Add test for rendercontrol + rendererinterface

Also add support for doing
QQuickWindow::setSceneGraphBackend(QSGRendererInterface::Unknown). This
becomes relevant especially in tests, where we may request a specific
graphics API, but then want to switch back to the default behavior.

Change-Id: Ib09c411432fc37bd4d36ce55d54d20af3f83860a
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 12 insertions, 5 deletions

diff --git a/src/quick/scenegraph/qsgrhisupport.cpp b/src/quick/scenegraph/qsgrhisupport.cpp
index aa5661fc94..4ba0cca65e 100644
--- a/src/quick/scenegraph/qsgrhisupport.cpp
+++ b/src/quick/scenegraph/qsgrhisupport.cpp
@@ -268,11 +268,18 @@ void QSGRhiSupport::checkEnvQSgInfo()
 
 void QSGRhiSupport::configure(QSGRendererInterface::GraphicsApi api)
 {
-    Q_ASSERT(QSGRendererInterface::isApiRhiBased(api));
-    QSGRhiSupport *inst = staticInst();
-    inst->m_requested.valid = true;
-    inst->m_requested.api = api;
-    inst->applySettings();
+    if (api == QSGRendererInterface::Unknown) {
+        // behave as if nothing was explicitly requested
+        QSGRhiSupport *inst = staticInst();
+        inst->m_requested.valid = false;
+        inst->applySettings();
+    } else {
+        Q_ASSERT(QSGRendererInterface::isApiRhiBased(api));
+        QSGRhiSupport *inst = staticInst();
+        inst->m_requested.valid = true;
+        inst->m_requested.api = api;
+        inst->applySettings();
+    }
 }
 
 QSGRhiSupport *QSGRhiSupport::instance()