[Interest] How long is QMatrix obsolete?

Guido Seifert wargand at gmx.de
Sat Aug 9 09:55:28 CEST 2014

Yes, and even QTransform has a constructor, which uses the old QMatrix.
Naturally all this QMatrix dependencies cannot be removed without breaking thousands of programs,
but it makes one wonder what sense it makes to mark QMatrix as obsolete. It can never be removed.
And if in the unlikely event that a bug is discovered in QMatrix, it has to be fixed. For the same
reason that it cannot be removed: Far too much code depends on it. I doubt that even for a Qt 6 
version this kind of breakage will be accepted.


On Sat, 9 Aug 2014 11:30:35 +0400
Иван Комиссаров <abbapoh at gmail.com> wrote:

> See QImage QImage::transformed(const QTransform & matrix, Qt::TransformationMode mode = Qt::FastTransformation) const
> QTransform differs from QMatrix(obsolete) in that it is a true 3x3 matrix, allowing perspective transformations. QTransform's toAffine() method allows casting QTransform to QMatrix(obsolete). If a perspective transformation has been specified on the matrix, then the conversion will cause loss of data.
> QTransform is the recommended transformation class in Qt.

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