[Development] Request for QtQuick2 performance test using PhotoViewer demo

[Nils Jeisecke]

Hi,

During the QtCS 2012 I brought my rusty old MacBook with me that
showed really bad performance for QtQuick 2 based applications like
the PhotoViewer demo.

With help of the nice Trolls we figured out how to improve performance:

diff --git a/src/quick/scenegraph/qsgcontext.cpp
b/src/quick/scenegraph/qsgcontext.cpp
index 20b383a..e063b3e 100644
--- a/src/quick/scenegraph/qsgcontext.cpp
+++ b/src/quick/scenegraph/qsgcontext.cpp
@@ -369,7 +369,7 @@ QSurfaceFormat QSGContext::defaultSurfaceFormat() const
     QSurfaceFormat format;
     format.setDepthBufferSize(24);
     format.setStencilBufferSize(8);
-    format.setSamples(16);
+    format.setSamples(0);
     return format;
 }

The downside of this is of course rendering qualitiy, e.g. of rotated elements.

I thought that this would be a problem of that particularly old
machine. However back in the office I checked this using my Mac Pro.
While at first sight performance of the PhotoViewer demo is good with
the default samples value (16) I've noticed that when resizing the
photoviewer window while viewing a photo collection, the performance
is actually really bad too - I cannot resize the window in real time,
it's totally laggy.

In an actual application with a rather complex scene it's even worse.

The Mac Pro uses a "NVIDIA GeForce GT 120". Probably not the best in
town but certainly not the worst.

It would be great if we could collect some performance observations
using the PhotoViewer demo. I you want to help, please try to resize
the window while viewing a photo collection and report if that is
smooth or not.

cd qtdeclarative/examples/demos/photoviewer
../../../../qtbase/bin/qmlscene photoviewer.qml

Here's the task:
http://bugreports.qt-project.org/browse/QTBUG-26268

Thanks!

Nils