Avoid breaking BC with new virtuals in QOpenGLPaintDevice

Task-number: QTBUG-41046
Change-Id: Iab628d2d6811d528e2cc513b6f8a74baa628541d
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

src/gui/opengl/opengl.pri

@@ -11,6 +11,7 @@ contains(QT_CONFIG, opengl)|contains(QT_CONFIG, opengles2) {
                opengl/qopenglframebufferobject.h  \
                opengl/qopenglframebufferobject_p.h  \
                opengl/qopenglpaintdevice.h \
+               opengl/qopenglpaintdevice_p.h \
                opengl/qopenglbuffer.h \
                opengl/qopenglshaderprogram.h \
                opengl/qopenglextensions_p.h \

src/gui/opengl/qopenglpaintdevice.cpp

@@ -35,6 +35,7 @@
 #include <qpaintengine.h>
 #include <qthreadstorage.h>
 
+#include <private/qopenglpaintdevice_p.h>
 #include <private/qobject_p.h>
 #include <private/qopenglcontext_p.h>
 #include <private/qopenglframebufferobject_p.h>
@@ -98,23 +99,6 @@ QT_BEGIN_NAMESPACE
 
 */
 
-class QOpenGLPaintDevicePrivate
-{
-public:
-    QOpenGLPaintDevicePrivate(const QSize &size);
-
-    QSize size;
-    QOpenGLContext *ctx;
-
-    qreal dpmx;
-    qreal dpmy;
-    qreal devicePixelRatio;
-
-    bool flipped;
-
-    QPaintEngine *engine;
-};
-
 /*!
     Constructs a QOpenGLPaintDevice.
 
@@ -151,6 +135,14 @@ QOpenGLPaintDevice::QOpenGLPaintDevice(int width, int height)
 {
 }
 
+/*!
+    \internal
+ */
+QOpenGLPaintDevice::QOpenGLPaintDevice(QOpenGLPaintDevicePrivate *dd)
+    : d_ptr(dd)
+{
+}
+
 /*!
     Destroys the QOpenGLPaintDevice.
 */
@@ -350,17 +342,6 @@ bool QOpenGLPaintDevice::paintFlipped() const
     return d_ptr->flipped;
 }
 
-/*!
-  This virtual method is called when starting to paint.
-
-  The default implementation does nothing.
-
-  \sa endPaint()
- */
-void QOpenGLPaintDevice::beginPaint()
-{
-}
-
 /*!
     This virtual method is provided as a callback to allow re-binding a target
     frame buffer object or context when different QOpenGLPaintDevice instances
@@ -375,15 +356,4 @@ void QOpenGLPaintDevice::ensureActiveTarget()
 {
 }
 
-/*!
-  This virtual method is called when the painting has finished.
-
-  The default implementation does nothing.
-
-  \sa beginPaint()
-*/
-void QOpenGLPaintDevice::endPaint()
-{
-}
-
 QT_END_NAMESPACE

src/gui/opengl/qopenglpaintdevice.h

@@ -44,7 +44,6 @@
 
 QT_BEGIN_NAMESPACE
 
-
 class QOpenGLPaintDevicePrivate;
 
 class Q_GUI_EXPORT QOpenGLPaintDevice : public QPaintDevice
@@ -54,6 +53,7 @@ public:
     QOpenGLPaintDevice();
     explicit QOpenGLPaintDevice(const QSize &size);
     QOpenGLPaintDevice(int width, int height);
+    QOpenGLPaintDevice(QOpenGLPaintDevicePrivate *dd);
     virtual ~QOpenGLPaintDevice();
 
     int devType() const { return QInternal::OpenGL; }
@@ -73,9 +73,7 @@ public:
     void setPaintFlipped(bool flipped);
     bool paintFlipped() const;
 
-    virtual void beginPaint();
     virtual void ensureActiveTarget();
-    virtual void endPaint();
 
 protected:
     int metric(QPaintDevice::PaintDeviceMetric metric) const;

src/gui/opengl/qopenglpaintdevice_p.h

@@ -0,0 +1,81 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** 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 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QOPENGL_PAINTDEVICE_P_H
+#define QOPENGL_PAINTDEVICE_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 <qopenglpaintdevice.h>
+
+QT_BEGIN_NAMESPACE
+
+class QOpenGLContext;
+class QPaintEngine;
+
+class Q_GUI_EXPORT QOpenGLPaintDevicePrivate
+{
+public:
+    QOpenGLPaintDevicePrivate(const QSize &size);
+    virtual ~QOpenGLPaintDevicePrivate() { }
+
+    static QOpenGLPaintDevicePrivate *get(QOpenGLPaintDevice *dev) { return dev->d_func(); }
+
+    virtual void beginPaint() { }
+    virtual void endPaint() { }
+
+public:
+    QSize size;
+    QOpenGLContext *ctx;
+
+    qreal dpmx;
+    qreal dpmy;
+    qreal devicePixelRatio;
+
+    bool flipped;
+
+    QPaintEngine *engine;
+};
+
+QT_END_NAMESPACE
+
+#endif // QOPENGL_PAINTDEVICE_P_H

src/gui/opengl/qopenglpaintengine.cpp

@@ -59,6 +59,7 @@
 #include "qopenglgradientcache_p.h"
 #include "qopengltexturecache_p.h"
 #include "qopenglpaintengine_p.h"
+#include "qopenglpaintdevice_p.h"
 
