Mark layers in the SW rasterizer as opaque if possible

If the content of a layer completely covers every pixel of
it, mark that layer as opaque so that we can avoid alpha
blending where possible.

Change-Id: Ia0be4e7a96ecddd31a26f353509de976bcc9e397
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
Reviewed-by: Volker Krause <volker.krause@kdab.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
index 02cf8209d1..30088846a6 100644
--- a/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgabstractsoftwarerenderer.cpp
@@ -193,6 +193,12 @@ QRegion QSGAbstractSoftwareRenderer::optimizeRenderList()
         }
     }
 
+    if (m_obscuredRegion.contains(m_background->rect().toAlignedRect())) {
+        m_isOpaque = true;
+    } else {
+        m_isOpaque = false;
+    }
+
     // Empty dirtyRegion (for second pass)
     m_dirtyRegion = QRegion();
     m_obscuredRegion = QRegion();