[Development] What is the correct way to use QTransform to rotate a QImage by the Y axis?

JiDe Zhang zccrs at live.com
Wed Jul 20 10:43:36 CEST 2022


I trying fix https://bugreports.qt.io/browse/QTBUG-75954, I think the problem is related to it.
________________________________
From: Allan Sandfeld Jensen <kde at carewolf.com>
Sent: Wednesday, July 20, 2022 16:32
To: development at qt-project.org <development at qt-project.org>
Cc: JiDe Zhang <zccrs at live.com>
Subject: Re: [Development] What is the correct way to use QTransform to rotate a QImage by the Y axis?

On Mittwoch, 20. Juli 2022 07:48:47 CEST JiDe Zhang wrote:
> I want to rotate the image to 45 degrees by Y axis, what should I do?
>
Why rotate it around the Y axis? Would that just be a squeezing scale
transform? 45 degrees would be scaling to cos(45) of the width. Are you sure
you don't want to rotate around the Z axis?

But yes, seems weird it would run out of memory when transforming to a smaller
image.

Best regards
Allan


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