         }
 #endif
-        } else if (!context->hasExtension(QByteArrayLiteral("GL_ARB_vertex_array_object"))
+    } else if (context->hasExtension(QByteArrayLiteral("GL_APPLE_vertex_array_object")) &&
-                   && context->hasExtension(QByteArrayLiteral("GL_APPLE_vertex_array_object"))) {
+               !context->hasExtension(QByteArrayLiteral("GL_ARB_vertex_array_object"))) {
-            GenVertexArrays = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLsizei , GLuint *)>(context->getProcAddress(QByteArrayLiteral("glGenVertexArraysAPPLE")));
+        helper->GenVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_GenVertexArrays_t>(context->getProcAddress(QByteArrayLiteral("glGenVertexArraysAPPLE")));
-            DeleteVertexArrays = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLsizei , const GLuint *)>(context->getProcAddress(QByteArrayLiteral("glDeleteVertexArraysAPPLE")));
+        helper->DeleteVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_DeleteVertexArrays_t>(context->getProcAddress(QByteArrayLiteral("glDeleteVertexArraysAPPLE")));
-            BindVertexArray = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLuint )>(context->getProcAddress(QByteArrayLiteral("glBindVertexArrayAPPLE")));
+        helper->BindVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_BindVertexArray_t>(context->getProcAddress(QByteArrayLiteral("glBindVertexArrayAPPLE")));
         tryARB = false;
     }
 
-        if (tryARB) {
+    if (tryARB && context->hasExtension(QByteArrayLiteral("GL_ARB_vertex_array_object"))) {
-            GenVertexArrays = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLsizei , GLuint *)>(context->getProcAddress(QByteArrayLiteral("glGenVertexArrays")));
+        helper->GenVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_GenVertexArrays_t>(context->getProcAddress(QByteArrayLiteral("glGenVertexArrays")));
-            DeleteVertexArrays = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLsizei , const GLuint *)>(context->getProcAddress(QByteArrayLiteral("glDeleteVertexArrays")));
+        helper->DeleteVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_DeleteVertexArrays_t>(context->getProcAddress(QByteArrayLiteral("glDeleteVertexArrays")));
-            BindVertexArray = reinterpret_cast<void (QOPENGLF_APIENTRYP)(GLuint )>(context->getProcAddress(QByteArrayLiteral("glBindVertexArray")));
+        helper->BindVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_BindVertexArray_t>(context->getProcAddress(QByteArrayLiteral("glBindVertexArray")));
     }
-    }
+}
-
-    inline void glGenVertexArrays(GLsizei n, GLuint *arrays)
-    {
-        GenVertexArrays(n, arrays);
-    }
-
-    inline void glDeleteVertexArrays(GLsizei n, const GLuint *arrays)
-    {
-        DeleteVertexArrays(n, arrays);
-    }
-
-    inline void glBindVertexArray(GLuint array)
-    {
-        BindVertexArray(array);
-    }
-
-private:
-    // Function signatures are equivalent between desktop core, ARB, APPLE, ES3 and ES 2 extensions
-    void (QOPENGLF_APIENTRYP GenVertexArrays)(GLsizei n, GLuint *arrays);
-    void (QOPENGLF_APIENTRYP DeleteVertexArrays)(GLsizei n, const GLuint *arrays);
-    void (QOPENGLF_APIENTRYP BindVertexArray)(GLuint array);
-};
 
 class QOpenGLVertexArrayObjectPrivate : public QObjectPrivate
 {
@@ -142,7 +121,7 @@ public:
     union {
         QOpenGLFunctions_3_0 *core_3_0;
         QOpenGLFunctions_3_2_Core *core_3_2;
-        QVertexArrayObjectHelper *helper;
+        QOpenGLVertexArrayObjectHelper *helper;
     } vaoFuncs;
     enum {
         NotSupported,
@@ -175,7 +154,7 @@ bool QOpenGLVertexArrayObjectPrivate::create()
 