 #include <string.h> //for memcpy
 #include <qmath.h>
@@ -1994,7 +1995,7 @@ bool QOpenGL2PaintEngineEx::begin(QPaintDevice *pdev)
     d->ctx = QOpenGLContext::currentContext();
     d->ctx->d_func()->active_engine = this;
 
-    d->device->beginPaint();
+    QOpenGLPaintDevicePrivate::get(d->device)->beginPaint();
 
     d->funcs.initializeOpenGLFunctions();
 
@@ -2046,7 +2047,7 @@ bool QOpenGL2PaintEngineEx::end()
 {
     Q_D(QOpenGL2PaintEngineEx);
 
-    d->device->endPaint();
+    QOpenGLPaintDevicePrivate::get(d->device)->endPaint();
 
     QOpenGLContext *ctx = d->ctx;
     d->funcs.glUseProgram(0);

src/widgets/kernel/qopenglwidget.cpp

@@ -45,6 +45,7 @@
 #include <QtGui/private/qguiapplication_p.h>
 #include <QtGui/private/qopenglextensions_p.h>
 #include <QtGui/private/qfont_p.h>
+#include <QtGui/private/qopenglpaintdevice_p.h>
 #include <QtWidgets/private/qwidget_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -454,15 +455,24 @@ QT_BEGIN_NAMESPACE
     due to resizing the widget.
 */
 
+class QOpenGLWidgetPaintDevicePrivate : public QOpenGLPaintDevicePrivate
+{
+public:
+    QOpenGLWidgetPaintDevicePrivate(QOpenGLWidget *widget)
+        : QOpenGLPaintDevicePrivate(QSize()),
+          w(widget) { }
+
+    void beginPaint() Q_DECL_OVERRIDE;
+
+    QOpenGLWidget *w;
+};
+
 class QOpenGLWidgetPaintDevice : public QOpenGLPaintDevice
 {
 public:
-    QOpenGLWidgetPaintDevice(QOpenGLWidget *widget) : w(widget) { }
-    void beginPaint() Q_DECL_OVERRIDE;
+    QOpenGLWidgetPaintDevice(QOpenGLWidget *widget)
+        : QOpenGLPaintDevice(new QOpenGLWidgetPaintDevicePrivate(widget)) { }
     void ensureActiveTarget() Q_DECL_OVERRIDE;
-
-private:
-    QOpenGLWidget *w;
 };
 
 class QOpenGLWidgetPrivate : public QWidgetPrivate
@@ -518,7 +528,7 @@ public:
     bool flushPending;
 };
 
-void QOpenGLWidgetPaintDevice::beginPaint()
+void QOpenGLWidgetPaintDevicePrivate::beginPaint()
 {
     // NB! autoFillBackground is and must be false by default. Otherwise we would clear on
     // every QPainter begin() which is not desirable. This is only for legacy use cases,
@@ -539,19 +549,20 @@ void QOpenGLWidgetPaintDevice::beginPaint()
 
 void QOpenGLWidgetPaintDevice::ensureActiveTarget()
 {
-    QOpenGLWidgetPrivate *d = static_cast<QOpenGLWidgetPrivate *>(QWidgetPrivate::get(w));
-    if (!d->initialized)
+    QOpenGLWidgetPaintDevicePrivate *d = static_cast<QOpenGLWidgetPaintDevicePrivate *>(d_ptr.data());
+    QOpenGLWidgetPrivate *wd = static_cast<QOpenGLWidgetPrivate *>(QWidgetPrivate::get(d->w));
+    if (!wd->initialized)
         return;
 
-    if (QOpenGLContext::currentContext() != d->context)
-        w->makeCurrent();
+    if (QOpenGLContext::currentContext() != wd->context)
+        d->w->makeCurrent();
     else
-        d->fbo->bind();
+        wd->fbo->bind();
 
     // When used as a viewport, drawing is done via opening a QPainter on the widget
     // without going through paintEvent(). We will have to make sure a glFlush() is done
     // before the texture is accessed also in this case.
-    d->flushPending = true;
+    wd->flushPending = true;
 }
 
 GLuint QOpenGLWidgetPrivate::textureId() const