Make QOpenGLWidget public

QOpenGLWidget is now public.

In addition Qt::WA_AlwaysStackOnTop is introduced to support the
special case of semi-transparent QOpenGLWidget or QQuickWidget on
top of regular widgets.

hellogl_es2 becomes the qopenglwidget example. This example performs
painting both via QPainter and native GL commands and has the OpenGL
widget combined with other, normal widgets.

The widget stack receives some changes when it comes to renderToTexture
widgets like QQuickWidget and QOpenGLWidget. Calling update() will now
result in a paint event, which is essential for QOpenGLWidget since we
want it to behave like a regular widget. The dirty region handling is
extended specially for such widgets due to performance reasons.
(an OpenGL content update must not result in any backingstore painting,
and is thus handled as a different kind of dirtiness)

[ChangeLog] Added QOpenGLWidget. This widget serves as a replacement for QGLWidget.

Task-number: QTBUG-36899
Task-number: QTBUG-40086
Change-Id: Ibf7f82fea99b39edfffd2fc088e7e0eadbca25cf
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

1 files changed, 49 insertions, 14 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index e692a985eb..43ce9a82f7 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -5492,18 +5492,22 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
                 //paint the background
                 if ((asRoot || q->autoFillBackground() || onScreen || q->testAttribute(Qt::WA_StyledBackground))
                     && !q->testAttribute(Qt::WA_OpaquePaintEvent) && !q->testAttribute(Qt::WA_NoSystemBackground)) {
+                    beginBackingStorePainting();
                     QPainter p(q);
                     paintBackground(&p, toBePainted, (asRoot || onScreen) ? flags | DrawAsRoot : 0);
+                    endBackingStorePainting();
                 }
 
                 if (!sharedPainter)
                     setSystemClip(pdev, toBePainted.translated(offset));
 
                 if (!onScreen && !asRoot && !isOpaque && q->testAttribute(Qt::WA_TintedBackground)) {
+                    beginBackingStorePainting();
                     QPainter p(q);
                     QColor tint = q->palette().window().color();
                     tint.setAlphaF(qreal(.6));
                     p.fillRect(toBePainted.boundingRect(), tint);
+                    endBackingStorePainting();
                 }
             }
 
@@ -5513,24 +5517,30 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
                      << "geometry ==" << QRect(q->mapTo(q->window(), QPoint(0, 0)), q->size());
 #endif
 
+            bool grabbed = false;
+#ifndef QT_NO_OPENGL
             if (renderToTexture) {
                 // This widget renders into a texture which is composed later. We just need to
                 // punch a hole in the backingstore, so the texture will be visible.
-#ifndef QT_NO_OPENGL
-                QPainter p(q);
-
-                if (backingStore) {
-                    p.setCompositionMode(QPainter::CompositionMode_Source);
-                    p.fillRect(q->rect(), Qt::transparent);
-                } else {
-                    // We are not drawing to a backingstore: fall back to QImage
-                    p.drawImage(q->rect(), grabFramebuffer());
+                if (!q->testAttribute(Qt::WA_AlwaysStackOnTop)) {
+                    beginBackingStorePainting();
+                    QPainter p(q);
+                    if (backingStore) {
+                        p.setCompositionMode(QPainter::CompositionMode_Source);
+                        p.fillRect(q->rect(), Qt::transparent);
+                    } else {
+                        // We are not drawing to a backingstore: fall back to QImage
+                        p.drawImage(q->rect(), grabFramebuffer());
+                        grabbed = true;
+                    }
+                    endBackingStorePainting();
                 }
-#endif
-            } else {
+            }
+#endif // QT_NO_OPENGL
+
+            if (!grabbed) {
                 //actually send the paint event
-                QPaintEvent e(toBePainted);
-                QCoreApplication::sendSpontaneousEvent(q, &e);
+                sendPaintEvent(toBePainted);
             }
 
             // Native widgets need to be marked dirty on screen so painting will be done in correct context
@@ -5586,6 +5596,13 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
     }
 }
 
+void QWidgetPrivate::sendPaintEvent(const QRegion &toBePainted)
+{
+    Q_Q(QWidget);
+    QPaintEvent e(toBePainted);
+    QCoreApplication::sendSpontaneousEvent(q, &e);
+}
+
 void QWidgetPrivate::render(QPaintDevice *target, const QPoint &targetOffset,
                             const QRegion &sourceRegion, QWidget::RenderFlags renderFlags)
 {
@@ -11968,7 +11985,7 @@ QOpenGLContext *QWidgetPrivate::shareContext() const
     }
     QWidgetPrivate *that = const_cast<QWidgetPrivate *>(this);
     if (!extra->topextra->shareContext) {
-        QOpenGLContext *ctx = new QOpenGLContext();
+        QOpenGLContext *ctx = new QOpenGLContext;
         ctx->setShareContext(QOpenGLContextPrivate::globalShareContext());
         ctx->setFormat(extra->topextra->window->format());
         ctx->create();
@@ -11978,6 +11995,24 @@ QOpenGLContext *QWidgetPrivate::shareContext() const
 #endif // QT_NO_OPENGL
 }
 
+#ifndef QT_NO_OPENGL
+void QWidgetPrivate::sendComposeStatus(QWidget *w, bool end)
+{
+    QWidgetPrivate *wd = QWidgetPrivate::get(w);
+    if (!wd->textureChildSeen)
+        return;
+    if (end)
+        wd->endCompose();
+    else
+        wd->beginCompose();
+    for (int i = 0; i < wd->children.size(); ++i) {
+        w = qobject_cast<QWidget *>(wd->children.at(i));
+        if (w && !w->isWindow() && !w->isHidden() && QWidgetPrivate::get(w)->textureChildSeen)
+            sendComposeStatus(w, end);
+    }
+}
+#endif // QT_NO_OPENGL
+
 Q_WIDGETS_EXPORT QWidgetData *qt_qwidget_data(QWidget *widget)
 {
     return widget->data;