     if (ctx->isOpenGLES()) {
         if (ctx->format().majorVersion() >= 3 || ctx->hasExtension(QByteArrayLiteral("GL_OES_vertex_array_object"))) {
-            vaoFuncs.helper = new QVertexArrayObjectHelper(ctx);
+            vaoFuncs.helper = new QOpenGLVertexArrayObjectHelper(ctx);
             vaoFuncsType = OES;
             vaoFuncs.helper->glGenVertexArrays(1, &vao);
         }
@@ -197,11 +176,11 @@ bool QOpenGLVertexArrayObjectPrivate::create()
         } else
 #endif
         if (ctx->hasExtension(QByteArrayLiteral("GL_ARB_vertex_array_object"))) {
-            vaoFuncs.helper = new QVertexArrayObjectHelper(ctx);
+            vaoFuncs.helper = new QOpenGLVertexArrayObjectHelper(ctx);
             vaoFuncsType = ARB;
             vaoFuncs.helper->glGenVertexArrays(1, &vao);
         } else if (ctx->hasExtension(QByteArrayLiteral("GL_APPLE_vertex_array_object"))) {
-            vaoFuncs.helper = new QVertexArrayObjectHelper(ctx);
+            vaoFuncs.helper = new QOpenGLVertexArrayObjectHelper(ctx);
             vaoFuncsType = APPLE;
             vaoFuncs.helper->glGenVertexArrays(1, &vao);
         }

src/gui/opengl/qopenglvertexarrayobject.h

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Klaralvdalens Datakonsult AB (KDAB).
+** Copyright (C) 2014 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Sean Harmer <sean.harmer@kdab.com>
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtGui module of the Qt Toolkit.

src/gui/opengl/qopenglvertexarrayobject_p.h

@@ -0,0 +1,119 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Sean Harmer <sean.harmer@kdab.com>
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QOPENGLVERTEXARRAYOBJECT_P_H
+#define QOPENGLVERTEXARRAYOBJECT_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of the Qt OpenGL classes.  This header file may change from
+// version to version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qglobal.h>
+
+#ifndef QT_NO_OPENGL
+
+#include <QtGui/qopengl.h>
+
+QT_BEGIN_NAMESPACE
+
+class QOpenGLVertexArrayObjectHelper;
+class QOpenGLContext;
+
+void Q_GUI_EXPORT qtInitializeVertexArrayObjectHelper(QOpenGLVertexArrayObjectHelper *helper, QOpenGLContext *context);
+
+class QOpenGLVertexArrayObjectHelper
+{
+    Q_DISABLE_COPY(QOpenGLVertexArrayObjectHelper)
+
+public:
+    explicit inline QOpenGLVertexArrayObjectHelper(QOpenGLContext *context)
+        : GenVertexArrays(Q_NULLPTR)
+        , DeleteVertexArrays(Q_NULLPTR)
+        , BindVertexArray(Q_NULLPTR)
+    {
+        qtInitializeVertexArrayObjectHelper(this, context);
+    }
+
+    inline bool isValid() const
+    {
+        return GenVertexArrays && DeleteVertexArrays && BindVertexArray;
+    }
+
+    inline void glGenVertexArrays(GLsizei n, GLuint *arrays) const
+    {
+        GenVertexArrays(n, arrays);
+    }
+
+    inline void glDeleteVertexArrays(GLsizei n, const GLuint *arrays) const
+    {
+        DeleteVertexArrays(n, arrays);
+    }
+
+    inline void glBindVertexArray(GLuint array) const
+    {
+        BindVertexArray(array);
+    }
+
+private:
+    friend void Q_GUI_EXPORT qtInitializeVertexArrayObjectHelper(QOpenGLVertexArrayObjectHelper *helper, QOpenGLContext *context);
+
+    // Function signatures are equivalent between desktop core, ARB, APPLE, ES 3 and ES 2 extensions
+    typedef void (QOPENGLF_APIENTRYP qt_GenVertexArrays_t)(GLsizei n, GLuint *arrays);
+    typedef void (QOPENGLF_APIENTRYP qt_DeleteVertexArrays_t)(GLsizei n, const GLuint *arrays);
+    typedef void (QOPENGLF_APIENTRYP qt_BindVertexArray_t)(GLuint array);
+
+    qt_GenVertexArrays_t GenVertexArrays;
+    qt_DeleteVertexArrays_t DeleteVertexArrays;
+    qt_BindVertexArray_t BindVertexArray;
+};
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_OPENGL
+
+#endif // QOPENGLVERTEXARRAYOBJECT_P_H