Fix up QQuickWidget and QQuickRenderControl docs

Change-Id: I4df82c62afc12dace513ccbf6475d980c041867e
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

2 files changed, 14 insertions, 2 deletions

diff --git a/src/quick/items/qquickrendercontrol.cpp b/src/quick/items/qquickrendercontrol.cpp
index 8c18c58224..8b69447002 100644
--- a/src/quick/items/qquickrendercontrol.cpp
+++ b/src/quick/items/qquickrendercontrol.cpp
@@ -124,6 +124,10 @@ extern Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_
   To send events, for example mouse or keyboard events, to the scene, use
   QCoreApplication::sendEvent() with the QQuickWindow instance as the receiver.
 
+  \note In general QQuickRenderControl is supported in combination with all Qt
+  Quick backends. However, some functionality, in particular grab(), may not be
+  available in all cases.
+
   \inmodule QtQuick
 */
 
@@ -209,8 +213,9 @@ void QQuickRenderControl::prepareThread(QThread *targetThread)
 }
 
 /*!
-  Initializes the scene graph resources. The context \a gl has to
-  be the current context.
+  Initializes the scene graph resources. The context \a gl has to be the
+  current OpenGL context or null if it is not relevant because a Qt Quick
+  backend other than OpenGL is in use.
 
   \note Qt Quick does not take ownership of the context. It is up to the
   application to destroy it after a call to invalidate() or after the
diff --git a/src/quickwidgets/qquickwidget.cpp b/src/quickwidgets/qquickwidget.cpp
index b25e2d348d..ad04c76783 100644
--- a/src/quickwidgets/qquickwidget.cpp
+++ b/src/quickwidgets/qquickwidget.cpp
@@ -468,6 +468,13 @@ QObject *QQuickWidgetPrivate::focusObject()
     Qt::WA_TranslucentBackground on the top-level window, request an alpha channel, and
     change the Qt Quick Scenegraph's clear color to Qt::transparent via setClearColor().
 
+    \section1 Support when not using OpenGL
+
+    In addition to OpenGL, the \c software backend of Qt Quick also supports
+    QQuickWidget. Other backends, for example the Direct 3D 12 one, are not
+    compatible however and attempting to construct a QQuickWidget will lead to
+    problems.
+
     \sa {Exposing Attributes of C++ Types to QML}, {Qt Quick Widgets Example}, QQuickView
 */