[Digikam-devel] [digikam] [Bug 322789] Enabling "color managed view" in editor slows down tool startup

[Peter Albrecht]

https://bugs.kde.org/show_bug.cgi?id=322789

--- Comment #23 from Peter Albrecht <px79 at crazymonkeys.de> ---
Update:
I found the reason, why there are 70 calls to "IccTransform::apply()": Tiling!
 - the PreviewWidget is based on Q3ScrollView.
 - during opening of an image editor tool, this Q3ScrollView recieves a
QEvent::Paint
 - in Q3ScrollView::eventFilter(), there is a call to
PreviewWidget::viewportPaintEvent()
 - and in this function, there are two nested for-loops which seem to split the
image in tiles of 128x128 pixels
 - in case of my screen resolution (image size on screen: width ~= 1280, height
~= 896) there are 10 * 7 for-loop iterations => 70 iterations
 - and every iteration calls paintPreview(), which itself calls
"IccTransform::apply()"

=> one Paint-Event causes 70 "IccTransform::apply()".

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