[Interest] Text is not being anti-aliased.

[william.crocker at analog.com]

On 01/30/2015 11:56 AM, Jason H wrote:
> Back in Qt4, (the last time I wrestled with this issue - Win XP)
> there was a setting in Windows about anti-aliased fonts.
> Qt respected that setting, unless you explicitly told Qt to override it.
>I think you're in a similar situation.
>

Sure enough, If I "Turn on clear type"

     Start->ControlPane->Display->
                      AdjustClearTypeText/TurnOnClearType

The fonts are rendered anti-aliased.
But, I think I told Qt to override this with

     painter.setRenderHint(QPainter::TextAntialiasing,true);

Also, I don't think a Display setting should affect
how my program renders to a file.

Search results suggested that AA required specification
of the background color (which seems reasonable), but the
following did not help.

     QBrush bg(Qt::white); painter.setBackground(bg);
     painter.setBackgroundMode(Qt::OpaqueMode);

The bottom line is that my original Qt code was good enough
for Linux but not for Windows.

Thanks.

Bill

>
>> Sent: Friday, January 30, 2015 at 10:56 AM
>> From: "william.crocker at analog.com"<william.crocker at analog.com>
>> To: "interest at qt-project.org"<interest at qt-project.org>
>> Subject: [Interest] Text is not being anti-aliased.
>>
>> Hello:
>>
>> I have code to create a PNG file from a QGraphicsScene.
>> When I run this on Linux, text is anti-aliased. This is good.
>> When I run this on Windows, text is NOT anti-aliased. This is bad.
>> I would like the text to be anti-aliased.
>>
>> Am I doing something wrong?
>> Is this a Windows bug?
>> Is there a workaround?
>>
>> Thanks.
>>
>> Bill
>>
>> Qt 4.8.6
>> Visual Studio 2008
>>
>> ---------------------------------
>> void
>> MyScene::exportImagePNG( const QString&fn ) {
>>       QRectF scene_rect = sceneRect();
>>       QSize size(qRound(scene_rect.width()),qRound(scene_rect.height()));
>>       QImage im(size,QImage::Format_RGB32);
>>       QPainter painter(&im);
>>       painter.setRenderHint(QPainter::Antialiasing,true);
>>       painter.setRenderHint(QPainter::TextAntialiasing,true);
>>       painter.fillRect(im.rect(),Qt::white);
>>       render(&painter);
>>       im.save(fn,"PNG");
>> }
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>
>