Hi,
Calibre builds are irreproducible, various png icons differ slightly
between builds [1]. I know where the issue occurs, but I'm at a loss where
the fix should be applied. We have Qt experts and enthusiasts in Fedora,
so I thought I'd post here…
Icons are rendered [2] using the following code:
img = QImage(path).scaled(int(width), int(height),
Qt.AspectRatioMode.IgnoreAspectRatio,
Qt.TransformationMode.SmoothTransformation)
img.save(dest)
With python3-pyqt6-6.8.0-0.1.fc42.x86_64, we get a difference in how the
icons are rendered:
calibre-7.20.0-1.fc42.x86_64
modified-S.5........ /usr/share/icons/hicolor/16x16/apps/calibre-gui.png
modified-S.5........ /usr/share/icons/hicolor/32x32/apps/calibre-ebook-edit.png
modified-S.5........ /usr/share/icons/hicolor/32x32/apps/calibre-gui.png
modified-S.5........ /usr/share/icons/hicolor/32x32/apps/calibre-viewer.png
...
There are some tiny differences in shading of some pixels. The difference
is not discernible visually for me. [1] has example icons attached.
Is this a bug in Qt and implementation of QImage.scaled [3] ?
[1] https://pagure.io/fedora-reproducible-builds/project/issue/20
[2] https://github.com/kovidgoyal/calibre/blob/3855552c193dceb8a75dbe1a29fbc40f004133c3/src/calibre/linux.py#L1315
[3] https://doc.qt.io/qt-6/qimage.html#scaled-1
Zbyszek
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