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Saving rotated QImage
I have a Problem saving rotated QImages. I load an Image, rotate it by some angle and want to save the result.
Unfortunately the results look very strange, either black or black & white patterns. (for 90° it works)
Even when i rotate the image and cut out a rectangular part, saving this smaller part has the same problems.
I somehow could not find any related problems.
maybe i should post my code :)
QImage pic = m_currentImage.transformed(trans,Qt::SmoothTransformation);
// n18 is a point in the original image, so i map it with trans and calculate borders of the rect used // later
QPoint tl = (trans.map(n18.toPoint()) - QPoint(75,150));
QPoint br = (trans.map(n18.toPoint()) + QPoint(75,150));
QRect rec = QRect(tl,br);
// this would cut out the rectangle, it also shows in my program as a perfect rectangle
// pic = pic.copy(rec);
QImageWriter w(QCoreApplication::applicationDirPath() + "/imagedat/blub.png","png");
And the output picture does not look any familiar with the original image. Just totally weird.
If i set the angle to 90° it outputs the right picture rotated by 90°.
If anyone is interested in the Solution:
I now tried to apply the transformation to the pixmap and converted back to QImage and this works!!!
I still wonder why exactly this is the case.