Properly cleanup the old page when attaching a new one

This patch fixes two issues:
- The RWHV delegate of the old page would not be detached from the view
  when attaching a new page to that view. Call reattachRWHV as we do on
  the new page to make sure that the delegate gets unparented from the
  view.
- QtWebKit documents that a page having the view as its QObject parent
  should be deleted when setPage is called with a new page. This would
  cause QupZilla to leak the page when opening a new window through a
  link.

This also adds a workaround to avoid a crash when unparenting the
delegate where QOpenGLWidget would try to call paintGL without a valid
QSurface.

Change-Id: Icd2659f441d2220c26dc175d66424e6c26125861
Reviewed-by: Andras Becsi <andras.becsi@digia.com>

2 files changed, 8 insertions, 0 deletions

diff --git a/src/webenginewidgets/api/qwebengineview.cpp b/src/webenginewidgets/api/qwebengineview.cpp
index 3e6efafbd..47afca8ce 100644
--- a/src/webenginewidgets/api/qwebengineview.cpp
+++ b/src/webenginewidgets/api/qwebengineview.cpp
@@ -72,6 +72,9 @@ void QWebEngineViewPrivate::bind(QWebEngineView *view, QWebEnginePage *page)
         if (QWebEnginePage *oldPage = view->d_func()->page) {
             oldPage->disconnect(view);
             oldPage->d_func()->view = 0;
+            oldPage->d_func()->adapter->reattachRWHV();
+            if (oldPage->parent() == view)
+                delete oldPage;
         }
         view->d_func()->page = page;
     }
diff --git a/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp b/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp
index 7c012e54c..6c3f1cb1c 100644
--- a/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp
+++ b/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp
@@ -192,6 +192,11 @@ void RenderWidgetHostViewQtDelegateWidget::initializeGL()
 
 void RenderWidgetHostViewQtDelegateWidget::paintGL()
 {
+#if (QT_VERSION < QT_VERSION_CHECK(5, 3, 1))
+    // A workaround for a missing check in 5.3.0 when updating an unparented delegate.
+    if (!QOpenGLContext::currentContext())
+        return;
+#endif
     QSGNode *paintNode = m_client->updatePaintNode(rootNode->firstChild(), sgRenderContext.data());
     if (paintNode != rootNode->firstChild()) {
         delete rootNode->firstChild();