Add QQuickWidget::setClearColor()

And make qquickviewcomparison able to demonstrate how to create a
partially transparent QQuickWidget.

Avoid also recreating the QQuickView/QQuickWidget multiple times
when switching between the radio buttons.

[ChangeLog] Added QQuickWidget::setClearColor() in order to support
semi-transparent QQuickWidgets.

Change-Id: I319ad4afbe909530274d09f2a7fcff23730d6ebd
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/src/quickwidgets/qquickwidget.cpp b/src/quickwidgets/qquickwidget.cpp
index 2541359fdd..0a521984e1 100644
--- a/src/quickwidgets/qquickwidget.cpp
+++ b/src/quickwidgets/qquickwidget.cpp
@@ -1115,4 +1115,23 @@ QImage QQuickWidget::grabFramebuffer() const
     return const_cast<QQuickWidgetPrivate *>(d_func())->grabFramebuffer();
 }
 
+/*!
+  Sets the clear \a color. By default this is an opaque color.
+
+  To get a semi- or fully transparent QQuickWidget, call this function with \a
+  color set to Qt::transparent and set the Qt::WA_TranslucentBackground widget
+  attribute.
+
+  \note The limitations for having widgets underneath visible that are described
+  in QOpenGLWidget::setFormat() apply also to QQuickWidget. In that case use
+  Qt::WA_AlwaysStackOnTop instead of Qt::WA_TranslucentBackground.
+
+  \sa QQuickWindow::setColor()
+ */
+void QQuickWidget::setClearColor(const QColor &color)
+{
+    Q_D(QQuickWidget);
+    d->offscreenWindow->setColor(color);
+}
+
 QT_END_NAMESPACE