[Qt-qml] on device performance

[jevon.beckles at orange-ftgroup.com]

Hello,

On Mon, 13 Dec 2010 17:15:42 +0100, Thorbj?rn Lindeijer
thorbjorn.lindeijer at nokia.com wrote:

> Short answers:

> * Make sure you're using OpenGL when you do any blending, scaling or 
> rotating. (-opengl to qmlviewer or QGLWidget as viewport of 
> QDeclarativeView)

> * Run fullscreen rather than maximized to avoid compositing overhead. 
> (-fullscreen to qmlviewer or use showFullscreen() rather than show())


I am also experiencing performance issues especially for scaling and
rotating. I am sub-classing a QDeclarativeView as the main widget of my
application and I have tried to utilize a QGLWidget as the viewport as
recommended (shown below).


class myView : public QDeclarativeView
{
    Q_OBJECT

public:
    // major implementation steps in constructor
    myView (QWidget *parent = 0) : QDeclarativeView(parent) {
        // setup data model
        // setup context properties
	  setViewport(new QGLWidget());
        // set main QML source
    }
    
private:
    //my data members
    

private slots:
    // my private slots
};

It seems to work fine on Windows using Qt 4.7.0 (I see a slight
difference in the rendering), but the same program does not compile for
Symbian^3 using Qt 4.7.0. I get the following error:

"GL/gl.h: No such file or directory"

This error is due to the file C:\Qt\4.7.0\src\opengl\qgl.h having the
following lines (line 77-79): 

# include <GL/gl.h>
# ifndef QT_LINUXBASE
#   include <GL/glu.h>


Please advise.

Regards,
Jevon Beckles
Orange Labs
Building 10, Chiswick Park
566 Chiswick High Road
London W4 5XS
tel. +44 208 987 1906
jevon.beckles at orange-ftgroup.com


------------------------------------------------------------------------
---
Message: 3
Date: Mon, 13 Dec 2010 17:15:42 +0100
From: Thorbj?rn Lindeijer <thorbjorn.lindeijer at nokia.com>
Subject: Re: [Qt-qml] on device performance
To: qt-qml at trolltech.com
Message-ID: <4D0646AE.2020206 at nokia.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Well, Thunderbird ate my reply when I cancelled sending when I noticed 
that I was once again replying the author and not the list...

On 12/13/2010 04:59 PM, ext Alexey Zaryanov wrote:
> Hi. I was really surprised when I saw the performance of QML
> applications on the device (n900) ( deckarative demos : twitter, rss
> etc. ). Its only about 12-15 fps. Its not smooth ! Look at any iphone
apps!
> But video on youtube shows me very fast UI. What wrong ?

Short answers:

* Make sure you're using OpenGL when you do any blending, scaling or 
rotating. (-opengl to qmlviewer or QGLWidget as viewport of 
QDeclarativeView)

* Run fullscreen rather than maximized to avoid compositing overhead. 
(-fullscreen to qmlviewer or use showFullscreen() rather than show())

Regards,
Bj?rn

-- 
Thorbj?rn Lindeijer
Software Engineer
Nokia, Qt Development Frameworks