Qt-interest Archive, February 2008
drawPoint bug
Message 1 in thread
I am drawing lines and points with QPainter.
This is the result without antialiasing (you can see the small 1 pixel
black points)
http://www.galinette.org/noAA.png
This is the result with antialiasing:
http://www.galinette.org/AA.png
As you can see, the antialiased points are bugged...
Etienne
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Message 2 in thread
Quoting Etienne Sandré-Chardonnal <etienne.sandre@xxxxxxxxxxxxxxxxx>:
> I am drawing lines and points with QPainter.
Hi
Which version of Qt, OS, compiler etc?
A+
Paul
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Message 3 in thread
Sorry for that...
I'm using Qt 4.3.2, MinGW(gcc3.4.2), Windows XP
Etienne
Paul Floyd wrote:
> Which version of Qt, OS, compiler etc?
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Message 4 in thread
And to be more precise, I am drawing into a QPixmap whose size is kept
equal to my widget size. I call QPainter::drawPoint after having set the
brush to Qt::nobrush and the pen to Qt::black
Another thing : my world matrix inverts the y axis, by calling
painter->scale(zoom, -zoom). This causes some bugs in drawImage and
drawPixmap (previous post), so maybe it is in cause here. However, we
should be able to invert the y axis, as most engineer or scientific
coordinate systems are oriented like that.
Etienne
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Message 5 in thread
Similar things were happened to me.
Qt 4.2.2 with Debian Linux/64bit
Qt 4.3.2 with Windows XP
Qt 4.3.? with Debian Lenny
I draw the pixel to QImage and used drawImage()
Sam.
-----Original Message-----
From: Etienne Sandré-Chardonnal [mailto:etienne.sandre@xxxxxxxxxxxxxxxxx]
Sent: Friday, February 15, 2008 10:18 AM
To: qt-interest@xxxxxxxxxxxxx
Subject: drawPoint bug
I am drawing lines and points with QPainter.
This is the result without antialiasing (you can see the small 1 pixel
black points)
http://www.galinette.org/noAA.png
This is the result with antialiasing:
http://www.galinette.org/AA.png
As you can see, the antialiased points are bugged...
Etienne
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[ signature omitted ]
Message 6 in thread
Hi,
> This is the result without antialiasing (you can see the small 1 pixel
> black points)
> http://www.galinette.org/noAA.png
>
> This is the result with antialiasing:
> http://www.galinette.org/AA.png
>
> As you can see, the antialiased points are bugged...
Wow! That looks bad! Such problems are usually caused by the graphics driver.
Which graphics card are you using? Have you tried upgrading the driver? Are
you able to reproduce the problem on a different PC with a different graphics
card?
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Message 7 in thread
I'm on a Lenovo Thinkpad T60 with an Intel 945GM chipset with integrated
video, the drivers are up to date. I'll try on my desktop with a Geforce
FX to compare. I will also try on the nvidia under linux if required. I
give you some feedback in a couple of days.
> Wow! That looks bad! Such problems are usually caused by the graphics
> driver. Which graphics card are you using? Have you tried upgrading the
> driver? Are you able to reproduce the problem on a different PC with a
> different graphics card?
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