Allows skip clear color before render on software renderer

Fixes: QTBUG-120061
Change-Id: I28b32b042abd8cb34a4d1ce3959cdbab49bfbeca
Reviewed-by: Laszlo Agocs <[email protected]>

2 files changed, 18 insertions, 2 deletions

diff --git a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
index 0c2af5e23b..50caeff85d 100644
--- a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
@@ -95,8 +95,10 @@ QRegion QSGAbstractSoftwareRenderer::renderNodes(QPainter *painter)
 
     auto iterator = m_renderableNodes.begin();
     // First node is the background and needs to painted without blending
-    auto backgroundNode = *iterator;
-    dirtyRegion += backgroundNode->renderNode(painter, /*force opaque painting*/ true);
+    if (m_clearColorEnabled) {
+        auto backgroundNode = *iterator;
+        dirtyRegion += backgroundNode->renderNode(painter, /*force opaque painting*/ true);
+    }
     iterator++;
 
     for (; iterator != m_renderableNodes.end(); ++iterator) {
@@ -306,4 +308,14 @@ void QSGAbstractSoftwareRenderer::markDirty()
     m_dirtyRegion = QRegion(m_background->rect().toRect());
 }
 
+void QSGAbstractSoftwareRenderer::setClearColorEnabled(bool enable)
+{
+    m_clearColorEnabled = enable;
+}
+
+bool QSGAbstractSoftwareRenderer::clearColorEnabled() const
+{
+    return m_clearColorEnabled;
+}
+
 QT_END_NAMESPACE
diff --git a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer_p.h b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer_p.h
index b0426a0b37..89a39abcc1 100644
--- a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer_p.h
+++ b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer_p.h
@@ -40,6 +40,9 @@ public:
 
     void markDirty();
 
+    void setClearColorEnabled(bool enable);
+    bool clearColorEnabled() const;
+
 protected:
     QRegion renderNodes(QPainter *painter);
     void buildRenderList();
@@ -70,6 +73,7 @@ private:
     QRegion m_obscuredRegion;
     qreal m_devicePixelRatio = 1;
     bool m_isOpaque = false;
+    bool m_clearColorEnabled = true;
 
     QSGSoftwareRenderableNodeUpdater *m_nodeUpdater;
 };